VOLUME 

WILDERNESS 

ANNEX 

R 

{200) 

Q}3 

NO.Bl) 

v.l 

MINERAL 

POTENTIAL 
WILDERNESS MINERAL POTENTIAL 

ASSESSMENT OF MINERAL-RESOURCE POTENTIAL IN 

U.S. FOREST SERVICE LANDS STUDIED 1964-1984 
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A T L A 

Distribution of U . . Forest Service wilderness lands studied 1964-84. 

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Cover design by Arthur Isom. 

Diagrammatic east-west cross section of the United States. 

iv 
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(Joo) 

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no .).300 

V· I 

WILDERNESS MINERAL POTENTIAl.J 

Assessment of Mineral-Resource Potential in 

U.S. Forest Service Lands Studied 

1964-1984 

Edited by S. P. MARSH S. J. KROPSCHOT, and R. G. DICKINSON 

GEOLOGICAL SURVEY PROFESSIO AL PAPER 1300 

Volume 1 

Prepared in cooperation with the 

U.S. Bureau of Mines 

U N I T ED STATE G 0 V E R M E T P R I NT I N G 0 F F I C E, W A H I G T 0 : 1 9 8 4 
UNITED STATES DEPARTMENT OF THE INTERIOR 

JAMES G. WATT, Secretary 

GEOLOGICAL SURVEY 

Dallas L. Peck, Director 

Library of Congres Catalog Number 

83-600569 

For sale by the Superintendent of Documents 

U.S. Government Printing Office 

Washington, D.C. 20402 
FOREWORD 

For nearly three decades our ation has been debating how the national domain .should be used. This has led to much study of the resources of the land, 

especially renewable resources such as timber and wildlife, and nonrenewable 

resources such as minerals and mineral fuels. This book contains information on 

the mineral resources of part of the public lands. 

Provided here are summaries of the mineral resources of many present and potential wilderness areas primarily in the national forest land . The summarieswhich cover about 45 million acres distributed over nearly 800 areas-are 

distillations of longer, more technical reports prepared during the last 20 years 

by geologists and mining engineers of the U.S. Geological Survey and the U.S. 

Bureau of Mines. This work was required by the Wilderness Act of 1964 (Public 

Law 88-577) and a number of subsequent acts. 

The mineral endowment of the ation is the sum of the deposits that have 

been discovered and the deposits that have not been discovered. Earth science in 

its present state of development can deal more precisely with discovered 

deposits than with undiscovered deposits, although it is by no means powerless 

in dealing with the latter. Deposits that have already been discovered are 

generally discussed in terms of tons of reserves and resources and estimates of 

grades of specific commodities. Undiscovered deposits are generally considered 

from the point of view of favorable ground assessments-the demarkation of 

land areas favorable for the occurrence of minerals accompanied by a listing of 

the types of minerals that are expected to occur in them. 

One point about our studies needs emphasis. Resource assessments are influenced by the eras in which they are prepared. They reflect the economic circumstances of the time and a variety of considerations linked to them; they 

reflect the state of development of the earth sciences as they pertain to detecting concealed deposits; they reflect the needs of the audience for which they are 

prepared; and they reflect the inherent limitations of manpower, time, and 

budget. It follows that mors -refine6. and penetrating resource assessments will 

be made in the future, especially .lp · ~~ e domain of undiscovered deposits. 

These reservations notwithstand.ii1'g, it ;sh'o.uld also be emphasized that the 

resource assessmen'ts presented here are ill. :a& vance of any executed on comparable tracts and acreage anyWhere in the Wb~d. In our 20 years of wilderness 

surveys we have broken much new scietltiflc ground in understanding the 

geological structure and rnllier~ e~~o~rrfu11t 6f the United States and in improving the methodologies of reseurce assessment. Because the methods developed 

appear to be reliable and applicable to all the public lands, when they are carried 

forward, they will furnish a practical assessment of the mineral value of the 

national domain. 

Dallas L. Peck 

Director, Geological Survey 

Robert C. Horton 

Director, Bureau of Mines 

yjj 

PREFACE 

The work on these volumes began in February 1982, but in a broader sense the 

production began nearly 20 years ago with passage of the Wilderness Act of 

1964 that required the Geological Survey and the Bureau of Mines to conduct 

mineral surveys of Forest Service lands. This two-volume professional paper 

consists of summaries of the results of those mineral surveys and represents 

about 1,000 man-years of effort by professionals in the two agencies. Since the 

program began in 1964, the amount of land to be studied has increased from the 

original 14.8 million acres to 45 million acres, of which about 14 million acres 

have been added since 1979. 

In February 1982, we began identifying the areas that should be included in 

this professional paper. The names and approximate boundaries of about 800 

areas included in these 332 summaries are usually the same as they were at the 

time the work was done, but may differ somewhat from the current boundaries 

of the lands. These discrepancies are the result of revisions in boundaries and 

changes in names by legislative and executive acts during the 20 years of the 

program. After we had identified the areas that were to be included in these 

volumes, definitions of resources and resource potential for all metallic, 

nonmetallic, and energy minerals and a standardized outline for writing these 

summaries were determined. Resource and resource potential terminologies 

have changed during the last 20 years and differences may be seen from other 

published works. Techniques used for resource assessment have also evolved; 

those used in the early years of the program often are not those in use today. 

The summaries in these volumes reflect this evolution of methodology, as well 

as development of more advanced concepts about the assessment of mineral· 

resource potential. With all these differences, the use of a single set of defini· 

tions allows for comparison of resource potential described in work done within 

the 20- year framework of the wilderness program, including work that was not 

quite completed when tlus professional paper was being prepared. 

The ummaries in these volumes, which have been organized alphabetically 

by tate, include a de cription of the character and geologic setting, a discus· 

sion of the resource potential, and a reference list of selected material published 

as part of the wilderness program. Many of the summaries include suggestions 

for further study. Our hope is that these summaries, designed to provide a quick 

overview of a 20- year program, will be of use to concerned individuals as well as 

to those legislators and administrators who must make difficult and critical 

land-use decision that will affect our nation now and in the future. 

From the inception of this project, the support and assistance of a large 

number of colleagues and administrators in the Geological Survey and Bureau 

of Mines have made it possible for us to collect, edit, and present these sum· 

maries. Special acknowledgment and appreciation are extended to those col· 

leagues who reviewed the papers in these volumes; they are C.S. Bromfield, L. C. 

Craig*, R. E. Erickson, G. H. Goudarzi, M. E. MacLachlan, W. P. Pratt, P. K. 

Sims, V. E. Swanson, and R. B. Taylor, of the Geological Survey, and L. W. 

Gibbs of the Bureau of Mines. In addition, we wish to acknowledge the contribu· 

tions of E. J. Swibas, who with the assistance of W. J. Gerstel and V. H. Sable, 

coordinated the preparation of the illustrations; and J.E.H. Taylor, who coor· 

dinated the typing and telecommunication of the text. The generous assistance 

of D. C. Schnabel was invaluable in speeding thes volumes to completion. 

Finally, we appreciate the support, guidance, and advice of members of the 

Branch of Central Technical Reports and the Office of Scientific Publications of 

the Geological Survey during all phases of this project. 

· Deceased. 

Sherman P. Mar h 

Susan J. Kropschot 

Robert G. Dickinson 

i.x 

CONTENTS 

Introduction, by Donald A. Brobst and Gus H. Goudarzi .... . . 

Alabama ........ . 

Adams Gap and Shinbone Creek Roadless Areas, Alabama, 

by T. L. Klein and Donald K. Harrison 

Big Sandy, West Elliotts Creek, and Reed Brake Roadless 

Areas, Alabama, by Sam H. Patterson and Michelle K. 

Armstrong ...... . ................. . .. . 

Sipsey Wilderness and Additions, Alabama, by Stanley P. 

Schweinfurth and Peter C. Mory .................... . 

Alaska . . . . . . . . . . . . . . . . .......... . . . ... . ..... . 

Study areas within the Chugach National Forest, Alaska, by 

Steven W. Nelson and Uldis J ansons ......... . . 

Glacier Bay ational Monument Wilderness study area, 

Alaska, by David A. Brew and Arthur L. Kimball ..... 

Granite Fiords Wilderness study area, Alaska, by Henry C. 

Berg and Tom L. Pittman .................. . 

Tracy Arm-Fords Terror Wilderness study area and vicinity, 

Alaska, by David A. Brew and A. L. Kimball ......... . . . 

Western Chichagof and Yakobi Islands Wilderness study 

area, Alaska, by Bruce R. Johnson and Arthur L. Kimball . 

Arizona . . . . . . . . . . . .................. ... . . ... . 

Arnold Mesa Roadless Area, Arizona, by Edward W. Wolfe 

and Robert A. McColly . . . . . . . . . . . . . . . . . . . . . . . . .... 

Blue Range Wilderness, Arizona and ew Mexico. by James 

C. Ratte and R. G. Raabe . . . . . . . . . . . ............. . 

Chiricahua Wilderness, Arizona, by Harald Drewes and 

Frank E. Williams ...... . ............. . 

Dragoon Mountains Roadless Area, Arizona, by Harald 

Drewes and T. J . Kreidler .............. . .... . 

Fossil prings Roadless Area, Arizona, by L. S. Beard and 

CE E~ ..................... . ............. . 

Galiuro Wilderness and contiguous roadless areas, Arizona, 

by S. C. Creasey and J . E. Jinks ............... . 

Hells Gate Roadless Area, Arizona, by Clay M. Conway and 

Robert A. McColly ................ . 

Hells Hole Roadless Area, Arizona and New Mexico by 

James C. Ratte and John P. Briggs ...... - .... . 

Kanab Creek Roadle s Area, Arizona, by George H. Billingsley and Clarence E. Ellis .... . .... . ... . ........... . . . 

Lower San Francisco Wilderness study area and contiguous 

roadless areas, Arizona and New Mexico. by James C. 

Ratte and Michael E. Lane . . . . . ..... . ..... . .... . 

Mazatzal Wilderness and contiguous roadless areas. 

Arizona, by Chester T. Wrucke and Clarence E. Ellis ..... 

Mount Baldy Wilderness, Arizona, by Tommy L. Finnell and 

John H. Soule. . ......................... . 

North End Roadless Area, Arizona, by Harald Drewe and 

P. R. Bigsby .................. . 

Pine Mountain Wilderness, Arizona, by Frank C. Canney 

and Frank W. Williams . . . . . . . . . . ...... . 

Pusch Ridge Wilderness, Arizona, by Margaret E. Hinkle 

and George S. Ryan . . . . . . ...... . .. . .. . 

Rattlesnake Roadless Area, Arizona, by Thor . V. Karlstrom and Robert McColly .... . ... . 

VOLUME 1 

13 

15 

17 

21 

27 

29 

33 

35 

39 

43 

47 

49 

53 

55 

59 

63 

65 

69 

73 

77 

79 

83 

89 

91 

95 

97 

101 

Rincon Wilderness Study Area, Arizona, by Charles H. Thorman and Michael E. Lane . . . . . . . . . . . . . . . . . . . . . . . 103 

Sierra Ancha Wilderness. Arizona, by Chester T. Wrucke 

and Thomas D. Light . . . . . . . . 107 

Strawberry Crater Roadless Areas, Arizona, by Edward W. 

Wolfe and Thomas D. Light . . . . . . . . . . . . . . . . . . 111 

Superstition Wilderness, Arizona, by Donald W. Peterson 

andJimmieE.Jinks . . .. . .............. 113 

Sycamore Canyon Primitive Area, Arizona, by Lyman C. 

Huff and R. G. Raabe . . . . . . . . . . . . . 117 

West Clear Creek Roadless Area, Arizona, by George E. 

Ulrich and Alan M. Bielski . . . . . . . . . . . . . . . . . . . . . . . . . . 121 

Wet Beaver Roadless Area, Arizona, by George E. Ulrich 

and Alan M. Bielski . . . . . . . . . . . . . . . . 123 

Whetstone Roadless Area, Arizona, by Chester T. Wrucke 

and Robert A. McColly . . . . . . . . . . . . . . . . . . . . . . . . 127 

Winchester Roadless Area, Arizona, by William J . Keith and 

Terry J . Kreidler . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 

Arkansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 

Bell Star East and West Roadless Areas, Arkansas, by Mary 

H. Miller and Lyle E. Harris . . . . . . . . . . . . . . . . . . . 137 

Belle Starr Cave Wilderness Study Area, Arkansas, by Boyd 

R. Haley and Raymond B. Stroud . . . . . . . . 141 

Black Fork Mountain Roadless Area, Arkansas and Oklahoma, by Mary H. Miller . . . . . . . . . . . . . . . . . . . . . 143 

Caney Creek Wilderness, Arkansas, by George E. Ericksen 

and Maynard L. Dunn . . . . . . . . . . . 145 

Dry Creek Wilderness Study Area, Arkansas, by Boyd R. 

Haley and Raymond B. Stroud . . . . . . . . . . . . . . . . . . . . 149 

Little Blakely Roadless Area, Arkansas. by Mary H. Miller 

and Robert H. Wood . . . . . . . . . . . . 151 

Richland Creek Roadless Area, Arkansas, by Mary H. Miller 

and Robert H. Wood II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 

Richland Creek Wilderness Study Area, Arkansas, by Boyd 

R. Haley and Raymond B. Stroud . . . . . . . . . . . . . 157 

Upper Buffalo Wilderness and Buffalo Addition Roadless 

Area, Arkansas, by Mary H. Miller and Michelle K. Armstrong . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 

California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 

Agua Tibia Primitive Area, California, by William P. Irwin 

and HoraceK. Thurber . . . . . . . . . . . . . 165 

Andrews Mountain, Mazourka, and Paiute Roadless Areas, 

California, by Edwin H. McKee and Steven W. Schmauch . 167 

Arroyo Seco Roadless Area, California, by Robert E. Powell 

and Peter N. Gabby . . . . . . . . . . . . . . . . . . . 171 

Bald Rock and Middle Fork Feather River Roadless Areas, 

California, by Martin L. Sorensen and Alan R. Buehler . . . . 175 

Benton Range Roadless Area, California, by Edwin H. 

McKee and Richard L. Rains . . . . . . . . . . . . . . . . . . 179 

Black Butte an Elk Creek Roadless Areas, California, by 

Henry N. Ohlin and R. J . Spear . . . . . . . . . . . . . . . 181 

Blanco Mountain and Black Canyon Roadless Areas, California, by Michael F. Diggles and Richard L. Rains . . 185 

Bucks Lake and Chips Creek Roadless Areas, California, by 

Martin L. Sorensen and J. Mitchell Linne .. _ . . . . . . . 189 

xi 
Buttermilk Roadless Area, California, by Edwin H. McKee 

and Stephen R. Iverson ........................... . 

Cactus Springs Roadless Area, California, by J onathan C. 

Matti and Lucia Kuizon . . . . . . . .... ... .... . .. . 

Caribou Wilderness and Trail Lake Roadless Area, California, by Alison B. Till and Edward L. McHugh .......... . 

Carson-Iceberg Roadless Areas. California, by William J. 

Keith and MichaelS. Miller ...... . ....... . . 

Chanchelulla Roadless Area, California, by Donald F. Huber 

and Scott A. Stebbins ..... 

Condrey Mountain Roadless Area, California, by R. G. Coleman and Ron Mayerle . . . . ...... . 

Coyote Southeast and Table Mountain Roadless Areas, California, by Edwin H. McKee and Donald 0. Capstick 

Cucamonga Roadless Areas, California, by Douglas M. 

Morton and Thomas J. Peters . . ...... . 

Cypress Roadless Area, California, by George L. Kennedy 

and Donald 0. Capstick . . . . . . . . . . . ......... . 

Desolation Valley Wilderness, California, by F.C.W. Dodge 

and P. V. Fillo . . . . . . . . . . . . . . . . . . ........... . 

Devil Canyon-Bear Canyon Primitive Area, California, by 

Dwight F. Crowder and Paul V. Fillo . . . . . . ....... . . 

Dinkey Lakes Roadless Area, California, by F.C.W. Dodge 

and F. E. Federspiel . .. .. .. . 

Domeland Wilderness, Domeland Addition, and Woodpecker 

Roadless Areas, California, by Joel R. Bergquist and 

James M. Spear .............. .. . . . . 

East part of the Raymond Peak Roadless Area, California, 

by David A. John and Frank E. Federspiel 

East Yuba and West Yuba Roadless Areas, California, by 

Joel R. Bergquist and William W. White .. ........ . 

Emigrant Basin and Hoover Wildernesses and adjoining 

roadless areas, California, by Edwin W. Tooker and 

Nicholas T. Zilka . . . . . . . . . . . .. . ... . . . 

Fisher Gulch Roadless Area, California, by Donald F. Huber 

and Eric E. Cather .................. . 

Freel and Dardanelles Roadless Areas, California, by David 

A. John and Douglas F. Scott ................... . ... . 

Golden Trout Wilderness, California, by David A. Dellinger 

and Nicholas T. Zilka . . . . . ........ . 

Granite Chief Wilderness study area, California, by David S. 

Harwood and Francis E. Federspiel ......... . . 

Granite Peak Roadless Area, California, by Donald F. Huber 

and Horace K. Thurber ... . .. .. . . 

High Sierra Primitive Area, California, by James G. Moore 

and Lawrence Y. Marks ...... . 

Ishi, Mill Creek, Polk Springs, and Butt Mountain Roadless 

Areas, California, by Jocelyn A. Peterson and David K. 

Denton . . . . . . . . . . . . . . . . ...... . 

John Muir Wilderness, California, by David A. Dellinger and 

Frederick L. Johnson . . . 

Kaiser Wilderness, California, by David A. Dellinger and 

Andrew Leszcykowski . . . 

Kings River, Rancheria, Agnew, and Oat Mountain Roadless 

Areas, California, by Warren J . Nokleberg and Warren D. 

Longwell ..... . . . ......... . .. .... ..... . .. . 

Lake Eleanor Roadless Area, California, by Donald F. Huber 

and Eric E. Cather . . ... . ... . ... .. ......... . 

Laurel-McGee and Wheeler Ridge Roadless Areas, Califor· 

nia, by Michael A. Cosca and Donald 0 . Capstick .. 

Lost Creek Roadless Area, California, by L. J. Patrick 

Muffler and Harry W. Campbell .. .. ...... . 

Marble Mountain Wilderness, California, by Mary M. 

Donato and William N. Hale ... 

lUJ 

193 

195 

199 

203 

205 

209 

211 

215 

217 

221 

225 

227 

231 

235 

237 

241 

245 

249 

251 

255 

259 

261 

263 

267 

271 

273 

279 

281 

283 

287 

Minarets Wilderness and adjacent areas, California, by 

N. King Huber and HoraceK. Thurber ..... .......... . 

Miranda Pine, Horseshoe Springs. Tepusquet Peak, La Brea, 

Spoor Canyon, Fox Mountain. and Little Pine Roadless 

Areas, California, by Virgil A. Frizzell, Jr., and Lucia 

Kuizon . . . . . . . . . . . . . . . . . . . . . . . ........ . 

Mokelumne Wilderness and adjacent roadless areas, California, by Edwin H. McKee and Francis E. Federspiel 

Moses and Dennison Peak Roadless Areas, California, by 

Richard J. Goldfarb and David A. Lipton ............. . 

Mount Eddy and Castle Crags Roadless Areas, California, 

by J ocelyn A. Peterson and David K. Denton, Jr ...... . 

Mount Raymond Roadless Area, California, by . King 

Huber and Donald 0 . Capstick . . . . . . . . . . . . . ....... . 

Mount Shasta Wilderness study area, California, by Robert 

L. Christiansen and Ernest T. Tuchek ..... . 

North Fork of the American River Wilderness study area, 

California, by David . Harwood and Francis E. Federspiel . . . . . . . . . ........ .. ................... . 

North Fork Smith River Roadless Area, California and 

Oregon, by Floyd Gray and Michael Hamilton ......... . 

Orleans Mountain Roadless Area (B5079), California, by 

Mary M. Donato and J. Mitchell Linne ............... . 

Orleans Mountain Roadless Area (C5079, B5079), California, 

by A. S. J ayko and L. Y. Marks . . . . . . . .......... . 

Pleasant View Roadless Area, California, by Brett Cox and 

David A. Lipton . . . . . . . ...... ...... . . 

Pyramid Roadless Area, California, by Augustus K. Armstrong and Douglas F. Scott .. ....... . .............. . 

Raywood Flat Roadless Areas, California, by Jonathan C. 

Matti and Stephen R. Iverson . . . . . . . . ....... . 

Rubicon Roadless Area, California, by David . Harwood 

and Eric E. Cather . . . . . . . . . . . . . . . . . . . . ........ . 

Salmon-Trinity Alps Wilderness, California, by Preston E. 

Hotz and Horace K. Thurber ................... .. .. . 

San Gorgonio Wilderness, California, by Brett F. Cox and 

Nicholas T. Zilka . . . . . . . . . . . . . . . . . . . . . . . . ... 

San Jacinto Wilderness, California, by Brett F. Cox and 

Martin D. Conyac . . . . ........... .. .. . 

San Joaquin Roadless Area, California, by Edwin H. McKee 

and Donald 0. Capstick . . . . . . . . . . . ............ . 

San Rafael Primitive Area, California by H. D. Gower and 

Arthur C. Meisinger . ..... .. ................ . 

Santa Lucia Wilderness, and Garcia Mountain, Black Moun· 

tain, La Panza, Machesna Mountain, Los Machos Hills, 

Big Rocks, and Stanley Mountain Roadless Areas, California, by Virgil A. Frizzell, Jr., and Lucia Kuizon . ........ . 

Scodies Roadless Area, California, by Jocelyn A. Peterson 

and Donald 0 . Capstick .......... . 

Sespe-Frazier, Diablo, Matilij a, Dry Lakes, SawmillBadlands, Cuyama, Antimony, and Quatal Roadless 

Areas, California, by Virgil A. Frizzell, Jr., and William 

Hale 

Sheep Mountain Wilderness Study Area and Cucamonga 

Wilderness and Additions, California, by James G. Evans 

and James Ridenour . . ... ... ..... . .. . 

Sill Hill, Hauser, and Caliente Roadless Areas, California, by 

Victoria R. Todd and Thomas J. Peters ......... . . .. . 

Snow Mountain Wilderness Study Area, California, by 

Robert D. Brown and Francis E. Federspiel . . . ....... . 

South Warner Wilderness, California, by Wendell A. Duf· 

field and Robert E. Weldin .... 

Sugarloaf Roadless Area, California, by Robert E. Powell 

and Harry W. Campbell .... .... . ..... . .... . ....... . 

291 

293 

297 

301 

303 

307 

309 

313 

315 

319 

323 

327 

331 

333 

339 

341 

343 

347 

351 

353 

357 

361 

363 

367 

371 

373 

377 

379 
Sweetwater Roadless Area, California and Nevada, by 

George L. Kennedy and Robert H. Lambeth 

Thousand Lakes Wilderness, California, by Alison B. Till 

and Edward L. McHugh .......... . . . 

Timbered Crater Roadless Area, California, by Jocelyn A. 

Peterson and Leon E. Esparza . . . . . . . ..... . .... . 

Tioga Lake, Hall Natural Area, Log Cabin-Saddlebag, and 

Horse Meadows Roadless Areas, California, by J. F. Seitz 

and F. E. Federspiel . . .... .. ............ . 

Tuolumne River Roadless Area, California, by Joy L. Harner 

and Paul C. Hyndman . . . ........ . ........... . . 

Ventana Wilderness, California, by R. C. Pearson and P. V. 

Fillo ............... . .. .. .......... . .. . .. . 

Ventana Wilderness Additions and Black Butte, Bear Mountain, and Bear Canyon Roadless Areas, California, by 

Victor M. Seiders and Leon E. Esparza ............ . . 

Weaver Bally Roadless Area, California, by M. C. Blake, Jr. 

and T. J. Peters . . .. . ..... . 

White Mountains and Birch Creek Roadless Areas, California and Nevada, by Michael F. Diggles and Steven W. 

Schmauch ..... . . . . . . . . . . . . ...... . 

Wild Cattle Mountain and Heart Lake Roadless Areas, California, by L. J. Patrick Muffler and David K. Denton .. 

Yolla Bolly-Middle Eel Wilderness and Big Butte-Shinbone, 

East Fork, Murphy Glade, and Wilderness Contiguous 

Roadless Areas, California, by M. C. Blake, Jr. and A. M. 

Leszcykowski .......... . ........ . 

Colorado 

Buffalo Peaks Wilderness Study Area, Colorado, by D. C. 

Hedlund and R. E. Wood .......................... . 

Cannibal Plateau Roadless Area and Powderhorn Wilderness study area, Colorado, by William . Sharp and M. E. 

Lane . . . . . . . . . . . ........ · 

Chama-Southern an Juan Mountains Wilderness study 

area, Colorado, by Maurice R. Brock and Alec E. Lindquist . . . . . . . . . . . . . . . . . . . . . . . . . . . ............. . 

Comanche-Big South, eota-Flat Top, and ever Summer 

wilderness study areas, Colorado, by R. C. Pearson and 

L. L. Patten ..... . ................. · · · · · · · · · · · · · · 

Eagles est Wilderness. Colorado, by Ogden Tweto and 

Frank E. Williams ......... . ......... · · · · · · · · · · · · · 

Flat Tops Primitive Area, Colorado, by W. W. Mallory and 

R. B. Stotelrneyer ... . .. . ........ · .. · · · · 

Fossil Ridge Wilderness tudy Area, Colorado, by Ed 

DeWitt and Steven E. Kluender ............ · · · · · · · · 

Greenhorn Mountain Wilderness tudy Area, Colorado. by 

Margo I. Toth and G. David Baskin ........... · · · · · · · · 

Hunter-Fryingpan Wilderness and Porphyry Mountain Wilderness study area, Colorado, by Steve Ludington and 

Clarence E. Ellis . . . . . . . ........ · · · · · · · · · · · 

Indian Peaks Wilderness. Colorado, by Robert C. Pearson 

and Charles N. Speltz . .......... . . · · · · · · · · · · · · · · · · · 

La Garita Wilderness, Colorado, by Thomas A. Steven and 

C. L. Bieniewski .. . .. 

Maroon Bells-Snowmass Wilderness and additions, Colorado, by ValL. Freeman and Robert C. Weisner ... 

383 

387 

391 

393 

397 

401 

405 

407 

411 

415 

419 

423 

425 

427 

431 

433 

437 

439 

443 

447 

451 

453 

455 

459 

Mount Zirkel Wilderness and vicinity, Colorado, by George 

L. Snyder and Lowell L. Patten . . . 

Oh-Be-Joyful Wilderness Study Area, Colorado, by Steve 

Ludington and Clarence E. Ellis ............... . 

Piedra Wilderness Study Area, Colorado, by Steven M. 

Condon and S. Don Brown .... . .................... . 

Rawah Wilderness, Colorado, by R. C. Pearson and L. L. 

Patten ........................ . 

Sangre de Cristo Wilderness Study Area, Colorado, by Bruce 

R. Johnson and Clarence E. Ellis . . . . .............. . 

Service Creek Roadless Area, Colorado, by Paul W. Schmidt 

and S. A. Kluender ............................... . 

Spanish Peaks Wilderness Study Area, Colorado, by Karin 

E. Budding and Steven E. Kluender ...... . 

Uncompahgre Primitive Area, Colorado, by R. G. Luedke 

and M. J . Sheridan . . . . . . . . . . . .. .. . 

Study areas contiguous to the Uncompahgre Primitive Area, 

Colorado, by Thomas A. Steven and Carl L. Bieniewski . . 

Vasquez Peak Wilderness study area, and St. Louis Peak 

and Williams Fork Roadless Areas, Colorado, by P. K. 

Theobald and A.M. Bielski ....... . 

Weminuche Wilderness, Colorado, by T. A. Steven and F. E. 

Williams . . . . . . . . . . . ......... . 

West Elk Wilderness, Colorado, by D. L. Gaskill and H. C. 

Meeves .................................. . 

West eedle Wilderness Study Area, Colorado. by Richard 

E. Van Loenen and David C. Scott . . . . . . . . . 

Wheeler Wilderness Study Area, Colorado, by William H. 

Raymond and Carl L. Bieniewski . . . . . . . . . . . . . . . . . . 

Wilson Mountains Wilderness, Colorado, by Calvin S. Bromfield and Frank E. Williams .... 

Florida ...... . 

BradweU Bay Wilderness and the Sopchoppy River Wilderness study area, Florida, by Cornelia C. Cameron and Peter 

CM~ . ... .. .. . ...... . ... . .......... .. . .. . Clear Lake Roadless Area, Florida, by Sam H. Patterson and 

Thomas M. Crandall . . . . . . . . . . . . . . . . . . . . . . ...... . 

Faries Prairie and Buck Lake Roadless Areas. Florida, by 

Sam H. Patterson and Thomas M. Crandall ... 

atural Area Roadless Area, Florida, by Sam H. Patterson 

and Thomas M. Crandall . . . ....... . 

Savannah Roadless Area, Florida, by Sam H. Patterson and 

Thomas M. Crandall ...... . 

Georgia .. 

Blood Mountain Roadless Area, Georgia, by Robert P. Koeppen and Michelle K. Armstrong 

Chattahoochee Roadlcss Area, Georgia, by Arthur E. elson 

and Robert A. Welsh ....... .. ......... . 

Cohutta Wilderness, Georgia and Tennessee, and Hemp Top 

Roadless Area, Georgia, by Jacob E. Gair and Gertrude C. 

Gazdik ...................... . 

Overflow Roadless Area, Georgia and orth Carolina, by 

Robert P. Koeppen and Michael P. Davis . . . ........ . 

Rich Mountain Roadless Area, Georgia, by Michael P. Foose 

and Robert M. Thompson . 

Tray Mountain Roadless Area, Georgia, by Arthur E. 

Nelson and Mark L. Chatman ....... . 

463 

467 

469 

473 

475 

479 

483 

485 

489 

493 

497 

499 

503 

507 

509 

513 

515 

517 

521 

523 

527 

531 

533 

535 

539 

543 

545 

549 

xiii 
VOLUME 2 

Idaho . . . . . . . . . . . . . . . . . . . . . . . 553 

Boulder-Pioneer Wilderness study area, Idaho, by Frank S. 

Simons and Ernest T. Tuchek . . . . . . . 555 

Idaho Wilderness, Idaho, by Fred W. Cater and R. D. 

Weldin . . . . . . . . . . . . . . . . . . . 559 

Italian Peak and Italian Peak Middle Roadless Areas, Idaho 

and Montana, by Betty Skipp and Robert H. Lambeth . . 563 

Salmon River Breaks Primitive Area and vicinity, Idaho, by 

Thor H. Kiilsgaard and Ernest T. Tuchek 567 

Eastern part of the Sawtooth National Recreation Area, 

Idaho, by Thor H. Kiilsgaard and Ronald M. VanNoy . 569 

Sawtooth Wilderness, Idaho, by Thor H. Kiilsgaard and 

JosephS. Coffman . . . . . . . . . . . . . . 573 

Selkirk Roadless Area, Idaho, by Fred K. Miller and John R. 

Benham . . . . . . . . . . . . . . . . . . . . . 577 

Selway-Bitterroot Wilderness, Idaho and Montana, by 

Margo I. Toth and Nicholas T. Zilka .. . . 581 

Special Mining Management Zone-Clear Creek, Idaho, by 

Karen Lund and Leon E. Esparza . . . . . . . . . . . . 583 

Ten Mile West Roadless Area, Idaho, by Thor H. Kiilsgaard 

and John R. Benham . . . 587 

Upper Priest Roadless Area, Idaho, by F. K. Miller and D. K. 

Denton, Jr . . . . . . . . . . . . . . . . . . 591 

West and East Palisades Roadless Areas, Idaho and Wyoming, by StevenS. Oriel and John Benham . . . . . . . . 595 

White Cloud-Boulder Roadless Area, Idaho. by Frederick S. 

Fisher and Frederick L. Johnson . . . . . . . . . . . . . . . . 599 

Illinois . . . . . . . . . . . . . . . . . . . . . 603 

Burden Falls Roadless Area, Illinois, by John S. Krasner and 

Robert M. Thompson . . . . 605 

Lusk Creek Roadless Area, Illinois, by John S. Krasner and 

Robert M. Thompson . . . . . . . . . . . . . . . . . . . 607 

Kentucky . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 611 

Beaver Creek Wilderness, Kentucky, by K. J. Englund and 

R. W. Hammack . . . . . . . . . . . . . . . . . . . . 613 

Troublesome Roadless Area, Kentucky, by W. R. Sigleo and 

R. W. Hammack . . . . . . . . . . . . . . . . . . . . . . . . 615 

Louisiana . . . . . . . . . . . . . . . . . . . . . . . . . . . . 619 

Kisatchie Hills Wilderness, Louisiana, by Boyd R. Haley and 

GeorgeS. Ryan . . . . . . . . . . . . . . . . . . . . . . . . . . 621 

Michigan . . . . . 623 

Rock River Canyon Wilderness Study Area, Michigan, by 

Jesse W. Whitlow and Peter C. Morey . . . . . . . . . . . . . 625 

Sturgeon River Wilderness Study Area, Michigan, by W. F. 

Cannon and James J. Hill . 627 

Mississippi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 629 

Sandy Creek Roadless Area, Mississippi, by Boyd R. Haley 

and Richard F. Bitar . . . . . . . . . . . . . . . . . . . . . . 631 

Missouri . 635 

Bell Mountain Wilderness Study Area, Missouri, by Walden 

P. Pratt and Clarence Ellis . . . . . . . . . . . . 637 

Hercules Glades Wilderness, Missouri, by Mary H. Miller 

and George S. Ryan . . . . . . . . . . . . . . . 639 

irish Wilderness Roadless Area, Missouri, by Allen V. Hey! 

and George S. Ryan . . . . . . . . . . . . . . . . . 643 

Paddy Creek Wilderness Study Area, Missouri, by Walden 

P. Pratt and Clarence Ellis 645 

Piney Creek Wilderness, Missouri, by Walden P. Pratt and 

Clarence Ellis . . . . . . . . . . . . . 649 

Rock Pile Mountain Wilderness Study Area, Missouri. by 

Walden P. Pratt and Clarence Ellis . . 653 

XJV 

Montana . . . . . . . . . . . . . . . . . . . . . 657 

Absaroka Primitive Area and vicinity, Montana, by Helmuth Wedow, Jr., and D'Arcy P. Bannister ... 

Anaconda-Pintlar Wilderness, Montana, by J. E. Elliott and 

T. J. Close ...... . ..... . ................. . 

Beartooth Primitive Area and vicinity, Montana and Wyoming, by FrankS. Simons and Ronald M. Van oy .. 

Big Snowies Wilderness tudy Area and contiguous roadless 

areas, Montana, by David A. Lindsey and Francis E. 

659 

661 

665 

Federspiel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 669 

Blue Joint Wilderness Study Area, Montana, and Blue Joint 

Roadless Area, Idaho. by Karen Lund and John R. 

Benham . . . . . . . ....................... . 

Cabinet Mountains Wilderness, Montana, by David A. Lindsey and D' Arcy P. Banister . . . . . . . . . . . . ..... . 

Centennial Mountains Wilderness study area, Montana and 

Idaho, by Irving J . Witkind and James Ridenour . 

Charles M. Russell Wildlife Refuge. Montana, by Dudley D. 

673 

677 

679 

Rice and MichaelS. Miller . . . . . . . . . . . . . . . . . . . . . . . . . . 683 

Dolus Lakes Roadless Area, Montana, by James E. Elliott 

and Dale W. A very .............................. . 687 

Eastern Pionner Mountains, Montana, by Robert C. Pearson . . . . . . . . . . . . . ................ 691 

Elkhorn Wilderness Study Area, Montana, by W. R. Greenwood and Terry J. Close . . . ............... .. ... . 

Flint Creek Range Wilderness study area, Montana, by 

George E. Ericksen and Lawrence Y. Marks ........ . 

Gallatin Divide Roadless Area, Montana, by Frank 

Simons and Terry J. Close ............. ...... . 

Gates of the Mountains Wilderness and adctitions, Montana, 

by Mitchell W. Reynolds and Terry J. Close ....... . 

Jack Creek basin. Montana, by Thor H. Kiilsgaard and 

Ronald M. Van oy . . . . . . . . . . . . . . ....... . 

Mactison Roadless Area, Montana, by Frank S. Simons and 

Robert H. Lambeth ..................... . 

Middle Fork of the Juctith River Wilderness Study Area, 

Montana, by Mitchell W. Reynolds and Michael Ham.i.lton . 

Middle Mountain-Tobacco Root Roadless Area, Montana, by 

J. Michael O'Neill and Eric E. Cather ................ . 

Mission Mountains Wilderness. Montana, by Jack E. Har695 

697 

701 

705 

709 

713 

717 

721 

rison and Eldon C. Pattee . . . . . . . . . . . . . . . . . . . 725 

Mount Henry Roadless Area, Montana, by Richard E. Van 

Loenen and Martin C. Conyac . . . . . . . . . . . . . . . . . . . . . . . 727 

North Absaroka study area, Montana, by J. E. Elliott and 

R. B. Stotelmeyer . . . . . . . . . 731 

Rattlesnake Roadless Area, Montana, by C. A. Wallace and 

Ronald T. Mayerle . . . . . . . . . . . . . . . 735 

Sapphire Wilderness Study Area and contiguous roadless 

areas, Montana, by C. A. Wallace and D.P. Bannister . . . . 737 

Scapegoat Wilderness and adctitions, Bob Marshall and 

Great Bear Wildernesses, and adjacent study areas, Montana, by Robert L. Earhart and Lawrence Y. Marks 7 41 

Scotchman Peak Wilderness study area, Montana and 

Idaho. by R. L. Earhart and N. T. Zilka . . . . . . . . . . . . 745 

Spanish Peaks Primitive Area, Montana, by James A. 

Calkins and Eldon C. Pattee ... . . 747 

Ten Lakes Wilderness Study Area, Montana, by James W. 

Whipple and Michael M. Hamilton . . 751 

Welcome Creek Wilderness, Montana, by D. J. Lidke and 

T. J. Close . . . . . . . . . . . 755 

West Pioneer Wilderness Study Area, Montana, by Byron R. 

Berger and John H. Benham . . . . . . . . . . . . 757 
Nevada ......... . ...... ... .. . ..................... . 

Charles Sheldon Antelope Range and Sheldon National 

Antelope Refuge, Nevada and Oregon, by J. B. Cathrall 

and E. T. Tuchek .......... . 

Highland Ridge Roadless Area, evada, by Donald H. 

Whitebread and S. Don Brown . . . . . . . ... . . 

Jarbidge Wilderness, Nevada, by Robert R. Coats and L. Y. 

Marks ....... . 

Lincoln Creek Roadless Area, evada, by David A. John and 

Scott A. Stebbins ...... . . 

Mount Moriah Roadless Area, evada, by Robert R. Carlson 

and Robert H. Wood II .......................... . 

Sugarloaf Roadless Area, Nevada, by Edwin H. McKee and 

Steven W. Schmauch .. ...... . ................... . 

Wheeler Peak Roadless Area, evada, by Donald H. Whitebread and Steven E. Kluender .... . . . ..... . ...... . 

New Hampshire . . . . . . . ..... . . 

Wilderness and roadless areas in White Mountain National 

Forest, New Hampshire, by Robert H. Moench and Gertrude C. Gazdik . . . . ... . .. . . . 

New Mexico . . . . . . . . . . .......... . 

Black Range Primitive Area, ew Mexico, by George E. 

Ericksen and George R. Leland ....... . 

Bunk Robinson Peak and Whitmire Canyon Roadless Areas, 

New Mexico and Arizona, by Philip T. Hayes and S. Don 

Brown ...... . . . 

Caballo and Polvadera Roadless Areas, ew Mexico, by Kim 

Manley and Michael E. Lane . . . . . . . . . . . . . . . ....... . 

Chama River Canyon Wilderness and contiguous roadless 

area, New Mexico, by J ennie L. Ridgely and Thomas D. 

Light . . . . . . . . . .............. . 

Columbine-Hondo Wilderness study area and Wheeler Peak 

Wilderne s, ew Mexico, by Steve Ludington and S. Don 

Brown . ..... . .................................. . 

Gila Wilderness, ew Mexico, by James C. Ratte and Ronald 

B. totelmeyer .... . .......................... . .. . 

Guadalupe Escarpment Wilderness Study Area, ew Mexico, by Philip T. Hayes and John R. Thompson ....... . 

Little Dog and Pup Canyons Roadless Area, ew Mexico, by 

Philip T. Hayes and Philip R. Bigsby ................. . 

Manzano Wilderness, ew Mexico, by C. H. Maxwell and 

Thomas D. Light . . . . . . . . . . . . . ........ . 

Pecos Wilderness, ew Mexico, by Robert H. Moench and 

Michael E. Lane .................... . ... . ... · 

Ryan Hill Roadless Area, ew Mexico, by C. H. Maxwell and 

C. E. Ellis .............................. · · · · · · · · · 

San Pedro Parks Wilderness, ew Mexico, by Elmer S. 

Santos and Robert C. Weisner . . . . . . . . . . . ...... · · 

Sandia Mountain Wilderness, ew Mexico, by D. C. Hedlund and R. F. Kness . . . . . . . . . . . . . ... · · · · · · 

White Mountain Wilderness, ew Mexico, by Kenneth 

Segerstrom and R. B. Stotelmeyer . . . ......... · · · 

North Carolina .................... ... . . 

Craggy Mountain Wilderness study area and Extension, 

North Carolina, by Frank G. Lesure and Bradford B. 

Williams ............. · . · · · · · · · · · · · · · · · · 

Joyce Kilmer-Slickrock Wilderness, North Carolina and Tennessee, by Frank G. Lesure and James J. Hill .... · .... · · 

Linville Gorge Wilderness and Additions, orth Carolina. by 

John P. D'Agostino and Gertrude C. Gazdik ..... · .. · · · · 

Lost Cove and Harper Creek Roadless Areas, North Carolina, by W. R. Griffitts and T. M. Crandall ....... . 

Shining Rock Wilderness, North Carolina by Frank G. 

Lesure and Maynard L. Dunn, Jr .. 

763 

765 

769 

771 

775 

777 

781 

783 

787 

789 

793 

795 

799 

801 

805 

807 

811 

815 

817 

21 

823 

827 

831 

833 

837 

84 1 

843 

845 

849 

851 

855 

Snowbird Roadless Area, orth Carolina, by Frank G. 

Lesure and Mark L. Chatman .......... . .......... . . 

Oregon .......................................... . . 

Deschutes Canyon Roadless Area, Oregon, by George W. 

Walker and Richard A. Winters ..................... . 

Diamond Peak Wilderness, Oregon, by David R. Sherrod 

and Philip R. Moyle . . . ........................... . 

Eagle Cap Wilderness and adjacent areas, Oregon, by Thor 

H. Kiilsgaard and Ernest T. Tuchek ................. . 

Gearhart Mountain Wilderness and contiguous roadless 

area, Oregon, by George W. Walker and James Ridenour .. 

Hells Canyon Study Area, Oregon and Idaho, by George C. 

Simmons and Terry J. Close . . . . . . . . . . . . . . . ...... . 

Homestead, Lake Fork, and Lick Creek Roadless Areas, 

Oregon, by James G. Evans and Martin D. Conyac 

Kalmiopsis Wilderness, Oregon, by orman J. Page and 

Michael S. Miller ...... . ................. . 

Mount Hood Wilderness and adjacent areas, Oregon, by 

T.E.C. Keith and J.D. Causey . . ........ . 

Mount J efferson Primitive Area, Oregon, by George W. 

Walker and Eldon C. Pattee ............... . 

Mount Washington Wilderness, Oregon, by Edward M. 

Taylor and J. Douglas Causey . . . . . . . . . . . . . . .. 

North Fork J ohn Day River Roadless Area. Oregon. by 

James G. Evans and Martin D. Conyac ............ . .. . 

Olallie Roadless Area, Oregon, by George W. Walker and 

Terry R. Neumann . . . . . . . . . . . . . ....... . 

Pine Creek Roadless Area, Oregon, by George W. Walker 

and David K. Denton . . . . .......... . 

Sky Lakes Roadless Area and Mountain Lakes Wilderness. 

Oregon, by James G. Smith and John R. Benham ... 

Strawberry Mountain Wilderness, Oregon. by T. P. Thayer 

and Ronald B. Stotelmeyer . . . . . . . . ......... . 

Three Sisters Wilderness, Oregon, by Norman S. MacLeod 

and J. Douglas Causey . . . . . . . . . . . . . ......... . . 

Wild Rogue Wilderness, Oregon, by Floyd Gray and Michael 

S. Miller . . . . . . . . .............. . 

Windigo-Thielsen Roadless Area, Oregon, by David R. Sherrod and John R. Benham .......................... . 

Pennsylvania . . . . . . . . . . . . . . . . . . . . .... . 

Allegheny Front and Hickory Creek Roadless Areas, Pennsylvania, by Stanley P. Schweinfurth and Vaughn P. Girol . 

Clarion River Roadless Area, Pennsylvania, by Stanley P. 

Schweinfurth and Robert A. Welsh ........ . ........ . 

Cornplanter Roadless Area, Pennsylvania, by Frank G. 

Lesure and Robert A. Welsh, Jr .. . ...... . 

South Carolina . . . . . . . . . . . . ........ . 

Ellicott Rock Wilderness and Additions, South Carolina, 

North Carolina, and Georgia, by Henry Bell II I and 

Gertrude C. Gazdik ........... . .... . ....... . 

Hell Hole Bay, Wambaw Swamp, Little Wambaw Swamp. 

and Wambaw Creek Wildernesses, South Carolina, by Cornelia C. Cameron and Clay M. Martin .. . ............. . 

Tennessee . . . . . . . . . ..... . . . 

Big Frog Wilderness Study Area and Additions, Tennessee 

and Georgia, by John F. Slack and Gertrude C. Gazdik .... 

Citico Creek Wilderness Study Area, Tennessee, by John F. 

Slack and Paul T. Behum ................... . . 

Flint Mill Roadless Area, Tennessee, by Wallace R. Griffitts 

and Jay G. Jones . . 

Gee Creek Wil erness, Tennessee. by Jack B. Epstein and 

Gertrude C. Gazdik .................. . 

Little Frog Roadless Area, Tennessee, by Eric R. Force and 

Gertrude C. Gazdik . . . . ............ . 

57 

861 

863 

867 

69 

873 

875 

79 

883 

885 

889 

893 

897 

899 

903 

905 

909 

911 

915 

917 

921 

923 

927 

931 

935 

937 

939 

943 

945 

947 

951 

953 

957 

XV 
Pond Mountain and Pond Mountain Addition Roadless 

Areas. Tennessee, by W. R. Griffitts and Richard Bitar .... 

Unaka Mountain Roadless Area, Tennessee, by Wallace R. 

Griffitts and Mark Chatman .................... ... . 

Texas ... . . . . . . . . . . . . .................. . 

Chambers Ferry Roadless Area, Texas, by B. B. Houser and 

George S. Ryan . . . . . . . . . . . . . . .. .... ..... . 

Four otch Roadless Area, Texas, by B. B. Houser and 

George S. Ryan . . . . . . . . . . . . ......... . 

Graham Creek Roadless Area, Texas, by B. B. Houser and 

George S. Ryan ..................... . 

u~ .. . .............. . Birdseye, ephi, and Santaquin Roadless Areas, U~. by 

Martin L. Sorensen and Stanley L. Korzeb . . . . . . ..... . 

High Uintas Primitive Area, U~. by Max D. Crittenden, 

Jr. and Michael J. Sheridan . . . ...... . 

Lone Peak Wilderness study area, U~. by Calvin S. Bromfield and Lowell L. Patten . . . . . . . . . . . . . ... .. .. . 

Mount Naomi Roadless Area, U~ and Idaho, by James H. 

Dover and Philip R. Bigsby . . . . . . ....... . 

Stansbury Roadless Areas, U~. by Martin L. Sorensen and 

Richard F. Kness ........ . 

The Box-Death Hollow Roadless Area, U~. by Gordon W. 

Weir and Michael E. Lane . . . . . ........ . .... . 

Vermont .. . ..... .. .................... . 

Bread Loaf Roadless Area, Vermont, by John F. Slack and 

Richard F. Bitar . . . . . . . . . . . . ....... .. . 

Bristol Cliffs Wilderness, Vermont, by John F. Slack and 

Peter C. Mory .... 

Devils Den Roadless Area, Vermont, by John F. Slack and 

Andrew E. Sabin .. ....... . ... .................... . 

Lye Brook Wilderness, Vermont, by Robert A. Ayuso and 

D. K. Harrison . . . . . . . . ........................ . 

Virginia ................. . ......... . 

Devils Fork Roadless Area, Virginia, by Kenneth J. Englund 

and Paul T. Behum . . . . . . . . . . . . . . . . . . ...... . 

Dolly Ann Roadless Area, Virginia, by Frank G. Lesure and 

Jay G. Jones . . . . . . . . . ....... . 

James River Face Wilderness, Virginia, by C. Ervin Brown 

and Gertrude C. Gazdik . . . . . . . . . . . ......... . 

Mill Creek Wilderness Study Area, Virginia, by Frank G. 

Lesure and Bradford B. Williams ... 

Mountain Lake Wilderness Study Area, Virginia and West 

Virginia, by Frank G. Lesure and Bradford B. Williams ... 

Peters Mountain Wilderness Study Area, Virginia, by Frank 

G. Lesure and Bradford B. Williams .... 

Ramseys Draft Wilderness Study Area, Virginia, by Frank 

G. Lesure and Peter C. Mory . . . . ........ . 

Southern Massanutten Roadless Area, Virginia, by Frank G. 

Lesure and Mark L. Chapman . . . . . . ... . .. . 

Washington . . . . . . . . . . . . . . . . . . . . ........... . 

Alpine Lakes Wilderness study area, Washington, by J . L. 

Gualtieri and H. K. Thurber . . . . . . ............ . 

Cougar Lakes-Mount Aix Wilderness study area, Washington, by George C. Simmons and Ronald M. Van oy 

Eagle Rock Roadless Area, Washington, by S. E. Church 

and F. L. Johnson . . . . . . . . . . . . .......... . 

Glacier Peak Roadless Area, Washington, by S. E. Church 

and F. L. Johnson .. .......... .. . 

Glacier Peak Wilderness study area, Washington, by S. E. 

Church and R. a·. Stotelmeyer . 

Glacier View Roadless Area, Washington, by Russell C. 

Evarts and Donald J . Barnes . . . ....... . 

Goat Rocks Wilderness and adjacent roadless areas, Washington, by S. E. Church and T. J. Close 

xvi 

959 

963 

967 

969 

971 

975 

979 

981 

983 

987 

989 

993 

997 

999 

1001 

1003 

1007 

1009 

1013 

1015 

1017 

1021 

1023 

1027 

1029 

1033 

1035 

1039 

1041 

1045 

1047 

1051 

1055 

1059 

1063 

Indian Heaven Roadless Area, Washington, by S. E. Church 

and D. J. Barnes . . ............... . 

Long Swamp Roadless Area, Washington, by Russell C. 

Evarts and John R. Benham .......... ... . 

Mount Adams and contiguous roadless areas, Washington, 

by Wes Hildreth and M. Miller . . . . . . . . . . . .. . . .. . . . 

Northern part of the North Cascades National Park, Washington, by Mortimer H. Staatz and Ronald M. VanNoy ... 

Pasayten Wilderness. Washington, by Mortimer H. Staatz 

and Ronald M. VanNoy .................. . 

Salmo-Priest Wilderness study area, Washington and Idaho, 

by F. K. Miller and S. W. Schrnauch ...... ... . 

Tatoosh Roadless Area, Washington, by Russell C. Evarts .. 

Wenaha Tucannon Wilderness, Washington and Oregon, by 

Donald A. Swanson and Steven R. Munts ........... . 

Wonder Mountain Roadless Area, Washington, by S. E. 

Church and S. R. Iverson . . . . . ......... .. . . . 

West Virginia ......................... .. ........ . 

Cheat Mountain Roadless Area, West Virginia, by K. J. 

Englund and P. T. Behurn ........ . ... . .. . 

Cranberry Wilderness Study Area, West Virginia, by 

Charles R. Meissner, Jr. and P. C. Mory . .. 

Dolly Sods Wilderness, West Virginia, by Kenneth J. 

Englund and James J. Hill ............ ... . 

Otter Creek Wilderness, West Virginia, by Ralph C. Warlow 

and Paul T. Behum . . . . . . . . . ....... . 

Wisconsin . . . . . . . . . . . . ............ . 

Blackjack Springs Wilderness, Wisconsin, by Klaus J . 

Schulz .. ... ... ........ ..... ........ . ........ . 

Rainbow Lake Wilderness and Flynn Lake Wilderness Study 

Area, Wi consin, by W. F. Cannon and Maynard L . Dunn . . 

Round Lake Wilderness Study Area, Wisconsin, by W. F. 

Cannon and Bradford B. Williams .. .. ............... . 

Whisker Lake Wilderness, Wisconsin, by Klaus J. Schulz .. . 

Wyoming . . . . . . . . . . . . ...... · · .. · · · · · · · · · 

Bridger Wilderness and Green-Sweetwater Roadless Area, 

Wyoming, by Ronald G. Worland George . Ryan ...... . 

Cloud Peak Primitive Area and adjacent areas, Wyoming, by 

Thor H. Kiilsgaard and Lowell L. Patten ............ . 

Cloud Peak Contiguous, Rock Creek, Piney Creek, and Little 

Goose Roadless Areas, Wyoming, by Kenneth Segerstrom 

and Don S. Brown ...... . . . ...... . .. . ...... ... .... . 

Glacier Primitive Area, Wyoming, by Harry C. Granger and 

Lowell L. Patten . . . . . . . . . . . . . . . . . . . . . ........ . 

Gros Ventre Wilderness study area, Wyoming, by Frank S. 

Simons and CarlL. Bieniewski .. ..... ...... . .. . 

Huston Park Roadless Area, Wyoming, by Robert S. 

Houston and Michael E. Lane ........ .. ..... . . 

Laramie Peak Wilderness study area, Wyoming, by Kenneth 

Segerstrom and R. C. Weisner ................ .. . 

North Absaroka Wilderness, Wyoming, by Willis H. Nelson 

and Frank E. Williams . . . . . . . . . . . . . . .... .. .... . 

Popo Agie Primitive Area, Wyoming, by Robert C. Pearson 

and L. L. Patten . . . . . . .............. . 

Savage Run Wilderness, Wyoming, by M. E. McCallum and 

Steven E. Kluender .... . ................ . 

Sheep Mountain Wilderness study area, Wyoming, by 

Robert H. Houston and Lowell L. Patten . . . . ......... . 

Snowy Range Wilderness, Wyoming, by Robert S. Houston 

and Philip R. Bigsby . . . . . . . . . . . . . . . . . . . . . . ... .. . 

Stratified Primitive Area, Wyoming, by C. S. Bromfield and 

R. G. Raabe . . . . . . . . . . . . . ...... . 

Teton Wilderness, Teton Corridor, and Du Noir Addition to 

Washakie Wilderness, Wyoming, by J. C. Antweiler and 

F. E. Williams . . . . . . ................. . 

1067 

1069 

1073 

1077 

1079 

1083 

1087 

1089 

1093 

1097 

1099 

1101 

1106 

1110 

1113 

1115 

1117 

1121 

1123 

1127 

1129 

1133 

1135 

1139 

1141 

1145 

1149 

1151 

1153 

1157 

1159 

1163 

1165 

1169 
Northern West Slope Tetons Roadless Area, Wyoming, by W. Bradley part of the Washakie Wilderness and nearby roadless areas, Wyoming, by John C. Antweiler and Carl L. Myers and Steven E. Kluender . . . . . . . . 1177 

Bieniewsk:i . . . . . . . . . . . 1173 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 0 

ILLUSTRATIONS 

VOLUME 1 

Figure 1.- Diagram showing the role of nonfuel minerals in the United States economy, 1982 . . . . . . . . . . . . . . . . 2 

Figure 2.-Geologic time scale . . . . . . . . . . . . . . . 5 

Figure 3.-Graph showing cumulative acreage of Federal lands designated for study 1964- 1984 . . . . . . . . . . . . . . . . 9 

Figures 4-160.-Maps showing generalized geology and mineral-resource potential of areas discussed in accompanying summary reports. 

VOLUME 2 

Figures 161-335.- Maps showing generalized geology and mineral-resource potential of areas discussed in accompanying summary reports. 

TABLES 

VOLUME 1 

Table !.- Domestic production of major metallic commodities in 1982 . . 

Table 2.-Domestic production of major nonmetallic commodities in 1982 

3 

3 

xvii 
• 
INTRODUCTION 

By D O ALD A. BROBST A D Gu H. Go DARZI 

PURPOSE 

Under the provisions of the Wilderness Act (Public 

Law 88-577, September 3, 1964) and subsequent related 

legislation, the U.S. Geological Survey (USGS) and the 

U.S. Bureau of Mines (USBM) have been conducting 

mineral surveys of wilderness and primitive areas, and 

of other national forest lands being considered for 

wilderness designation. The Wilderness Act directs that 

the results of these surveys are to be made available to 

the public and are to be submitted to the President and 

the Congress. This professional paper is a synopsis of 

the mineral surveys made from 1965 to 1983. It summarizes our current knowledge of mineral and energy 

resources and of the potential for the occurrence of undiscovered mineral and energy resources in 45 million 

acres of Federal lands, chiefly in national forests. 

This book, in two volumes, consists of 332 summary 

articles, arranged alphabetically by State, in which the 

mineral-resource potential of about 800 individual areas 

is discussed. The summaries of the mineral surveys 

were written during 1982- 83, generally by those who 

made the surveys. Index maps of each state show the 

location of the areas studied, numerically keyed to an 

alphabetic list. The national distribution of the 

wilderness lands studied is shown on the frontispiece. 

Where lands were in proximity or were added to expand 

previously designated areas, they often are described in 

a single article. 

Each article begins with a short summary of the 

results of the mineral survey followed by a discussion of 

the character and geologic setting of the area. Mineral 

resources (if any) are discussed, and the potential for undiscovered mineral resources is assessed; these are 

keyed to the generalized geographic and geologic map of 

each area Areas that have geologic characteristics indicative of different degrees of potential for the occurrence of mineral resources are shown in shades of red on 

each map. Some articles have a section on suggestions 

for further study to better define the mineral-resource 

potential of the area A list of pertinent references 

(including many of the maps and reports prepared during the mineral survey) is provided at the end of each 

article. 

This introduction contains some basic concepts about 

mineral resources and mineral-resource potential to try 

to make the book more useful to those who are not 

familiar with the fields of earth science and mineralresource assessments. The legislation dealing with the 

wilderness program is reviewed briefly, because this 

evolving legislation has imparted a continuing and 

changing influence on the mineral-resource surveys. The 

introduction concludes with a description of the publications of the Geological Survey that report in greater 

detail the results of the joint wilderness studies by the 

Geological Survey and the Bureau of Mines. 

REASONS FOR ASSESSING 

WILDERNESS MINERAL POTENTIAL 

Minerals can be subdivided into metallic, nonmetallic, 

and energy (including uranium, fossil fuels, and geothermal waters) and these resources often are referred to as 

commodities. They are vital to our everyday lives. Nobody passes through a single day without using materials that have been made from, processed by, fertilized 

with, or are in some other way affected by products 

from mineral resources. Our highly productive agriculture has been made possible by extensive mechanization 

and efficient use of fuel, fertilizer, and soil conditioners. 

Most of our foods come from fields that are treated with 

phosphate and potash mineral fertilizers or with 

nitrogen-based fertilizers made from natural gas. Our 

food is cooked in metal pots (recovered from minerals) 

and is served on chinaware (made from clay minerals). 

Energy for cooking and baking comes from mineral 

fuels (gas or petroleum products) or from electricity produced from coal, oil, gas, or uranium in plants using 

generators made of metal. Even solar energy is collected 

and distributed by equipment made from metals and 

petroleum. Buildings, other than those made of wood, 

consist chiefly of processed materials of mineral 

origin- brick, ·oncrete, glass, rock wool, insulation, 

ceramics, tile, metal fixtures, and plasterboard. Plastic 

products, which are pervasive in our society, are derived 

from oil, natural gas, or coal. We travel in vehicles made 

of metal and plastics and powered by mineral fuels. 

1 
Silver is used in the film for our cameras, and several 

rare metals (such as europium in color television picture 

tubes) are essential to electronic equipment. 

Mineral resources are the foundation of our national 

economy, which now generates a gross national product 

(GNP) of slightly more than $3 trillion annually. The 

role of nonfuel minerals in the United States economy in 

1982 is shown in figure 1. The value of domestically produced mineral raw materials (excluding fuels) was about 

$20 billion and the value of imported mineral raw materials was about $4 billion. On the basis of 1981 U.S. 

Department of Energy estimates, domestically produced fuels had a value of $178 billion and imported 

fuels, mostly oil and gas, had a value of $70 billion. The 

value of all the minerals (including fuel) represents an indispensable part of the GNP, about 10 percent. 

The major metallic commodities produced in the 

United States in 1982, ranked by dollar value, are 

shown in table 1. Our reliance on imports, shown in this 

table as a percentage of domestic primary consumption, 

varies greatly from commodity to commodity because 

U.S. NATURAL 

RESOURCE S 

of some combination of geologic availability and economic conditions, such as price, demand, and cost of 

production. For example, although the United States 

has sufficient iron ore to increase production, the current economic conditions and those of the recent past 

make importing ore less costly. For bauxite, an ore of 

aluminum, the circumstances are quite different. 

Domestic deposits are small and their geologic nature 

make it unlikely that any new large deposits of bauxite 

will be found in the United States. Molybdenum, an element essential for alloying special types of steel, is 

abundant in the United States; our Western States supply nearly 65 percent of the world's production. 

The domestic production of major nonmetallic mineral commodities in 1982, ranked by dollar value, is 

shown in table 2. The net import reliance, shown as a 

percentage of domestic primary consumption, is controlled by geologic and economic factors. The United 

States has large resources of phosphate rock, borates, 

and sodium carbonate, and is a leading producer and exporter of these nonmetallic minerals. Construction 

PROCESSED MATERIALS 

OF MINERAL ORIGIN 

STEEL, ALUMINUM , GROSS NATIONAL 

PRODUCT 

ROCKS, 

MINERALS, 

WATER, AIR 

EXTRACTIVE 

INDUSTRIES. 

DOMESTIC MINERAL 

RAW MATERIALS 

IRON ORE, 

COPPER ORE, 

SAND, GRAVEL, 

STONE 

VALUE 

$20 BILLION 

MINERAL COPPER, OTHER 

METALS, BRICK, ~ $3060 BILLION 

2 

INCLUDING 

MINING, 

L---------' QUARRYING 

FOREIGN 

MINERAL 

r----::-FO~R:-:E:-:-I G:-:N-:-----, OPERA T 10 N S 

OF 

NATURAL 

RESOURCES U.S. FIRMS 

L-----,..-----.J AND (OR) 

1 PROCESSING GLASS, CEMENT, 

\ INDUSTRIES, INORGANIC 

\ INCLUDING CHEMICALS, PLASTICS, L I 

\ SMELTING, FERTILIZERS 1 

\REFINING VALUE I 

\ $202 BILLION I 

\---- ------, RECLAIMING r ___ i_ ____ , '

11 

I DOMESTIC RECLAIMED I AND I u.s. SCRAP AND I 

I METALS AND MINERAL I RECYCLING I WASTE MATERIALS I 

I MATERIALS I INDUS Rl s IRON, STEEL, I 

I SCRAP IRON :.::..:.; __ _:!'_~~ ALUMINUM 

I GLASS ' 1

' SCRAP I ' I 

I VALUE OF II DEALERS II COPPER, BRASS, I BRONZE, LEAD, I I OLD SCRAP II I ZINC, GLASS, I 

I $4 BILLION 1 I BRICK I L--- ------~ L ________ j 

IMPORTS INTO U.S. 

OF M INERAL RAW 

MATERIALS 

COPPER ORE, 

IRON ORE, 

BAUXITE 

IMPORTS INTO U.S. 

OF PROCESSED 

MATER IALS OF 

MINERAL ORIGIN 

STEEL, 

ALUMINUM , 

INORGANIC 

CHEMICALS 

EXPORTS FROM U.S. 

OF MINERAL RAW 

MATERIALS AND 

PROCESSED 

MATERIALS OF 

M INERAL ORIGIN 

MOLYBDENUM, 

FOREIGN 

FIRMS VALUE 

1.....---------------~ $25 BILLION 

VALUE 

$4 BILLION 

INORGANIC 

CHEMICALS, 

STEEL 

FERTILIZERS 

VALUE 

$19 BILLION 

Figure 1.-The role of nonfuel minerals in the United States economy for the first 8 months of 1982. Statistical data from 

U.S. Department of Commerce. 
TABLE !.-Domestic production of major metallic mineral 

commodities in 1982 

!Data from Ule U.S. Bureau of Mines! 

Metallic Estimated Estimated Estimated 

mineral product.ion value net import reliance commodity (melric tons) (million dollars) lin percent) of domestic 

primary consumption 

Copper ------ 1.100,000 1,800 7 

Iron ore ----- '35,900,000 1,500 36 

Molybdenum - 36.500 362 et export. Lead -------- 510,000 292 1 

Silver ------- 1,120 286 59 

Zinc -------- 300,000 255 53 

Vanadium --- '4.260 55 14 

1\mgsten ---- 1,450 20 48 

Bauxite ----- 700,000 17 97 

Mercury ----- 860 '10 43 

Platinum ---- .19 1 85 

group metals. 

1 Preliminary estimate. 

'value calculated is based on an average price of 5390 per flask. 

materials (cement, crushed stone, and sand and gravel), 

are mined or produced close to where they are used 

because of their bulk, weight, and resulting high cost of 

transport. 

With few exceptions, most minerals are consumed in 

use. Mineral commodities either are committed to an 

irretrievable use in a permanent structure (for example, 

sand, gravel, crushed rock, cement, glass, and steel and 

other metals used in roads and buildings); are converted 

into a useful product from which they cannot be reclaimed (chemicals, paints, plastics); or are converted 

chemically to products that are dispersed into the 

ground or into the atmosphere (fertilizers and fossil 

fuels). Although some metals, including aluminum, antimony, copper, lead, gold, iron, and silver, can be 

recovered by recycling and provide a substantial part of 

domestic consumption, a steady source of mineral raw 

materials, available in limited supply, is essential to 

maintain our present standard of living. 

Concentrations of useful minerals rich enough to form 

ore deposits are rare phenomena Commercially extractable concentrations form only where special physical 

and chemical conditions have favored their accumulation. Certain types of mineral deposits are associated 

with certain geologic environments as characterized by 

the type of rocks and structures, depth of formation, 

and source and nature of mineralizing fluids. For example, throughout the world many major deposits of copper, lead, zinc, silver, and gold are associated with 

granitic igneous rocks such as those found in the 

Western United States and in Western South America 

Chromium deposits commonly are associated with other 

kinds of igneous rock; although these deposits are rare 

in North America, they are abundant in southern 

Africa. Large deposits of bauxite occur in deeply weathered rocks formed in tropical climates. Many of the 

world's largest deposits of lead and zinc are associated 

with limestone strata, like those of southeastern 

Missouri. The organic fuels- oil, gas, and coal- are 

formed from materials deposited in specific sedimentary environments. Field and laboratory observations 

and studies provide information about where and why 

minerals accumulate. Studies formulating the theoretical basis for resource accumulation have provided for 

the understanding of some of the many types of geologic environments that offer potential for the occurrence of mineral deposits (Brobst and Pratt, 1973). As a 

result of these studies, criteria have been established 

that define geologic, geochemical, and geophysical properties of these deposits (which may be referred to as 

modeling); that is, a comparison of data with known 

occurrences. 

Just as not every haystack has a needle, not every 

favorable geologic environment has a mineral deposit of 

economic value. For example, of every 1000 mineral 

prospects examined in Canada in 1969, only one was 

favorable for mine development (Roscoe, 1971). 

As might be expected from the wide geographic 

distribution of the wilderness lands (see tontispiece), 

these lands contain rocks formed in a great variety of 

geologic environments. Many of these environments are 

favorable for the occurrence of mineral resources and 

many kinds of resources may be present. As the authors 

of the Wilderness Act of 1964 realized, prudent use of 

land requires knowledge of its resources, including 

water, timber, wildlife, and recreational assets as well as 

minerals. In recognition of the importance of metallic, 

nonmetallic, and energy mineral resources to the economy, the Congress specifically required that these resources be surveyed on land in, or being considered for, 

TABLE 2.-Domestic production of major nonmetallic mineral 

commodities in 1982 

!Data from Ule U.S. Bureau of Mines! 

Nonmetallic Estimated Estimated Estimated 

mineral production value net import reliance 

commodity (Ulousand (million dollars) (in percent) of domestic 

m~tric LOns) primary consumption 

Cement ---------- 57,500 3,260 4 

Crushed stone ----- 717,000 2,920 0 

Sand and gravel ---- 568,000 2,020 et export. 

Sulfur ----------- 9,800 980 4 

Phosphate rock ---- 37,400 950 et export. 

~~~~b~~~~-== 32,200 830 et export. 7,090 721 et export. 

Lime ------------ 12,800 700 2 

Salt ------------- 34,050 673 11 

Boron (boria ------- 550 385 et export. 

B,OJ. 

3 
inclusion in the National Wilderness System, in order to 

aid those who must make decisions about land use. 

THE NATURE OF 

MINERAL-RESOURCE ASSESSMENTS 

The term "mineral resource" refers to a concentration 

of naturally occurring solid, liquid, or gaseous material 

in or on the Earth's crust in such a form and amount 

that economic extraction is currently or potentially 

feasible. The assessment of mineral resources in a 

designated area requires both the estimation of the 

amount and grade of identified resources and the assessment of the potential for the presence of as yet undiscovered mineral resources. Identified resources are 

specific bodies of mineralized rock whose location, quality, and quantity have been measured. The likelihood of 

the presence of undiscovered mineral resources is determined from earth science information and is presented 

as a statement of mineral-resource potential. 

The major difficulty in making assessments of 

mineral-resource potential is the need to describe and 

quantify an unknown that can be neither seen nor measured. At present, the best approach to assessment is to 

collect all available data on an area, to synthesize and 

integrate this data using geologic theories, and to compare all this with similar data from areas that have identified mineral deposits. This process of comparison, 

combined with experience and judgement, enables the 

earth scientist to reason the likelihood and types of 

deposits that might occur in an area 

CLASSIFICATION OF 

MINERAL RESOURCES AND 

MINERAL-RESOURCE POTENTIAL 

If a body of rock containing concentrations of useful 

minerals is exposed at the Earth's surface or has been 

penetrated by drill holes, it can be sampled and its 

dimensions measured. The samples can be analyzed, 

and the size of the body can be calculated. The result is a 

quantitative measurement or estimate of the amount of 

mineral-bearing rock that is known to occur, and the 

quantities of metals, nonmetals, or mineral fuels that it 

contains. Most of the resource assessments in these 

volumes are for study areas in which mineralized rocks 

are not exposed or are only partly exposed at the surface 

and have not been penetrated by drill holes. Assessments of resources in these areas are qualitative rather 

than quantitative. Of equal importance is the assessment of the likelihood that mineral or energy resources 

may or may not occur in the area. Mineral-resource 

4 

potential is the characteristic attributed to a geologic 

terrane that suggests the possible presence of mineral 

resources- metallic, nonmetallic, or energy. For consistency in these volumes only, therefore, the following 

terms and definitions were established so that uniform 

terminology would be used in these summaries of the 

many reports produced through two decades by many 

individuals. 

1. Areas that have substantiated mineral-resource 

potential are shown in red on the maps. The term "substantiated" is based on a record of past production or 

the occurrence of identified resources, and (or) on an 

assemblage of geologic data that strongly indicate the 

presence of undiscovered mineral resources. 

2. Areas that have probable mineral-resource potential are shown in pink on the maps. The term "probable" 

is based on an assemblage of data that support the 

interpretation that undiscovered mineral resources may 

be present. In some areas, probable and substantiated 

mineral-resource potential overlap. In these areas, a 

darker shade of red is used. 

3. Where data could be obtained, the resources at 

mines, deposits, or quarries are specified by tonnage 

and grade (concentration of the desired material or 

materials per unit of measure, commonly expressed in 

such terms as percent, ounces per ton, grams per metric 

ton, or barrels per acre). Where a mineral resource is 

defined in terms of tonnage and grade, it is referred to 

as " identified, " "demonstrated," and (or) " inferred" 

using the following definitions of the U.S. Bureau of 

Mines and the U.S. Geological Survey (1980, p. 2). 

Identified resources are those whose location, 

grade, quality, and quantity are known or estimated 

from specific geologic evidence. 

Demonstrated resources is a term for the sum of 

measured and indicated resources whose quantity is 

computed from dimensions revealed in outcrops, 

trenches, workings, or drill holes and whose grade 

and (or) quality are computed from the results of 

detailed sampling. 

Inferred resources is a term for resource estimates that are based on assumed continuity beyond 

those of the measured and (or) indicated categories 

for which there is geologic evidence that might or 

might not be supported by samples or 

measurements. 

Mines, quarries, or deposits of limited extent for 

which demonstrated or inferred resources are reported 

in the text are shown on the maps by a red mine symbol. 

Mines discussed in the text but for which no quantity of 

demonstrated or inferred resources can be reported are 

shown by a black mine symbol. Mineral occurrences for 

which no quantity of demonstrated or inferred resources 

is reported are shown by a black "X". 
Subdivisions in use by the U. S. Geological Survey Age estimates.!! of 

boundaries in 

million years lm.y.l 

Quaternary Holocene Epoch 

Period 0.010 - Pleistocene Epoch 

2 11.7-2.21-

Cenozoic Neogene Pliocene Epoch 

Era Subperiod 5 14.9-5.31-

Tertiary Mioce,le Epoch 

Period 24 123 -261-

Pa leogene Oligocene Epoch 

Subperiod 38 134-381-

Eocene Epoch 

55 154-561-

Paleocene Epoch 

63 163 -661-

Late Cretaceous Epoch 

Mesozoic Cretaceous Period 96 195-971- Phanerozo ic 

Era Early Cretaceous Epoch 

Eon 

Jurassic 138 1135-1411 -

Period Late, Middle, and Early Jurassic Epochs 

Triassic 205 1200-2151-

Period Late, Middle, and Early Triassic Epochs 

Perm ian 

'V 240 -

Period Late and Early Permian Epochs 

Pennsylvan ian Late, Middle, and Early 290 1290-3051-

Carboniferous 

Periods Period Pennsylvanian Epochs "-' 330 Mississippian Late and Early - Paleozoic 

Period Mississippian Epochs 360 1360-3651 - Era Devonian 

Period Late, Middle, and Early Devonian Epochs 

Siluriar. 

410 1405-4151 -

Period Late, Middle, and Early Silurian Epochs 

Ordovician 435 1435-440 1-

Perio d Late, Middle, and Early Ordovician Epochs 

Cambrian 500 1495-5101 -

Period Late, Middle, and Early Cambrian Epochs 

rv 570 .Y -

Late Proterozoic~ or Proterozoic Z !I 

Prot erozoic 900 -

Eon Middle Proterozoic~ or Proterozoic Y !I 

1,600 - Early Prote rozo ic11 or Proterozoic X~ 

Late Archean~ 

2,500 -- Archean 

Eon Middle Ar chean~ 

3,000 

Early Archean~ 

3,400 

3,800? -

.l! Ran ges reflect uncertainties of isotopic and biostratigraphic age assignments. Age of boundaries not closely bracketed 

by existing data shown by - . Decay co nstants and isotop e ratios employed are cited in Steiger and Jager 119771. 

1.! Rocks older than 570 m.y. also called Precambria n, a time te rm without specific rank . 

~ Geochronometric units 

~ Formerly used time terms 

Figure 2.- Geologic time scale, showing major goechronologic units (Geologic Names Committee, U.S. Geological Survey, 1983). 

5 
4. For coal resources and coal resource potential, the 

reporting system was modified slightly. Demonstrated 

coal resources are estimated separately for coal in beds 

more than 28 in. thick and for coal in beds between 14 

and 28 in. thick. Areas underlain by coal beds more than 

28 in. thick are shown on the map in each summary as 

areas of substantiated coal resource potential. Areas 

underlain by coal beds between 14 and 28 in. thick are 

discussed in the text, but are not shown on the map. 

5. The remaining areas are those that do not have 

identified mineral resources and (or) those lacking 

evidence of mineralization indicative of a potential for 

the occurrence of mineral resources. 

PROCEDURES OF 

MINERAL-RESOURCE ASSESSMENTS 

The staffs of the Geological Survey and the Bureau of 

Mines collaborated on the many investigations required 

to assess the mineral resources of the wilderness lands 

designated by Congress for study. The work involved 

geologic, geochemical, and geophysical studies by the 

Geological Survey. The Bureau of Mines sampled and 

mapped mines and prospects, compiled information on 

claims, and compiled data from exploration, mining, 

and production records. 

A geologic map was prepared for each area. Data from 

field observations and measurements, with existing 

geologic maps as a starting point, were used to compile 

the map that shows the distribution and structure of 

the various types of rocks- features that generally control the location of mineral resources. The geologic maps 

were prepared at scales appropriate to show the information necessary to make the assessment, generally at 

scales between 1:50,000 and 1:100,000 (1 inch equals 0.8 

miles and 1 inch equals 1.6 miles). A geologic time scale, 

which is a key to the ages of rocks discussed in the summaries, is shown in figure 2. In addition, more detailed 

geologic studies were made where they were considered 

necessary to the mineral-resource assessment. These 

studies included examination of rock sequences that 

may contain mineral resources; determination of the age 

and temporal sequence of the emplacement of intrusive 

rocks; determination of the time and nature of rock 

deformation and chemical alteration; and examination 

of hydrothermal (hot water) alteration zones and 

features that might be related to mineral deposits. 

Geochemical surveys were made of most areas as a 

means of determining patterns of anomalous (unusually 

high) metal values that might indicate undiscovered 

mineral deposits. Many kinds of mineral deposits are 

characterized by suites of elements that can be used to 

classify deposit types. Geochemical studies are used to 

6 

identify these suites and to help find and classify the 

areas that may have resource potential. The sampling 

and analytical techniques used were designed specifically to identify resource potential in the geologic environment of each particular area Most geochemical samples 

were of stream sediments, but samples of rocks, soils, 

and waters, and of heavy concentrates from stream 

sediments, were also collected and analyzed in many 

areas. Mineral deposits that are being eroded impart 

anomalously high metal values to stream sediments and 

concentrates. These high values can readily be distinguished from the normal or background values from 

drainage areas in which no mineral deposits are exposed. Analyses of stream sediments and their heavymineral fractions provide information not only about 

the metals present in mineral and rock fragments, but 

also about metals adsorbed by clay minerals from surface or ground water. 

Geophysical surveys using aeromagnetic, gravity, 

electromagnetic, and airborne gamma-ray techniques 

were made in many areas. These techniques provide 

information about the physical properties of the rocks 

and their distribution below the surface of the ground, 

and information that may be indicative of mineral and 

fuel deposits or of structures that might have controlled 

resource accumulation. 

Studies of mines, prospects, and mining claims included some surveying and geologic mapping, the 

sampling of specific areas, the analyzing of samples, 

and the collecting of data on production and reserves on 

present and past exploration and mining operations. 

Possible extensions of mineralized structures in existing workings were evaluated and the quantity and 

grade of resources were determined where possible. 

Detailed studies included sampling of mineralized areas 

identified in the geochemical survey; metallurgical tests 

were made when necessary. 

The results of all these studies were then integrated to 

compile a mineral-resource assessment report that 

describes the identified resources and outlines areas 

favorable for the occurrence of mineral resources. 

Singer and Mosier (1981) reviewed more than 100 

papers on regional mineral-resource assessment and 

found that of 15 methods of assessment the most widely 

used was one based on extrapolation from known areas, 

in which estimates were made directly by one or more 

individuals on the basis of their knowledge and experience. The extrapolation method has been used in the 

mineral assessments of wilderness lands because of constraints in time, money, and staff; the problems in dealing with undiscovered resources; and the lack of available subsurface data The method necessitated that 

knowledgeable, experienced people be assigned to study 

the lands in question and to make the assessments. 
The extrapolation method applied in the wilderness 

assessment starts with the synthesis of all available information on the geology, geologic history, and identified mineral and energy resources. The information 

thus generated sets general limits on the types of 

mineral deposits that might occur in a given area The 

area under investigation could then be compared with 

areas of known ore deposits, petroleum reservoirs, 

geothermal fields, or other resources. In such a way can 

be reasoned the likelihood of the occurrence of 

resources, and hence the mineral potential of the area 

under study. 

Activity by the mineral industry is one factor that 

must be considered in the assessment of an area. The 

presence of known deposits is a favorable attribute for 

any area, but the absence of known deposits does not 

necessarily indicate that the area has no mineralresource potential. Even the lack of evidence of mineral 

development and exploration may not be a negative 

sign about mineral-resource potential, especially for 

remote areas in which high costs discourage activity, or 

for areas in which newly recognized types of deposits 

can now be postulated. The studies summarized in these 

volumes assumed that undiscovered mineral deposits 

might be present in any area until information indicated 

that there was little likelihood for the occurrence of 

resources. Thus, a positive approach was maintained 

and the resource potential of areas was not reduced 

merely because adequate data were unavailable. 

The credibility of all assessments of mineral-resource 

potential is a matter of concern. The data available for 

virtually all wilderness lands are incomplete; subsurface 

data are lacking. Assessment of mineral-resource potential is by its nature speculative and involves considerable uncertainty. Construction of uniform quantified 

assessments is currently impossible. Assessing the resources of any mineral commodity on any parcel of land 

is a continuing process that as yet lacks universally applicable methods (Harris and Agterberg, 1981; Harris 

and Skinner, 1982). Thus, professional but subjective 

judgement is important to the assessments summarized 

in these volumes. 

THE NEED FOR 

CONTINUING ASSESSMENTS 

Assessments of mineral-resource potential are of a 

dynamic nature regardless of how they are conducted, 

or of the methods that are used. Final, once-and-for-all 

assessments of mineral-resource potential cannot be 

made. Areas should be reassessed periodically as new 

data become available, as new concepts of the factors 

that influence the concentration of minerals are developed, as new uses and extractive technologies for minerals are devised, and as the world's economy changes. 

For these reasons, the Congress specified that " recurring mineral surveys " of the wilderness lands should be 

made. 

Geology, technology, and economics are tightly entwined in mineral-resource assessment. Mineral resources have geologic limits and controlling technologic 

and economic factors that govern their utility 

(DeYoung and Singer, 1981). This perspective was expressed by Downing and Mackenzie (1979) who favored 

continuing reevaluation of exploration and development 

data They pointed out that geology offers information 

based on observation and concept, mineral-deposit genesis, and deposit modeling; that technology offers information on extraction methods, beneficiation, smelting, 

and refining and material use; and that economics offers 

information on market dynamics, the ability of a 

deposit or material to compete with other deposits or 

materials, and the effect of byproducts and coproducts 

on costs. Thus, the three fields are interrelated, and each 

has an important bearing on the others; communication 

between these fields needs to be nurtured and increased. 

Man cannot create mineral deposits, but he does 

create mineral resources as he learns to use the 

materials of the Earth, or, as Zimmerman (1964) said, 

"Resources are not, they become." Most regions on the 

Earth's crust may contain mineral deposits of some 

possible use if a market for the materials in the deposit 

should develop. To say that an area has no mineralresource potential is inadvisable, even though some 

areas may be classified as having little chance for the occurrence of resources of a particular mineral. Some of 

the areas that have no identifiable resource potential 

may contain new types of mineral deposits, recognizable 

and exploitable only in the future. For example, gold 

deposits of the Carlin-type (Nevada) in which the gold is 

too finely disseminated to be visible would not have 

been recognized prior to 1962; their characteristics were 

not known. Many common rocks contain small amounts 

of valuable minerals, but are not considered resources at 

present because extraction is too costly, or requires too 

much energy. Technology of the future may change 

what is now considered common rock into a useful resource if lower cost energy can be made available, a 

trend not currently seen. 

LEGISLATIVE HISTORY OF THE 

WILDERNESS SURVEYS 

The wildern ss concept was formalized by the Forest 

Service, U.S. Department of Agriculture, in 1924 with 

the designation of the Gila Wilderness in the Gila N a7 
tional Forest in New Mexico. The designated wilderness 

areas (Wild and Primitive) totalled 88 units, containing 

14.6 million acres by 1964. 

The Wilderness Act of 1964 designated as wilderness 

54 National Forest System areas comprising 9.3 million 

acres. It also required a study of each of the 34 National 

Forest primitive areas totaling 5.5 million acres, with a 

report to Congress by 197 4 as to their suitability or nonsuitability for wilderness. Included in the provisions of 

the Wilderness Act was a requirement for the Secretary 

of the Interior to direct mineral surveys of suitable 

areas under his jurisdiction in the National Park and 

National Wildlife Refuge Systems. 

The mineral-resource assessments of Federal lands 

described in these volumes were made in response to the 

Wilderness Act, Public Law 88-577, September 3, 1964. 

The Act specified in Sec. 4(d)(2) that the Geological 

Survey and the Bureau of Mines shall conduct mineral 

surveys of wilderness lands on a planned and recurring 

basis. The law also specified that the wildernesses 

would remain open to mining access until January 1, 

1984, at which time all the areas would be closed to access under existing mining and leasing laws. 

The resource assessments of the primitive areas 

began in 1965 because those areas had to be reported 

upon by September 1974. By the time the studies of the 

primitive areas were completed in 1973, many of the 

boundaries had been revised and 1.6 million acres had 

been added, an increase in area of about 30 percent. 

In 1970, the Forest Service, because of public and congressional interest, began to add new areas as candidates for wilderness designation. By 1973, these 

parcels, now referred to as study areas, included 3.7 million acres in 53 designated areas. 

In October 1973, the Forest Service added 274 more 

study areas in a program sometimes referred to as 

RARE (Roadless Area Review and Evaluation) that 

comprised about 12.3 million acres, including 1.9 million 

acres previously designated for study. 

In 1974, interest in establishing some wildernesses in 

the Eastern States led to a request by the Forest Service for mineral studies in about 600,000 acres in 58 proposed areas in that region. Congress passed the Eastern 

Wilderness Act (Public Law 93-622) on January 3, 

1975, which designated 207,000 acres as wilderness and 

125,000 acres of study areas to be examined and reported to the Congress by January 1980. 

In 197 4, Interior Secretary Rogers C. B. Morton requested a mineral survey of about 7.8 million acres in 

six areas administered by the Interior Department. 

These areas included: Glacier Bay National Monument, 

Alaska; Charles M. Russell Wildlife Refuge, Montana; 

Charles Sheldon Antelope Range, Sheldon National 

Antelope Refuge, and Desert Game Range, Nevada; and 

8 

Kofa Game Range and Cabeza Prieta Game Range, 

Arizona 

By early 1975; a total of 32.2 million acres of National 

Forest land had been designated wilderness or wilderness study areas, a designation that necessitated management according to wilderness standards, and that 

also required mineral surveys. 

The second Roadless Area Review and Evaluation 

(RARE II) was begun in June 1977. It identified 2,920 

roadless areas encompassing 62 million acres in National Forest and National Grasslands. The administration released the results of the study on April16, 1979, 

and recommended that 36 million acres be assigned to 

nonwilderness, that 15.4 million acres be assigned to 

wilderness, and that decisions on 10.6 million additional 

acres be deferred for further planning for all options. 

The status of lands in the "further planning" category 

was to be decided by 1985 through the regular landmanagement planning process by the Forest Service. 

In 1980, the 96th Congress established several 

wildernesses and wilderness study areas in New Mexico, Idaho, Alaska. Colorado, South Carolina, Missouri, 

Louisiana, and South Dakota Mineral surveys were required in wilderness study areas (totaling 2.7 million 

acres) within 3 years of the passage of these "State" 

bills. The rapid increase in the amount of land that 

required mineral surveys is shown on figure 3. 

The legislative acts, with their dates, that are pertinent to the evolution of the wilderness system can be 

obtained from the U.S. Forest Service. The legislative 

history and the texts of all the acts are available for 

inspection at the Library of Congress in Washington, 

D.C. 

WILDERNESS PROGRAM PUBLICATIONS 

Many of the results of mineral-resource assessments 

have been published as U.S. Geological Survey Bulletins. Some information was released as Open-File 

Reports to meet legislative and adminstrative requirements, and some were republished as more complete, 

formal reports. In 1979, a new publication format was 

introduced that uses maps for presentation of most 

data The joint report on mineral-resource potential by 

the Geological Survey and the Bureau of Mines is a map 

with a marginal text and an accompanying pamphlet, in 

the U.S. Geological Survey Miscellaneous Field Studies 

Map (MF) series. The mineral-resource potential report 

summarizes the information that led to the conclusions 

and outlines the areas of mineral-resource potential of 

each area. Other maps in the MF series on each area 

generally include the following: (1) a geologic map with a 

marginal text; (2) geochemical maps showing distribu-
a: 

<{ 

w 

>-

>-

en 

~ 

0 

:::::> 

f-

(./) 

a: 

0 

u.. 

0 

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(./) 

w 

0 

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1980 State Wilderness Bi lls 

APPROXIMATE 

TOTAL 

45 million acres 

2.7 million acres 

1979 RARE II Further Planning 

10.6 million acres 

1974-1975 Eastern Wilderness 0.6 million acres 

1973 Study areas 

7.2 million acres 

(adjusted) 

1970 Wi lderness additions 

3.7 million acres 

1964 Wilderness /> ct ------------ PL 88-577 

16.4 million acres 

1924 1964 1970 1973 1974 1975 1979 1980 

CHRONOLOGY, IN YEARS 

Figure 3.-Graph showing cumulative acreage of Federal lands designated for mineral surveys, 

1965- 19 3. 

40 

30 

(./) 

w 

a: 

u 

<{ 

u.. 

0 

(./) 

z 

0 

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_J 

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20 z 

w 

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10 

9 
tion of analytical values and anomalous areas for one or 

more chemical elements, with a marginal text; (3) geophysical maps showing various kinds of data and 

marginal notes of explanation; and (4) mine, prospect, 

claim, and sample-site maps with explanatory text prepared by the Bureau of Mines. 

Much of the raw geochemical and geophysical data 

supporting the resource assessment have been released 

as Open-File Reports by the Geological Survey. Much of 

the Bureau of Mines data have been released as OpenFile Reports; these are available at their field centers 

and in Washington, D.C. Both the Geological Survey 

and the Bureau of Mines announce the release of their 

respective Open-File Reports in their monthly list of 

publications. 

REFERENCES 

Brobst, D. A., and Pratt, W. P., eds., 1973, United States mineral 

resources: U.S. Geological Survey Professional Paper 820, 722 p. 

10 

DeYoung, J. H., Jr., and Singer, D. A., 1981, Physical acto ~ that 

could restrict mineral supply, in Skinner, B. J., ed., Eco11omic 

geology, 75th anniversary volume: Economic Geology Publishing 

Co., p. 939- 954. 

Downing, D. 0 ., and Mackenzie. B. W., 1979, Public policy aspects of 

information exchange in Canadian mineral explor[ltion: 

Kingston, Ontario, Queen's University, Centre for Resource 

Studies, Working Paper 15, 53 p. 

Harris, D. P., and Agterberg, F. P .. 1981, The appraisal of mineral 

resources, in Skinner, B. J., ed., Economic geology, 75th anruver· 

sary volume: Economic Geology Publishing Co., p. 897- 938. 

Harris, D. P., and Skinner, B. J ., 1982, Assessment of long-term supplies of minerals, in Smith, V. K., and Krutilla, J. V., eds., xplorations in natural re.lource economics: Johns Hopkins T>ress, 

p. 24 7- 326. 

Roscoe, W. E., 1971, Probability of exploration discovery in C811ada: 

Canadian Mining and Metallurgic:-! Bulletin. v. 64, no. 707, 

p. 134- 137. 

Singer, D. A., and Mosier, D. L., 1981, A review of regional mineral 

resource assessment methods: Economic Geology, v. 76. 110. 4, 

p. 1006- 1015. 

U.S. Bureau of Mines and U.S. Geological Survey, 1980, Principles of 

a resource/reserve classification for minerals: U .. Geological 

Survey Circular 831, 5 p. 

Zimmerman, E. W., 1964, Introduction ~ world resources: ew York, 

Harper and Row, 220 p. 

A 

34° 

32° 

12 

L A B A 

88<l 

-...../--

Tenn 

E:.s'see 

~ 

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~\ c::. 

~ 

• 1 

Birmingham 

( 0 

r6 

; 

Tuscaloosa 

e 3 

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Location of areas studied. 

M A 

8SO 

100 

MILES 
ALABAMA 

Map 

No. Name of Area 

2 Adams Gap and Shinbone Creek Roadless Areas 

3 Big Sandy, West Elliotts Creek, and Reed Brake Roadless Areas 

1 Sipsey Wilderness and Additions 

13 
14 

Graphit e 

MAP LOCATION 

0 3 

MILES 

EXPLANATION 

D Low-grade metasedimentary rocks of 

Talladega as used by Neathery, 1973 

---- Contact 

B (Paleozoic) 

Cheaha quartzite as used by Bearce , 1973 

(Paleozoic) 

Hillabee Chlorite Schist (Paleozoic) 

Poe Bri dge Mountain Formation --High-grade 

metamorphic rocks (Paleozoic) 

4 • Thrust fault--Sawteeth 

on upper plate 

X Mineral occurrence 

'X' Mine 

Figure 4.- Adams Gap and Shinbone Creek Roadless Areas. Alabama 
ADAMS GAP AND SHINBONE CREEK ROADLESS AREAS, ALABAMA 

By T. L. KLEI 1,

1 U . . GEOLO I L U RVEY, and 

D O ALD K. HARRI ON, U .. B REAU OF MI E 

SUMMARY 

The Adams Gap and Shinbone Creek Road.less Areas were evaluated for their 

mineral potential in 1982. The only resource within the established boundary of 

the road.less area is quartzite suitable for crushed rock or refractory-grade aggregate. The quartzite contains deleterious impurities and is found in abundance 

outside the areas. No other mineral or energy resources were identified in the 

road.less areas. 

CHARACTER AND SETTING 

The Adams Gap and Shinbone Creek Road.less Areas, 

Clay County, Alabama, cover approximately 15 sq mi. 

The areas, which are contiguous, were examined 

together and are referred to in this report as the study 

area They are bounded on the north by the Cheaha 

State Park and the Horse Creek drainage, on the west 

by USFS Route 600 (the Skyway Motorway), on the 

south by County Road 46, and on the east near County 

Road 31 and State Road 49. The study area includes 

Cedar Mountain, Robinson Mountain, and Talladega 

Mountain from Adams Gap to near McDill Point. Altitudes range from a low of 1000 ft above sea level where 

Horse Creek leaves the study area in the northeast to 

2342 ft above sea level at Odum Point. 

The study area contains low-grade regionally metamorphosed sedimentary rocks (Talladega group as used 

by Neathery, 1973) that are exposed from the coastal 

plain overlap in east-central Alabama to Cartersville, 

Georgia where they have been overthrust by rocks of 

the Blue Ridge Province, which lie to the east. The 

Talladega forms the frontal crystalline thrust sheet of 

the southern Appalachians in Alabama The Talladega 

overlies the easternmost fold and thrust belt of 

sedimentary rocks in the Valley and Ridge Province 

along a low-angle fault which dips eastward. The 

Talladega is composed of interlayered sandstones, 

siltstones, phyllites, slates, and lenses of conglomerate 

(Robinson and others, in press). 

Outcrops of the Hillabee Chlorite Schist and highgrade metamorphic rocks of the Poe Bridge Mountain 

'With con!Jibut.ions by G. R. Robinson. Jr .. USGS. 

Formation occur nearby to the south and east of the 

study area, but are separated from the Talladega within 

the study area by two eastward-dipping thrust faults. 

The USGS made a reconnaissance geochemical 

survey of the Adams Gap and Shinbone Creek Road.less 

Areas (Robinson and others, in press) to test for unidentified or unexposed mineral deposits that might be 

recognized by their geochemical halos. The rock, soil, 

and bulk stream-sediment samples collected by the 

USGS were analyzed by semiquantitative methods for 

31 elements in the USGS laboratories, Denver, Colorado (Erickson and others, 1983). No metallic deposits 

or unusual metal concentrations are reported to be in 

the study area, and none were found during the reconnaissance geologic mapping or reconnaissance geochemical survey. 

MINERAL RESOURCES 

Manganese, iron, and silica aggregate occur in the 

low-grade metasedimentary rocks of the Talladega 

within the study area but only the silica aggregate is 

considered to be a resource. Natural gas or petroleum 

may exist at depth (Robinson and others, 1983). 

Manganese and limonite prospects in the Talladega 

northeast of the study area occur along a trend which 

enters the eastern edge of the study area The 

manganese- and iron-bearing units in the study area are 

small in size, low in grade, have high phosphorous content, and are difficult to beneficiate. Therefore, no iron 

or manganese resource potential was identified. 

Quartzite from the Cheaha quartzite unit as used by 

Bearce (1973) was quarried for silica refractory brick at 

15 
the southern end of the study area Operations were 

discontinued because of excessive iron content, but two 

samples of quartzite collected several miles north of the 

quarry meet standards for refractory brick (Harrison 

and Armstrong, 1982, p. 14). Impurities in much of the 

rock and prohibitive quarrying and crushing costs make 

the Cheaha in the study area unattractive for both silica 

refractory or silica sand use. The quartzite in the study 

area is suitable for crushed stone, riprap, or common 

building stone but abundant resources for this commodity exists outside the area 

The Hillabee Chlorite Schist, outside the east and 

south boundary of the study area, contains pyrite, copper, zinc, and gold which occur in lenticular pods or 

zones. However, the geologic relationships of this unit 

indicate that it is not present in the study area 

Mineral resources associated with the high-grade 

metamorphic rocks of the Poe Bridge Mountain Formation include mica, graphite, and gold. Mica has been 

mined outside the study area from small tabular or lensshaped coarse-grained granitic rocks within the formation. Graphite, associated with graphitic schists, and 

gold, associated with quartzite layers, also occur in this 

formation. There is no current or recent production of 

mica, graphite, or gold from this group of rocks. The 

Poe Bridge Mountain Formation occurs only in a small 

southern part of the study area, and geological relationships indicate it does not underlie the rocks in the study 

area 

The rocks of the Talladega in the study area have 

been thrust over younger unmetamorphosed sedimentary rocks (Thomas and others, 1980). These younger 

sedimentary rocks may contain oil and gas resources. 

The low degree of metamorphism implies that both oil 

or natural gas could be present at appropriate depths. 

Because of the thrust fault contact separating the 

Talladega from underlying rocks, surface structures in 

the Talladega cannot be used to determine subsurface 

structures (and possible hydrocarbon traps) beneath the 

plane of the thrust fault. 

16 

SUGGESTIONS FOR FURTHER STUDIES 

Detailed seismic studies and deep drilling tests are 

needed before a reasonable estimate of hydrocarbon 

potential can be made. 

REFERENCES 

Bearce. D. N .. 1973, Geology of the Talladega metamorphic belt in 

Cleburne and Calhoun Counties. Alabama: American Journal of 

Science, v. 273. p. 742- 754. 

Erickson, M.S., Hanley. J. T., Kelley, D. L., and Sherlock, L. J .. 1983, 

Analyses and descriptions of geochemical samples, Adams Gap 

and Shinbone Creek Roadless Areas. Clay County, Alabama: 

U.S. Geological Survey Open-File Report OF- 3- 335. 

Harrison, D. K., and Armstrong, M. K., 1982, Mineral resources of 

Shinbone Creek and Adams Gap RARE I l Further Planning 

Area, Clay County, Alabama: U .. Bureau of Mines Open-File 

Report MLA-43-82, 19 p. 

eathery, T. L., 1973, The Talladega front- Synopsis of previous 

work, in Carrington, T. J .. ed, Talladega metamorphic front: Alabama Geological Society Guidebook, 11th Annual Field Trip, 

p. 1-9. 

Robinson, G. R., Jr., Klein, T. L .. and Lesure. F. G .. in press. Geologic 

map of Adams Gap and Shinbone Creek Roadless Areas, Clay 

County, Alabama: U.S. Geological urvey Miscellaneous Field 

Studies MF- 1561 - A, scale 1:48,000. 

Robinson, G. R .. Jr .. Klein, T. L., Lesure. F. G .. and Hanley, J. T .. 

in press, Geochemical survey of the Adams Gap and hinbone 

Creek Roadless Areas: U.S. Geological Survey Miscellaneous 

Field Studies MF- 1561- B, scale 1:48,000. 

Robinson, G. R., Jr., Klein, T. L., Lesure, F. G., Hani on, D. K.. and 

Armstrong, M. K., 1983, Mineral resource potential map of the 

Adams Gap and Shinbone Creek Roadless Areas, Clay County, 

Alabama: U.S. Geological Survey Miscellaneous Field tudies 

Ma!J MF-1561-C, scale 1:48,000. 

Thomas. W. A., and others. 1980, Geological synthesis of the 

southernmost Appalachians, Alabama and Georgia, in Wones. 

D. R., ed., Proceedings-The Caledonides in the U A: Virginia 

Polytechnic Institute, Department of Geology Sciences Memoir 

2, Blacksburg, VA, p. 91 - 97. 
BIG SANDY, WEST ELLIOTTS CREEK, AND 

REED BRAKE ROADLESS AREAS , ALABAMA 

By AM H . P ATTERSO , 1 U.S. GEOLOGICAL R EY a nd 

MIC HELLE K. ARM TRONG, .S. B REA OF Ml E 

SUMMARY 

Mineral surveys done in 1979-80 in the Big Sandy, West Elliotts Creek, and 

Reed Brake Roadless Areas, Alabama, indicate that the areas have little promise for the occurrence of metallic mineral resources. The three areas, however, 

have a probable potential for oil or gas. Probable coal resource potential exists in 

the Big Sandy and the West Elliotts Creek Roadless Areas. Clay and abundant 

sand resources occur in the roadless areas. Clayey sand has been used to 

stabilize USFS roads and in road grade construction. The clay and sand have little value as mineral resources because these commodities are abundant 

elsewhere in the region. 

CHARACTER AND SETTING 

The Big Sandy, West Elliotts Creek, and Reed Brake 

Roadless Areas are located about 10 mi south of 

Tuscaloosa in west-central Alabama The Big Sandy 

Roadless Area occupies 5 sq mi of which most is in 

Tuscaloosa County but small parts extend into Hale 

and Bibb Counties. The West Elliotts Creek Roadless 

Area containing 6.6 sq mi is in Hale County. The Reed 

Brake Roadless Area of 1 sq mi is in Bibb County. 

The exposed rocks in the three areas consist of the 

Coker and Gordo Formations that make up the Cretaceous Tuscaloosa Group and Pleistocene and Holocene 

alluvium (Szabo and Patterson, 1983). The two Cretaceous formations consist chiefly of sand, silt, and clay and 

contain minor quantities of gravel and sandstone. The 

Coker is 400-500 ft thick and the Gordo is 100-400 ft 

thick. The alluvium is composed of lenticular beds of 

fine- to coarse-grained sand, gravel, and clay. It occurs 

under the flood plains of the major streams. 

The Tuscaloosa Group is unconformably underlain by 

Paleozoic sedimentary rocks. The Paleozoic rocks 

underlying the Big Sandy and West Elliotts Creek 

Roadless Areas are equivalent to the Pennsylvanian 

Pottsville Formation of Pennsylvania Where exposed 

in the central and northern parts of Tuscaloosa County 

this formation consists of sandstone, shale, clay, and 

coal, and it has a thickness of 2500-4400 ft. The Potts1

Wi1Jl contribuLions from Pc!U C. M ory. U BM . 

ville Formation is probably missing below the Tuscaloosa Group in the Reed Brake Roadless Area where it 

is presumably underlain, at depths of no gre<~ter than 

700-800 ft below the surface, by one or more of the 19 

pre-Pottsville formations known to be present in outcrops in easternmost Tuscaloosa County and the central 

part of Bibb County. 

The Cretaceous Tuscaloosa Group in the three areas 

has undergone little deformation, but older rocks are 

more disturbed. The strata in the Tuscaloosa Group dip 

uniformly to the southwest at 30-40 ftJmi; no faults or 

folds were found in them in the three areas. The Pottsville Formation below the major unconformity between 

the Cretaceous and Paleozoic formations dips approximately 175 fUmi to the southwest. The pre-Pottsville 

rocks that probably underlie the Tuscaloosa Group in 

the Reed Brake Roadless Area are likely to be folded 

and faulted much like those cropping out farther to the 

northeast. 

MINERAL RESOURCES 

Bituminous coal of the Pottsville Formation is currently mined in northern and central Tuscaloosa County, and in northeastern Bibb County. Eight coal groups, 

each containing two to six coal beds, are recognized in 

Tuscaloosa County. Approximately half of the estimated 34 coal beds exposed in the county have been 

mined commercially. Coal has been mined 9.5 mi northeast of the Big Sandy Roadless Area in Tuscaloosa 

17 
l 

33° 

00' 

MAP LOCATION 

A -'-~~~ - ---- . . l 

I 

._ , 

Oil and gas, coal 

0 

L-. 

A-\ 

Big Sandy\S . \ \ 

08214 \ 

~ 

2 

MILES 

87°25' 

EXPLANATION 

D Geologic terrane with probable 

mineral-resou rce potential 

Alluvium (Quaternary) 

Coker Formation (Cretaceous) 

Gordo Formation (Cretaceous) 

--- Contact 

Figure 5.-Big Sandy, West Elliotts Creek, and Reed Brake Roadless Areas. Alabama 

Oil and gas 
County and has been mapped on the surface 5.5 mi 

northeast of this area 

Contours on top of the Pottsville Formation indicate 

the presence of this formation at depths ranging from 

less than 350 ft below the Big Sandy Roadless Area to 

about 750 ft below the West Elliotts Creek Roadless 

Area Although coal has not been proven to exist 

beneath these areas, its presence is highly likely if the 

subsurface geology of the Pottsville Formation in this 

location is similar to that in exposures a few miles to the 

north. Regional structural trends of the Birmingham 

anticline and the Helena thrust fault northeast of the 

areas (Szabo and Patterson, 1983) suggest that the coalbearing Pottsville Formation is absent under the Reed 

Brake Roadless Area 

The Big Sandy and West Elliotts Creek Roadless 

Areas have a probable resource potential for coal in the 

Pottsville Formation to depths of no more than 4000 ft. 

An average of 15,400 tons/acre has been used in 

estimating coal resources in central and northern Tuscaloosa County. On the assumption that coal is as abundant in the Pottsville Formation in the Big Sandy and 

West Elliotts Creek Roadless Areas as it is farther 

north, these two areas may contain approximately 100 

million tons of probable deep coal resource potential. 

Coal bed gas is presently produced in two coal 

degasification projects in the region of the three 

roadless areas, and natural gas has been found in two 

other gas fields (Thomas Sexton, oral commun., 1982). 

The producing Brookwood Degasification Coal Field is 

only about 15 mi northeast of the Big Sandy Roadless 

Area The other producing coal bed gas field, the 

Oakgrove Field, is farther northeast. The two nonproducing natural gas areas are the Wiley Dome and 

Lexington fields which are located about 35 mi north of 

the Big andy Roadless Area The natural gas in both 

fields is in the Mississippian and Pennsylvanian Parkwood Formation (Frank Hinkle, oral commun., 1982). 

The three roadless areas have probable resource 

potential for oil and gas, a conclusion based largely on 

industry activities in the National Forest and on 

geologic inferences. During the last seven years, 

numerous applications for oil and gas leases in the three 

roadless areas have been submitted to the U.S. Bureau 

of Land Management and several leases were in effect in 

May, 1981. Periodic seismic investigations along roads 

throughout the ational Forest (B. W. Fenton, oral 

cornmun., 1980) also indicate continuing interest by oil 

and gas companies. However, little is known about 

possible hydrocarbon host rocks at depth in the areas. 

They seem as favorable for the occurrence of natural gas 

as in northern Tuscaloosa County, where the Wiley 

Dome and Lexington fields have been found. The Parkwood Formation, which contains gas in these two fields, 

probably is present at depths of no more than 5000 ft in 

the region; however, this likelihood is no more than an 

inference because no deep holes have been drilled near 

the roadless areas. Coal beds, thought to be present in 

the Pottsville Formation in the subsurface of two of the 

roadless areas, are even more likely to contain gas than 

the degasification fields to the north because of greater 

depth of burial. Porous clastic beds in the Pottsville 

Formation may also serve as traps for hydrocarbons, 

because containing seals are likely to have been provided by impermeable zones in the upper part of the formation. Such zones are known to be too impermeable to 

permit the flow of ground water. 

In the three roadless areas plastic clay that may be 

suitable for use in structural clay products (Armstrong 

and Mory, 1982) occurs in two zones in the Gordo Formation and carbonaceous clay having bloating properties may be present in the Coker Formation. A clay zone 

at the base of the Gordo Formation is present in all 

three roadless areas. A zone near the middle of the formation is present in the West Elliotts Creek Roadless 

Area and is probably present in the Reed Brake Roadless Area The clays are chiefly mixtures of kaolinite 

and quartz and contain minor amounts of chlorite and 

muscovite. 

Current production of clay in the vicinity of the 

roadless areas is limited to two interrnitter.tly active 

pits. One of the pits is about 10 mi southeast of the 

Reed Brake Roadless Area Plastic clay from this pit 

has been used in making terra cotta at a plant in Birmingham (B. W. Fenton, oral commun., 1979). The 

other pit is located 12 mi farther southeast. The clay 

from this pit is used in local pottery. 

Preliminary ceramic evaluations indicate that clays in 

the roadless areas may be suitable for structural clay 

products (Armstrong and Mory, 1982). However, similar materials are abundant in the region (Patterson, and 

others, 1983). Clay and shale moved during coal stripping and discarded on waste dumps in Tuscaloosa and 

Bibb Counties are also a ceramic resource and would be 

more easily recovered than any of the clays from the 

three roadless areas. 

The Tuscaloosa Group and the alluvium in the three 

roadless areas and surrounding region contain enormous resources of sand and gravel that have been used 

for road construction and maintenance. Most deposits 

in the Tuscaloosa Group are in tabular and lenticular 

units having an average thickness of about 10 ft. Thin 

stringers of sandstone, cemented with iron oxide, and 

clay zones occur in some deposits. Little is known about 

the alluvium of the flood plains along South Sandy and 

Elliotts Creeks, but considerable quantities of sand are 

present in both lowlands. A pit consisting of three small 

workings in the eastern part of West Elliotts Creek 

19 
Roadless Area is intermittently active and has been the 

only mining in the three areas in recent years. 

The sand deposits in the three roadless areas are not 

shown on the map because of the large resources scattered throughout the region. The USFS has several inactive borrow pits outside the three roadless areas 

which are adequate for local needs. The city of Tuscaloosa, located about 10 mi north of the Big Sandy Roadless Area, is amply supplied with sand and gravel by extensive deposits in the Tuscaloosa Group and terraces 

along the Black Warrior River. Similar deposits occur 

along the Cahaba River, about 10 mi east of the roadless 

areas. 

SUGGESTIONS FOR FURTHER STUDIES 

Meaningful contributions to the energy resource 

potential of the three roadless areas would require new 

information on the rocks at depth, that are likely to con20 

tain coal and possibly oil and gas. Costly geophysical investigations and drilling would be required to obtain 

such information. 

REFERENCES 

Armstrong, M. K., and Mory, P. C., 1982, Mineral resources of Big 

Sandy and West Elliotts Creek RARE II and Further Planning 

Areas and Reed Brake RARE II Wilderness Area. Tuscaloosa, 

Hale, and Bibb Counties. Alabama: U . . Bureau f Mine 

Mineral Land As essmentOpen·File Report 50- 2, 23 p. 

Patterson, S. H., Armstrong, M. K., and Mory. P. C .. 1983, Mineral 

resource potential map of the Big andy, West Elliotts Creek, 

and the Reed Brake Roadless Areas, 1'uscaloo a, Hale, and Bibb 

Counties. Alabama: U .. Geological Survey Miscellaneous Field 

Studies Map MF- 1505- B. scale 1:250.000. 

Szabo, M. W., and Patterson. . H .. 1983, Geologic maps oi the Big 

andy, West Elliotts Creek, and Reed Brake Roadle Areas, 

Tuscaloosa, Hale, and Bibb Counties. Alabama: U . . Geological 

Survey Miscellaneous Field Studies Map MF- 1505-A, scale 

1:48,000. 
SIPSEY WILDERNESS AND ADDITIONS , ALABAMA 

By STA LEY P. SC HWEI f RTH , 1 U .. GE LO !CAL S R E , and 

PETER C. M O RY, .. B REA Of MINES 

SUMMARY 

On the basis of geologic, geochemical, and mineral surveys made in 1978- 79, 

the Sipsey Wilderness and additions are deemed to have little promise for the 

occurrence of metallic mineral resources. Although limestone, shale, and sandstone resources that occur in the area are physically suitable for a variety of 

uses, similar materials are available outside the area closer to transportation 

routes and potential markets. A small amount of coal has been identified in the 

area, occurring as nonpersistent beds less than 28 in. thick. Areas underlain by 

beds less than 28 in. thick, despite their contained coal, are not shown on the 

map. Oil and (or) natural gas resources may be present if suitable structural 

traps exist in the subsurface. Therefore, the area has a probable oil and gas 

potential. Small amounts of asphaltic sandstone and limestone, commonly referred to as tar sands, may also occur in the subsurface. 

CHARACTER AND SETTING 

The combined Sipsey Wilderness and seven roadless 

areas, hereinafter called the study area, comprise about 

66 sq mi in the William B. Bankhead ational Forest, 

Lawrence and Winston Counties, Alabama. These 

tracts are about 14 mi south-southwest of Moulton, Alabama, the county eat of Lawrence County. The U.S. 

Government owns about 95 percent of the surface and 

mineral rights in the study area. A mineral survey was 

made in 1978-79 and the results were published by 

Schweinfurth and others (1982). 

The study area lies in the Cumberland Plateau section 

of the Appalachian Plateaus physiographic province 

and is near the northern edge of the Warrior coal field. 

It is situated in the most rugged part of the northcentral section of Alabama and is traversed by deeply 

incised stream valleys with high, rock-cliff walls which 

contain numerous rock shelters and caves, and an occasional natural bridge or stand of rock pinnacles. Altitudes of the plateau surface in the study area range 

from about 1050 ft along the northern boundary to 

about 880 ft along Cranal Road on the south. Topographic relief averages approximately 400 ft throughout the study area 

'With contributions from Hobert B. !loss. Jr .. and Paul T. Behum. USBM. 

About 880 ft of Upper Mississippian to upper Lower 

Pennsylvanian sedimentary rocks crop out in the study 

area, and as much as 6800 ft of older Paleozoic sedimentary rocks may be present in the subsurface (Schweinfurth and others, 1981). The basal part of the exposed 

section consists of marine limestone assigned to the 

Bangor Limestone of Late Mississippian age. Overlying 

rocks of the Parkwood (Pennsylvanian) and the Pottsville (late Early Pennsylvanian) Formations consist of 

interbedded, coarse- to fine-grained, clastic continental 

and marine rocks. The Parkwood Formation crops out 

along valley walls and the Pottsville Formation forms 

the upland throughout the study area The Bangor 

Limestone is separated from the overlying Parkwood 

Formation by an erosional unconformity, which may be 

angular in the eastern third of the study area. The 

Parkwood in turn is separated from the overlying Pottsville Formation by an erosional unconformity that is 

angular in the eastern third of the area. Deposits of 

locally derived colluvium mantle the valley walls. 

Alluvium, consisting of unconsolidated clay, silt, sand, 

gravel, and large boulders, lies along the valley floors. 

The strata of the western part of the study area dip to 

the south at an average rate of about 55 ftJmi. The eastem part of the area is dominated by a low-relief, 

southward-plunging structural nose. The average 

plunge of the crest of this nose is about 40 ftJmi to 

21 
34° 

25' 

34° 

20' 

22 

87°30' 

Approximate roadless boundary 

I 

\ 

87°25' 

.... 

~\8211 ~---~---~ Approximate boundary 

0 

MILES 

87°20' 87°15' 

' 'v- (~ , __ /\08210 

') 

MAP LOC ATIO N 

5 

EXPLANATION 

D Geologic terrane with probable oil and 

gas potential 

-¢- Dry oil and gas test-hole 

llRocks 

C Rocks 

of Pennsylvanian age 

of Mississippian age 

--- Contact 

-...,.--- Fault--Bar and ball on downthrown side 

( Structural nose of anticline, showing direction 

of plunge--Approximately located 

Abandoned coal adit 

Abandoned quarry 

F igure 6.- Sipsey Wilderness and Additions. Alabama. 
the south. The nose is believed to be the result of at 

least two periods of local uplift during Early Pennsylvanian time followed by southward tilting in postPennsylvanian time. A large positive gravity anomaly 

and a large positive magnetic anomaly are associated 

with the structural nose. o faults were found in the 

study area, but evidence from nearby areas suggests 

that normal faults having throws of as much as 100 ft 

may exist wi thin it. 

MINERAL RESOURCES 

Limestone is the major resource found in the Sipsey 

Wilderness and additions and a large tonnage has been 

quarried from the Bangor Limestone near the study 

area, although most quarries have been abandoned. 

Road-abrasion and polish tests indicate the limestone is 

suitable for road metal and paving aggregates. Because 

of its durability and lack of porosity, the limestone may 

also be suitable for dimension stone. The USFS has 

quarried the Bangor Limestone for road metal and for 

construction of bridge abutments but in recent years 

crushed stone has been trucked in from quarries outside 

the national forest. Chemical analyses of sampled beds 

indicate that they have a high calcium-carbonate content, and are low in silica and magnesium carbonate 

(Mory and others, 1981). However, limestone resources 

are not shown on the map because extensive deposits of 

Bangor Limestone occur nort h of the study area in the 

Moulton Valley where they are more favorably located 

relative to transportation routes and potential markets. 

Large resources of clay, shale, and sandstone are presenL within the study area in the Parkwood and Pottsville Formations. Preliminary ceramic tests of clay and 

shale samples show that all samples were suitable for 

structural clay products such as building brick, floor 

brick, and tile. Five samples bloated during quick-fire 

tests and may indicate materials suitable for expanded 

lightweight aggregate. These commodities also are not 

shown on the map because similar materials are available outside the area closer to transportation routes and 

market . 

Thick beds of high-silica sandstone occur within the 

study area and some thinner beds of quartzose, feldspathic, and ferruginous sandstone also occur. Weakly 

cemented high-silica sandstone may be suitable for use 

as filter, furnace, molding, and abrasive (sand-blasting) 

sand, and low-grade glass sand. Other potential uses include construction sand, filler sand, and engine (traction) and. orne dense, well-cemented sandstone may 

be suitable for rough building stone, or dimension stone. 

Access to the sandstone within the study area is poor 

and more accessible sandstone resources are widely 

distribu ted throughout northern Alabama. 

As many as five thin, nonpersistent coal beds may be 

present in the Parkwood Formation in or near the study 

area. Of the five coal bed observed within the study 

area, only two beds are between 14 in. and 2 in. thick 

and contain demonstrated resources of coal; the remainder are less than 14 in. thick. Demonstrated coal 

resources are separately estimated for coal beds more 

than 28 in. thick and for coal in beds between 14 and 

28 in. thick. Areas underlain by beds less than 28 in. but 

more than 14 in. thick, despite their contained coal, are 

not shown on the map. Analyses of weathered coal 

samples from one of the beds indicate that the bed has a 

high ash content and a low to high sulfur content. The 

demonstrated coal resources of the area underlain by 

the two beds are estimated to be 7 27,000 short tons. 

Both coal beds are exposed in relatively steep valley 

walls where they are overlain by a thick sequence (as 

much as 300 ft) of massive beds of sandstone and shale. 

Coal has been mined for local domestic and blacksmithing use but no attempt was made to quantify the 

amount of coal removed from the study area; past mining is considered negligible. 

Heavy oil, dead oil, oil staining, and shows of natural 

gas have been reported from several rock units penetrated by tests drilled in or near the study area, but 

neither oil nor natural gas has been produced. The structural nose in the eastern part of the area doe3 not show 

closure at the urface but it is associated with strong 

geophysical anomalies and may contain closure at 

depth. ormal faults which are present near and possibly within the study area could produce structural 

traps in the subsurface in conjunction with the structural nose. ormal faults alone may also produce structural traps in the regionally southward clipping strata 

lying to the east and west of the stuructural nose. 

The structural nose has been tested by only one drill 

hole, the Brooks o. 1 U.S.A. (State permit o. 919), 

which was drilled to a total depth of 1815 ft in Upper 

Ordovician rocks. Oil shows were reported in the 

Bangor Limestone, Hartselle Sandstone, and Tuscumbia Limestone of Mississippian age. This test well did 

not penetrate the entire stratigraphic sequence reported 

to have had shows of oil and gas in other tests in northern Alabama. For example, a large show of natural gas 

was recorded in rocks of the Knox Group of Ordovician 

and Cambrian age penetrated in a test well (State permit o. 2284) about mi southwest of the study area. 

The Knox is considered by Haley (1981) to have the best 

possibility for the discovery of oil or gas in the area, but 

it was not reached in the Brooks test well. One other 

test hole was drilled in the study area The Murphy Oil 

Corp. test o. 2 (State permit o. 1587), was completed 

as a dry hole t a depth of 908 ft in the upper part of the 

Hartselle Sandstone. Slight shows of oil and asphalt 

were reported in the Hartselle. The Sipsey Wilderness 

23 
and additions is assessed as having a probable oil and 

gas resource potential. 

Limestone and sandstone beds of Mississippian age 

contain potentially valuable tar-sand deposits in northern Alabama. Asphaltic sandstone has been mined from 

outcrops of the Hartselle Sandstone in northern 

Lawrence County and used as road metal (Haley, 1981). 

However, the Hartselle does not crop out in the study 

area and the two tests drilled in the study area did not 

penetrate any major tar-sand impregnated intervals. 

o metallic mineral deposits were identified in the 

study, and none have been reported in the literature. A 

geochemical survey of the area disclosed no major geochemical anomalies (Grosz, 1981). 

SUGGESTIONS FOR FURTHER STUDIES 

The available geologic, geochemical, and geophysical 

data indicate that there is little promise for the occurrence of metallic mineral resources in the study area 

Oil and gas resources may underlie the area, but addi24 

tiona! exploration, especially deep drilling, is necessary before the area can be fully evaluated. 

REFERENCES 

Grosz. A. E .. 198t Geochemical survey of the ipsey Wilderness and 

additions, Lawrence and Winston Counties. Alabama: U .. Geological urvey Miscellaneous Field tudies Map MF- 1288-A, 

scale 1:50,000. 

Haley, B. R., 1981. Oil and natural gas potential ( ipsey Wilderness 

and additions): U.S. Geological Survey Admini trative Report, 

7 p. 

Mory, P. C., Ross, R. B., Jr .. and Behum, P. T., 1981, ineral 

resources of the Sip ey Wilderness and RARE II areas, 

Lawrence and Winston Counties. Alabama: U.S. Bureau of Mine 

Open· File Report MLA- 19-81, 42 p. 

Schweinfurth. . P .. Trent. V. A., and Helton, E. 0 ., 19 1, Geologic 

map of the Sip ey Wilderness and additions, Lawrence and 

Winston Counties, Alabama: U.S. Geological rvey 

Miscellaneous Field tudies Map M F - 1288- B, scale 1:50,000. 

Schweinfurth, S. P., Mory, P. C., Ross, R. B .. Jr., and Behum, P. T., 

19 2, Mineral resource potential map of the Sipsey Wilderness 

and additions, Lawrence and Winston Counties, Alabama: U.S. 

Geologica l Survey, M isce llaneou Field tudies Map 

MF- 12 8- 0,scale1:50,000. 

A L A s K A 

0 

~ 300 

Location of areas studied. 

26 
ALASKA 

M ap 

No. ameof Area 

1 Chugach National Forest, study areas 

2 Glacier Bay National Monument Wilderness study area 

5 Granite Fiords Wilderness study area 

4 Tracy Arm-Fords Terror Wilderness study area and vicinity 

3 Western Chichagof and Yakobi Islands Wilderness study area 

27 
61 

2 

0 

Geologic terrane with substantiated 

mineral-resource potential D Geologic terrane with probable 

mineral-resource potential 

Cu Copper 

Au Gold 

Pb Lead 

Ag Silver 

Zn Zinc 

~ Mine or deposit 

X Mineral occurrence 

~ Mine 

50 

M ILES 

Alluvium and glacial deposits (Quaternary) 

Sedimentary rocks (Pleistocene to Eocene) E.,.::,~:-:='1 

Intrusive rocks (Ol igocene and Eocene) 

Sedimentary rocks of the Orca Group 

=~= (Eocene? and Paleocene) D Volcanic rocks of the Orca Group 

(Eocene ? and Paleocene) D Valdez Group (Upper Cretaceous) 

--- Contact 

Fault 

B Area discussed in text 

Figure 7.-Study areas within the Chugach ational Forest. Alaska 
STUDY AREAS WITHIN THE CHUGACH NATIONAL FOREST ALASKA 

By STE EN W . EL N, 

LDI j AN 0 1 , 

. GEOLOG I AL R \'EY, and 

. B REA OF MINE. 

SUMMARY 

A multidisciplinary mineral survey conducted from 1979-82 in the Chugach 

National Forest wilderness study lands, including roadless areas and the College 

Fiord- ellie Juan Wilderness Study Area, has determined that there are areas 

with substantiated resource potential for gold, silver, copper, and zinc and areas 

with probable resource potential for all of the above metals as well as molybdenum, nickel, manganese, chrome, antimony, and lead. Areas in the southeast 

part of the national forest have substantiated potential for coal, oil, and gas 

resources. 

CHARACTER AND SETTING 

The Chugach National Forest, located in the KenaiChugach Mountains physiographic province of Alaska 

is an area of about 9000 sq mi. It is located 45 rni by 

road from Anchorage. The towns of Whittier and Cordova are within the forest boundary; Valdez lies north of 

the national forest. 

Much of the region encompasses Prince William 

Sound, one of the largest embayments in the coast of 

Alaska. The area was extensively glaciated and glaciers 

are still present in the Chugach Mountains which attain 

an altitude of 13,250 ft within the forest. 

The Chugach National Forest is underlain principally 

by two major geologic units, the Valdez Group (Upper 

Cretaceous) and the Orca Group (Paleocene to Eocene?). 

Both groups consist of metamorphosed graywacke, siltstone, and shale in deposits forming marine turbidites. 

They also include mafic complexes consisting of sheeted 

dikes, pillow basalt flows, and minor gabbro and 

ultramafic bodies. Sedimentary rocks younger than the 

Orca Group range from Eocene to Pleistocene in age. 

These rocks were deposited in a continental margin 

basin where marine regression and transgression took 

place during the middle Eocene and possibly during the 

early Miocene and are only exposed in the southeastern 

part of the forest. 

Plutonic rocks were emplaced in the Eocene and 

Oligocene. Most of the plutons are granitic in composition, but an early phase of the Oligocene plutons ranges 

in composition from quartz diorite to gabbro. 

Geochemical surveys were conducted to help identify 

the resource potential of the national forest (R. J. 

Goldfarb and Peter Folger, written cornmun. 1982; R. J. 

Goldfarb and others, written cornmun., 1982; Jansons, 

1981). Stream-sediment, panned concentrate, rock, and 

mineral samples were collected and analyzed. Suites of 

elements present in anomalous concentrations were 

used to assist identification of areas with potential for 

the various types of mineral resources which occur 

within the national forest. 

A gravity study shows a regional decrease in gravity 

from south to north and west, of about 130 milligals, 

which probably represents an approximate 12- rni increase in crustal thickness between the Continental 

Shelf and the Chugach Mountains. A major gravity 

feature that is well developed is an arcuate high that 

trends northward from Elrington Island, through 

Knight Island and apparently connects with an eastward trend from Glacier Island through Ellamar and 

further eastward. This gravity high roughly coincides 

with outcrops of the Orca Group mafic volcanic rocks, 

and indicates a thickness of as much as 6.5 rni for these 

rocks. Regional gravity data in this area is probably not 

useful for detailed analysis or detection of local 

mineralization. 

The aeromagnetic survey data show a pair of regional 

gradients defined by contours almost paralleling the 

northern and western boundaries of the national forest 

and indicating a decreasing field strength to the north 

and west. Almost all of the other major features of the 

magnetic data seem to be associated with the distribution of the more magnetic mafic volcanic rocks. Most 

granitic plutons seem to have weak magnetic signatures 

29 
and low susceptibilities. The Perry Island pluton has 

the strongest magnetic expression of these plutons and 

has several unique features including minor amounts of 

tungsten in associated quartz veins. 

Placer gold was discovered on the Kenai and Russian 

Rivers in 1848. Placer mining began in the Hope area in 

about 1896 and continued into the early 1900 's. Since 

1980, 15-20 placer operations producing 1000-2500 oz 

gold/year were active during the 3- to 4-month mining 

season in the Kenai Peninsula area Currently approximately 1860 placer claims are located within the 

Chugach National Forest. Lode gold has been mined at 

several places in the national forest. The first lode 

claims were located in 1898. Although production 

figures are incomplete, ar1 estimated 264,400 oz of gold 

has been recovered from the national forest from both 

lode and placer sources. 

Copper prospects have been developed in the area 

since 1897 and substantial production has come mainly 

from four mines and minor amounts from at least 17 

other operations. Production from the national forest is 

estimated at nearly 206,400,000 lb of copper; silver and 

gold were also recovered from copper ores. 

Coal was produced intermittently in the early 1900's 

from the southeastern part of the national forest. About 

20,000 tons were extracted. 

Petroleum exploration started in 1901, and oil was 

produced from the southeastern part of the national 

forest and refined at Katalla from 1904 to 1933. Production was nearly 154,000 barrels. 

MINERAL RESOURCES 

The principal areas of probable and substantiated 

resource potential for base and precious metals are 

made up of Valdez and Orca Group volcanic and sedimentary rocks. Although it has been commonly accepted that the Valdez and Orca Groups represent two 

different mineral provinces (Tysdal and Case, 1982), the 

Valdez Group characterized by gold mineralization and 

the Orca Group characterized by copper mineralization, 

the current study indicates that both kinds of mineralization occur in each group. Substantiated resource 

potential for base or precious metals occurs in 11 areas 

and 9 additional areas have probable resource potential 

for base or precious metals. Numerous mines with 

demonstrated resources are shown on the map. 

Four areas have substantiated resource potential for 

copper-zinc sulfide deposits (areas A-D, on map) that are 

spatially related to mafic volcanic rocks. The base-metal 

sulfide deposits may represent sites of submarine thermal hot springs which provided both the sulfur and the 

metals by leaching from ocean floor sediments and 

30 

underlying rocks. Six additional areas have probable 

potential for copper-zinc sulfide deposits (areas E-J). 

Additional resource potential for lead, nickel, chrome, 

gold, and silver would occur in these areas. 

The geology of the gold mineralization is somewhat 

more complex. Gold in the Valdez Group is found in 

quartz veins that have been dated at 53 million years 

which cut sedimentary rocks, and quartz veins in 

34-million-year-old plutons in the Port Wells district. 

Within the Valdez Group sedimentary rocks, the goldbearing quartz veins occur along fractures and shears 

which crosscut regional structure and fabric. Seven 

areas of substantiated precious-metal resource potential 

(areas K-Q) and three areas of probable precious-metal 

potential (areas R-T) are in the Valdez Group rocks. In 

the Orca Group, gold mineralization is restricted to 

quartz veins cutting sedimentary rocks near the 

51-million-year-old McKinley Lake pluton, quartz veins 

cutting greenstone on Culross Island, and on Bligh 

Island and Blue Fiord. These areas have a substantiated base- and precious-metal resource potential. 

Favorable conditions for gold mineralization were met 

both near granitic plutons of both Eocene and Oligocene 

age, and regionally where the rocks were subjected to 

low greenschist facies metamorphic conditions. 

Mineral-resource potential for copper, lead, zinc, 

molybdenum, arsenic, and antimony as byproducts occur in the areas of precious-metal resource potential. 

Placer gold resources are principally confined to the 

Kenai Peninsula area on the west side of the national 

forest, although occurrences have been identified in 

almost all of the metal-bearing resource potential areas. 

These areas are not shown on the map because of problems of scale. 

Extensive coal deposits occur in rocks in the Bering 

River area on the east side of the national forest. Although the extent of the field is great and structurally 

complex, large tonnages of minable coal appear to be 

present. The area is classified as one of substantiated 

coal resource potential; the coal rank includes bituminous, semianthracite, and anthracite. 

The Katalla area, just south of the Bering River area, 

is one of substantiated potential for oil and gas. Although the production of the Katalla field over a 

30-year period was relatively small, and the complex 

structure and lack of suitable reservoir rocks in the area 

suggest that major fields are unlikely. The past history 

of production and abundant surface evidence-including 

oil and gas seeps-may indicate that continued exploration is warranted. 

SUGGESTIONS FOR FURTHER STUDY 

Future study in the Chugach National Forest should 
focus on several aspects of the geology and mineralresource occurrences to improve the understanding of 

the deposits. The determination of sedimentary facies 

associated with sedimentary hosted copper deposits 

would help to identify areas of greatest resource 

possibility. A study of stable isotopes in massive sulfide 

deposits is needed to better define genesis of the 

deposits. The study of the low-flow ground-water component of glacial melt would assist in the geochemical 

assessment of areas with extensive glacial cover. A 

study of stratigraphic units and sedimentary facies of 

the Orca Group would help to decipher controls for 

mineralization. An investigation of the relationship of 

metamorphic grade to the gold lode deposits and 

evaluation of zinc and barium geochemical anomalies 

found on Kayak Island and in the Don Miller Hills is 

needed to better assess resource potential. A study of 

textural and geometric relationships of sulfide minerals 

from deposits in shear zones and from unsheared areas 

will provide for a better understanding of the structural 

controls of sulfide mineralization. The study of the trace 

elements in sulfide minerals, and an attempt to establish timing of sulfide mineralization in sediment and 

volcanic hosted sulfide deposits is needed for a better 

understanding of the genesis and distribution of these 

resources. 

REFERENCES 

Jansons, Uldis, 1981, 1979 Bureau of Mines sampling sites and 

analytical results for san1ples collected in the Chugach ational 

Forest. Alaska: U .. Bureau of Mines Open-File Report 3- I. 

229 p. 

Nelson. S. W., Barnes. D. F .. Dumoulin. J. A .. Goldfarb. R. J .. Koski, 

R. A., Miller, M. L .. Mull. C. G .. Pickthom. W. J., Janson , Uldis. 

Hoekzema R. B .. Kurtak. J. M., and Fechner. . A .. in pr 

Mineral resource potential map of the Chugach ational Forest. 

Alaska: U.S. Geological urvey Miscellaneous Fi ld tudies Map 

MF- 1645- A. scale 1:250,000. 

1'ysdal, R. G .. and Case. J. E., 1982, Metalliferous mineral re ource 

potential of the Seward and Blying Sound quadrangles, south rn 

Alaska: U.S. Geological Survey Mi celleanous Field tudie Map 

MF-880- H. scale 1:250,000. 

31 
138° 

32 

137° 

Approximate 

Zn , Cu 

/Cr. Co , Ni, Cu , Zn, Pb 

MAP LOCATION 

0 

MILES 

EXPLANATION 

- Geologic terrane with substantiated 

mineral-resour..:e potential 

Geologic terrane with probable D mineral-resource potential 

Cr Chromium 

Co Cobalt 

Cu Copper 

Au Gold 

25 

Pb 

M o 

Ni 

Ag 

w 

Zn 

~ 

B 

136° 

I C H t. G 

Lead 

Molybdenum 

Nickel 

Silver 

Tungsten 

Zinc 

Mine or deposit 

Location discussed in text 

Figure 8.-Glacier Bay ational Monument Wilderness study area. Alaska. 

D 
GLACIER BAY NATIONAL MONUMENT 

WILDERNESS STUDY AREA, ALASKA 

By D A\ 10 A. BREv , U .. GEOLOC I , 1. RYE\' , and 

ARTH R L. KIMBALL .S. B REA F MI NE 

SUMMARY 

Glacier Bay National Monument is a highly scenic and highly mineralized 

area about 100 mi west of Juneau, Alaska. Four deposits with demonstrated 

resources of nickel, copper, zinc, and molybdenum have been identified within 

the monument and eleven areas of probable or substantiated mineral-resource 

potential have been identified, according to studies conducted in 1975- 79. The 

monument is highly mineralized in comparison with most areas of similar size 

elsewhere in southeastern Alaska, and present estimates of mineral resources 

are considered conservative. 

CHARACTER AND SETTING 

The Glacier Bay National Monument is an area of 

about 4400 sq mi in the Pacific Border Ranges 

physiographic province, centered about 100 mi westnorthwest of Juneau, Alaska. It was studied by the 

USGS and USBM and the results were published in 

1978 (Brew and others, 1978). 

The monument includes a variety of environments 

favorable for metalliferous mineral deposits and contains significant known magmatic segregation, 

porphyry-molybdenum, porphyry-copper, vein-gold, 

base-metal skarn, volcanogenic-base-metal, and beachplacer deposits. It also includes environments favorable 

for coal, oil and gas, geothermal energy, and industrial 

minerals, but none of these are likely to be present in 

significant amounts. 

The USGS studies included reconnaissance geologic 

mapping, reconnaissance bedrock, and stream-sediment 

geochemical sampling, and field examination of a few of 

the mines, prospects, and metallic mineral occurrences 

studied in more detail by the USBM. Statistical analysis (Johnson, 1978) identified samples that contained 

anomalous amounts of one or more significant elements. 

The USBM mining engineering studies included mining claim record search; on-site claim, mine, and prospect investigations; mapping and sampling of stained 

zones, altered zones, and geochemically anomalous 

sites; and evaluation and interpretation of private 

reports concerning mines and prospects. 

About 1200 claims, most of them lode, have been 

recorded in the Haines and Juneau recording districts 

as being within the area studied. A search by the U.S. 

ational Park Service determined that about 200 were 

active in 1977. Between 7000 and 8000 oz of gold wer 

produced from the Reid Inlet gold district between 1938 

and 1970, and about 4000 oz of gold and an unknown 

amount of platinum were produced from the Pacific 

Coast beach placers between 1890 and 1917. 

Geologically, the monument is extremely complex, 

reflecting a long history of sedimentation, volcanism, 

intrusion, and deformation in part near the boundary 

between the orth American continental crustal plate 

and the Pacific oceanic crustal plate. Layered sedimentary and volcanic rocks range from early Paleozoic age 

through Pleistocene, with apparent large gaps in the 

late Paleozoic and early and middle Mesozoic. Intrusive 

rocks range from Middle Jurassic age through Middle 

Tertiary, the major subdivisions being (1) foliated 

granitic rocks of mid-Cretaceous age, (2) locally foliated 

granitic rocks of Tertiary or Cretaceous age, (3) layered 

cumulus-type gabbro complexes of Tertiary age in the 

Fairweather Range, and (4) unfoliated granitic rocks of 

mid-Tertiary age. 

MINERAL RESOURCES 

Four deposits with important demonstrated 

mineral resources are known in the monument. They 

are, from west to east, (1) the Brady Glacier nickelcopper deposit in the Fairweather Range, (2) the 

Margerie Glacier copper deposit near Tarr Inlet, (3) the 

Orange Point zinc-copper deposit on Johns Hopkins Inlet, and (4) the unatak molybdenite deposit. 

33 
The Brady Glacier nickel-copper deposit (no. 1 on 

map) is a largely glacier covered magmatic-segregation 

sulfide occurrence in peridotite and gabbro at the base 

of a layered gabbro complex of unknown age in the 

Crillon-La Perouse area. The deposit is estimated to contain 90 million tons of demonstrated resources of 0.53 

percent nickel, 0.33 percent copper, and resources of 

platinum group metals. An additional 90 million tons of 

resources of the same grade are also likely to be present. 

The Margerie Glacier copper deposit (no. 2) is a fairly 

well exposed porphyry-copper occurrence in granitic 

rocks of probable Tertiary age. The deposit is estimated 

to contain 160 million tons of demonstrated resources of 

0.2 percent copper, 0.008 oz gold/ton, 0.13 oz silver/ton, 

and 0.01 percent tungsten. Higher grade sulfide-bearing 

quartz veins occur within this large volume. 

The Orange Point deposit (no. 3) is interpreted to be a 

volcanogenic zinc-copper sulfide occurrence. The host 

rocks are moderately well exposed metamorphosed 

andesites of late Paleozoic or Mesozoic age. The deposit 

is estimated to contain 270,000 tons of demonstrated 

resources of 2.7 percent copper, 5.2 percent zinc, 0.03 oz 

gold/ton, and 1.0 oz silver/ton, and an additional 

530,000 tons of demonstrated resources of 0.4 percent 

copper, 0.3 percent zinc, 0.006 oz gold/ton, and 0.35 oz 

silver/ton. 

The unatak molybdenum deposit (no. 4) is a 

porphyry-molybdenum occurrence in hornfels of original early to middle Paleozoic age and is probably 

related to nearby Tertiary granitic bodies. The wellexposed deposit is estimated to contain 145 million tons 

of demonstrated resources of 0.04 to 0.06 percent 

molybdenum and 0.02 percent copper accessible to surface mining, and an additional 9.1 million tons of 

demonstrated resources containing 0.06 percent molybdenum and 0.02 percent copper below sea level near 

shoreline. Within this volume is a potentially important 

higher grade section. 

In addition to the four known deposits, five areas 

within the monument are considered to have substantiated mineral-resource potential: the Crillon-La 

Perouse nickel-copper area (A, on map), Margerie 

Glacier porphyry c_opper area (B), Reid Inlet gold area 

34 

(C), Rendu Glacier copper area (D), and Muir Inlet 

copper, zinc, and molybdenum area (E). 

Six areas considered to have probable mineralresource potential are recognized within the monument. 

They are, from west to east, the Mount Fairweather 

chrome, cobalt, nickel, and copper area (F), Margerie 

Glacier northeastern extension copper area (G), 

Margerie Glacier southern extension zinc-copper area 

(H), Muir Inlet extension copper and molybdenum area 

(I), Casement Glacier porphyry copper and molybdenum 

area (J), and White Glacier zinc and copper (K) favorable 

areas. 

Three other areas are also believed to have probable 

mineral-resource potential as they contain previously 

unknown geochemical and (or) geophysical anomalies 

that may indicate the existence of undiscovered 

resources. The anomalies which have not been field 

checked are porphyry copper and molybenum (L), 

chrome, cobalt, nickel, copper, lead, and zinc (M), and 

copper, lead, zinc, silver, and gold ( ). 

SUGGESTIONS FOR FURTHER STUDIES 

There are a few areas in the northern part of the 

monument that have not yet been mapped in even 

reconnaissance fashion, a great many intrusive bodies 

of undetermined Jurassic or Cretaceous age that are 

critical to the definition of contrasting intrusive belts, 

and a major ancient suture zone; all of these may have 

had direct or indirect effects on the mineralization and 

more detailed studies would improve our understanding 

of the resource potential. 

REFERENCES 

Brew, D. A., Johnson, B. R., Grybeck. Donald, Griscom, Andr w, 

Barne , D. F., Kimball, A. L., Still, J.C., and Rataj, J. L. , 1978, 

Mineral resources of Glacier Bay ational Monument Wildeme s 

Study Area, Alaska: U.S. Geological Survey Open·File Report 

7 - 494, 670 p. 

J ohnson, B. R., 1978, Statistical analysis of geochemical data frorr 

Glacier Bay ational Monument, Alaska: U.S. Geological Surve} 

Open· File Report 78-495. 
GRANITE FIORDS WILDERNESS STUDY AREA, ALASKA 

By HENRY C. BERG 

TOM L. PITTMA 

.S. GEOL ,I AL RVEY , and 

.. B REA OF MI. E 

SUMMARY 

Mineral surveys in 1972-73 and in 1975-78 of the Granite Fiords Wilderness 

study area revealed areas with probable and substantiated mineral-resource 

potential. In the northeastern sector, areas of probable and substantiated 

resource potential for gold, silver, and base metals in small, locally high grade 

vein and disseminated deposits occur in recrystallized Mesozoic volcanic, 

sedimentary, and intrusive rocks. In the central part, areas of probable resource 

potential for gold, silver, copper, and zinc in disseminated and locally massive 

sulfide deposits occur in undated pelitic paragneiss roof pendants. A 

molybdenite-bearing quartz vein has been prospected in western Granite Fiords, 

and molybdenum also occurs along with other metals in veins in the northeastern sector and in geochemical samples collected from areas where there is 

probable resource potential for low-grade porphyry molybdenum deposits in 

several Cenozoic plutons. o energy resource potential was identified in the 

course of this study. 

CHARACTER AND SETTING 

The Granite Fiords Wilderness study area is in 

southeastern Alaska, about 35 mi northeast of the town 

of Ketchikan. About 1 mi of the northern border is the 

International Boundary between Alaska and British 

Columbia. The area is entirely within the Tongass ational Forest and encompasses about 1000 sq mi of 

remote, nearly virgin wilderness. There are no roads or 

well-developed trails in the study area The Granite 

Fiords Wilderness study area was incorporated into 

Misty Fiords National Monument by the Alaska National Interest Lands Classification Act of 1981. 

The part of the area that borders Behm Canal is accessible by boat. Elsewhere, access is by foot and 

helicopter, and by float-equipped airplanes that can land 

on several of the lake£. The northeastern part of the area 

can also be reached by glacier and cross-country trek 

from the head of an old, partly obliterated trail that 

leads from the village of Hyder to the eastern boundary 

of the study area. 

The scenery in Granite Fiords is dominated by glacially sculpted features such as deep fiords and broad 

U-shaped valleys walled by sheer cliffs more than 3000 

ft high. Most of the area was completely overridden by 

glacial ice, resulting in broad, rounded ridge crests. In 

the northern reaches, however, the mountains locally 

stood above the highest level of the ice and are 

characterized by matterhorns and knife-edged ridges, 

punctuated by spires and pinnacles. Small permanent 

snowfields and ice tongues dot the mountains throughout the study area but in the northern reaches, the land 

is still in the grip of glacial ice. There, only isolated 

spires and razor-backed ridges of bedrock penetrate the 

massive icefields and coalescing valley glaciers. 

The average elevation of the rounded ridges is about 

3000 ft. Along the deep fiords that indent the western 

part of the study area, these ridges rise directly from sea 

level, resulting in spectacular halfdomes and buttresses 

closely resembling those in Yosemite Valley, California 

The highest peaks in Granite Fiords are along and near 

the northern boundary. At 7499 ft, Mount John Jay on 

the International Boundary is the highest, and at least 

half a dozen other nearby peaks exceed 6000 ft. 

The climate is characterized by heavy precipitation, 

probably equivalent to more than 100 in. of rainfall per 

year. Vegetation consists of dense, nearly impenetrable 

rain forest at low elevations, and brush, moss, and 

lichen at higher levels. Significant forest cover is 

restricted to the area near Behm Canal and along the 

major river alleys. 

Granite Fiords Wilderness study area lies mainly 

within the Coast Range batholithic complex, a terrane 

mainly of Mesozoic or Cenozoic plutonic rocks and of 

35 
36 

130°30' 

' " · · ·MAP LOC ATION 

0 10 

M ILES 

EXPLANATION 

- Geologic terrane with substantiated 

mineral-resource potential 

D Geologic terrane with probable 

mineral-resource potential 

Cu Copper 

Au Gold 

Pb Lead 

M o Molybdenum 

Ag Silver 

w Tungsten 

Zn Zinc 

X Mineral occurrence 

D Granodiorite and quartz monzonite 

(Tertiary) 

D Undivided plutonic and subordinate 

metamorphic rocks (Mesozoic or 

Cenozoic) 

-- - Granodiorite (Mesozoic) 

• • ~ : ;. ' Andesitic volcanic and sedimentary • < • rocks (Mesozoic) 

LZJ Paragneiss (Age unknown) 

Contact 

B Area discussed in text 

Figure 9.-Granite r'iords Wilderness study area, Alaska 
high-grade metamorphic rocks of unlrnown age. Other 

rocks in the study area include recrystallized Mesozoic 

andesitic volcanic rocks, detrital sedimentary rocks, 

and granodiorite that crop out near the northeastern 

boundary and Quaternary lava flows that underlie small 

areas near the southwestern boundary. 

The mineral resources of the Granite Fiords Wilderness study area were surveyed in 1972-73 (Berg and 

others, 1977) and in 1975-78 (Berg and others, 1978). 

Two-thirds of the batholithic complex in the Granite 

Fiords study area is of plutonic rocks-chiefly quartz 

diorite, granodiorite, and quartz monzonite-that range 

in structure from strongly gneissoid to massive and 

nonfoliated. The plutons are progressively more silicic 

and massive northeastward across the batholith. The remaining third of the complex consists of banded gneiss 

derived mainly from sedimentary rocks (paragneiss) and 

minor amphibolite that originally was intermediate to 

mafic igneous rocks. In some places, the paragneiss 

grades imperceptibly into the adjacent granitic plutons; 

in others it occurs in striking, sometimes even bizarre 

patterns of angular, elongate, and swirled inclusions of 

dark rock in the lighter granite. The paragneiss is 

regionally metamorphosed in the amphibolite facies 

throughout the study area 

MINERAL RESOURCES 

Studies by the USGS included reconnaissance 

geologic mapping, geochemical sampling of rocks and 

stream sediments, and study of geologic relationships of 

some of the prospects and mineral occurrences. The 

mineral-resource evaluation also utilized a reconnaissance aeromagnetic survey by a commercial vendor 

under contract to the USGS. 

Mining engineering studies by the USBM included 

mining claim records search, on-site claim and prospect 

investigations, and mapping and sampling of altered 

zones and geochemically anomalous rock sample sites. 

The previously known mineral resources in the 

Granite Fiords area consist of metalliferous bedrock 

deposits containing small amounts of gold, silver, 

molybdenum, copper, lead, and zinc. No new deposits 

were found during the investigation, but the anomalous 

amounts of gold, silver, molybdenum, copper, lead, and 

zinc that occur in the geochemical samples suggest that 

metalliferous resources may exist. 

ineteen vein-type and disseminated mineral occurrences are known to have been prospected within the 

boundaries of the study area. Sixteen of them are in the 

remote northeastern part of Granite Fiords. The other 

three are near tidewater: one near the mouth of the 

Chickarnin River and two at Walker Cove. Most of these 

occurrences were originally staked in the early 1900's; 

about half a dozen were being prospected in 1972. 

Except for a 1-ton test shipment in 1925 from the 

northeastern sector, there is no record of any mineral 

production. 

The occurrences in the northeastern part of the 

Granite Fiords area are sulfide-bearing quartz-fissure 

veins and stringer lodes, massive sulfide stringers, or 

disseminated sulfide deposits. Their sulfide minerals include arsenopyrite, chalcopyrite, galena, molybdenite, 

pyrite, pyrrhotite, sphalerite, and tetrahedrite. The occurrences are mainly in recrystallized Mesozoic b dded 

and intrusive rocks that have been intruded by Cenozoic 

quartz monzonite and granodiorite. The information obtained during this investigation suggests that any 

mines that may be developed in the northeastern part of 

the study area probably would be underground operations mining less than 500 tons per day from veins or 

aggregates of veins. 

The occurrence near the mouth of the Chickamin 

River is in quartz diorite and consists of a quartz vein 

that contains pyrite and a little molybdenite. The principal occurrence at Walker Cove is a 75 ft-wide zone of 

iron-stained paragneiss containing disseminated pyrite 

and chalcopyrite. Samples from this occurrence gave 

results of 0.3 to 1.5 percent copper as well as small 

amounts of zinc, gold, and silver. Similar types of 

deposits may occur elsewhere in the paragneiss unit. 

Analysis of geochemical samples showed that the 

only valuable metals present in greater than background amounts are gold, silver, molybdenum, copper, 

lead, and zinc. However, most anomalous values were 

not much higher than background amounts, and only 

about 25 percent of them were as much as two or three 

times background. Most samples contained only 1 

metal in anomalously high amounts, and only 7 contained 3 or more metals. 

The distribution of known mines, prospects, and mineral occurrences and of anomalous geochemical samples 

show three principal areas with potential for metallic 

mineral resources: (1) The area in the northeastern part 

of the study area underlain by recrystallized Mesozoic 

bedded and intrusive rocks has substantiated potential 

for small, locally high grade vein-type deposits containing gold, silver, copper, lead, zinc, molybdenum, and 

tungsten (area A on map). (2) The area of undated 

paragneiss in the west-central part of the study area has 

probable potential for low-grade disseminated and 

massive sulfide deposits containing gold, silver, copper, 

and zinc (area B on map). (3) The areas of Cenozoic 

granodiorite, quartz monzonite, and granite plutons in 

the eastern part of the study area have probable potential for large low-grade porphyry molybdenum deposits 

(area C on map); these plutons also occur sporadically 

37 
elsewhere in the study area. A major prophyry molybdenum deposit currently (1982) under development 

about 10 mi south of the study area is in a mid-Cenozoic 

granite porphyry stock similar to those found in area C. 

SUGGESTIONS FOR FURTHER STUDIES 

Although the Granite Fiords Wilderness study area 

contains no productive mines or extensively explored 

prospects, there are two major mineral deposits close to 

its borders. The Granduc copper mine in British Columbia is about 1 mi from the northeastern extremity of the 

study area, and the Quartz Hill porphyry molybdenum 

deposit is about 10 miles south of the southern bound3 

ary. Our reconnaissance investigations suggest t at additional detailed geochemical, geophysical, or geological 

mapping studies, combined with drilling or other 

physical exploration might reveal comparable mineral 

deposits within the boundaries of Granite Fiords. 

REFERENCES 

Berg, H. C., Elliott, R. L., m.ith, J. G., Pittman, T. L., and Kimball, 

A. L., 1977, Mineral resources of the Granite Fiords Wilderness 

study area, Alaska: U . . Geological urvey Bulletin 1403, r 1 p. 

Berg, H. C .. Elliott. R. L .. and Koch. R. D., 197 , Map an tables 

describing areas of metalliferous mineral-resource potential in the 

Ketchikan and Prince Rupert qu adrangles, Alaska: U.S. 

Geological Survey Open· File Report 78- 73M. 48 p. 
TRACY ARM-FORDS TERROR WILDERNESS STUDY AREA 

AND VICINITY, ALASKA 

By DAVrD A. BREW, U.S. GEOLOG! AL R EY, and 

A. L. KIMBALL, U.S. BUREA OF Mr E 

SUMMARY 

The spectacularly scenic Tracy Arm-Fords Terror Wilderness study area lies 

on the southwest flank of the Coast Range about 45 mi southeast of Juneau, 

Alaska A mineral-resource survey of the area in 1972-1975 identified two areas 

with substantiated mineral-resource potential: the Sumdum Glacier mineral belt 

with gold, copper, and zinc potential; and the Endicott Peninsula area with zinc, 

silver, and gold potential. The Sumdum Glacier belt is estimated to contain between 3 and 15 mineral deposits and there are 5 known mining areas in the Endicott Peninsula 

CHARACTER AND SETTING 

The study area consists of about 1250 sq mi on the 

southwest side of the Coast Range in southeastern 

Alaska; it is about 45 mi southeast of Juneau, Alaska 

An additional 550 sq mi between the study area and the 

International Boundary with Canada and in part contiguous with the southwest boundary of the wilderness 

study area, was evaluated because of its importance to 

the mineral-resource assessment of the area The information presented here is abstracted from Brew and 

others (1977) and from a revised version of that same 

report (Brew and others, 1983). 

The area is one of spectacular scenery, with fiords, 

forests, glacier-covered peaks to 8095 ft high, tidewater 

glaciers, icebergs, and some broad river valleys. 

Studies by the USGS in 1972-1975 included reconnaissance geochemical sampling of stream sediments 

and rocks; and study of geologic relationships of some 

of the mines, prospects, and mineral occurrences. The 

mineral-resource evaluation also utilized an aeromagnetic survey of the area. Mining engineering studies 

by the USBM included mining-claim records search; onsite claim, mine, and prospect investigations; and 

mapping and sampling of stained zones, altered zones, 

and geochernically anomalous sites. 

About 670 claims, approximately 90 percent of them 

lode, are recorded in the area studied. Seventy percent 

of these were within the wilderness study area Approximately 24,000 oz of gold and probably a similar quantity of silver were produced from the Sumdum Chief 

lode property at the tum of the century. 

Geologically, the area spans most of the Coast Range 

plutonic-metamorphic complex (an informal term). The 

Coast Range complex is bounded on the west ~' a long 

foliated tonalite sill of probable early Tertiary age; to its 

northeast lies the main part of the complex, consisting 

of a broad terrane of complexly deformed amphibolitefacies gneiss, marble, and some schist of uncertain, but 

probably original late Paleozoic and (or) Mesozoic age. 

Near the International Boundary with Canada, this terrane is intruded by a series of generally unfoliated 

granodiorite bodies of mid-Tertiary age which are locally associated with migmatite zones. To the west of 

the sill, the rocks consist of low-grade metamorphics 

which are locally intruded by granite and other rocks. 

MINERAL RESOURCES 

Almost all of the mineralization within the wilderness 

study area occurs in the western metamorphic belt, 

parallel and adjacent to the western side of the Coast 

Range batholithic complex (an informal term). Little 

significant mineralization appears to be present within 

the batholithic complex. 

The western metamorphic belt has been recognized as 

having mineral-resource potential since the early 1900's 

when most of the occurrences investigated were located. 

The present study has identified two areas within this 

belt in the stt dy area with substantiated resource 

potential for gold, copper, zinc, and silver; these are, in 

the order of decreasing importance, the Sumdum 

Glacier mineral belt and the Endicott Peninsula area 

39 
40 

• Cu 

Au 

Ag 

Zn 

~ 

X 

X WHITING 

RIVER 

PROSPECT 

0 

MILES 

EXPLANATION 

Geologic terrane with substantiated 

mineral-resource potential 

Copper 

Gold 

Silver 

Zinc 

Mine or deposit 

Mineral occurrence 

D 

D 

20 

Coast Range plutonic 

metamorphic complex 

Coast Range batholitic complex 

Contact 

Figure 10.- Tracy Ann-Fords Terror Wilderness study area and vicinity, Alaska. 
The Sumdum Glacier mineral belt extends for about 

32 mi along the southwest side of the Coast Range 

batholithic complex and contains three known important mineralized areas: the Tracy Arm zinc-copper prospect, the Sumdum copper-zinc prospect, and the newly 

discovered Sweetheart Ridge gold-copper occurrence. 

The deposits in the belt consist of pyrrhotite, chalcopyrite, sphalerite, pyrite, galena, and some gold in lenses 

and pods parallel to the foliation or disseminated in the 

metamorphic rocks. 

These three deposits have demonstrated resources 

and warrant further exploration. The Tracy Arm zinccopper deposit is estimated to contain 187,000 tons of 

rock averaging 3.42 percent zinc, 1.42 percent copper, 

0.43 oz silver/ton, and 0.008 oz gold/ton. The Sumdum 

copper-zinc prospect is estimated to contain 26.7 million 

tons of rock averaging 0.57 percent copper, 0.37 percent 

zinc, and 0.30 oz silver/ton. A 147-ft-long portion of the 

Sweetheart Ridge mineralized zone is estimated to contain 7300 tons of rock per 100 ft of depth that average 

0.23 oz gold/ton and 0.7 percent copper. 

The entire Sumdum Glacier mineral belt is considered 

favorable ground for the occurrence of mineral deposits 

and the available information is used to suggest, therefore, that the number of deposits that may occur is 

somewhere between 3 and 15. The minimum number 

represents the deposits described above; the additional 

12 could include some of the poorly known or unexplored prospects or mineral occurrences already known 

in the belt. 

The Endicott Peninsula area has been prospected 

since before 1869 and several occurrences have long 

been known: the Point Astley zinc-silver deposit, the 

Sumdum Chief gold mine, the Taylor Lake area prospects, the Holkam Bay gold prospect, and the Spruce 

Creek area gold lodes and placers. The deposits in the 

area are largely either sulfide minerals in lenses and 

stringers along the foliation in phyllite or disseminated 

through it, or gold-bearing quartz veins in shaly limestone, limy slate, or phyllite. The area, as a whole, is 

poorly exposed because of extensive timber and brush. 

The one known significant deposit in the area consisted of gold-bearing quartz veins in shaly limestone 

at the Sumdum Chief gold mine. The Sumdum Chief deposit was mined before 1905; it produced about 

24,000 oz of gold from ore that contained about 0.4 oz 

gold/ton. The other prospects and mines had very little 

or no production. The Taylor Lake occurrences are 

geologically similar to the Sumdum Chief. The Point 

Astley zinc-silver prospect has not been thoroughly explored. The deposit appears to be extremely irregular 

and the lateral and vertical continuity of the mineralized 

zones are not known. The gold mines and prospects near 

Spruce Creek occur mainly along quartz stringers in 

broad altered zones, and all appear to have low gold 

contents that only rarely exceed 0.25 oz gold/ton. The 

Holkam Bay prospect is similar and had some small 

production. 

The area was studied for radioactive minerals, oil, 

gas, coal, and industrial mineral deposits as well as geothermal energy, but there is little promise for the occurrence of these resources. 

SUGGESTIONS FOR FURTHER STUDY 

Since release of the report by Brew and others (1977), 

several exploration companies have been active in the 

Sumdum Glacier mineral belt, but further work, particularly in the southern part of the belt, would be of significant help in refining the evaluation of that area. 

Relatively little activity has occurred in the Endicott 

Peninsula area; intense geochemical and geophysical 

work would remove many of the present uncertainties 

and probably would refine the present limit of the 

favorable areas. 

REFERENCES 

Brew, D. A., Grybeck. Donald. Johnson, B. R .. Jachens, R. C., Nutt, 

C. J ., Barnes, D. F., Kimball, A. L., Still, J. C., and Rataj, J. L., 

1977, Mineral resources of the Tracy Arm-Fords Terror 

Wilderness Study Area and vicinity, Alaska: U.S. Geological 

Survey Open-File Report 77- 649,300 p. 

__ 1983, Mineral resources of the Tracy Arm-Fords Terror 

wilderness study area and vicinity, Alaska: U.S. Geological 

Survey Bulletin 1525 (in press). 

41 
42 

-

D 

Co 

Cu 

Au 

Mo 

Ni 

Ag 

~ 

58° 

oo· 

45' 

30' 

N/00 MINE 

Ni, Cu . 

HIRST 

SLOCUM ARM 

0 10 

MILES 

EXPLANATION 

Geologic terrane with substantiated nickel, 

copper, and chromium resource potential 

and probable gold resource potential 

Geologic terrane with substantiated 

mineral-resource potential 

Geologic terrane with probable 

mineral-resource potential 

Cobalt 

Copper 

Gold 

Molybdenum 

Nickel 

Silver 

Mine or deposit 

Approximate boundary 

B 

Sitka Graywacke (Cretaceous) 

Kelp Bay Group (Cretaceous) 

Greenstone and marble (Triassic) 

Metavolcanic and metasedimentary 

rocks (Paleozoic and Mesozoic) 

Contact 

Fault 

Area discussed in text 

Figure 11.-Westem Chichagof and Yakobi Islands Wilderness study area, Alaska. 
WESTERN CHICHAGOF AND YAKOBI ISLANDS 

WILDERNESS STUDY AREA, ALASKA 

By BR CE R. j OH 1 Ot , . GE LOGICAL R\ 'EY, and 

ARTH R L. KIMBALL, . B REA F MI, E ' 

SUMMARY 

On the basis of mineral-resource studies by the USGS and USBM in 1980 of 

the Western Chichagof and Yakobi Islands Wilderness study area, southeastern 

Alaska, five areas of substantiated mineral-resource potential and four areas of 

probable mineral-resource potential have been delineated. o energy resource 

potential was identified in this study. 

CHARACTER AND SETTING 

Western Chichagof and Yakobi Islands are part of the 

Alexander Archipelago of southeastern Alaska. The 

wilderness study area is within the Tongass ational 

Forest, is approximately 60 mi long and as much as 20 

mi wide, and has an area of 633 sq mi. Topography is 

moderately rugged with high peaks and ridges at about 

3000 ft separated by river valleys and lakes at or near 

sea level. The southwestern coastline is particularly irregular, consisting of myriad small islands, peninsulas, 

fiords, and reefs. 

The sedimentary and metamorphic rocks of western 

Chichagof and Yakobi Islands can be divided into four 

roughly linear northwest-trending stratigraphic belts 

which are progressively younger toward the southwest 

(Johnson and Karl, 1982). The oldest rocks form a 

discontinuous belt along Hoonah Sound and Lisianski 

Inlet of metamorphosed sedimentary and volcanic 

rocks. The second belt of rocks, to the southwest, is 

composed of the Triassic(?) Goon Dip Greenstone and 

Whitestripe Marble. These two belts have been intruded 

by Jurassic and Cretaceous diorite, quartz diorite, 

and tonalite plutons that exhibit a general northwest 

foliation. 

A major fault, the Border Ranges fault, forms the 

boundary between the belts described above and two 

younger belts to the southwest. The Cretaceous Kelp 

Bay Group, the third belt, immediately southwest of the 

Border Ranges fault consists of a complex assemblage 

of metasedimentary and metavolcanic rocks. The fourth 

and youngest belt, the Cretaceous Sitka Graywacke, is 

southwest of the Kelp Bay Group and in fault contact 

with it. · All of the belts have been intruded by 

Tertiary(?) plutonic rocks following movement on the 

Border Ranges fault. 

MINERAL RESOURCES 

The Western Chichagof and Yakobi Islands VVilderness study area lies within the Sitka recording district 

and the Chichagof mining district. The following 

descriptions of mineral resources are abstracted from 

Johnson and others (1982). Detailed descriptions of the 

mines, prospects, and occurrences within the study 

area, as well as details of the individual resource calculations are given in Kimball (1982) and Still and Weir 

(1981). 

The older rocks of the northeastern belts and the Kelp 

Bay Group and younger rocks to the southwest are cut 

by small, felsic to intermediate stocks and dikes. The 

dikes, which are believed to be related to Tertiary(?) 

plutonism (Loney and others, 1975), tend to be most 

abundant near localities of known mineralization. Many 

gold-bearing veins occur near bends in fault surfaces or 

at intersections of main faults and lesser splits. The ore 

zones containing the veins tend to be tabular, dip steeply, and are commonly a few feet thick and a few hundred 

feet long. The mineralogy of the gold-bearing veins is 

relatively constant throughout the study area Quartz 

veins carry from 0.5 to 3 percent pyrite, and smaller 

amounts of arsenopyrite, galena, sphalerite, chalcopyrite, and gold, with local occurrences of tetrahedrite and 

scheelite. 

Gold occurrences in an area of probable resource potential along the west coast of Chichagof Island (A, on 

map), include nearly all the production in the Chichagof 

43 
mining district. The occurrences are in weakly metamorphosed sedimentary and volcanic host rocks of the Kelp 

Bay Group and the structurally overlying Sitka 

Graywacke. The host rocks are cut by numerous strikeslip and thrust(?) faults and mineralization in the form 

of hydrothermal gold-quartz veins commonly occurs 

along northwesterly striking, steeply dipping shear 

zones within graywacke, schist, and marble. Numerous 

precious-metal prospects occur within area A and several small mines have produced small amounts of gold 

and silver. There is a probable resource potential for additional occurrences of gold along faults in this area. 

Area A surrounds a center of mining activity and production at Doolth Mountain (B). This area has substantiated gold and silver resource potential and contains 

the Chichagof£ and Hirst-Chichagof mines, which have 

demonstrated resources of 316,000 oz gold and 88,000 

oz silver, almost all of the gold resources of the study 

area 

The Chichagof£ mine is located along the Chichagof 

fault, which has a traceable strike length of at least 12 

mi. The mine opened in 1905 and closed in 1942 with a 

recorded production of 660,000 oz of gold and 200,000 

oz of silver from over 600,000 tons of ore. The mine and 

adjacent mineralized area consists of 29 patented claims 

and ranks as the third largest lode-gold producer in 

Alaska Mining reached a depth of 2700 ft below sea 

level, and underground workings explore the fault for 

4800 ft in a horizontal direction and 4300 ft vertically. 

Twenty-three percent of the area explored by underground workings was mined. Almost all mine workings 

are currently inaccessible. 

The Hirst-Chichagof mine is along the Hirst fault 

which is parallel to and approximately 0.8 mi southwest 

of the Chichagof fault. The property was staked in 1905 

and operated from 1922 to 1943. The structure is explored along 5000 ft of strike, as much as 2200 ft vertically and mining reached a depth of 1800 ft below sea 

level. It produced 131,000 oz of gold and 33,000 oz of 

silver from over 140,000 tons of ore. Old records indicate that less than ten percent of the area explored by 

underground workings was mined. Almost all the old 

workings are currently inaccessible. The mine and adjacent mineralized area are partially covered by 12 

patented claims. 

The Lisianski Gold area of probable gold and silver 

resource potential (area E) is characterized by goldquartz occurrences along northeast-striking faults, fractures, and shear zones in diorite, amphibolite, 

greenstone, and schist within the belt of Mesozoic or 

older metamorphic rocks. Area E includes five properties that produced about 18,000 oz of gold and 2,500 oz 

of silver and twelve others with reported gold occurrences. Based on gold production area D is an area of 

44 

substantiated gold and silver resource potential which 

contains a number of gold occurrences (130 recorded 

claims), including the Apex-El Nido mine, and is the 

most important portion of the Lisianski Gold area (E). 

The Apex and El Nido gold-bearing quartz veins were 

discovered in 1919 and 1920, respectively, and produced 

about 17,000 oz of gold and 2400 oz of silver in the 

periods 1924-28, 1934-35, and 1937-39. Currently, 

there are 41 unpatented lode and 3 placer claims, mostly 

on the northeast side of Apex Mountain. The deposits 

consist of steeply dipping, gold-bearing quartz veins, 1 

to 4 ft thick, along faults in diorite and amphibolite. 

Sporadically distributed scheelite (CaWO,) also occurs 

in the veins. 

Nickel-copper-cobalt deposits occur in 3 areas having 

resource potential in the wilderness study area (two 

substantiated and one probable). The deposits are 

massive sulfide magmatic segregations in noritic and 

gabbro-noritic facies of composite Tertiary(?) stocks 

that are generally potassium poor and vary widely from 

tonalite to norite. The stocks intrude Cretaceous 

metavolcanic and metasedimentary rock of the Kelp 

Bay Group and turbidites of the Sitka Graywacke. Contact metamorphic halos surround the stocks. The 

deposits consist generally of pentlandite, chalcopyrite, 

and pyrrhotite in either massive or disseminated bodies. 

The massive sulfide bodies are podlike, small, and difficult to explore or delineate without extensive drilling. 

Bohemia Basin is an area of substantiated nickelcopper-cobalt re ource potential (area C), on Yakobi 

Island. It is the largest of the three known nickelcopper-cobalt areas and 980 mining claims have been 

recorded since 1920, of which 265 are unpatented active 

claims and 9 are patented claims. Extensive surface exploration and more than 50,000 ft of diamond drilling 

have partially delineated three mineralized bodies. The 

two largest bodies in this area are reported to contain at 

least 20,100,000 tons of demonstrated resources averaging 0.31 percent nickel, 0.18 percent copper, and 0.04 

percent cobalt (Inspiration Development Company, 

press release, April 3, 1978). 

Similar magmatic segregations are known in an area 

of substantiated nickel-copper-cobalt resource potential 

in mafic rocks 15 mi to the southeast, on Chichagof 

Island near Mirror Harbor (area F). These occurrences 

have been known since 1911 and 330 claims have been 

recorded, with 114 claims presently current. Exploration, including diamond drilling, has been conducted 

during the past several seasons in this area and 

although tonnage estimates are not available, seven diamond drill holes have intercepts of nickel, copper, and 

cobalt similar in grade to Bohemia Basin. The Squid 

Bay-Lost Cove area of probable nickel-copper-cobalt 

resource potential (area G) is about 8 mi south of 
Bohemia Basin on Yakobi Island and northwestern 

Chichagof Island. Host rocks at this locality are similar 

to the Mirror Harbor occurrences, but USBM samples 

from this area contain low copper values, with minor 

nickel and cobalt. 

Ninety claims have been recorded near Mt. Baker, an 

area of substantiated copper resource potential (area H). 

The largest known concentration of copper is in a northwesterly striking vertical zone in greenstone 350 to 400 

ft long. Several trenches (now sloughed), a shallow 

shaft, and a crosscut have been opened. Sample analyses from a trench at the southeastern end of the zone 

show 2.0 percent copper across a 13ft width, and from a 

shallow shaft at the northwest end of the zone show 7.5 

percent copper across a 2 ft width. Minor gold and silver 

values are also present. 

The Slocum Arm Molybdenum area (I) is 1.5 mi east 

of Hidden Cove, at the southern end of Slocum Arm. 

Ten claims are currently active. Molybdenum mineralization occurs in small quartz veins, dikes, and country 

rock across an area 0.75 mi wide by 1.5 mi long near a 

dioritic intrusion. The area has probable molybdenum 

resource potential. 

SUGGESTIONS FOR FURTHER STUDIES 

Current knowledge of the detailed geology of the 

study area is confined to areas adj acent to the wellknown mineral deposits such as at Doolth Mountain 

and at Bohemia Basin. The remainder of the study area 

is well mineralized, but the extent of mineralization is 

inadequately known. Detailed geologic and geochemical 

studies of the lesser known areas such as Squid BayLost Cove, Mt. Baker, and Slocum Arm would provide a 

more complete resource assessment. 

REFERENCES 

J ohnson. B. R .. and Karl, S. M .. 19 2. Reconnaissance geologic map 

of the Western Chichagof and Yakobi Islands Wilderne tudy 

Area, southeastern Alaska: U .. Geological Survey Miscellaneous Field Studies Map MF - 1476- A. scale 1:125,000. 

J ohnson. B. R.. Kimball, A. L .. and Still, J. C .. 1982, Mineral resource 

potential of the Western Chichagof and Yakobi Islands Wilderness Study Area, southeastern Alaska: U .. Geological urvey 

Miscellaneous Field Studies Map MF- 1476- B. cale 1:125,000. 

Kimball, A. L., 1982, Mineral land assessment of Yakobi I land and 

adj acent parts of Chichagof Island, southeastern Alaska: U . . 

Bureau of Mines M LA 97-82, 199 p. 

Loney, R. A., Brew, D. A .. Muffler, L.J.P .. and Pomeroy, J ... 1975. 

Reconnaissance geology of Chichagof, Baranof. and Kruzof 

Islands. southeastern Alaska: U .. Geological Survey Profe -

sional Paper 792, 105 p. 

Still, J. C .. and Weir, K. R., 1981, Mineral land assessment of the west 

portion of western Chichagof island, southeastern Alaska: U. 

Bureau of Mines Open-File Report 89- 81,1 6 p. 

45 
114° 

0 MILES 

46 

A R I z 0 

1 

0 

~oo 0~0 G 

<~ ~ 

Flagstaff 2 

3 0 

4 

Prescott ~"" 6 0 ~ 

8 I c:· . 11 ~ 

10 

• 

N 

. 13 

A 

11 0° 

. 15 

18 • 

• 19 

Tucson . 20 0 . 21 

• 25 . 23 

100 

Location of areas studied. 

14. 

161 

17 ~ 

. 22 

24 • 
ARIZONA 

M ap 

Na. 

7 Arnold Mesa Roadless Area 

Name of Area 

14 Blue Range Wilderness, Arizona and New Mexico 

26 Bunk Robinson Peak and Whitmire Canyon Roadless Areas, New Mexico 

and Arizona-See New Mexico 

24 Chiricahua Wilderness 

23 Dragoon Mountains Roadless Area 

9 Fossil Springs Roadless Area 

18 Galiuro Wilderness and contiguous roadless areas 

10 Hells Gate Roadless Area 

17 Hells Hole Roadless Area, Arizona and New Mexico 

1 Kanab Creek Roadless Area 

16 Lower San Francisco Wilderness study area and contiguous roadless 

areas, Arizona and New Mexico 

11 Mazatzal Wilderness and contiguous roadless areas 

12 Mount Baldy Wilderness 

22 North End Roadless Area 

8 Pine Mountain Wilderness 

19 Pusch Ridge Wilderness 

4 Rattlesnake Roadless Area 

21 Rincon Wilderness Study Area 

13 Sierra Ancha Wilderness 

2 Strawberry Crater Roadless Areas 

15 Superstition Wilderness 

3 Sycamore Canyon Primitive Area 

6 West Clear Creek Roadless Area 

5 Wet Beaver Roadless Area 

25 Whetstone Roadless Area 

20 Winchester Roadless Area 

47 
34° 

30' 

48 

111 °55' 

/ 

I 

I 

I 

\ 

CHICKEN 

WIRE 

MINE~ 

I 

.,-_..., 

\ 

\ ' .,..- -..... ~--' / 

,-

/ 

,, 

--

,y 

I .,.. ...... , \ ,, I 

{'fRDt 

J 

( 03092 

' ,; ,, ---~~ l. \ 

T 

'------~ \ 

Approximate)"-\ 

roadless ' 

boundary ' 

0 5 

MILES 

EXPLANATION --- Contact 

\ ,_,., ( 

B Verde Formation (Cenozoic) 

--r-- Fault--Bar and ball on 

Volcanic and sedimentary rocks, 

undifferentiated (Cenozoic and 

Paleozoic) 

B Tonalite (Proterozoic) 

Metamorphic rocks of Squaw 

Peak Canyon (Proterozoic) 

of Gap Creek 

downthrown side 

Figure 12.-Arndd Mesa Roadless Area Arizona 

111 °45' 

MAP LOC ATION 
ARNOLD MESA ROADLESS AREA, ARIZONA 

By EDWARD W. WOLFE, U .. G EOLOG I AL S R EY and 

ROBERT A. M CCOLLY, U .. B REAU F MI E 

SUMMARY 

Geologic, geochemical, and aeromagnetic investigations and a survey of 

mines and prospects in 1980 in the Arnold Mesa Roadless Area, Arizona, provide little evidence for the occurrence of mineral or energy resources. Buried 

Proterozoic basement rocks are possible hosts for porphyry-type copper and 

massive sulfide deposits but the thick cover of Paleozoic sedimentary rocks and 

upper Cenozoic volcanic rocks precluded assessment of this possibility. 

Chemistry and temperature of spring and well waters suggest that a geothermal 

resource may exist near the eastern margin of the roadless area, but the anomaly has not been tested by drilling and this resource remains unverified. No 

other energy resources were identified. 

CHARACTER AND SETTING 

The Arnold Mesa Roadless Area comprises about 44 

sq mi in and along the flanks of the Black Hills south of 

Camp Verde, Arizona The crest and southwest flank of 

the Black Hills within the roadless area are moderately 

dissected rolling uplands. The northeast flank, which is 

steep terrain that forms the western wall of the Verde 

River Valley, has a total relief within the roadless area 

of almost 4000 ft and is deeply incised by canyons such 

as those of Gap and Chasm Creeks. 

The roadless area is within the transition zone between the Colorado Plateaus and the Basin and Range 

Province. The zone is underlain by Precambrian rocks 

and gently dipping Paleozoic strata that are similar to 

Precambrian and Paleozoic rocks in the southern part of 

the Colorado Plateau in the Grand Canyon. 

Proterozoic rocks just north of the roadless area, in 

the vicinity of Squaw Peak Canyon, include foliated 

mafic and, locally, intermediate volcanic rocks of 

greenschist facies that are intruded by a Proterozoic 

pluton composed mainly of tonalite. The tonalite is 

locally exposed in the northern and central parts of the 

roadless area In the southern part of the roadless area, 

Proterozoic rocks exposed along Gap Creek, in Chalk 

Tank Canyon, and locally along the Verde River are 

dominantly relatively unmetamorphosed dacite and 

rhyolite with subordinate mafic volcanic or volcaniclastic rocks. 

Gently dipping Paleozoic dolomite and limestone with 

subordinate sandstone and siltstone rest unconformably on the Proterozoic rocks. These strata, Cambrian 

to Pennsylvanian or Permian in age, have an aggregate 

maximum thickness of 730 to 910ft, but they pmch out 

locally between the Proterozoic tonalite and the upper 

Cenozoic Hickey Formation. 

The transition zone in central Arizona was the locus 

of voluminous eruptions of basaltic lava and pyroclastic 

deposits that rest on the eroded surface of the Paleozoic 

and Precambrian rocks. Dacitic to rhyolitic lava flows 

and pyroclastic deposits, also of late Miocene age, occur 

locally within the roadless area 

Northwest-trending linear basins of late Cenozoic age 

characterize the transition zone and indicate extension 

and basin subsidence. The roadless area includes the 

southernmost part of one of these basins, the 30 mi-long 

Verde basin alined approximately along the Verde 

River, that contains late Cenozoic basin-fill deposits 

more than 3100-ft thick (Nations, 1974) of the Verde 

Formation. 

The Verde basin and its sedimentary fill are bounded 

on the southwest by the Verde fault, which, in the 

northern part of the roadless area, is a conspicuous, 

single, steep, normal fault. Near Chasm Creek, however, 

the single fault splays southward into several highangle faults that can be traced only a short distance 

southeast of Chasm Creek. Another fault system, 

similar to the Verde fault in trend and sense of movement but offset en echelon from it, extends from the upper part of Gap Creek to the southern boundary of the 

roadless area 

49 
MINERAL RESOURCES 

Prospecting and claim staking have occurred intermittently from about the mid- 1800's to the present. No 

mine production is known from within the roadless area 

and at the time of field examination, no mining or exploration work was occurring within the roadless area. 

At the Squaw Peak mine, just north of the Arnold 

Mesa Roadless Area, the Proterozoic tonalite pluton is 

the host for a porphyry-type copper deposit (Roe, 1976). 

The Squaw Peak mine is not currently active, and the 

only recorded production was from 1944 to 1946. During that period, 1000 tons of ore produced 5.4 tons of 

98.82 percent molybdenite (Mo82) and 36 tons of concentrate averaging 22.85 percent copper, 1.92 oz silver/ton, 

and 0.016 oz gold/ton (Hill, 1949). Roe has shown that 

the deposit does not extend into the roadless area, and 

no outcrop evidence of similar occurrences exists in the 

roadless area There is a small possibility that similar 

porphyry-type mineral deposits may occur in the subsurface throughout the roadless· area; however, overlying Paleozoic sedimentary and Cenozoic volcanic rocks 

as much as 1500 ft thick cover any such porphyry-type 

copper deposits. 

A minor amount of gold with an estimated value of a 

few hundred to a few thousand dollars has been produced north of the roadless area at the Chicken Wire 

gold mine from brecciated tonalite adjacent to quartz 

veins. Although quartz veins do occur in the roadless 

area, they are relatively scarce in the outcrop areas of 

tonalite and no resource potential for the occurrence of 

small vein- or fracture-related deposits of silver or gold 

was identified. 

The Proterozoic volcanic rocks of Gap Creek underlie 

the southern part of the roadless area They are broadly 

like the host rocks for the massive sulfide deposit of 

Jerome, Arizona (Anderson and Creasey, 1958; Donnelly and Hahn, 1981), and there may be a possibility 

for the occurrence of similar ores of copper, silver, and 

gold. The unit is largely buried by younger sedimentary 

and volcanic rocks as much as 2500 ft thick and because 

direct evidence of a massive sulfide deposit has not been 

found. However, this does not preclude the occurrence 

of massive sulfide deposits under the cover of younger 

rocks within the volcanic rocks of Gap Creek. Therefore, 

the possibility exists for such deposits in the southern 

part of the roadless area, but due to the lack of conclusive data, no resource potential was identified. 

Rock suitable for crushing into aggregate occurs 

throughout the roadless area, and tonalite has been 

quarried locally for use in flood-control construction on 

the Verde River. However, deposits of potential aggregate material outside the roadless area are more accessible and closer to markets. No potential was ident1fied 

50 

for the occurrence of resources in the Paleozoic and 

Cenozoic rocks that cover most of the roadless area 

Evidence gathered by Ross and Farrar (1980) indicates that ground water near the eastern boundary of 

the roadless area has been in contact with reservoir 

rocks of elevated temperature. The sampled springs and 

wells all lie within and east of the Verde fault zone and 

its projection to the southeast. Their modestly elevated 

temperatures suggest a possible geothermal resource, 

but this resource remains untested. 

The results of geologic, geochemical, and aeromagnetic investigations and a survey of mines and prospects (McColly and Korzeb, 1981) in 1980 indicate little 

likelihood that the Arnold Mesa Roadless Area has occurrences of metallic mineral resources in porphyry 

copper-type settings, but a greater likelihood in the area 

for massive sulfide-type deposits (Wolfe and others, 

1983). 

SUGGESTIONS FOR FURTHER STUDIES 

Additional detailed examination and geochemical 

sampling of the exposed Proterozoic rocks represent the 

most direct approach to identifying geochemical patterns that might offer further evidence on the presence 

or absence of mineral deposits. Geophysical studies and, 

ultimately, drilling are the most likely techniques for 

additional evaluation of the weak geothermal anomaly. 

REFERENCES 

Anderson, C. A .. and Creasey, S.C., 1958. Geology and ore deposits of 

the Jerome area, Yavapai County, Arizona: U.S. Geological 

Survey Professional Paper 308, 185 p. 

Donnelly, M. E .. and Hahn. G. A., 1981, A review of the Precambrian 

volcanogenic massive sulfide deposits in central Arizona and the 

relationship to their depositional environment, in Dickinson, 

W. R., and Payne, W. D., editors, Relations of tectonics to ore 

deposits in the southern Cordillera: Arizona Geological Society 

Digest, v. 14, p. 11 - 21. 

Hill, J. M., 1949, Report on the Squaw Peak copper mine, Yavapai 

County, Arizona, in Squaw Peak Mine: Arizona Department of 

Resources Open-File Report, 10 p. 

McColly, R. A., and Korzeb, S. L .. 1981, Mines and prospects map of 

the Arnold Mesa RARE II Further Planning Area, Yavapai 

County, Arizona: U.S. Bureau of Mines Open-File Report MLA 

31-81, scale 1:24,000. 

McKee, E. H., and Anderson, C. A., 1971, Age and chemistry of Tertiary volcanic rocks in north-<:entral Arizona and relation of the 

rocks of the Colorado Plateaus: Geological Society of America 

Bulletin, v. 82, p. 2767- 2782. 

Nations, J. D., 1974, Paleontology. biostratigraphy, and paleoecology 

of the Verde Formation of late Cenozoic age, north-<:entral 

Arizona, in Karlstrom, T.N.V., Swann, G. A., and Eastwood, 

R. L., eds., Geology of northern Arizona with notes on archeology 

and paleoclimate, Part 2- Area studies and field guides: 

p. 611 - 629. 
Roe, R. R., 1976, Geology of the Squaw Peak porphyry coppermolybdenum deposit, Yavapai County, Arizona: Tuscon, Arizona 

University, unpublished M.S. thesis, 102 p. 

Ross, P. P., and Farrar, C. D., 1980, Map showing potential 

geothermal-resource areas, as indicated by the chemical 

character of ground water, in Verde Valley, Yavapai County, 

Arizona: U.S. Geological Survey Water-Resources Investigations 

Open-File Report 80- 13. 

Wolfe. E. W., Wallace. A. R., McColly, R. A., and Korzeb. . L., 1983, 

Mineral resource potential map of the Arnold Mesa Roadless 

Area. Yavapai County, Arizona: U.S. Geological Survey Miscellaneous Field Studies Map MF- 1577- A, scale 1:24,000. 

51 
52 

33° 

30' 

0 

MILES 

EXPLANATION 

D 

Cu 

Mo 

Geologic terrane with probable 

mineral-resource potential 

Copper 

Molybdenum 

Ag Silver 

D 

~ 

~ 

• 

• 

10 

NEW 

MEXICO 

MAP LOCATION 

Sedimentary and volcanic 

rocks (Quaternary and 

Tertiary) 

Rhyolitic rocks (Tertiary) 

Rhyolitic volcanic 

center (Tertiary) 

Andesitic volcanic 

center (Tertiary) 

Contact 

Fault--Bar and ball on 

downthrown side 

Figure 13.-Biue Range Wilderness, Arizona and ew Mexico. 
BLUE RANGE WILDERNESS, ARIZONA AND NEW MEXICO 

By jAMES C. RATTE, U.S. G EOLO I AL R EY, and 

R. G. RAABE, U.S. B RE F MI ES 

SUMMARY 

A mineral survey of the Blue Range Wilderness was completed in 1969 and it 

was determined that a probable resource potential for molybdenum, copper, and 

silver is present in volcanic rocks of middle Tertiary age in the southern and 

southwestern parts of the area. There is also a likelihood for the occurrence of 

base-metal resources (including porphyry copper deposits) of Laramide age 

beneath the middle Tertiary volcanic rocks that cover the area, but data are insufficient to assess the resource potential. 

CHARACTER AND SETTING 

The Blue Range Wilderness comprises about 380 sq 

mi, about 35 sq mi of which are in Catron County, New 

Mexico and the remainder of which are in Greenlee 

County, Arizona. The wilderness is part of an irregular 

mountainous region that is bisected north to south by 

the Blue River. Altitudes range from 4500 ft to about 

9400 ft, giving a maximum relief of nearly 5000 ft in the 

canyon of the Blue River. 

A mineral-resource appraisal of the area that is now 

the Blue Range Wilderness (formerly the Blue Range 

Primitive Area) was completed by the U.S. Geological 

Survey and U.S. Bureau of Mines, and published by the 

USGS and USBM in 1969, (Ratte and others, 1969); the 

significance of an aeromagnetic anomaly in the southwestern part of the wilderness was described by Eaton 

and Ratte (1969). Although there have been no further 

studies in the Blue Range by either the USGS or the 

USBM, considerable work in adjacent areas by both 

agencies now provides a better understanding of the 

regional setting as it pertains to mineral resources, and 

additional data have been obtained from exploratory 

drilling of mineral-resource targets within the wilderness by private industry. 

The Blue Range Wilderness is near the western edge 

of the Mogollon-Datil volcanic field of middle Tertiary 

age, which covers a large part of southwestern New 

Mexico and adjoining parts of Arizona This volcanic 

field constitutes the mountainous transition zone between the Colorado Plateau and the Basin and Range 

physiographic and structural provinces. The rocks in 

the wilderness are all volcanic in origin except for 

stream-deposited conglomerate that has buried the 

volcanic rocks over about 25 percent of the wilderness. 

A number of eruptive and intrusive centers for the 

volcanic rocks are present, particularly in the southwestern part and near the southern border of the wilderness. Red Mountain is a rhyolitic eruptive center that is 

superimposed upon a much larger andesitic volcano, the 

likely center of which is a few miles south of Red Mountain, as indicated by a swarm of andesitic to quartz 

latitic dikes and a positive magnetic anomaly. Other 

silicic eruptive centers occur both west and east of the 

Blue River in the southern part of the wilderness. These 

silicic centers and the andesite center have local areas of 

intensely argillized and silicified rocks that contain 

disseminated pyrite and minor fracture coatings of 

secondary copper minerals. The rhyolite of Red Mountain has been altered locally by solfataric action, which 

produces brightly colored iron-stained outcrops, and 

minor fluorite was seen in some rhyolite breccia Elsewhere in the wilderness, the rocks consist mainly of 

laharic and mudflow breccias derived from the andesitic 

volcano, and of thick, younger lava flows of basalt and 

basaltic andesite. Rhyolitic ash-flow tuffs, prevalent 

mainly in the northeastern part of the area, are the 

distal outflow sheets from eruptive sources in the 

Mogollon Mountains, east of the wilderness. 

Pre-Tertiary rocks are nowhere exposed at the surface 

within the wilderness, but their presence or absence in 

the subsurface is critical to an assessment of the potential for ore deposits beneath the volcanic rocks. Exploratory drilling by private mining companies in the wilderness since 1969 has shown that below the Tertiary 

volcanic rocks, the Mesozoic(?) and Paleozoic rocks, 

which are 600 to 800ft thick, overlie Precambrian rocks 

at depths of as little as 2300 ft beneath the surface. 

The Blue Rar1ge Wilderness is along a major northnortheast-trending zone of faults that may mark a deep53 
seated regional fracture system. Thus, most faults that 

cut the rocks in this area have north to northeast trends 

like the Blue Fault. There are also strong west to northwest faults like the Strayhorse fault. 

Rock and stream-sediment samples were collected 

within the wilderness and chemically analyzed. Anomalously high metal values for molybdenum, copper, and 

silver were found largely in samples of altered rocks 

around the volcanic centers or in stream sediments adjacent to them. 

There is no record of mineral or petroleum production, 

nor of patented mining claims, within the Blue Range 

Wilderness. Several groups of unpatented claims, totalling at least 600, are present in the southwestern part of 

the wilderness and along its southern boundary, and 

these have been sites of active mineral exploration, both 

before and since 1969. At least eight deep exploration 

core holes totalling about 25,000 ft have been drilled 

within or adjacent to the wilderness since 1969 by 

private mining companies. 

Major copper deposits at Morenci, Arizona, which 

have produced more than 3 million tons of copper, occur 

at the southwest end of the north-northeast-trending 

structural zone, about 20 mi south of the Blue Range 

Wilderness. Other nearby metal mining districts, in 

rocks similar to those in the Blue Range, include 

Mogollon and Steeple Rock, New Mexico, which have 

produced modest amounts of silver, gold, and copper. 

MINERAL RESOURCES 

Tne mineral-resource potential of the Blue Range 

Wilderness consists of the following: (1) An area of probable resource potential for molybdenum, silver, and copper deposits is associated with middle Tertiary volcanic 

centers of andesite to high-silica rhyolite compositions 

in the southern part of the wilderness. The resource 

potential in these rocks is supported by geologic and 

geophysical evidence of intrusive activity and intensely 

altered and weakly mineralized rocks at several volcanic 

centers. (2) The wilderness also has a likelihood for the 

occurrence of base-metal veins or porphyry copper 

deposits of Laramide age (Late Cretaceous-early Tertiary) beneath the middle Tertiary volcanic rocks that 

cover this area, but data are insufficient to assess the 

resource potential. Major copper deposits of the same 

54 

age occur in the area adjacent to the wilderness, particularly at Morenci, Arizona It is reasonable to expect 

that the pre-middle Tertiary geologic terrane beneath 

the wilderness is similar to that near Morenci, and 

therefore, could include Laramide intrusive rocks and 

copper deposits. 

That the Blue Range Wilderness is located on the 

same north-northeast-trending structural zone as the 

Laramide ore deposits at Morenci could be favorable 

evidence for the emplacement of intrusives or ore deposits of either Laramide or mid-Tertiary age. This has 

been a factor in exploration in the wilderness by several major mining companies since the USG&USBM 

mineral-resource appraisal in 1969. 

The results of private exploration, which has included 

a total of about 25,000 ft of deep-core drilling, are not 

adequate to assess the mineral-resource potential of the 

area Mineralized and altered rocks were encountered in 

some drill holes in both middle Tertiary volcanic rocks 

and pre-Tertiary rocks (best assays for 10- ft intervals 

were 0.56 percent copper and 0.19 oz silver/ton). Although the companies who have drilled in the wilderness have discontinued their projects there, drilling to 

date has not been sufficient to determine the presence or 

absence of significant mineral resources. 

SUGGESTIONS FOR FURTHER STUDIES 

Improved techniques for interpreting geophysical 

data collected over complex volcanic terranes should be 

applied in an effort to identify Laramide intrusives 

beneath the middle Tertiary rocks. Additional geologic 

studies of the major faults and volcanic centers might 

enhance mineral-deposit target definition in the middle 

Tertiary rocks. 

REFERENCES 

Eaton, G. P., and Ratte, J. C .. 1969, Significance of an aeromagnetic 

anomaly in the southwestern part of the Blue Range Primitive 

area, Arizona·New Mexico: U.S. Geological Survey Open·file 

report, 5 p. 

Ratte, J. C., Landis, E. R., Gaskill. D. L., and Raabe, R. G .. 1969, 

Mineral resources of the Blue Range Primitive area, Greenlee 

County, Arizona and Catron County, ew Mexico, with a section 

on Aeromagnetic intepretation by G. P. Eaton. U.S. Geological 

Survey: U.S. Geological Survey Bulletin 1261- E, 91 p. 
CHIRICAHUA WILDERNESS, ARIZONA 

By H ARALD DREWES, 1 U .S. GEOL GICAL SURVEY, and 

FRA K E. W ILLIAMS, U .S. BUREAU OF Mr E 

SUMMARY 

Based on the results of geologic, geophysical, geochemical, and mines and 

prospect studies in 1972, the Chiricahua Wilderness in southeasternmost 

Arizona was assessed to have three small areas of probable resource potential 

for silver, gold, and molybdenum. The remainder of the area has little promise 

for the occurrence of energy and mineral resources. Samples from the areas with 

probable resource potential are enriched in silver, gold, and molybdenum probably associated with widely scattered quartz veinlets. Other kinds of mineral 

deposits like those in nearby mining camps, that conceivably could be present in 

the area, would be covered by several thousand feet of volcanic rocks younger 

than mineralized rocks of the region. 

CHARACTER AND SETTING 

The Chiricahua Wilderness covers an area of about 

28 sq mi in the central, high part of the Chiricahua 

Mountains in extreme southeastern Arizona The area 

lies in Cochise County about midway between Douglas 

and Willcox, Arizona, and Lordsburg, New Mexico; it is 

about 10 mi south of the Chiricahua National Monument, 6 mi southwest of the village of Portal, Arizona, 

and lies entirely within the Coronado National Forest. 

The wilderness is centered around Chiricahua Peak, 

almost 9800 ft high, and has a local relief of 3000 ft. The 

area is forested and has fairly abundant, if somewhat 

intermittent, stream water as a result of a yearly precipitation of about 20 in. Access to the area is by means of 

roads up the canyons from the highways in the intermontane valleys east and west of the mountains, and 

from roads that cross the mountains at Onion Saddle 

and between Tex and Rucker Canyons that serve recreation areas. Trails are abundant within the wilderness. 

Mining history of the region around the study area 

began in 1881, when claims that later became the Hill 

top mine, 6 mi north of the area, were first placed. Early 

production came from lead oxides near the surface, 

largely in Paleozoic host limestone. The California 

(Chiricahua) mining district, which covers most of the 

range of mountains contains 4100 unpatented claims, 

all outside the study area, and only 12 claims within 

1

Wit.h contributions from G. P. Eaton. USGS. 

2 mi of it. Recorded production from 1902, when the 

Hilltop mine was developed, to 1950 amounted to 

28,700 tons of ore and concentrates valued at about 

$1.1 million. This ore yielded 290 oz gold, 117,000 oz 

silver, 4035 tons lead, 582 tons zinc, and 176 tons 

copper, with most of the production corning from the 

Hilltop mine. 

The wilderness is underlain mostly by mid-Tertiary 

volcanic and plutonic rocks and by some Cretaceous 

sedimentary and volcanic rocks (Sabins, 1957; Drewes, 

1981a). These rocks overlie a sequence of Paleozoic 

rocks, mainly limestone, like those at the Hilltop mine. 

Most of the Cretaceous rocks are the Bisbee Formation (in places known as the Bisbee Group), estimated to 

be at least 2500 ft thick. The Bisbee is mainly a 

medium- to dark-gray shale and siltstone that has interbedded sandstone, limestone, and conglomerate 

(Drewes and Williams, 1973). 

In the northern and northeastern part of the study 

area dacitic lava, volcanic breccia, and conglomerate 

and sandstone derived from dacitic material unconformably overlie the Bisbee Formation. The probable age of 

these dacitic rocks is Late Cretaceous-early Tertiary. 

Most of the wilderness is underlain by rhyolite and 

latite in a volcanic pile at least 3000 ft thick. These 

rocks include much welded tuff, some unwelded tuff and 

tuff breccia, and lava flows. Monzonite which is mostly 

a brownish-gray rock with abundant coarse crystals, intrudes these volcanic rocks and locally was effusive 

upon them, apparently forming shallow laccoliths and 

55 
56 

31 ° 

50' 

109°20' 

Approximate boundary 

D 

Au 

Mo 

0 

MILES 

EXPLANATION 

Geologic terrane with probable 

mineral-resource potential 

Gold 

Molybdenum 

Ag Silver 

MAP LOCATION 

4 

Sedimentary rocks (Cretaceous) 

Volcanic and intrusive rocks 

(Tertiary) 

Contact 

Figure 14.-Chlricahua Wilderness, Arizona 
some extrusive domes. The rhyolite tuff and welded 

tuffs make the spectacular and colorful yellowish-brown 

cliffs along the canyons on the east side of the range. 

Several of these volcanic units in nearby parts of the 

Chiricahua Mountains are dated at 25 to 28 million 

years, or early Miocene-late Oligocene. 

Quartz veinlets are scattered in west- to northwesttrending steeply inclined fractures in the monzonite of 

the northeastern and southwestern parts of the study 

area Mostly the veinlets are less than 2 in. thick; to the 

southwest, one is about 2ft thick. Although almost entirely quartz, the vein material, based on laboratory 

study, contains small amounts of silver, gold, molybdenum, and other metals (Drewes and Williams, 1973, 

p. A24- A33). 

Several rhyolite and andesite dikes cut the volcanic 

and sedimentary rocks of the study area, but appear 

unrelated to the sparse mineralization. 

The rocks of the wilderness are cut by a few normal 

faults. These trend northerly, dip steeply or are vertical, 

and have large displacement. The older rocks of nearby 

areas are typically more severely faulted and are locally 

folded; presumably such structural features also occur 

in the subvolcanic rocks of the wilderness. Marj aniemi 

(1968) proposed that the central part of the Chiricahua 

Mountains is underlain by a large subcircular area of 

volcanic collapse, or a caldera; this has not been confirmed, however, it would place potential subvolcanic 

mineral targets far below the reach of modern exploration and development methods. 

MINERAL RESOURCES 

The results of the combined geologic, geophysical, 

geochemical, and mining-history investigations indicate 

that the Chiricahua Wilderness is largely unrnineralized. Weak silver, gold, and molybdenum mineralization 

occurs in a few small areas mainly near the northeast 

and southwest borders of the area 

The observed areas of probable mineral-resource 

potential are associated with rocks that contain quartz 

veinlets or oxidized or leached areas. A large quartz vein 

was explored and 12 tons of ore was shipped in 1945 

from a mine 3 mi from the wilderness; the mineral content and value of the ore is unknown. An area of leached 

rock near the northeast corner of the study area was 

also explored by drilling, but, again the results are 

unknown. 

Possible mineralization of Cretaceous and Paleozoic 

rocks beneath the volcanic pile is highly speculative and 

would be difficult to explore. Although in nearby areas 

these older rocks are more abundantly mineralized than 

are the Tertiary volcanic rocks, the estimated overlying 

thickness of 3000 ft of the volcanic rocks in the wilderness is so large that underlying mineral deposits would 

be difficult to locate. 

Potential resources of industrial materials were not 

recognized in the study area; most rock types within the 

area with any possible industrial material also occur 

outside of it in far more accessible situations. 

Petroleum and natural gas have not been produced in 

nearby parts of Arizona and New Mexico. The nearest 

wildcat well (Portal Drilling Company, Portal No.1) was 

drilled to a depth of 5353 ft, bottoming in Tertiary volcanics (Pierce and others, 1970, p. 193). 

From these observations and this evaluation, the wilderness has very little promise for the occurrence of 

energy resources. 

SUGGESTIONS FOR FURTHER STUDIES 

Some of the rhyolite ash-flow tuff sheets of the northern Chiricahua Mountains are believed to have come 

from a volcanic center in the high, central part of the 

mountains, and contain anomalous concentrations of 

tin. Although tin is not typically a resource from such 

rocks, further study on tin occurrences in this and other 

areas in the region would be desirable. 

Petroleum and gas exploration has increased in southeastern Arizona in recent years, with the recognition 

that an overthrust belt in the region (Drewes, 1981b) 

may provide a deep-drilling target, even through a thick 

volcanic cover. The results of deep seismic studies, 

which are used to spot specific targets, would be 

valuable to assess the possibility for oil and gas 

resources. 

REFERENCES 

Drewes, Harald, 1981a, Geologic map and sections of the Bowie 

Mountain South quadrangle, Cochise County, Arizona: U.S. 

Geological Survey Miscellaneous Investigations Map l-1363, 

scale 1:24,000. 

__ 1981b, Tectonics of southeastern Arizona: U.S. Geological 

Survey Professional Paper 1144,96 p. 

Drewes, Harald, and Williams, F. E .. 1973, Mineral resources of the 

Chiricahua Wilderness area, Cochise County, Arizona: U.S. 

Geological Survey Bulletin 1385- A, 53 p. 

Marjaniemi, D. K., 1968, Tertiary volcanism in the northern 

Chiricahua Mountains, Cochise County, Arizona, in Southern 

Arizona Guidebook 3: Arizona Geological Society, p. 209- 214. 

Pierce, H. W., Keith, S. B., and Wilt, J. C., 1970, Coal, oil, natural gas. 

helium, and uranium in Arizona: Arizona Bureau of Mines Bulletin 182, 289 p. 

Sabins, F. E .. Jr., 1957, Geology of the Cochise Head and western 

part of the V anar quadrangles, Arizona: Geological Society of 

America Bulletin, v. 68, no. 10, p. 1315- 1342. 

57 
32° 

58 

Cu . Pb, Zn. 

Mo , W 

a 

MAP LOCATION 

0 

5JCu , Pb, Zn , Au, Ag 

1 ~GOLDEN RULE MINE 

Approximate boundary 

Ag, W 

5 

MILES 

EXPLANATION 

CJ Geologic terrane with probable 

mineral-resource potential D Alluvium on gravel 

(Quaternary) 

Cu D Stocks, mainly granite 

Au 

Pb 

Mo 

Ag 

w 

Zn 

~ 

Copper 

Gold 

Lead 

Molybdenum 

Silver 

Tungsten 

Zinc 

Mine 

D (Tertiary) 

Sedimentary and 

metasedimentary rocks 

(Mesozoic, Paleozoic, and 

Precambrian) 

--- Contact 

---- Fault 

2 Location discussed in text 

Figure 15.-Dragoon Mountains Roadless Area, Arizona. 
DRAGOON MOUNTAINS ROADLESS AREA, ARIZONA 

By H RALD DREWES,' .S. GEOLOG I AL R EY , and 

T. j . KREIDLER, U . . BU REA OF MINE 

SUMMARY 

The mineral and hydrocarbon resource potential of the Dragoon Mountains 

Roadless Area was assessed in 1980-82 and six areas of probable mineralresource potential were identified. The area may contain metamorphic skarntype mineralization of copper, lead, molybdenum, and zinc, and some of these 

may contain silver and gold. More remotely, the area could also contain 

stockwork molybdenum mineralization and replacement or vein-type 

mineralization of beryllium, fluorite, thorium, tin, and tungsten. Rock products 

exist within the area and are discussed due to the proximity of a railroad, but 

similar materials occur outside the area. There is little promise for the occurrence of energy resources. 

CHARACTER AND SETTING 

The Dragoon Mountains Roadless Area lies in the 

northern end of the Dragoon Mountains near the center 

of Cochise County in southeastern Arizona It covers an 

area of about 52 sq mi, lying between the village of 

Dragoon to the north and the county road through Middle Pass to the south, and between the San Pedro River 

valley to the west and Sulfur Springs valley to the east. 

The area is rugged and is in the Coronado National 

Forest. Scrubby forests cover the high terrain and 

grass, shrubs, and cactus cover the lower country. Surface water is scarce, with springs few and watercourses 

ephemeral. Access is by ranch or USFS roads from the 

highways in the adjacent valleys, and some of these 

roads extend well into the roadless area. 

Base and precious metals were mined from several 

sites in and near the roadless area. These deposits are 

from skarn-type alteration of mixed limestone and shale 

near granite. Most production probably was lead, zinc, 

and silver; a little gold and tungsten may have been produced. Production records for the patented claims and 

mines in and near the study area show that the total 

value of production was about $2 million. In one canyon, marble has been quarried. 

The roadless area is underlain by a wide variety of 

rocks that are stongly faulted and intruded by several 

'With conLribulions from K. C. Wotts. Jr .. IUld D. P. Klein. USGS. 

stocks and many dikes (Drewes and Meyer, 1983). A 

Precambrian basement is made up of schist, arkose, 

quartzite, sedimentary breccia, metavolcanic rock, and 

amphibolite, all intruded by granodiorite stocks. These 

are unconformably overlain by Paleozoic and Mesozoic 

sedimentary sequences. The Paleozoic rocks are mainly 

limestone but include some clastic rocks both near the 

base and top; the Mesozoic sequence is largely of clastic 

rocks. 

The basement rocks and sedimentary sequences are 

intruded by igneous rocks. A small Oligocene stock lies 

along the northwest flank of the mountains. The large 

Miocene to Oligocene Stronghold Granite, a stock, lies 

in the center of the mountains and extends beyond their 

west flank. Tertiary or Cretaceous plugs occur near the 

Golden Rule mine in the northeastern tip of the range. 

Most dikes in the area are also Miocene, and typically 

trend northwest across stock and host rock alike. 

Quaternary gravel deposits lap against the flanks of the 

range and west of the Stronghold stock they lie upon a 

pediment. 

The Dragoon Mountains are abundantly faulted. 

Many faults are steep northwest- or north-trending 

stuctures; others are gently inclined. Many of the faults 

are thrust faults formed under compressive deformation. A few tight folds or truncated folds occur with the 

thrust faults. Nearly all of these structural features are 

cut by the stocks and thus were available as conduits 

for fluids dispersing from the stocks and plugs, some of 

which probably carried metals. 

59 
MINERAL RESOURCES 

Six areas have probable mineral-resource potential 

based on observations of geology, geochemistry and 

geophysics (Drewes and others, 1983). 

Area 1 is around the Golden Rule mine, largely outside the northeast comer of the roadless area. The area 

is underlain by metamorphosed Paleozoic rocks, including the Abrigo and Martin Formations, intruded by 

the Tertiary rhyolite porphyry plugs. Mining records 

and analyses of mineralized rock on the dump show the 

presence of base metals, silver, and gold. Aeromagnetic 

and gravity anomalies, along with surface observations, 

suggest the concealed presence of a stock and of a 

strong northeast-trending fault at the northern flank of 

the range. The metamorphosed and locally mineralized 

formations dip southwest and are cut by the northeasttrending fault, as well as by bedding-plain thrust faults. 

These data suggest that area 1 has a probable resource 

potential for mineralization similar to that found at the 

mine, most likely down4p in the Abrigo and Martin 

Formations, along the fault, or beneath the gravels 

north of the range. This implied mineralization would be 

vein or skarn-type contact deposits like those at the 

surface. 

Area 2 is along the northwest flank of the Dragoon 

Mountains largely along the southeast wall of the 

Oligocene stock, where its roof is projected outward at a 

low angle. The site also extends south along a zone of 

steep faults and to an upwarped and up faulted, mineralized structural feature. Small mines and prospects lie 

along steeply inclined to vertical faults along which 

there are slivers of metamorphosed Paleozoic limestone. 

Geochemical anomalies appear to be more widespread 

than the known mineralization. A geophysical anomaly 

at the stock has a configuration suggesting that body 

has a shoulder to the southeast, where pods of aplite appear along the fault zone with the limestone slivers. 

These observations indicate that additional base metal 

and silver mineralization may exist, most likely along 

fault zones and in formations typically altered to skarn 

minerals. There is also a probable resource potential for 

stockwork molybdenum deposits or tungsten deposits. 

At area 3, on the northeast side of the Stronghold 

stock, a probable mineral-resource potential is inferred 

because the Abrigo and Martin Formations, and other 

units of the Paleozoic sequence dip gently northeastward over a shoulder of the stock. The area has some 

prospects and small mines, containing concentrations of 

base metals and silver. Area 3 also has favorable geochemical anomalies and a magnetic anomaly penetrating the area from the northeast. We feel there is a 

probable resource potential in area 3 for sm?ll skarntype deposits of base metals and silver down dip along 

50 

the favored formations, and perhaps also some enrichment along intersections of faults and dikes at higher 

stratigraphic levels in the northern half of the area 

Area 4 lies largely outside the roadless area along a 

prong of sedimentary and metamorphic rocks between 

two lobes of the Stronghold stock. The Abril and San 

Juan mines lie in this area, along with many prospects. 

These mines are on skarn-type replacement deposits in 

faulted Paleozoic limestone along faults and near the 

stock. The mines are on a north-trending linear 

magnetic anomaly. A base metals-tungsten-silver geochemical anomaly trends northwest along the faulted 

sedimentary and metamorphic rocks, and a thorium-tinberyllium geochemical anomaly trends northeast across 

the area, largely following the stock itself. These studies 

suggest that area 4 has a probable resource potential for 

additional deposits of base metals and silver, and. 

perhaps also of other metals in vein or replacement 

deposits. While most of the site is outside the Dragoon 

Mountains Roadless Area, some zones of faulted metamorphic and sedimentary rock near the stock may extend into the roadless area 

Area 5 covers some of the southwestern part of the 

roadless area, along a gently outward dipping wall of 

the Stonghold stock which intrudes the Abrigo and 

Martin Formations. Skarn-type mineralization appears 

in scattered prospects near the contact, with .ertrichment in base metals, silver, and tungsten. The linear 

magnetic anomaly of area 4 extends across the eastern 

part of area 5, too. Area 5 has a probable resource potential for occurrences of lead and silver enrichment where 

the favored host rocks are expected to lie at moderate 

depth. While the deposits may be small, the area is accessible and would thus be easier to explore than most 

parts of the other areas of probable mineral-resource 

potential. 

Area 6 is almost entirely south of the roadless area, 

lying along a zone of northwest-trending faults mostly 

in Paleozoic and Mesozoic rocks. The Black Diamond 

mine, south of Middle Pass, is in this belt near the point 

at which the present study ends. The north end of this 

area is close to a gently south dipping part of the 

Stronghold stock. With the exception of this northern 

end and some slices of limestone along fault zones, the 

rocks are unaltered. Part of the area coincides with a 

magnetic anomaly. Geochemical anomalies for silver 

and tungsten occur in most of the area, and for gold in 

the southern part of the area These data indicate that 

there is a probable resource potential for occurrences of 

small deposits of base metals, silver, gold, and perhaps 

tungsten, in replacement bodies in fault slices of 

limestone or along heavily fractured ground near the 

larger faults. 

Several industrial rock products occur in the roadless 
area Marble for use as crushed rock or as flux may be 

obtained in several zones in the southern end of the 

roadless area, with the most promising marble in the 

Escabrosa and Horquilla Limestones of the Paleozoic 

sequence. The Horquilla Limestone may also be suitable 

for use in cement production, as it is near Tucson. A 

quartzitic variety of Pinal Schist of the basement rocks, 

near the mouth of Fourr Canyon may prove suitable for 

flux in copper smelters. Although in each of these instances the rock products are close to a railroad, other 

areas outside the roadless area also contain an abundance of these commodities. 

Conditions for the accumulation of petroleum and 

natural gas are believed to be negligible. The roadless 

area does lie in the proposed southern extension of the 

overthrust belt in which exploration for possible deep 

targets has been in progress for a few years. The local 

accumulation through thrust faulting of a thick pile of 

sedimentary rocks not withstanding, the entrapment 

conditions near so many young (mid-Tertiary) stocks, 

plugs, and dikes are probably poor. 

SUGGESTIONS FOR FURTHER STUDIES 

Further study of several of the areas indicated as having probable mineral-resource potential and of areas 

containing industrial rock products may be desirable. 

Extending this study for base metals and silver would 

probably involve more closely spaced geochemical sampling of alluvium and altered rock chips along fractures 

in those parts of areas 1, 3, and 5 overlying down-<iip extensions of suitable host rocks of mineralization, and a 

similar check along faults of areas 2, 3, 4, and 6. More 

detailed geophysical work may also help to indicate the 

configuration of shoulders or cupolas of concealed parts 

of stocks. 

The simplest single extension of this study would be 

to check the key rock types like the Horquilla Formation or the metamorphosed northern part of the area for 

suitability in use for lime rock or cement production. 

REFERENCES 

Drewes, Harald, Kreidler, T. J .. Watts, K. C .. Jr .. and Klein, D. P., 

19 3. Mineral resource potential of the Dragoon Mountain 

Roadless Area. Cochise County, Arizona: U .. Geological urv y 

Mi cellaneous Field tud.ies Map MF- 1521 - B, cal 1:50.000. 

Drewe . Harald. and Meyer. G. A .. 19 3, Geologic map of th 

Dragoon Mountains Roadless Area. Cochise County. Arizona: 

U. . Geological urvey Mi cellaneous Field tud.ie Map 

MF- 1521-A, scale 1:50.000. 

61 
62 

34° 

22' 

05" 

111°30' 

FIBgStiJif 

~/ ) I(G 

TERTIA RY VOLCANIC ROCKS(J J~ 

,... r-=d) 

03046--! \. ......,r \ f 

s NO R')CK ~ \ ="- \ Approximate f) CA r. '~) ,.) I ) roadless r 

I t1 1 ._,. boundary J ~' , ~ - ~--~ ~ rJ 0- , p.U' __f.S!..-v-:;-- _I "~--.:-< f\ ~ C. CAN.:::~ LMOGOI LON Rlr' 

'_/\ .J.,. _, If-~ I {/ / 

' .l., ..1. ,. , \ ,I 

I r. s. ~ a /~/ '>' Sir,..., rry 

.v 

PALEOZOIC SEDIMENTARY AND 

HARDSCRABBLE MESA 

UNDIFFERENTIATED PRECAMBRIAN , 

BASAL PALEOZOIC , 

AND TERTIARY ROCKS 

MAP LOCATION 

0 5 

MILES 

Figure 16.- Fossil Springs Roadless Area Arizona 
FOSSIL SPRINGS ROADLESS AREA, ARIZONA 

By L. S. BEARD , 1 U .. GEOLOGI AL R EY , a nd 

C. E. ELLIS, U .S. B REA OF MI I:: 

SUMMARY 

Based on field studies conducted by the USGS and the USBM during 

1980-81, the Fossil Springs Roadless Area in central Arizona is concluded to 

have little promise for the occurrence of mineral or energy resources. Rocks in 

the Supai Formation (Pennsylvanian-Permian) near the central part of the 

roadless area contain widespread but spotty copper mineralization and trace 

amounts of uranium. Analyses obtained during the study define geochemical 

anomalies in two portions of the area that remain unexplained. The suites of 

anomalous metals suggest the possibility of hydrothermal veins and the 

presence of ultramafic rocks; neither were found in the field. Construction 

materials present within the roadless area-chiefly basalt, sandstone, limestone, 

and dolomite-are readily available in abundance and more accessible in adjacent areas. The presence of oil and gas is unlikely; the only producing wells in 

Arizona are in formations not present in the Fossil Springs Roadless Area. 

CHARACTER AND SETTING 

The Fossil Springs Roadless Area includes about 

22 sq mi of plateau and canyons in the Coconino National Forest in Yavapai, Gila, and Coconino Counties, 

Arizona. The roadless area lies near the Mogollon Rim, 

southern boundary of the Colorado Plateau, which in 

this vicinity is characterized by steep-walled canyons 

cut into a high tableland of relatively flat lying Paleozoic sedimentary rocks veneered locally with Tertiary 

volcanic rocks. 

Paleozoic and Cenozoic rocks present in the Fossil 

Springs Roadless Area have a cumulative thickness of 

about 3000 ft. The bulk of the outcrops in the canyon 

walls in the northeastern part of the area consist of 

sandstone, siltstone, shale, and minor limestone of the 

Supai Formation (Pennsylvanian and Permian) and 

crossbedded sandstone of the Coconino Sandstone (Permian). To the northwest, the plateau is covered by Tertiary volcanic rocks, a few tens to a few hundred feet 

thick. South of Fossil Springs the volcanic rocks, chiefly 

dark gray basalts and yellowish-gray basaltic and 

dacitic tuffs, thicken abruptly to more than 2000 ft 

against an ancestral Mogollon Rim (Twenter, 1962) cut 

1

Wi th conlribut.ions from G. W. \rVcir. USGS. 

into the Paleozoic section by prevolcanism erosion. 

Preserved locally beneath the volcanics are Tertiary 

gravel deposits containing clasts of lower Paleozoic and 

Precambrian lithologies. A K-Ar age of 10.16±0.22 million years for a basalt flow about 1250 ft above the floor 

of the canyon gives a minimum age of formation of the 

ancestral Mogollon Rim and subsequent deposition of 

the gravels (Pierce and others, 1979). A unique feature 

of the area is a deposit of travertine (Pleistocene and 

Holocene) that forms a conspicuous bench above Fossil 

Springs. Thin sheets of colluvium and masses of landslide blocks obscure much of the outcrop throughout the 

roadless area. 

The prevailing dip of the Paleozoic strata is low 

toward the north or northeast. This homoclinal structure is broken into several fault blocks in which the 

strata dip westerly or southerly. All the faults in the 

roadless area are high-angle normal faults that have displacements commonly ranging from about 50 to 400ft. 

The Tertiary volcanic rocks, which rest unconformably 

on the Paleozoic strata, are flat lying in the northern 

part of area, but south of Fossil Springs they dip gently 

southwestward. Most of the faults that cut Paleozoic 

strata seem to displace the volcanic rocks also, but with 

less displacement. The buried ancestral Mogollon rim 

appears to be in part structurally controlled, but this is 

difficult to prove because of poor exposures. Few of the 

63 
faults can be traced in the volcanics away from the canyon rims because of the lack of lithologic contrasts on 

the plateau top. 

MINERAL RESOURCES 

An aeromagnetic map of the Fossil Springs Roadless 

Area (Davis and Weir, 1983) shows variations in total 

magnetic intensity of the area related to magnetic property contrasts in the volcanic rocks and to magnetic 

contrasts between the basalts and the sedimentary 

rocks. There are no magnetic lows that might represent 

zones of alteration in which metallic mineral deposits 

may occur, nor of magnetic highs that would indicate 

any large masses of high magnetic susceptibility, other 

than basalt. 

Geochemical analyses obtained on samples of stream 

sediments, pan concentrates of stream sediments, bedrock, and mineralized rock from the copper-uranium 

occurrences define complex geochemical anomalies that 

as yet cannot be geologically accounted for. Panned concentrate samples containing anomalous levels of chromium, cobalt, and nickel normally associated with ultramafic rocks were found in the central part of the area, 

about 1 mi upstream from Fossil Springs. In the upper 

reaches of Calf Pen Canyon, large barium and beryllium 

anomalies in the pan concentrates suggest possible 

hydrothermal vein deposits. Neither ultramafic rocks 

nor vein systems were observed in the field. The source 

of these anomalies is not known. The chromium, cobalt, 

and nickel anomalies are perhaps related to either a thin 

mafic dike or flow or to mineralization along a fault 

zone; neither was observed in the field. The barium and 

beryllium anomalies might be related to barite veins; 

although none are known in the roadless area, occurrences have been reported to the south along Tertiary 

fault zones (C. M. Conway, oral commun. 1982). The 

anomalies do not seem to indicate the occurrence of 

mineral resources. 

The Fossil Springs Roadless Area does not lie within 

an organized mining district. Four bulldozer cuts originally made during coal prospecting and later utilized 

for copper and uranium exploration in Permian rocks 

are included in a block of claims located in 1962 and 

1969 in the central part of the roadless area The prospects were inactive in 1980 and early 1981. Quarries in 

Paleozoic sandstone and Tertiary basalt near the 

borders of the roadless area were also inactive in 1980 

and early 1981. 

Copper-uranium occurrences are found within a discontinous zone, a few tens of feet thick, in the lower 

third of the Supai Formation about 400 ft above the 

base of the formation. This zone is charac rized by 

lenses of limestone-pebble conglomerate, sandstone, 

64 

and carbonaceous shale, interstratified with lesser 

amounts of siltstone, shale, and sandstone. Radioactivity due to the uranium occurrences is generally confined 

to coaly layers within carbonaceous shale and most of 

the copper minerals also occur in the carbonaceous shale 

or in gray sandstone and conglomerate interlayered 

with carbonaceous shale. Mineralization is sporadic and 

not concentrated; the sparsely mineralized rock occupies only a small part of the zone and is commonly only 

a few inches to a few feet thick and extends a few feet to 

several tens of feet along the outcrop. This minor mineralization is not assessed as being a resource and no 

resource potential for the area was identified. 

Flagstone has been quarried from two small workings 

in the Coconino Sandstone near the southeast edge of 

the area Basalt quarried from three small workings on 

the southeast and south edges of the area was probably 

used locally as road material. Both of these commodities are in abundance outside the area No energy resource potential was identified in this study. 

SUGGESTIONS FOR FURTHER STUDY 

Although there is little promise for the occurrence of 

mineral resources in the Fossil Springs Roadless Area, 

studies to identify the source of the geochemical anomalies could have valuable implications for regional studies and mineral exploration in the surrounding area. 

Anomalies of this type are unexpected in terms of what 

is presently known of the geology of the area; of particular interest is that ultramafic bodies are not known to 

occur in this region. 

REFERENCES 

Davis, W. E., and Weir. G. W., 1983, Map showing aeromagnetic 

survey of the Fossil Springs Roadless Area. Yavapai, Gila, and 

Coconino Counties, Arizona: U .. Geological Survey Miscellan· 

eous Field Studies Map MF - 1568-B, scale 1:24,000 (in press). 

Pierce, H. W. , Jones, N. and Rogers, R., 1977, A survey of uranium 

favorability of Paleozoic rocks in the Mogollon Rim and slope 

region· east central Arizona: Arizona Bureau of Geology and 

Mineral Technology Circular 19.60 p. 

Pierce, H. W .. Damon, P. E. and Shafiqullah, M., 1979, An 

Oligocene(?) Colorado Plateau edge in Arizona. Tectonophysics, 

Vol. 61, p.1 - 24. 

Rogers, R. 0., 1977, Copper mineralization in Pennsylvanian-Permian 

rocks of the Tonto Rim segment of the Mogollon Rin1 in central 

Arizona: Tucson, Ariz., University of Arizona. unpublished M.S. 

thesis, 65 p. 

Twenter, F. R., 1962, The significance of the volcanic rocks in the 

Fossil Creek area. Arizona: New Mexico Geological Society, 

Guidebook 13th Field Conference. p. 107- 108. 

Weir, G. W., Beard, L. S., and Ellis, C. E., 1983, Mineral resource 

potential map of the Fossil Springs Roadless Area. Yavapai, 

Gila. and Coconino Counties, Arizona: U.S. Geological Survey 

Miscellaneous Field Studies Map MF- 1568-A, scale 1:24.000. 
GALIURO WILDERNESS AND CONTIGUOUS ROADLESS AREAS, ARIZONA 

By S.C. CREASEY , ' U.S. GEOLOC I L S RV EY, and 

j. E. Jr K , U.S. B RE OF MI E 

SUMMARY 

A mineral survey of the Galiuro Wilderness and contiguous roadless areas in 

southeastern Arizona during 1972 identified one area of substantiated and four 

areas of probable resource potential for base and precious metals. It is possible, 

however, that the dominant, Oligocene and Miocene Galiuro Volcanics, which 

cap most of the Galiuro Range, conceal other mineral occurrences within 

underlying, older rocks. No energy resources were identified in this study. 

CHARACTER AND SETTING 

The Galiuro Wilderness and contiguous roadless 

areas, to be referred to as the study area, are in the Coronado National Forest, in southeastern Arizona, about 

50 mi northeast of Tucson. The study area lies entirely 

within the Galiuro Range, one of the large northwesttrending mountain ranges that form the Basin and 

Range province in southern Arizona The range is 

bounded on the west by the San Pedro valley and on the 

east by the Aravaipa valley. In the study area, the 

range consists of two ridges separated by two medial 

valleys and a low pass. These deeply incised valleys, 

Rattlesnake and Redfield, are developed parallel to the 

lengths of the ranges, in contrast to most of the other 

streams in the area, which flow at high angles to the 

range fronts. The Galiuro Wilderness covers an area of 

about 96 sq mi, and lies at altitudes ranging from about 

4000 to 7650 ft; it forms a broad U-shaped area that 

opens to the north, and the area within the limb of the 

"U", essentially the floor of Rattlesnake valley, is 

excluded from the wilderness. The roadless areas surrounding the Galiuro Wilderness include most of the 

area lying between the boundary of the wilderness and 

the boundary of the Coronado National Forest. 

The Galiuro Range is a tilted fault block bounded on 

the west by a west-dipping high-angle normal fault. A 

parallel west-dipping n~rmal fault extends about threequarters of the way through the central part of the 

study area from the south boundary. Movement along 

these and other normal faults produced a gentle eastward dip in the Galiuro Volcanics, the sequence of volcanic rocks that covers most of the Galiuro Wilderness. 

'Abstrnc!OO from a report. by Creasey and oUlers (1981) by Susan Tufts. wiUl contributions 

from W. J. KeiUl. USGS. 

Mineralizing solutions carried small amounts of base 

and precious metals along the central fault, which was 

at least partly active during accumulation of the 

Galiuro Volcanics. These volcanic rocks, Oligocene and 

Miocene in age, conceal older rocks that include Precambrian schists, granites, and quartzites, Paleozoic quartzites, and Upper Cretaceous and (or) lower Tertiary 

volcanic rocks and granitic stocks. The mineral potential of study area lies primarily in the possibility that 

the Galiuro Volcanics conceal mineral occurrences 

within the underlying older rocks. 

Historically, two mining districts lie near the study 

area, Copper Creek (Bunker Hill) and Rattlesnake. The 

Copper Creek district is centered around the mines in 

Copper Creek just to the northwest of the study area, 

and the Rattlesnake district is in the approximate 

geographic center of the wilderness, where the boundary of the wilderness has been drawn to exclude known 

mines. Copper and gold production data on the two mining districts show that the Copper Creek district was 

the most significant, producing 1354 oz of gold, whereas 

the Rattlesnake district yielded only 163 oz of gold. 

The mineral appraisal of the Galiuro Wilderness and 

contiguous roadless areas consisted of geologic, geochemical, and geophysical studies and examination of 

mines and prospects (Creasey and others, 1981). The 

USGS geochemical studies consisted of sampling and 

analysis of minus-80 mesh stream sediments, altered 

bedrock, and rocks from prospect pits; the geophysical 

study consisted of an aeromagnetic survey made to help 

separate the areas favorable for mineral deposits from 

the unfavorable areas. Mine and prospect evaluation 

made by the USBM consisted of locating, mapping, and 

systematically sampling all claims, mines, and 

prospects. 

65 
66 

11 

32° 

30' 

t.. 

v 

0 

110°20' 

5 

MILES 

EXPLANATION 

-

D 

Cu 

Au 

Ag 

M o 

Geologic terrane with substantiated 

mineral-resource potential 

Geologic terrane with probable 

mineral-resource potential 

Copper 

Gold 

Silver 

Molybdenum 

Zn Zinc 

X' Mine 

MAP LOCATION 

proximate roadless 

boundary 

l 

Quaternary deposits 

110°10' 

Tertiary Galiuro Volcanics 

Tertiary and (or) Cretaceous rocks 

Paleozoic quartzites 

Precambrian rocks 

Contact 

Fault 

Figure 17 .-Galiuro Wilderness and contiguous roadless areas, Arizona. 
MINERAL RESOURCES 

The mineral potential of the Galiuro Wilderness and 

contiguous roadless areas is difficult to assess. The 

study area lies within the Arizona copper province, one 

of the world's most productive, but the main surface 

rock units in the wilderness are younger than the 

deposits of the copper province and, therefore, conceal 

the older rocks that could be the hosts for significant 

copper deposits. Some indication of the copper potential 

in these older rocks is given by the occurrence of copper 

deposits in the Copper Creek district, adjacent to the 

northwest corner of the wilderness, and by geologic and 

geochemical studies of the older rocks in that same area 

These studies revealed a large area of altered rock containing anomalous quantities of copper. This area of 

copper-bearing older rocks has a substantiated copper 

resource potential. These altered and mineralized older 

rocks no doubt extend eastward beneath the younger 

volcanic rocks in the adjoining corner of the study area, 

where they could be potential hosts for copper deposits. 

Based on these observations the northwest corner of the 

study area is assessed as having a probable copper 

resource potential. However, the extent of these older 

rocks beneath the volcanic cover is not known; the surface geology is not diagnostic and, although some drilling has been done, the drill logs are not available for 

study. 

Within the study area, altered (pyritic and argillic) 

volcanic rocks occur in two areas and along the major 

north-trending fault that extends almost throughout 

the length of the study area Clear signs of near-surface 

occurrences were not observed, although anomalies for 

several metals occur within these altered areas. 

Whether these near-surface metal anomalies indicate 

mineral deposits at depth in the older rocks beneath the 

volcanic rocks cannot be evaluated from data obtained 

from this study, but the areas are considered to have a 

probable resource potential for copper, zinc, molybdenum, silver, and gold. 

Altered rocks in the area between the Rattlesnake and 

Redfield Canyons contain anomalously high amounts of 

molybdenum and silver and could be interpreted to indicate copper and molybdenum at depth in the older 

rocks. Estimates of the depth from the surface to the 

older rocks in this area range from 800 to 2400 ft. 

Sampling in the area around the Sixteen-to-One mine on 

the west side of the wilderness and Jackson mines in the 

southern part of the wilderness indicates that anomalous amounts of metals are present. However, there are 

no indications of mineral resources in the rocks exposed 

at the surface, and the possibility of mineral occurrences 

at depth is conjectural. Geochemical sampling in the 

southeastern corner of the study area indicates baseand precious-metal anomalies in stream-sediments, but 

the origin of these metals is unknown. Neither surface 

outcrops of altered rocks nor prospects indicate mineralization and no resource potential was identified. Based 

upon the geochemical studies, it is unlikely that any 

large near-surface deposits of base metals, such as zinc, 

or molybdenum, tungsten, and tin, were overlooked during this study. The same assurance does not exist for 

the precious-metal deposits of silver and gold, because 

they form deposits at low concentrations relative to 

base-metal deposits and are harder to detect by sampling. However, careful prospecting over the past 

century has not revealed such deposits. 

Examination of claims, mines, and prospects by th 

USBM did not reveal demonstrated mineral resources. 

The alteration and mineralization associated with the 

Copper Creek district may extend under the northwest. 

corner of the study area However, this can be determined only by drilling or by sinking shafts in that area. 

There is near-surface gold in altered volcanic rocks 

containing pyrite around the divide between Rattlesnake and Redfield Canyons, which includes the Powers 

and Long Tom mines. However, this low-grade material 

occurs in small, disconnected pockets along faults and 

only a probable resource potential for gold has been 

identified. 

The Sixteen-to-One mine area, outside the wilderness, 

but inside the contiguous roadless area is in a pyritized 

area that has small pockets of gold mineralizati011 along 

fractures and faults and the area is judged to have a 

probable gold resource potential in the volcanic rocks at 

the surface. It is not likely that widespread copper mineralization occurs at depth in the older rocks, because of 

the small size of the pyritized area at the surface. 

The altered and mineralized areas around the Jackson 

mine and the prospects to the southeast are closely 

associated with the fault that runs through the central 

part of the study area The exposed alteration zone 

along the fault is narrow and the metal content low. 

Whether or not this fault zone contains deposits at 

depth where the fault cuts older rocks is conjectural, but 

the possibility exists and the area has a probable 

resource potential. Other metal anomalies along the 

fault appear to be isolated and do not indicate a resource 

potential. 

An aeromagnetic survey of the study area revealed a 

high magnetic intensity in the northwestern part of the 

area and several discontinuous high-gradient anomalies 

over the eastern part of the area. Although most of the 

major anomalies are associated with the volcanic rocks 

on the upper slopes and crests of the mountains, the 

host rocks in mining localities probably are expressed in 

the magnetic pattern. For example, the higher intensity 

in the northwestern part of the area may represent an 

67 
extension of the rocks that contain copper deposits in 

the Copper Creek mining district. None of the anomalies 

has sufficient amplitude to indicate large deposits of 

highly magnetic ore minerals lying at shallow depths in 

the study area 

Limestone, quartz sand, sand, and gravel, all occur in 

the study area, but all are found in abundance outside 

the area The Galiuro Volcanics have resources of construction stone and pumice, as well as vitrophyre and 

obsidian, some of which might be perlitic in the commerical sense of expanding on heating. However, the 

study area is far from potential markets and without access roads. The volcanic rocks in the study area are too 

old and too thin to retain enough heat for geothermal 

energy and the area has no known occurrences of 

uranium. The geologic setting is not favorable for the 

occurrence of fossil fuels. 

68 

SUGGESTIONS FOR FURTHER STUDIES 

Further sampling should be undertaken to confirm or 

disprove some of the apparent metal anomalies found 

during the reconnaissance sampling. In addition, drilling would be necessary, particularly in the northwestern 

comer of the study area, to determine whether the older 

rocks underlying the Galiuro Volcanics contain ore 

deposits. 

REFERENCE 

Creasey, S.C., Jinks, J. E., Williams, F. E., and Meeves, H. C., 1981, 

Mineral resources of the Galiuro Wilderness and contiguous Further Planning Areas, Arizona: U.S. Geological Survey Bulletin 

1490,94 p. 
HELLS GATE ROADLESS AREA, ARIZONA 

By CLAY M . CO WAY, . . G EOL L R\'EY, a nd 

ROBERT A. M e OLLY, .S. B REA OF MINE 

SUMMARY 

Although no mineral-resource potential was identified in the Hells Gate 

Roadless Area during mineral surveys in 1981, the area is largely underlain by a 

regionally extensive Proterozoic granite-rhyolite complex which is tin-bearing. 

The geologic setting precludes the occurrence of fossil fuel resources and no 

other energy resources were identified. 

CHARACTER AND SETTING 

The Hells Gate Roadless Area comprises approximately 49 sq rni in the northern part of the Tonto National Forest in Gila County, Arizona The area is 

roughly a 4 by 15 rni strip along a deeply incised segment of upper Tonto Creek. Altitudes range from 3000 

ft in the lower gorge to 6000 ft in hills above the upper 

gorge. Vegetation is light to moderately heavy. Intermediate to higher altitudes are forested with pinion 

pine, alligator juniper, and several oak varieties with 

stands of yellow pine above 5000 ft. Succulents, cactus, 

and chapparal are common at lower altitudes. 

The Hells Gate Roadless Area lies in the central 

mountain belt of Arizona at the base of the Mogollon 

Rim which is the physiographic margin of the Colorado 

Plateau. Geologically the area is a slightly structurally 

disrupted and erosionally stripped margin of the Colorado Plateau. Paleozoic and Middle Proterozoic sedimentary rocks, exposed nearby, have been entirely 

removed by erosion from the roadless area, exposing 

folded, faulted, and metamorphosed Early Proterozoic 

volcanic, plutonic, and sedimentary rocks (Gastil, 1958; 

Conway, 1976). These 1.7 billion year old rocks are locally blanketed with upper Tertiary lacustrine sand and 

gravel deposits. 

About 90 percent of the exposed Proterozoic rocks in 

the roadless area are intrusive and extrusive rhyolite, 

granophyre, and graniw, all of essentially the same composition. They formed as subaerial and hypabyssal 

parts of a great volcanic complex. This complex is 

overlain by quartzite which constitutes most of the remaining rocks exposed in the area. The granite-rhyolite 

complex is stratigraphically underlain by and intruded 

into a thick section of variable sedimentary and volcanic 

rocks immediately southeast of the roadless area. 

Geologic and geochemical studies have shown that the 

rhyolite, and particularly the granophyre and granite, 

have certain characteristics common to tin-bearing 

granites. 

MINERAL RESOURCES 

Little mining activity has occurred within 20 mi of the 

roadless area For a short period in the late 1800's, there 

was small-scale gold mining in quartz veins in diorite 

3-10 mi west of the roadless area. A few small mines 

have operated intermittently in the volcanic and clastic 

strata underlying the extrusive rhyolite south and east 

of the roadless area for gold, silver, copper, beryllium, 

and barite, but there has been very little production. 

There are no mines or claims of record in the roadless 

area; only a few barren prospect pits have been found. 

The absence of past mining in the roadless area, very 

few prospects and claim records, and the absence of 

geologic, geochemical or geophysical evidence for specific sites of mineralization, indicate that there is little 

promise for the occurrence of mineral resources in the 

Hells Gate Roadless Area However, the area is largely 

underlain by felsic igneous rocks, part of a regionally extensive suite (Tonto Basin, Mazatzal Mountains), which 

has petrographic and chemical characteristics indicating a possibility of tin mineralization. Widespread 

tin values in analyses of sediments and concentrates 

and the tin oxide, cassiterite, occur in the nearby Mazatzal Wilderness (Wrucke and others, 1983) and in the 

Hells Gate Roadless Area Associated with the anomalous tin are high niobium, tantalum, yttrium, and 

beryllium. 

69 
70 

34° 

15' 

34° 

oo· 

111 °15' 111 °00' 

MAP LOCATION 

0 10 

MILES 

EXPLANATION 

:------ :c Sedimentary rocks (Paleozoic) 

~1~f~~~~!i Granite and granophyre (Early Proterozoic) 

Intrusive and extrusive rhyolite (Early Proterozoic) 

Sedimentary, volcanic, and plutonic rocks 

'-------' (Early Proterozoic) 

Contact 

Fault 

Figure 18.-Hells Gate Roadless Area, Arizona 

) 
Upper parts of the granite and the overlying granophyre, which have the greatest possibility for tin, crop 

out along the northwest margin of the roadless area and 

dip beneath it. Most of this zone is outside the Hells 

Gate Roadless Area. 

There are small occurrences of barite along Miocene 

faults that extend into the roadless area, but barite 

veins in the region are sparce and no barite was observed while mapping the faults in the roadless area 

SUGGESTIONS FOR FURTHER STUDIES 

The potential for tin and associated metals in the 

Hells Gate Roadless Area and the region cannot be fully 

evaluated at this point. The granophyre and the upper 

part of the granite pluton along the northwestern 

margin of the area should be further explored. 

REFERENCES 

Conway, C. M., 1976. Petrology, structure, and evolution of a Precam· 

brian volcanic and plutonic complex, Tonto Basin, Gila County, 

Arizona: Pasadena, California Institute of Technology. un· 

published Ph.D. thesis, 460 p. 

Conway, C. M., McColly, R. A., Marsh, . P., Kulik. D. M., Martin. 

R. A .. and Kilburn, J. E., in pres . Mineral re ource potential map 

of the Hells Gate Roadless Area, Gila County, Arizona: U. . 

Geologica l Survey Mi cell a neous Fi eld t udies Map 

MF- 1644- A. scale 1:48,000. 

Gastil, R. G., 1958, Older Precambrian rocks of the Diamond Butte 

Quadrangle. Gila County, Arizona: Geological Society of America 

Bulletin v. 69. p. 1495-1514. 

Wrucke, C. T., Marsh, S. P., Conway, C. M .. Ellis, C. E., Kulik, D. M .. 

and Moss, C. K., 1983, Mineral resource potential map of the 

Mazatzal Wilderness and contiguous roadles areas. Gil a. 

Maricopa, and Yavapai Counties. Arizona: U. . Geological 

Survey Miscellaneous Field Studies Map MF - 1573·A. scale 

1:48,000. 

71 
72 

0 10 

MILES 

EXPLANATION D Geologic terrane with probable 

mineral-resource potential 

Cu Copper 

Au Gold 

Pb Lead 

Ag Silver 

u Uranium 

Zn Zinc 

~ Mine 

Quaternary and Tertiary 

8 conglomerate 

Tertiary 

Rhyolite of Mule Creek 

Andesite and basaltic andesite 

Coarsely porphyritic andesite 

intrusive 

Rhyodacite and rhyolite 

Rhyolite of Hells Hole 

Older andesite 

Contact 

___1.__ Fault--Bar and ball on 

downthrown side 

o Altered rocks 

*- Rhyolite and andesite dikes 

" Vent 

Figure 19.-Hells Hole Roadless Area, Arizona and New Mexico. 
HELLS HOLE ROADLESS AREA, ARIZONA AND NEW MEXICO 

By j AME C. R ATTE' U .. GEOLOG I ,AI. RV EY, and 

j O H P. BRIGG , U .. B RE OF MI E 

SUMMARY 

The Hells Hole Roadless Area was studied in 1979 and the southeast part was 

determined to have a probable mineral-resource potential for the discovery of 

base- or precious-metal deposits related to igneous intrusions of middle to late 

Tertiary age. There also is a probable resource potential for porphyry copper 

mineralization of Laramide age beneath the Tertiary volcanic rocks that cover 

the area There is little promise for the occurrence of energy resources in the area. 

CHARACTER AND SETTING 

The Hells Hole Roadless Area encompasses about 

50 sq mi along the Arizona-New Mexico State line 3 mi 

southwest of Mule Creek, New Mexico and 24 mi east of 

Clifton and Morenci, Arizona New Mexico and Arizona 

Highway 78 is the northern boundary of the roadless 

area 

The area is part of a northwest-trending mountainous 

region that merges with the Big Lue Mountains northwest of Arizona Highway 78. Altitudes in the area 

range from less than 5000 ft along the southwest flanks 

of the mountains to 7488 ft on Maverick Hill along the 

range crest. The range is cut by steep-walled canyons 

that drain north or northwestward to the San Francisco 

River or southwestward to the Gila River. 

Geologically the area is in the southwestern part of 

the Mogollon-Datil volcanic field of middle to late Tertiary age, which covers part of the transition zone between the Basin and Range and Colorado Plateau structural provinces. The study area is toward the northwest 

end of a fault-bounded, mountainous block that is about 

70 mi long and 25 mi wide. No pre-Tertiary rocks are exposed in the study area The nearest basement rocks to 

the mapped area crop out 5-6 mi to the west, where 

lower Paleozoic quartzite and limestone overlie Precambrian granitic, gabbroic, and metasedimentary rocks 

(J. E. Cunningham, written commun., 1980). A more 

complete section of Paleozoic rocks is exposed a few 

miles farther west in the Clifton-Morenci area (Lindgren, 1905). About 12 mi southeast of the mapped area, 

Mesozoic rocks unconformably overlie Precambrian 

granitic rocks without any intervening Paleozoic rocks. 

1

WiLh contributions from D. C. Hedlund. R. A. Martin. and J. R. Hassemer. USGS. 

Major porphyry copper deposits are being mined at 

Morenci, Arizona, 24 mi west, and at Tyrone, New Mexico, 50 mi southeast of the study area. These large, 

disseminated copper deposits occur in quartz monzonite 

intrusives of early Tertiary age, which are overlapped 

by mid-Tertiary volcanic rocks; similar deposits could 

underlie mid-Tertiary volcanic rocks in the intervening 

area between these deposits, including Hells Hole Roadless Area (Ratte and others, 1982). 

The Hells Hole Roadless Area does not lie within an 

organized mining district. There are no patented mining 

claims within the area nor has there been any recorded 

production from within its boundaries. Actual mining 

has been limited to two small workings. One is located 

on the west flank of Yellowjacket Peak, where secondary copper minerals occur in a narrow shear zone at the 

Y ellowj acket prospect; the other is at the Telluride mine 

on upper Sawmill Creek, where a narrow zone of discontinuous quartz veins is exposed in the stream bed. The 

only other prospect is the Paj aro Azul (Bluebird) 

uranium prospect on Coal Creek in the northeastern 

part of the area, where a siliceous, cemented fault zone, 

which cuts rhyolite breccia, is anomalously radioactive. 

Approximately 850 unpatented mining claims have 

been located within or adjacent to the mapped area 

(80 percent or more outside the study area), of which 

650 were in compliance with federal recordation requirements in 1980. A strip of claims connecting the Telluride mine and Yellowjacket Peak represents recent baseand precious-metal exploration efforts within the study 

area 

The southern portion of the study area adjoins the 

Steeple Rock (Mayflower, Twin Peaks) mining district. 

Production from the district totals about $7 million in 

silver, gold, and minor amounts of base metals and 

73 
fluorite. A characteristic, northwest-trending, faultfissure vein system extends into the northern part of 

the district, south of the study area A current base- and 

precious-metal exploration program is centered on a 

tract south of the western half of the study area and, on 

the New Mexico side, a similar program is being conducted. No recent production has been recorded from 

this northern portion of the Steeple Rock district; past 

production includes 1115 oz gold, 3640 oz silver, and 

1965 lbs copper. 

MINERAL RESOURCES 

A probable mineral-resource potential for base- or 

precious-metal deposits within the Hells Hole Roadless 

Area is based on the following: (1) A favorable geologic 

environment has been determined by geologic mapping 

(Ratte and Hedlund, 1982) and by geophysical interpretations (Martin, 1981). (2) Evidence of mineralization is 

provided by present and past mining activity in areas 

adjacent to the Hells Hole Roadless Area and by anomalously high elemental concentrations in geochemical 

samples taken in the area Stream-sediment concentrates, veins, and hydrothermally altered rocks were 

sampled within the mapped area (Hassemer and others, 

1981). 

The favorable geologic environment consists of a 

middle Tertiary volcanic center and a subjacent shallow 

stock or small batholith of silicic to intermediate composition that is believed to underlie most of the study 

area Volcanism and intrusive activity were sustained 

over an interval of about 10 million years during which 

time the magma, or magmas, evolved from andesite 

through rhyodacite and low-silica rhyolite to high-silica 

rhyolite. Ore deposit models indicate that this geologic 

environment is most conducive to the formation of 

stockwork molybdenum deposits, and epithermal 

precious-metal deposits of the fissure-vein type like 

those that occur in the nearby Steeple Rock mining 

district. The geologic setting is generally favorable for 

the occurrence of porphyry copper deposits; however, 

such deposits almost invariably are early Tertiary or 

Late Cretaceous in age in this region. Because of the 

proximity of major porphyry copper deposits at Morenci, Arizona, and Tyrone, New Mexico, the possibility 

exists that a similar deposit is buried beneath midTertiary volcanic rocks within the roadless area A tin 

porphyry system is also possible in this geologic environment (Sillitoe and others, 1975), and although it 

would be a unique and unlikely occurrence in this 

74 

region, the strategic importance of tin makes even the 

possibility of a tin porphyry system noteworthy. 

Panned concentrates from stream-sediment samples 

show anomalously high amounts of beryllium and niobium over the volcanic center, particularly from areas 

draining outcrops of the rhyolite of Hells Hole and near 

the vent for the rhyolite of Mule Creek. Anomalously 

high amounts of tin, boron, barium, and tungsten, 

although more dispersed, are also most common over or 

peripheral to the volcanic center. Anomalously high 

amounts of silver, copper, molybdenum, lead, zinc, 

bismuth, antimony, and arsenic, on the other hand, are 

concentrated both over and around the volcanic center 

and along the northwest fracture zone south of the 

roadless area Samples of altered and mineralized rock~ 

associated with the volcanic center contain significant 

values for beryllium, niobium, tin, barium, molybdenum, silver, and copper. Selected samples of altered 

and mineralized rocks from the northwest fracture zone 

are enriched in silver, copper, molybdenum, zinc, lead, 

and barium; one sample from the Twin Peaks mine contained gold. Fluorite is common in the concentrate 

samples in the northwest fracture zone, but was not 

seen in concentrates that might be associated with the 

rhyolites of the volcanic center within the Hells Hole 

Roadless Area 

Niobium in the minerals pseudobrookite and ilmenite 

(Hassemer and others, 1981) forms as much as 1 1/2 percent of the magnetic fraction of the gravel in some 

drainages across the major rhyolite outcrops, but there 

is little likelihood of sufficient volume or grade for 

economic niobium placer deposits. 

The silicic volcanic rocks, particularly the high-silica 

rhyolite of Mule Creek, are suitable source rocks for 

uranium-bearing solutions. A single prospect in the 

northwestern part of the roadless area (Pajaro Azul) has 

revealed a uranium occurrence, formed most likely by 

the movement of uranium-bearing ground water along a 

fracture zone in rhyolite. No evidence of other occurrences of this type, nor evidence for other types of 

uranium deposits was found within the mapped area 

As a result of this study, there is little promise for the 

discovery of oil, gas, energy resources, or any other 

mineral resources within the Hells Hole Roadless Area 

SUGGESTIONS FOR FURTHER STUDIES 

Additional geochemical and petrological studies of 

the rocks of the Hells Hole volcanic center and modeling 

of geophysical anomalies are necessary to adequately 

appraise the mineral-resource potential of the area. 
REFERENCES 

Hassemer, J. R., Watts, K. C., Fom, C. L., and Mosier, E. L., 1981, 

Methodology, statistical analysis, and listing of the spectrographic analysis of geochemical samples of the Hells Hole Further Planning Area (RARE II), Greenlee County, Arizona. and 

Grant County, New Mexico: U.S. Geological Survey Open-File 

Report81-661, 136p. 

Lindgren, W. E., 1905, Description of the Clifton quadrangle, 

Arizona: U.S. Geological Survey Geologic Atlas. Folio 129, scale 

1:62,500. 

Martin. R. A., 1981, Geophysical surveys of the Hells Hole Further 

Planning Area (RARE II), Greenlee County, Arizona. and Grant 

County, New Mexico: U.S. Geological Survey Miscellaneous 

Field Studies Map MF - 1344- B, scale 1:62,500. 

Ratte', J. C., Hassemer, J. R., and Martin, R. A., 1982, Mineral 

resource potential map of the Hells Hole Furthem Planning Area 

(RARE II), Greenlee County, Arizona and Grant County, New 

Mexico: U.S. Geological Survey Miscellaneous Field Studies Map 

MF - 1344E, scale 1:62,500. 

Ratte', J. C., and Hedlund, D. C., 1982, Geologic map of the Hells Hole 

Further Planning Area (RARE II), Greenlee County, Arizona, 

and Grant County, New Mexico: U . . Geological Survey Miscellaneous Field Studies Map MF- 1344- A, Scale 1:62,500. 

Sillitoe, R. H., Halls, C., and Grant, J. N., 1975, Porphyry tin deposits 

in Bolivia: Economic Geology, v. 70, no. 5, p. 813- 827. 

75 
76 

U, Cu roadless boundary 

G H u 

A r I 0 A 1 (, A M 

v f 

MAP 

8 

LOCATION 

0 5 

MILES 

EXPLANATION 

D Geologic terrane with probable 

mineral-resource potential 

Kaibab Formation (Permian) 

Cu Copper 

u Uranium 

Toroweap Formation (Permian) 

Hermit Shale (Permian) 

Esplanade Sandstone of 

Supai Group (Permian) 

--- Contact 

--r- Fault--Bar and ball on 

downthrown side 

Figure 20.-Kanab Creek Roadless Area, Arizona 
KANAB CREEK ROADLESS AREA, ARIZONA 

B y GEORGE H . BILL! G LEY I U .. Gt:OLOGI L RVEY , and 

CLARE CE E. ELL! , .. BURE OF MI E 

SUMMARY 

On the basis of a mineral survey in 1982, the Kanab Creek Roadless Area in 

north-central Arizona has a probable mineral-resource potential for uranium and 

copper in four small areas around five collapse structures. Gypsum is abundant 

in layers along the canyon rim of Snake Gulch, but it is a fairly common mineral 

in the region outside the roadless area. There is little promise for the occurrence 

of fossil fuels in the area 

CHARACTER AND SETTING 

The Kanab Creek Roadless Area encompasses about 

14 sq mi within the Colorado Plateau Province and is 

about 18 mi north of the Grand Canyon, Arizona. It is 

contiguous with the Kanab Canyon Wilderness on the 

west and south sides and lies within the Grand Canyon 

Game Preserve of the Kaibab National Forest. The rugged canyon area is over 1500 ft deep at its deepest point, 

and crosses Kanab Canyon in its westernmost part. 

Altitudes in the roadless area range from 3720 ft to 

6200 ft. 

The nearest settlements in the region are Fredonia, 15 

mi to the north, and Jacob Lake, 9 mi to the east; both 

towns are in Arizona and connected by State Highway 

89A. The roadless area can only be reached by a few unmarked, unimproved jeep and hiking trails. 

The rocks of the Kanab Creek Roadless Area consist 

of horizontal beds of sandstone, shale, and limestone, of 

Early Permian age. The rock units exposed include (in 

ascending order), the Esplanade Sandstone, Hermit 

Shale, Toroweap Formation (Seligman, Brady Canyon, 

and Woods Ranch Members), and the Kaibab Formation (Fossil Mountain and Harrisburg Members). The 

Triassic Moenkopi Formation is exposed 15 mi to the 

north. 

The upper 160 ft of the Esplanade Sandstone is exposed at the mouth of Snake Gulch and consists mainly 

of a dark-reddish-brown mudstone and siltstone capped 

with a resistant reddish-brown to white massive ledgeforming sandstone. An erosional surface with relief of 

'Wit.h conLributions from J ock Antweiler. USC . 

about 20 ft marks the unconformity between the Esplanade and Hermit Shale. The slope-forming Hermit 

Shale, (which is about 575 ft thick), consists of alternating bright-red-brown shaly mudstone and siltstone 

interbedded with pale-red-brown ledge-forming massive 

beds of sandstone. The contact with the overlying 

Coconino Sandstone, which is absent in the Kanab 

Creek Roadless Area, but exposed about 3 mi to the 

east-southeast, is a level surface with large tension 

cracks in the underlying Hermit Shale that are filled in 

with Coconino Sandstone. The Coconino Sandstone is a 

cross-laminated white sandstone only 14 ft thick in the 

upper 6 mi of Snake Gulch (outside of the roadless area) 

and nonexistent elsewhere. Reworked white Coconino 

Sandstone and red shale and sandstone of the Hermit 

form the interbedded layers of the basal Seligman 

Member of the Toroweap Formation. The Seligman 

Member, which is about 30 ft thick, forms a continuous 

cliff with the overlying Brady Canyon Member, which 

has a thickness of approximately 210 ft. The fossiliferous gray limestone beds of the Brady Canyon grade upward into slope-forming pale-red and gray shale and 

siltstone of the Woods Ranch Member of the Toroweap, 

which is about 160 ft thick. Thick layers of massive 

gypsum occur throughout the Woods Ranch Member. 

An erosional unconformity with as much relief as 10 ft 

marks the boundary between the Toroweap and the 

Kaibab. The basal unit of the Kaibab is a yellowish-gray 

fossiliferous cherty limestone representing the Fossil 

Mountain Member which is about 280 ft thick. An arbitrary boundary is drawn at a gradational contact between the cliff-forming Fossil Mountain Member and 

the overlying slope-forming Harrisburg Member. The 

Harrisburg, which is about 200 ft thick, is a series of 

77 
alternating gray and pale-red shale and siltstone interbedded with gray limestone and gypsifereous siltstone. 

The Harrisburg forms the serniresistant plateau surface 

around the Kanab Creek Roadless Area and has variable thicknesses because of recent erosion. Unconsolidated Quaternary deposits are scattered on the slopes 

of the canyon as colluvium, and elsewhere as flood-plain 

deposits, alluvial-valley deposits, alluvial fans, and a 

few travertine deposits. 

A few normal north-south trending faults occur at the 

east end and southeast of the Kanab Creek Roadless 

Area with a maximum throw of 1200 ft. One large fault, 

the Gunsight Point fault, occurs in Kanab Canyon just 

west of Snake Gulch. The sedimentary rocks of Snake 

Gulch dip very slightly from east to west, with a regional dip of 1 o . Collapse structures are scattered at 

random on the Plateau surface on both sides of the canyon. The collapsed structures are recognized by gently 

dipping strata from 1° to 10 ° towards a central point in 

the center of a circular-shaped area. The collapsed areas 

vary in diameter from about 50 ft to 0.75 mi, and are 

commonly brecciated to the depth of Mississippian 

strata to form breccia pipes'. Uranium often occurs in 

these structures. 

MINERAL RESOURCES 

The nearest known mineral deposits to the roadless 

area, until recently, were the copper deposits of the 

Jacob Lake-Warm Springs district, 4 mi east of Snake 

Gulch (Tainter, 1947). These are ribbon-like bodies of 

azurite and malachite at the intersection of vertical 

joints in beds of cherty sandy limestone of the Kaibab 

Limestone. Copper occurrences such as these could exist near the rims of Snake Gulch, but no copper minerals 

were observed within the Kanab Creek Roadless Area. 

The presence of uranium resources and several 

uranium prospects related to collapse structures in a 

contiguous area of similar geology indicate a probable 

mineral-resource potential for uranium adjacent to 

parts of the Kanab Creek Roadless Area Collapse struc78 

tures (breccia pipes) are near the Snake Gulch canyon on 

lands of the U.S. Bureau of Land Management and the 

Kaibab National Forest. A deposit of uranium in a collapse structure (Pigeon Pipe) occurs on the north rim of 

Snake Gulch and an area of probable uranium resource 

potential extends a small distance into the roadless 

area Three small areas of probable potential around 

four other collapse structures extend into the area. 

Elsewhere, the Snake Gulch canyon has a little promise 

for the occurrence of mineral deposits except for layers 

of gypsum that occur in the Woods Ranch Member of 

the Toroweap Formation along the rim of the canyon. 

Mineral prospects are rare or nonexistent, and no significant anomalies were found in geochemical samples collected within the roadless area. 

The deep Paleozoic rocks could be favorable for oil 

and gas in this area However, the nearest drill hole, 

about 12 mi northwest of the Kanab Creek Roadless 

Area, penetrated Cambrian strata, and was dry. 

SUGGESTIONS FOR FURTHER STUDIES 

It is unlikely that further study of the Kanab Creek 

Roadless Area would reveal evidence for mineral resources at the surface, but studies of collapse structures 

in surrounding adjacent areas might reveal significant 

mineralization at depth, such as the recent discovery of 

the uranium ore body at depth in the Pigeon Pipe. 

REFERENCES 

Billingsley. G. H., Antweiler, J. C., and Ellis, C, E .. in press. Mineral 

resource potential map of the Kanab Creek Roadless Area. 

Coconino and Mohave Counties, Arizona: U-8, Geological Survey 

Miscellaneous Field Studies Map MF- 1627- A 

Sorauf. J _ F., 1963, Structural geology and stratigraphy of the Whitmore area, Mohave County. Arizona: Dissertation Abstracts, 

v. 24, no. 2. 

Tainter, S. L., 1947, Apex copper property, Coconino Coun ty , 

Arizona: U-8. Bureau of Mines Report of Investigations, 

Rl-401 3, 23 p. 
LOWER SAN FRANCISCO WILDERNESS STUDY AREA AND 

CONTIGUOUS ROADLESS AREAS, ARIZONA AND NEW MEXICO 

By jAME C. RAITE,

1 U.S. G EOLOGICAL URV EY and 

' 

MICHAEL E. LAN E, U.S. BUREA OF MI 

SUMMARY 

The Lower San Francisco Wilderness study area and contiguous roadless 

areas were examined for mineral potential in 1980- 81 and found to have an area 

of probable mineral-resource potential for base- or precious-metal deposits in 

middle to upper Tertiary volcanic rocks. The entire area has a largely 

unassessable potential for base-metal deposits related to igneous intrusives of 

Laramide age, like those in the nearby Morenci mining district, Arizona. The 

contiguous roadless area has an area of probable mineral-resource potential for 

molybdenum or copper deposits related to intrusive igneous rocks in the core of 

a dacitic volcano of Oligocene age. An area in the west part of the study area has 

a probable geothermal-resource potential. 

CHARACTER AND SETTING 

The Lower San Franciso study area consists of about 

40 sq mi, in a strip between 1 and 6 m.i wide, along a 

20-30 m.i stretch of the San Francisco River in Arizona 

and New Mexico. The wilderness study area is almost 

equally divided between the two states, but the contiguous roadless area is entirely in New Mexico. Within 

the study area, the San Francisco River has cut a spectacular steep-walled canyon nearly 2000 ft deep. The 

area was studied in 1980-81 and the results were 

published in 1982 (Ratte and others, 1982). 

Clifton and Morenci, Arizona, are the closest towns 

down river about 10 mi west of the study area, and 

Glenwood, New Mexico, is about 5 m.i upriver. Elevations in the study area range from about 3800 ft, at the 

mouth of the Blue River at the west end of the area, to 

about 4500 ft at the east end, and 6600 ft on the north 

rim of the San Francisco River canyon. 

The study area is within the transition zone between 

the relatively stable Colorado Plateau and the more tectonically active Basin and Range structural and physiographic provinces. The transition zone was the site of intense faulting and igneous activity during Laramide 

1

Witll contributions by J. R. Hassemer and R. A. Martin. USG . 

time (Late Cretaceous to early Tertiary), and large 

volumes of basaltic to rhyolitic volcanic rocks were 

erupted along the transition zone in middle Tettiary 

time. The study area is entirely covered now by middle 

Tertiary and younger volcanic rocks or streamdeposited sedimentary rocks, but lower Tertiary and 

pre-Tertiary rocks may underlie parts of the study area 

at 1000 ft or less below the level of the San Francisco 

River. In fact, middle Tertiary volcanic rocks overlie 

Paleozoic sedimentary rocks and Precambrian granite 

only a few miles south of the study area 

The rocks within the study area are cut by 3 sets of 

high-angle normal faults that trend north-northeast, 

northwest, and west-northwest. Displacements on the 

faults of each set range from a few tens of feet to hundreds of feet. The other major structures in the study 

area are all constructional volcanic features, mainly 

eruptive centers, such as andesitic and basaltic cinder 

cones, a small stratovolcano, and rhyolite vents, plugs 

and breccia pipes. 

Mining activity within the study area has been practically nil, and there were no active mining claims 

within the area in 1980. However, since completion of a 

minerals survey in 1981, sizeable blocks of claims have 

been filed in the New Mexico part of the study area in 

Goat Basin, and southeast of Goat Basin on the north 

side of the San Franciso River. 

79 
80 

0 

D Geologic terrane with probable 

resource potential 

Cu Copper 

Au Gold 

Mo Molybdenum 

Ag Silver 

5 

MILES 

EXPLANATION 

Andesite and basalt 

flows and 

volcaniclastic 

sedimentary 

rocks 

Lower San Francisco 

contiguous roadless 

' 

• • • 

l( ~ l( 

area 

Intrusive-extrusive 

rhyolite 

Goat Basin 

Dacitic Volcano 

Contact 

Fault--Bar and ball on 

downthrown side 

Quartz-calcite veins 

Rhyolite dikes 

Altered rocks 

Figure 21.- Lower San Francisco Wilderness study area and contiguous roadless areas, Arizona and New Mexico. 
MINERAL RESOURCES 

Any ore deposits discovered in the study area are 

most likely to be of Laramide or middle Tertiary age. 

Laramide time is when most of the important copper deposits of the southwestern United States were formed, 

including the deposits at the Morenci and Metcalf 

mines, less than 15 mi southwest of the western end of 

the study area, which have produced more than 3 million tons of copper. Some subvolcanic intrusive centers 

of middle Tertiary age in the vicinity of the study area, 

as at Steeple Rock and Mogollon, New Mexico, have 

deposits of silver, gold, copper, and fluorite. 

Within the study area, the greatest incentive to 

mineral exploration is the possibility of discovering a 

porphyry copper deposit related to a Laramide intrusive 

buried beneath the middle Tertiary volcanic cover. The 

probability of such a blind intrusive occurring within 

the 40 sq mi area of the Lower San Francisco Wilderness study area and contiguous roadless area, and the 

further probability of its being mineralized sufficiently 

to form an ore deposit, is largely unassessable by the 

method used in this mineral survey. 

The best exploration target for ore deposits of midTertiary age is the Goat Basin volcano, north of the San 

Francisco River and entirely within the contiguous 

roadless area. The volcano is a stratified volcanic cone 

2-3 mi in diameter; it consists of explosive breccia, lava 

flows, and minor tuff of hornblende dacite and pyroxene 

andesite, 26-2 million years old. Its flanks are largely 

buried by younger andesite lava flows, but its center 

(Goat Basin) is eroded to a depth of 1200-1400 ft below 

the exhumed rim. A negative aeromagnetic anomaly of 

about 100 gammas, which is centered over the volcano, 

and the presence of small rhyolite dikes and altered and 

weakly mineralized rocks in the center of the volcano 

indicate a subvolcanic silicic intrusive at a depth of a 

few hundred to a few thousand feet beneath the volcano, 

and such an intrusive might be mineralized. Geochemical samples of silicified and pyritized rhyolite show 

molybdenum and copper. A probable molybdenumcopper resource potential exists in this area 

Weak signs of mineralized rocks also occur in the 

form of quartz and calcite veins peripheral to 18-21 

million year old (Miocene) rhyolite eruptive centers, and 

as silicified and argillized rocks within rhyolite south of 

Goat Basin, along and south of the San Francisco River. 

The rhyolite centers are exposed mainly along a narrow 

downdropped block, the west-northwest trending Potholes Country graben, which is expressed as an aeromagnetic low similar to and merging with the aeromagnetic low over the Goat Basin volcano. The magnetic 

pattern thus indicates the possibility that the 18-21 

million year old rhyolite extends beneath the volcano 

and is connected to the rhyolite dikes at its center. 

The 18-21 million year old rhyolites are high-silica 

rhyolites (greater than 77 percent Si02) and are chemically similar to rhyolites that are commonly associated 

with molybdenum-tin-tungsten mineral deposits. 

Samples of altered and mineralized rocks along individual quartz-calcite veins, and in siliceous or other 

altered zones within the rhyolite, commonly have very 

weak metal concentrations of silver, gold, copper, lead, 

antimony, tungsten, and manganese. Silicified zones in 

similar rhyolite in prospects in adjacent areas are highly 

anomalous in silver and gold. Panned concentrates from 

stream sediments in the vicinity of the rhyolite also 

show weakly anomalous abundances of molybdenum, 

tin, niobium, and thorium. This area has a probable 

resource potential for molybdenum, copper, gold, c.md 

silver. 

The Dix Creek north-northeast-trending fault block in 

the western part of the study area contains quartzcalcite veins along the faults on both sides of the block, 

and the fault block has been interpreted to have a possible large volume silicic intrusive at considerable depth 

beneath the surface. Samples from the veins lack metal 

values except for manganese in calcite, silver, gold, and 

copper in quartz at the north end of the fault block, just 

north of the wilderness study area It is unlikely that 

this structure is related to significant mineral resources. 

A probable potential for geothermal resources is present in the Lower San Francisco Wilderness study area 

according to a study by the University of Arizona for 

the U.S. Department of Energy (Witcher, 1979). The 

wilderness study area encloses a stretch of the San 

Francisco River that is between two known geothermal 

resource areas (KGRA's) as classified by the USGS 

(Muffler, 1979; Hatton, 1981). A KGRA is defined by 

the USGS as an area which has the necessary geothermal potential to justify spending money for development. Several springs along the river between the 

KGRA's, and within the wilderness study area, have 

surface temperatures that are above the average temperature of other springs and the river water. One of the 

springs with above average temperature (26 °C) has a 

calculated temperature at depth of 126°C. It also 

has chemical characteristics similar to the water of the 

nearby KGRA's, being a sodium-chloride water high in 

silica and lithium (Witcher, 1979, tables 1, 2). The 

spring occurs along the eastern fault of the Dix Creek 

fault block, which is also cut by a west-northwest fault 

in this area. Thus, the setting of this geothermal spring 

is consistent with an origin for the heated water by deep 

circulation of ground water through fractured rocks, the 

water rising to the surface again along a major fault 

zone. 

1 
In summary, there is a probable, though largely unassessable (without deep drilling), resource potential for a 

porphyry copper deposit beneath the middle Tertiary 

volcanic cover. Areas of probable mineral-resource 

potential exist for a molybdenum-copper deposit in the 

middle Tertiary volcanic rocks beneath the Goat Basin 

volcano, and for minor precious-metal deposits in rocks 

related to intrusive and extrusive rhyolite centers of 

Miocene age. Springs along the San Francisco River in 

the west part of the study area indicate a probable 

geothermal-resource potential. 

SUGGESTIONS FOR FURTHER STUDIES 

Additional geologic and geophysical studies are needed to assess the position and character of the postLaramide surface beneath the middle Tertiary volcanic 

rocks, and to characterize geophysical anomalies that 

might represent hidden Laramide-age intrusive bodies. 

Mathematical modelling of the aeromagnetic anomalies 

associated with the Goat Basin volcano and Miocene 

rhyolite eruptive centers, and additional geochemical 

82 

sampling in those areas are needed to better assess their 

mineral-resource potential. 

REFERENCES 

Hatton. K. S., 1981, Geothermal energy, in New Mexico's energy 

resources '80, annual report of Bureau of Geology in the mining 

and minerals division of New Mexico Energy and Minerals 

Department: New Mexico State Bureau of Mines and Mineral 

Resources Circular 181. p. 50-59. 

Muffler, L. P .. editor, 1979. Assessment of geothermal resources of 

the United States- 1978: U.S. Geological Survey Circular 790. 

163 p. 

Ratte, J. C., Hassemer, J. R., Martin, R. A., and Lane, Michael E .. 

Mineral resource potential of the Lower San Francisco Wilder· 

ness study area and contiguous roadless area, Arizona and ew 

Mexico: U.S. Geological Survey. Miscellaneous Field Studies 

Map MF- 1463-C, scale 1:62.500. 

Witcher. J.C .. 1979, A geothermal reconnaissance study of the San 

Franciso River between Clifton. Arizona and Pleasanton. New 

Mexico, in Hahman, W. R., Geothermal studies in Arizona with 

two area as essments: U. . Department of Energy report 

DOE/ID/12009-TI; available only from U.S. Department of Com· 

merce ational Technical Information Service. pringfield, 

Virginia 22161. 
MAZATZAL WILDERNESS AND 

CONTIGUOUS ROADLESS AREAS, ARIZONA 

By C H E TER T . WR CKE, 1 U. . GEOLO I AL R EY , and 

CLARE CE E. E LLIS, U. . B REA OF MINE 

SUMMARY 

A mineral survey conducted in 1979 and 1980 by the USGS and USBM has 

shown that the Mazatzal Wilderness has demonstrated resources of silver, gold, 

lead, and mercury, small areas of substantiated mineral-resource potential for 

silver and copper, and areas of probable resource potential for resources of 

silver, copper, lead, mercury, and molybdenum. Gold, silver, and copper 

resources occur in small deposits in the north-central, eastern, and southern 

parts of the wilderness. A small demonstrated mercury resource is located at the 

Sunflower mine near the southeastern corner of the wilderness adjacent to the 

well-known Sunflower mining district. Molybdenum mineralization found during this study in the Tangle Creek area west of the Verde River may extend 

eastward into the roadless area and the wilderness. Tin occurrences not 

previously known in the Mazatzal region were found in the central part of the 

wilderness, and uranium was found near Horseshoe Reservoir, but there is little 

promise for the occurrence of tin and uranium resources. o potential for fossil 

fuel resources was identified in this study. 

CHARACTER AND SETTING 

The Mazatzal Wilderness comprises 320 sq rni, and 

the contiguous roadless areas comprise an additional 

130 sq rni, in the mountainous region of central Arizona 

The dominant physiographic feature is the northern 

part of the Mazatzal Mountains. This part of the mountains rises steeply from an altitude of about 3500 ft in 

the valley east of the mountains to 7903 ft at Mazatzal 

Peak. To the west, the range slopes steeply from the 

forested crest, then more gently on the lower flanks to 

the desert lowlands at altitudes of about 2500 ft along 

the Verde River. Mountainous terrane on the west side 

of the Verde River is in the roadless area bordering the 

wilderness. The spectacular escarpment of the Mogollon 

Rim, marking the southern border of the Colorado 

Plateau, is a few miles north of the wilderness. It rises 

above mesas that extend southward into the wilderness 

and are separated from the Mazatzal Mountains by the 

deep canyon of the East Verde River, a tributary of the 

Verde River. The nearest town is Payson, 8 mi east of 

the wilderness. · 

'Wilh contributions from herman P. Marsh. lay M. Conway. Dolores M. Wilson IKutikl. 

and Cal vin K. Moss. USGS. 

Much of the Mazatzal Mountains, the canyon of the 

East Verde River, and the mountains west of the Verde 

River are underlain by a variety of Proterozoic stratified 

rocks that form several tilted, structurally fragmented, 

layered sequences that, if stacked together, would have 

a total stratigraphic thickness of about 55,000 ft. These 

rocks are little altered despite their antiquity even 

though some were invaded by a large mass of Proterozoic granite. The ancient layered rocks retain many 

features indicative of their origin as sedimentary and 

volcanic rocks. Overlying the Proterozoic rocks are 

much younger Paleozoic sedimentary strata that were 

deposited in shallow seas and today are extensively exposed as flat-lying beds along the Mogollon Rim. These 

rocks have been eroded from most of the wilderness and 

roadless areas but occur as cappings on a few ridges and 

as isolated exposures. Erosion of these and the older 

rocks has taken place over a long span of geologic time 

but was accelerated about 15 million years ago, after the 

begirming of faulting that broke central and southern 

Arizona into mountain blocks and intervening basins. 

Volcanic rocks that were erupted during the faulting 

partly buried all older rocks. These volcanic rocks and 

the sedimentary deposits that accumulated with them 

83 
84 

34° 

15' 

34° 

00' 

111 °45' 

0 

MILES 

111 °30' 

10 

/ 

M ercury 

Distnct 

MAP LOCATION 

EXPLANATION 

- Geologic terrane with substantiated 

mineral-resource potential D Geologic terrane with probable 

mineral-resource potential 

Cu Copper Pb Lead 

Au Gold Hg Mercury 

M o Molybdenum 

~ Mine or deposit Ag Silver 

f--""'"',---::1 

0-nh? 

Volcanic and sedimentary rocks (Cenozoic) 

Sedimentary rocks (Paleozoic) .·· .... ·:.:<·::::.-: Quartz monzonite (Early Proterozoic) ... ... 

Volcanic and sedimentary rocks (Early Proterozoic) 

Granite (Early Proterozoic) 

---Contact ---Fault 

Figure 22.-Mazatzal Wilderness and contiguous roadless areas, Arizona. 
are widely exposed in the wilderness. They, too, have 

been faulted repeatedly in the last few million years during the evolution of the present mountains and valleys. 

A mineral-resource study in 1979 and 1980 included 

geologic mapping, geochemical sampling and evaluation, geophysical studies (compilation and interpretation of gravity and aeromagnetic data), and an examination of mines, claims, and prospects in the area 

MINERAL RESOURCES 

Metallic mineral occurrences are widespread in and 

around the Mazatzal Wilderness. Within the wilderness 

are occurrences of silver, gold, copper, mercury, and (or) 

tin, and the roadless area along the west side of the 

wilderness has indications of uranium and molybdenum 

(Wrucke and others, 1982). Despite these abundant occurrences and their wide distribution, there is little 

promise for the occurrence of mineral deposits in much 

of the area 

Silver and gold occur in Proterozoic metamorphic and 

granitic rocks in and around the wilderness. The most 

favorable area for silver and gold in the wilderness is at 

and near the Storey mine. The vein deposits that have 

been mined are estimated to have demonstrated resources of 78,000 tons of additional mineralized rock, 

containing 1.9 oz silver/ton, 0.06 oz gold/ton, and 3.9 

percent lead. A geologically similar area occurs 0.5 mi 

north and northeast of the Storey mine and has a probable potential for gold, silver, and lead. An area of 

silver-gold-copper veins immediately east of the wilderness, north of Mazatzal Peak, has a probable mineralresource potential. Copper was produced in the 1880's 

from the silver-gold veins. The northern and southern 

ends of this area extend into the wilderness but chances 

are small that these veins extend a significant distance 

into the wilderness. The Copper Mountain area has a 

substantiated resource potential for silver and copper 

based on assay and geochemical data and the fact that 

485 oz of silver and 33.5 tons of copper ore were 

produced from the deposit in 1967. Silver also occurs 

in small sulfide veins in the Proterozoic granite north 

of Midnight Mesa, but no resource potential was 

identified. 

An occurrence of copper is in an area 3 mi west of the 

Storey mine southwest of Mazatzal Peak. Here bedded 

gossans suggest the possibility of massive sulfide 

mineralization. No evidence of a massive sulfide body 

was found by geophysical techniques above the maximum search depth of 400 ft. However, this area also 

has locally abundant copper minerals in veins and has a 

probable resource potential for copper. 

The Sunflower mercury district, located in metamorphosed Proterozoic sedimentary and volcanic rocks east 

of the southern end of the wilderness, has produced 

about 95 percent of the mercury recovered in Arizona. 

However, the total production from the district has 

been small, amounting to 3973 flasks of mercury 

(Beckman and Kerns, 1965). The mercury distribution 

in the district trends southwestward and extends into 

the wilderness at the southwestern end of the district. A 

demonstrated mercury resource estimated at a few hundred flasks of mercury occurs within the wilderness as 

an extension of the Sunflower mine. Farther inside the 

wilderness, evidence of mercury mineralization has not 

been found at the surface. 

Indications of porphyry molybdenum deposits were 

found during this study by geochemical sampling in 

granitic rock (Proterozoic quartz monzonite) exposed in 

the Tangle Creek area west of the wilderness. Although 

a traverse through the area revealed no obvious indications of molybdenum minerals, the data support a probable potential for a porphyry-type molybdenum resource. Interpretation of gravity and aeromagnetic data 

indicate that the granitic body may be of modest size 

and extend eastward into the roadless area, and 

possibly also into the wilderness beneath younger rocks. 

Exploration would be required to determine the distribution and grade of mineralized rock. 

Tin was identified in the Proterozoic granite during 

this study in the central part of the wilderness. Tin had 

not previously been reported as occurring in central 

Arizona High concentrations of tin were found in alteration zones of a kind associated with tin deposits in 

many parts of the world. However, available data offer 

little promise that the granite contains tin resources. 

Uranium occurrences exist in Cenozoic sedimentary 

rocks outside the wilderness near Horseshoe Reservoir, 

and barely inside the roadless area and the wilderness 

northeast of the reservoir. The concentration of 

uranium in these rocks is low and there is little promise 

for the occurrence of uranium resources in the area 

SUGGESTIONS FOR FURTHER STUDIES 

The broad features and many details of the geology 

and mineral resources of the Mazatzal Wilderness and 

contiguous roadless areas are known as a result of this 

study. However, the area contains tin-bearing rocks not 

previously reported in central Arizona and a possibly 

significant molybdenum deposit, neither of which is well 

understood. Detailed study of the Proterozoic granitic 

and metamorphic rocks that contain the tin and molybdenum mineralization may reveal further evidence of a 

potential for the occurrence of deposits of these commodities in and around the Mazatzal Wilderness. Further study of the Proterozoic metamorphic rocks also 

may provide information on their potential for massive 

85 
sulfide deposits of the kind known in similar rocks in 

northwestern Arizona 

REFERENCES 

Beckman, R. T., and Kerns, W. H., 1965, Mercury in Arizona, in 

Mercury potential of the United States: U.S. Bureau of Mines 

Information Circular 8252, p. 60- 74. 

86 

Wrucke, C. T., Marsh, S. P., Conway. C. M., Ellis. C. E .. Kulik, D. M .. 

and Moss, C. K., 1983, Mineral resource potential map of the 

Mazatzal Wilderness and contiguous roadless areas, Gila. 

Maricopa, and Yavapai Counties, Arizona: U.S. Geological 

Survey Miscellaneous Field Studies Map MF- 1573-A, scale 

1:48.000. 

To /'.feN r 

34° 

88 

(J R I 

J\ P \ C II 

\ 

\ 

Approximate boundary 

Mt Or 

( 

5 

Tertiary volcanic rocks 

M Batdy 

I I 

\ \ 

R f .., • \: \ 10 

0 

MILES 

109°30' 

T, sr" 1 rJ!?'vlle 

0 '• 

B 

5 

Figure 23.- Mount Baldy Wilderness. Arizona 

'\ 

ARIZONA 

• 

MAP LOCATION 

> ~ I 
MOUNT BALDY WILDERNESS, ARIZONA 

By TOMMY L. FI ELL, 1 • . G EO LO I AL S UR EY , and 

j O H H. So LE, U.S. B REA OF Ml E 

SUMMARY 

The Mount Baldy Wilderness, Arizona, was surveyed for mineral resources in 

1966 and was judged to have little or no promise for the occurrence of mineral 

resources. o mineral deposits, mining claims, or concentrations of trace metals 

were recognized within the area during the investigations of the USGS or the 

USBM. No oil test holes have been drilled within the area; holes drilled abou t 

35 mi north of the area were not productive. 

CHARACTER AND SETTING 

The Mount Baldy Wilderness occupies about 

11.5 sq mi in the White Mountains of east-central 

Arizona, about 140 mi east-northeast of Phoenix. The 

wilderness is very near the highest part of the White 

Mountains; elevations range from about 9200 ft to 

11,400 ft above sea level. Baldy Peak, the highest point 

in the White Mountains, is about a Y4 mi south of the 

wilderness and has an elevation of 11,403 ft. 

'I he wilderness is underlain by about 3500 ft of 

young (less than 26 million years old) volcanic flows 

and as much as 450 ft of glacial drift (Finnell and 

others, 1967). The volcanic rocks are mainly intermediate (dacite to rhyolite) porphyry, basalt, and 

basaltic scoria and tuff. The geologic structure of the 

rocks exposed in the wilderness is simple. The older 

basalt flows are steeply tilted locally, the intermediate 

flows above them slope gently to the northwest, north, 

east, and southeast, and the glacial deposits and 

younger basalts are flat lying. 

MINERAL RESOURCES 

The wilderness lacks significant faults of the kind 

that contains veins of gold and silver ore at Mogollon, 

New Mexico, about 53 mi to the southeast. Concentrations of visible ore minerals were not found, and a 

geochemical survey of the wilderness showed the metal 

content of all samples to be so low that the possibility 

of discovering mineral resources in the area is remote. 

'With contributions by C. Gilbert Oowlcs. U GS. 

A small cinder cone in the north part of the 

wilderness might be suitable for road metal, but many 

cinder cones east and north of the area are much larger 

and more easily reached. Sedimentary rocks that yield 

oil, gas, coal, uranium, and bleaching clay elsewhere in 

eastern Arizona either are absent from or are present 

only at great depth beneath the Mount Baldy Wilderness. The Coconino Sandstone (Permian), a potential 

reservoir for petroleum and natural gas, may be present 

at depth beneath the wilderness, but the existence of 

structural traps is highly conjectural. Thin coal beds 

may be present in sedimentary rocks at depths of 

3000 ft or more beneath the wilderness, but exploitation for thin coal at such depths is considered to be 

unlikely. Rocks of the type that yields bleaching clay 

are not found in the wilderness. Small deposits of 

uranium are in the Chinle Formation ('Triassic) about 

40 mi north-northwest of the area, but regional geologic 

relationships indicate that the Chinle Formation does 

not underlie the Mount Baldy Wilderness. Similarly, 

other uranium-bearing formations of the Colorado 

Plateau do not lie beneath the area. 

SUGGESTIONS FOR FURTHER STUDIES 

Further study of the Mount Baldy Wilderness would 

seem warranted only in the event that economic 

deposits of minerals or petroleum are found in nearby 

areas. 

REFERENCE 

Finnell, T. L., Sowle , C. G., and Soul e. J. H. , l967. Mineral resources 

of the Mount Baldy Primitive area, Arizona: U.S. Geological 

Survey Bull tin 1230- H, p. Hl- H14. 

9 
oo· 

90 

C'l 'R Atil 

•\ <)1\:A 

M l Ml 

L.. 

l 

MAP LOCATION 

0 

MILES 

EXPLANATION 

- Geologic terrane with substantiated 

mineral-resource potential 

D Geologic terrane with probable 

mineral-resource potential 

Ba Barium Mo Molybdenum 

Cu Copper Ag Silver 

Au Gold Zn Zinc 

Pb Lead 

'Y' Mine 

109°15' 

mate boundary 

Volcanic rocks (Tertiary) 

Sedimentary rocks (Cretaceous 

and Paleozoic) and granitic 

rocks (Precambrian) 

Contact--Dashed where 

approximately located 

Fault--Bar and ball on 

downthrown side. Arrows 

show direction of relative 

movement 

2 Location discussed in text 

Figure 24.- orth End Ro:..dless Area, Arizona 
NORTH END ROADLESS AREA, ARIZONA 

By H ARALD DREWE , 1 U .S . GEOLOG ICAL R E , and 

P. R. BIG BY, U. S. B REA OF MI , E 

SUMMARY 

Studies conducted in 1978-79 in the orth End Roadless Area indicate probable or substantiated metallic mineral-resource potential in about one-fifth of 

the area The area has potential for disseminated or stockwork-type 

molybdenum mineralization, copper-lead-zinc-silver veins, lead-zinc-silver 

limestone replacement deposits, and tungsten-bearing contact metamorphic 

skarn deposits. The area also contains cement rock and marble dimension stone, 

but has only slight promise for the occurrence of petroleum and natural gas. 

CHARACTER AND SETTING 

The orth End Roadless Area covers about 40 sq mi 

of the northern end of the Chiricahua Mountains near 

the southeastern comer of Arizona It lies adjacent to 

the north and east sides of the Chiricahua National 

Monument and is about midway between the towns of 

Portal and Bowie, in the Coronado National Forest. 

The roadless area covers moderately high terrain that 

is partly forested. Access to the area is by means of 

roads up the larger canyons from county roads or State 

highways in the intermontane valleys east and west of 

the mountains. A few trails facilitate access to the interior of the area 

The orth End Roadless Area is underlain by a wide 

variety of sedimentary, volcanic, and plutonic rocks, 

some of which are strongly faulted (Sabins, 1957; 

Drewes, 1981, 1982, 1983). Precambrian schist and 

granodiorite plutons are the oldest rocks of the area, 

forming a basement for four sequences of overlying 

sedimentary and volcanic rocks. The lowest of these is 

mainly a limestone sequence, about 8100 ft thick and of 

Paleozoic age. Next is a shale and sandstone sequence, 

about 6500 ft thick and of Mesozoic age. The third is a 

rhyolite and andesite volcanic sequence of Tertiary age; 

it is about 6500 ft thick near a major volcanic center in 

the eastern part of the area, but it thins rapidly and is 

absent over much of the area. The capping sequence, of 

Tertiary and Quaternary gravel, is thin in most of the 

area but is at least 6000 ft thick beneath the San Simon 

Valley east of the roadless area. 

'With COili.Jibul.iollS from c. L. r om , K. . M oos. and K. c. WaLLS. J r .. USG . 

The faults cutting these rocks are the key features 

that guided the emplacement of Tertiary granitic 

plutons, influenced the distribution of metamorphism, 

and probably controlled mineralization. The Apache 

Pass fault zone trends diagonally northwest to southeast through the area, forming a belt of broken rock 0.5 

to 1 mi wide. This fault zone is almost vertical and has 

been active at various times between the Precambrian 

and late Tertiary. A zone of thrust faults trends west 

across the northern part of the area, and is also related 

to the Apache Pass fault zone. The thrust faults dip 

moderately at the surface, but presumably flatten at 

depth, and are offset by some of the latest movement on 

the Apache Pass fault zone. These faults and the broken 

rock near them have helped granitic magma of Tertiary 

age and mineralizing fluids move upward from deep 

sources into the Paleozoic and Mesozoic rocks. Near the 

intrusive rocks the Paleozoic and Mesozoic rocks are 

metamorphosed, and locally contain lead, silver, zinc, 

and copper mineralization. 

Mining began in 1881 in the vicinity of the roadless 

area with the early development of claims that later 

became the Hilltop mine, 1 mi south of the area. Scattered prospects and a few patented claims lie within, or 

just outside the roadless area During the time of the 

study, there was sporadic development work at the 

King of Lead mine and nearby claims lying in an area 

between the Chiricahua National Monument and the 

roadless area. Base metals and silver ore have been produced from the Hilltop mine (about $1.1 million production between 1902 and 1950) and a small amount of 

similar ore was probably produced from the King of 

Lead mine and from mines in the Buckhorn Basin about 

0.5 mi west of the roadless area 

91 
MINERAL RESOURCES 

Seven areas of probable and substantiated mineral 

potential were identified in this study. These areas are 

discussed in order of their decreasing significance 

(although a few successive sites are of nearly equal 

significance), based on their known or inferred geologic, 

geophysical, and geochemical features. 

Although area 1 contains only a few small prospects it 

is regarded as having substantiated mineral-resource 

potential. It lies along the Apache Pass fault zone and 

is, in part, underlain by metamorphosed Paleozoic 

limestone, two Tertiary rhyolitic plugs, and a Tertiary 

granodiorite stock. Volcanic rocks in the northeastern 

part of the area are extensively pyritized and oxidized. 

Chip samples from prospects and outcrops show the 

presence of copper, lead, zinc, molybdenum, barium, and 

silver mineralization. Geochemical anomalies in streamsediment samples from area 1 suggest a possible focus 

of mineralization many hundreds to a few thousand feet 

below the center of the area (Watts and others, 1983). 

Three types of mineralization could occur in area 1; vein 

or replacement deposits of lead, zinc, and silver in the 

sedimentary rocks, skarn contact deposits near the 

granodiorite stock, and copper or molybdenum 

porphyry-type mineralization at moderate depth. 

Area 2 contains the Hilltop mine and numerous prospects (Drewes and others, 1983), and extends to the 

southeast beyond the North End Roadless Area It also 

lies along the Apache Pass fault zone and is underlain 

by Mesozoic and Paleozoic sedimentary rocks, a small 

stock and rhyolitic plugs north of Hilltop, and a large 

stock on its southern side. Sampling in the area gave 

data showing anomalous concentrations of base metals 

and silver. From aeromagnetic data, we infer that the 

crest of the large stock plunges gently northwest 

beneath Hilltop. A mineralized zone like that at the 

Hilltop mine is inferred to plunge to the northwest, extending below part of the study area, defining a zone of 

substantiated resource potential for base metals and 

silver. 

Area 3 has a probable resource potential for small 

lead-zinc-silver replacement or vein mineralization at 

moderate depths like that at the King of Lead mine 

(Drewes and others, 1983). This area also lies along, 

or within, the Apache Pass fault zone, and it is underlain by Mesozoic and Paleozoic sedimentary rocks and 

some small plugs and dikes (Sabins, 1957; Drewes, 

1982, 1983). There is less observed mineralization 

than at areas 1 and 2 and anomalous concentrations of 

copper and molybdenum are more widely scattered. 

Aeromagnetic data (Moss, 1983) shows positive 

anomalies suggestive of the presence of small buried 

stocks, which may provide a favorable environment for 

mineralization. 

92 

Area 4 lies northeast of the Apache Pass fault zone 

and is underlain by Tertiary volcanic rocks cut by some 

breccia pipes and normal faults. The area contains 

almost no signs of prospecting. Mineralized carbonate 

reefs along the faults contain high values for lead, 

barium, molybdenum, and silver. Aeromagnetic data 

shows the possible pr~sence of a stock beneath the 

eastern end of area 4. These signs are viewed as indicating probable resource potential for base metals and 

silver beneath the volcanic cover, possibly in veins 

along faults. 

Area 5 lies largely outside the roadless area and, also 

follows a strand of the Apache Pass fault zone. The area 

is underlain by Mesozoic and Paleozoic rocks that are 

intruded by a stock and by plugs and dikes. Observations of mineralization at the surface and of geochemical 

and geophysical features are suggestive of a probable 

resource potential for small replacement, vein, or contact metamorphic mineralization containing base and 

precious metals. 

Area 6 also has a probable mineral-resource potential 

for base and precious metals but lies largely outside the 

roadless area The area is underlain by the same kind of 

sedimentary rocks as the other sites but its thrustfaulted terrane has only a few plugs and dikes. The area 

contains geochemical anomalies and a few small mines. 

Aeromagnetic data suggests that area 6 is above the 

south flank of an eastward-plunging stock. The area is 

favorable for blind vein or replacement mineralization 

at accessible depths, and may also contain deeper contact mineralization. 

Area 7 has probable resource potential for base and 

precious metals, though evidence is weaker than for the 

other areas. It is underlain mainly by Mesozoic and 

Paleozoic sedimentary rocks intruded by Tertiary 

stocks and dikes. Some Precambrian granite is in the 

northern part of the area These rocks are cut by a 

strand of the Apache Pass fault zone and by a splay 

fault branching from the zone. Scattered prospects occur in area 7, and some of them contain copper, lead, 

zinc, arsenic, antimony, and silver. Geochemical 

samples of the alluvium suggest the possible presence 

of concealed mineralization near the boundary of the 

study area Aeromagnetic data suggests that a stock 

exposed west of the site has a crest that plunges gently 

northeastward below this possibly mineralized ground. 

Marble and lime rock occur in the area and other 

commodities-silica rock, sand and gravel, and 

graphite-are present or have been reported present in 

or near the roadless area All these products are more 

accessible and abundant at and near old quarries or outcrops outside the roadless area 

The North End Roadless Area lies within the overthrust belt (Drewes, 1980, 1981) and has become an area 

of interest for petroleum and natural gas resources. 
While rocks deep in the subsurface could contain traps 

for these fluids, the abundant steep faults and stocks in 

the roadless area suggest that such fluids would not 

likely be preserved. 

SUGGESTIONS FOR FURTHER STUDIES 

The abundance of areas deemed favorable for 

mineralization suggest the area warrants further study. 

The part of area 1 with disseminated sulfides warrants a more detailed geologic and geochemical investigation, and possibly studies using ground 

geophysical techniques. A more precise modeling of 

subsurface extensions of stocks and plugs at this site 

may also be desirable. A study of the alteration 

minerals in the volcanic terrane would also be useful. 

In several other areas where known or projected 

mineralization is associated with faults (areas 1, 2, 4, 5, 

and perhaps 7), a more detailed geochemical sampling 

program examining mineralized rock and alteration 

along fractures might determine areas of movement of 

hydrothermal solutions. 

REFERENCES 

Drewes, Harald, 1980, Tectonic map of southeastern Arizona: U.S. 

Geological Survey Geologic Investigations Series I- 1109, scale 

1:125,000. 

__ 1981, Geologic map of the Bowie Mountains South quadrangle, 

Cochise County, Arizona: U.S. Geological Survey Miscellaneous 

Investigations Series I- 1363, scale 1:24,000. 

__ 1982, Geologic map and sections of the Cochise Head 

quadrangle and adjacent areas, southeastern Arizona: U.S. 

Geological Survey Miscellaneous Geologic Investigations Series 

I-1312, scale 1:24,000. 

__ 1983, Geologic map of the orth End Roadless Area, Cochise 

County, Arizona: U.S. Geological Survey Miscellaneous Field 

Studies Map MF- 141 2-A, scale 1:48,000. 

Drewes, Harald, Forn, C. L., Moss, K. C., Watts, K. C .. Jr., and 

Bigsby, P. R., 1983, Mineral resource potential of the North End 

Roadless Area, Cochise County, Arizona: U.S. Geological Survey 

Miscellaneous Field Studies Map MF- 1412-D, scale 1:48.000. 

Moss, C. K., 1983, Geophysical maps of the North End Roadless 

Area. Coc.hise County, Arizona: U.S. Geological Survey Mineral 

Investigations Field Studies Map MF - 1412-C, scale 1:48,000. 

Sabins, F. F., Jr., 1957, Geology of the Cochise Head and western part 

of the V anar quadrangles: Geological Society of America 

Bulletin, v. 68, no. 10, p. 1315- 1342. 

Watt, K. C., Jr., Drewes, Harald, and Forn, C. L., 1983, Geochemical 

maps of the orth End Roadless Area, Cochise County, Arizona: 

U.S. Geological Survey Mineral Investigations Field Studies 

Map MF -1412- B, scale 1:48,000. 

93 
94 

34 .---------------------~ °~5~0' ----------------------~---------- ~----------------------~ 20' 

/ 

Approximate 

boundary 

Quarry 

• ARIZONA 

MAP LOCATION 

0 2 

MILES 

EXPLANATION 

Rhyolite plugs (Quaternary) 

Basalt (Tertiary) 

Limestone and sandstone 

(Paleozoic) 

G 

B 

Granitic rocks 

(Precambrian) 

Metamorphic rocks 

(Pre cam brian) 

Contact 

Fault--Bar and ball 

on downthrown 

side 

x Mineral occurrence 

Figure 25.-Pine Mountain Wilderness, Arizona 
PINE MOUNTAIN WILDERNESS, ARIZONA 

By FRA 'K C. CA EY,' U .S. GE LOGICAL R I::Y, and 

FRANK E. WILLiAM , U . . B REAU OF 

SUMMARY 

A geologic study and geochemical survey were made of the Pine Mountain 

Wilderness in 1966. Only slight traces of mineralization of no apparent 

significance were found and the results of the geochemical survey were negative. 

The presence of important near-surface mineral deposits in the area is considered unlikely. No evidence of nonmetallic or energy resources was identified 

during the course of this study. 

CHARACTER AND SETTING 

The Pine Mountain Wilderness comprises an area of 

about 31 sq mi in southeastern Yavapai County near 

the center of Arizona. The wilderness is between the 

Black Canyon Highway (Arizona State Route 69 and 

Interstate Highway 17) and the Verde River. It is about 

40 mi east-southeast of Prescott, the county seat of 

Yavapai County, and about 20 mi south of Camp Verde. 

The northwestern part of the area is in the Prescott National Forest, and the southeastern part is in the Tonto 

ational Forest. The Pine Mountain Primitive Area 

was studied in 1966 (Canney and others, 1967). Because 

the boundaries of the proposed wilderness were known 

in 1966, all the additional tracts of land outside the 

existing primitive area proposed for inclusion in the wilderness were also examined. The Pine Mountain Wilderness was formally established in 1973. 

The Pine Mountain Wilderness is characterized by 

rather diverse types of topography and vegetation, but 

in general it is rugged and mountainous. It forms the 

southeast end of the Black Hills, a northwest-trending 

range that bounds Verde Valley on the southwest, and 

extends northwestward to the famous Verde mining 

district. The wilderness is divided into two parts 

roughly equal in size but different in character. The part 

west and northwest of the Prescott-Tonto National 

Forest boundary is generally mesalike because of the 

nearly horizontal attitude of the Tertiary lava flows and 

moderately deep canyons have been cut into it by 

Bishop and Sycamore Creeks. Within the Prescott National Forest area a good network of horse and foot 

trails permits relatively easy access to much of the area. 

'Wi th contribu tions by William L. Lehmbeck. USGS. 

The part of the wilderness southeast and east of the 

Prescott-Tonto National Forest boundary is extremely 

rugged and is dissected by many moderately deep canyons. In the Tonto National Forest area travel is 

generally difficult owing to complete lack of trails and 

the vegetative cover is often so dense that to travel any 

distance is an extremely difficult, painful, and timeconsuming operation. 

Altitudes in the wilderness range from 6814 ft on Pine 

Mountain to slightly less than 4000 ft at several points 

on the southeast border. Turret Peak (alt. 5840 ft) and 

1 M Peak (alt. 5998 ft) are prominent and easily recognizable landmarks on the southwest edge of the area 

The vegetation is extremely varied, both in type and 

amount, as would be expected from the rather large differences in altitude between various parts of the area It 

ranges from plant communities composed of various 

species of shrubs and cacti characteristic of the Sonoran 

Desert to relatively open stands of ponderosa pine. 

The rocks in the Pine Mountain Wilderness vary 

greatly both in age and type. The Tonto National Forest 

section is underlain principally by very old (Precambrian) rocks, mostly granites and closely related types, 

although there are small areas of highly metamorphosed volcanic and sedimentary rocks. The metamorphic rocks are also well exposed in the deeper 

canyons in the Prescott National Forest section. Overlying Precambrian rocks, principally in the western part 

of the wilderness (Prescott National Forest section), are 

nearly flat-lying strata of sandstone and limestone of 

early to middle Paleozoic age (about 350- 550 million 

years old). These sedimentary rocks are covered nearly 

everywhere by basalt lava flows of Tertiary age, so are 

generally exposed only in the walls of the deeper canyons in the western part of the wilderness and in the 

east-facing cliffs along the Pine Mountain escarpment. 

95 
The Paleozoic rocks are missing from large areas in the 

southwestern part of the wilderness; presumably they 

were eroded before the advent of volcanic activity, for 

basalt flows rest directly on the old igneous rocks in 

those areas. The basalt flows that are widespread in the 

wilderness, and compose much of the exposed bedrock 

in the Prescott National Forest area, were deposited 

during an episode of extensive volcanic activity that occurred in north-central Arizona only a few million years 

ago. 

Strong tectonic forces elevated the Black Hills at 

least 3000 ft a few million years ago. Vigorous stream 

erosion since that time has shaped the landscape of the 

Pine Mountain Wilderness that we see today. The rocks 

in the wilderness responded to the stresses during the 

period of Cenozoic deformation principally by simple 

uplift and minor tilting; no folds have been recognized, 

and the principal structural features are vertical to highangle faults. 

MINERAL RESOURCES 

The 1966 mineral survey (Canney and others, 1967) 

found no evidence of any significant near-surface 

mineral deposits in the Pine Mountain Wilderness. This 

was not unexpected, because much prospecting has 

been done during the past 75-100 years in this part of 

Arizona in the hopes of finding large and rich deposits 

of gold, silver, copper, and zinc like those mined in the 

Verde mining district, 30-40 mi to the northwest. Certainly any surface indications of important mineralization would have been detected by these early prospectors. And considering how thoroughly this area 

must have been prospected, diggings are surprisingly 

scarce; only three prospects were noted during the 1966 

survey. 

Precambrian massive sulfide deposits and Precambrian fissure veins are the principal types of ore deposits 

in the Black Hills and in the Bradshaw Mountains to 

the southwest. Although most of the important known 

Precambrian ore deposits are found in a belt extending 

south and southwest of the Verde district, the geology 

of the wilderness is permissive for the occurrence of 

such deposits, because Precambrian igneous and metamorphic rocks are exposed in more than 50 percent of 

the area. 

Very few mineral claims have apparently been staked 

in the wilderness. In 1966, only the Frances Young 

group of 18 claims were believed to be in the wilderness, 

but fragmentary and incomplete land records prevented 

finding their precise location. Since the 1966 survey, ad96 

ditional claims were staked in 1972, 1979, and 1981 according to the USFS, but they have no record or 

knowledge of any physical exploration on these claims. 

Geochemical prospecting, using active-stream sediments and heavy-mineral concentrates, was the principal method employed to evaluate the mineral potential of the area No anomalies that might be considered 

indicative of the presence of near-surface metallic 

mineral deposits were found. 

Iron-stained zones, bleached areas, quartz-jasper 

stringers and veins, minor shear zones, and other miscellaneous types of altered rock are common in the 

metamorphic rocks of the wilderness. These occurrences 

were examined, and samples were collected for analyses 

from many of them. Only insignificant traces of metallic 

minerals were revealed by the analytical data and field 

studies. The presence of significant near-surface mineral 

deposits in the area therefore is considered unlikely. 

No nonmetallic or energy resources were identified in 

the wilderness in the course of this study. 

SUGGESTIONS FOR FURTHER STUDIES 

Additional studies do not appear warranted at this 

time. Ore deposits, if present, are probably of the 

massive sulfide type, and buried deeply beneath the 

ground surface, beyond the range of the various geochemical and geophysical tedmiques used in routine exploration. Some of the newer geophysical methods 

might possibly be capable of detecting such hidden ore 

bodies if not buried too deeply, but this would require 

blanketing the entire wilderness with expensive 

surveys; such techniques are usually used in limited 

areas where it is possible to define restricted target 

areas by other means, for example geochemical surveys, 

and such target areas were not defined by the 1966 

study. Future development of a geochemical method 

that could detect mineralization beneath a cover of 

younger barren rocks would, of course, be ample 

justification for conducting such a survey in the wilderness, especially the western part (Prescott National 

Forest section) where the Precambrian rocks are nearly 

everywhere covered by much younger sedimentary and 

volcanic rocks. 

REFERENCE 

Canney, F. C., Lehmbeck, W. L., and Williams, Frank E., 1967, 

Mineral resources of the Pine Mountain Primitive Area, Arizona: 

U.S. Geological Survey Bulletin 1230-J, 45 p. 
PUSCH RIDGE WILDERNESS, ARIZONA 

By M ARGARET E. HI KLE U.S. GEOLOGICAL R EY, and 

GEORGES . RYA N, U.S. BUREA OF MINES 

SUMMARY 

On the basis of a mineral survey in 1979 by the USGS and USBM, the Pusch 

Ridge Wilderness, located at the northern boundary of the city of Tucson, 

Arizona, offers little or no promise for the occurrence of energy resources. Only 

one area contains a probable potential for small, isolated contact-metamorphic 

deposits containing copper, molybdenum, tungsten, lead, and zinc. This area is 

located around the southwestern end of Pusch Ridge, adjacent to a residential 

area 

CHARACTER AND SETTING 

The Pusch Ridge Wilderness covers approximately 

88 sq mi of the Coronado National Forest on the southwest side of the Santa Catalina Mountains in Pima 

County, Arizona The wilderness abuts the northern 

edge of the city of Tucson, about 8 mi from the center of 

Tucson. Other borders of the wilderness are, roughly, 

the Caiiada del Oro and U.S. Highway 89 to the west, 

Cargodera Canyon to the north, and the Mount Lemmon Highway to the east. Access to the area is easily 

accomplished except on the north side. The terrain has 

rugged, steep canyons, sharp ridges, and pinnacle-type 

peaks. Altitudes range from about 2800 ft at the valley 

floor in the Sonoran desert environment, to 9160 ft in 

the coniferous forest environment at the summit of 

Mount Lemmon. 

A mineral survey was made of the Pusch Ridge Wilderness in the fall of 1979 and the area was evaluated 

for its mineral potential by analysis of geochemical 

samples by the USGS, and by examination of mines, 

prospects, and mineralized areas by the USBM. The 

results were published in 1982 (Hinkle and Ryan, 1982). 

The Pusch Ridge Wilderness is located in the southem Basin and Range province of the Western United 

States, where subparallel mountain ranges are separated by broad alluvial valleys. The Santa Catalina 

Mountains are part of a zone of metamorphic rocks that 

form mountain ranges in Arizona extending from the 

Rincon Mountains northwest through the Santa Catalina Mountains to the Picacho Mountains. 

The part of the zone of metamorphic rocks in which 

the Pusch Ridge Wilderness is located consists primarily of a Tertiary granitic and Proterozoic gneissic complex that is locally deformed and intruded by pegmatitic 

dikes and sills. Although identification of some of the 

rock units within the complex and opinions concerning 

the ages and origins of these similar appearing rocks 

have been and remain controversial, the rocks within 

the wilderness were apparently originally made up of 

Tertiary age granitic rocks that were intruded into Prcr 

terozoic granites (Banks, 1980; Keith and others, 1980). 

Both rock types have been widely converted to gneisses 

whose foliation forms a broad arch trending westerly 

across the wilderness. This part of the mountain range 

is bounded on the south by the Catalina fault zone, 

which juxtaposes gneissic rocks with middle Tertiary 

sedimentary rocks that lie just south of the wilderness. 

The old Pontatoc mine is located in this fault zone 

just outside of the wilderness boundary. The Pontatoc 

mine contained copper mineralization, minor molybdenite, and trace amounts of silver. The mine has not 

operated since 1918 and the workings are now within a 

residential area. Additional scattered old prospect pits 

and adits occur within the Catalina fault zone; all of 

these small faults and fractures which have been explored contained localized concentrations of copper and 

associated metals. 

Along the western border of the Santa Catalina 

Mountains the Pirate fault has juxtaposed Pliocene and 

Miocene(?) gravel and conglomerate against the Tertiary granitic and Proterozoic gneissic complex. The 

Pirate fault has a large displacement. Many fractures 

parallel the Pirate fault in the adjacent rocks of the 

complex. The fractures acted as localizing channels for 

pods and lenses of pegmatite rocks which intruded the 

granitic and gneissic rocks. An area of fractured and 

cemented rocks exists where the Pirate fault crosses 

97 
9 

32° 

25' 

110°55' 

gn 

""" Cu. Mo . W , Pb, Zn 

M

8 

AP LOCATION 

0 

CJ Geologic terrane with pr~bable mineral-resource potenttal 

Cu Copper 

Pb Lead 

Mo Molybdenum 

w Tungsten 

Zn Zinc 

110°50' 110°45' 

Ti 

5 

MILES 

EXPLANATION 

OTg Gravel (Quaternary and Tertiary) 

Ti Granitoid intrusives (Tertiary ) 

Td Diorite (Tertiary) 

;Jn Granite and gneiss (Tertiary and 

'--------' Precambrian) 

G Sedimentary rocks, metamorphosed . 

in part (Paleozoic and Proterozotc) 

Contact 

--,-- Fault--Bar and ball on downthrown 

side 

--+-- Anticline 

Figure 26.- Pusch Ridge Wilderness. Arizona 
Cargodera Canyon, and the granitic and gneissic rocks 

contain abundant inclusions of metamorphosed sedimentary rocks; a few old prospects occur in this area. 

The Romero Pass fault is a zone of fractured igneous 

rocks with intrusions of pegmatitic rocks that extends 

from Romero Pass westward approximately N. 60 ° W. 

and intersects the Pirate fault. A large mass of fractured and cemented rock occurs in the area of intersection. The eastward extension of the Romero Pass fault 

zone coincides with the series of valleys and streams 

extending southeast. Although a few outcroppings of 

copper-stained quartz and other rocks occur within the 

Romero Pass fault zone, no prospect pits were seen. 

MINERAL RESOURCES 

Although located within a highly mineralized region 

of Arizona, the Pusch Ridge Wilderness has very little 

history of mineral activity and no mineral production. 

The Pontatoc mine, just south of the wilderness yielded 

a small production of copper from the Catalina fault 

zone; the Oracle Ridge mining district (Old Hat district) 

about 3 mi northeast of the wilderness yielded a moderate copper production from Paleozoic carbonate rocks in 

contact with intrusive diorite. Though related metamorphosed carbonate rocks occur to a minor extent in the 

northeast part of the wilderness, the mineralizing 

diorite is missing. The central part of the wilderness 

seems characterized by barren gneissic granites; the 

periphery, chiefly along the Catalina and Pirate fault 

zones, has scattered claims and prospects. Most of the 

prospecting activity within the wilderness has been 

along and near these fault zones in veins stained with 

secondary copper or in pegmatite dikes, or in fractured 

areas that appeared to be favorable to mineral concentration. No resultant mineral production has come from 

these prospecting activities. Other than the aforementioned occurrences, the Pusch Ridge Wilderness apparently lacks appropriate geologic environments 

favorable for the occurrence of mineral resources. 

evertheless, the geochemical survey of the USGS 

and assays of samples from prospects by the USBM 

indicate that the Pusch Ridge Wilderness has anomalously high concentrations of copper, lead, zinc, tin, 

tungsten, and molybdenum in four broad geographic 

areas: (1) south and southeast of the Mount Lemmon 

Highway, primarily between the Palisade Ranger Station and Molino Basin, (2) along most of the length of 

the Pirate fault on the west side of the wilderness, and 

adjacent areas east of the fault, (3) scattered sites along 

the Catalina fault on the south side of the wilderness, 

and (4) at the intersection of the Pirate and Catalina 

faults at the southwestern end of the Pusch Ridge. West 

of the Mount Lemmon Highway, the anomalous metal 

values were not considered as indicating a resource potential as they could be the result of contamination by 

ore minerals washed down the drainages from isolated, 

small, mineral deposits east of the wilderness. Along the 

Pirate and Catalina faults there is little promise for the 

occurrence of mineral resources because the distribution 

of samples containing anomalous metal concentrations 

was discontinuous and erratic. The area near the intersection of the Pirate and Catalina faults, both of which 

have scattered areas that contain anomalously high 

amounts of metals and mineralized prospects, was 

determined to have probable mineral-resource potential. 

If mineral deposits exist in this area, they are probably 

small, discontinuous fracture-controlled deposits with 

copper, molybdenum, tungsten, lead, and zinc minerals. 

o additional areas with promise for mineral resources were found during the USG&USBM investigation of the Pusch Ridge Wilderness. No evidence for 

energy resources was identified in the course of this 

study. 

REFERENCES 

Banks, N. G., 1980. Geology of a zone of metamorphic core complexes 

in southeastern Arizona, in Crittenden. M. D., Jr., Coney, P. J., 

and Davis, G. H., Cordilleran metamorphic core complexes: Geological Society of America Memoir 153, p. 177- 215. 

Hinkle, M. E .. Kilburn, J. E., Eppinger, R. G., III, and Speckman, 

W. ., 19 1a Geochemical analysis of samples of stream 

sediments. panned heavy-mineral concentrates, rocks, and 

waters of the Pusch Ridge Wilderness Area Arizona: U.S. 

Geological Survey Open-File Report 81 - 435, 44 p. 

Hinkle, M. E., Kilburn, J. E., Eppinger, R. G., III, and Speckman, 

W. S., 1981b, Statistical analyses of data on stream sediments, 

panned heavy-mineral concentrates, rocks and waters of the 

Pusch Ridge Wilderness Area Arizona: U.S. Geological Survey 

Open-File Report81 - 436, 183 p. 

Hinkle, M. E., Kilburn, J. E., Eppinger, R. G., III, and Tripp, R. B., 

1981, Geochemical maps of the Pusch Ridge Wilderness Area 

Pima County. Arizona: U.S. Geological Survey Miscellaneous 

Field tud.ies Map MF-1356-A, scale: 1:50,000. 

Hinkle. M. E., and Ryan G. S., 1982, Mineral resource potential map 

of the Pusch Ridge Wilderness, Pima County, Arizona: U.S. Geological Survey Miscellaneous Field Stud.ies Map MF-1356-B, 

scale: 1:50,000. 

Keith, S. B., Reynolds, S. J., Damon. P. E., Shafiqullah, Muhanunad. 

Livingston. D. E .. and Pushkar, P. D., 1980, Evidence for multiple intrusion and deformation within the Santa CatalinaRincon-Tortolita crystalline complex, southeastern Arizona in 

Crittenden, M. D., Jr., Coney, P. J., and Davis, G. H., Cordilleran 

metamorphic core complexes: Geological Society of America 

Memoir 153, p. 217- 267. 

Ryan, G. S., 1982. Claim and sample location map of the Pusch Ridge 

Wilderness, Pima County, Arizona: U.S. Geological urvey Miscellaneous Field Stud.ies Map MF- 1356-C, scale: 1:50,000. 

99 
100 

> ' 

""J "-\ ... ' 

~ ,. t } L > 

• \i ' 

0 

MILES 

EXPLANATION 

Volcanic rocks (Tertiary) 

Conglomerates, fluviolacustrine deposits, and 

intercalated basaltic flows (Tertiary) 

• 

AR IZONA 

MAP LOCATION 

5 

---- Contact 

Fault--Bar and ball on 

downthrown side 

Borrow pit D Sedimentary rocks (Paleozoic) 

Figure 27.- Rattlesnake Roadless Area, Arizona 
RATTLESNAKE ROADLESS AREA, ARIZONA 

By THOR . V. KARLSTRO M , 1 U.S. GEOLOGI AL R EY, and 

R OBERT M CC LLY, U.S. B REA F MI E 

SUMMARY 

There is little promise for the occurrence of mineral or energy resources in the 

Rattlesnake Roadless Area, Arizona, as judged from field studies by the USGS 

and USBM in 1982. Significant concentrations of minerals within the roadless 

area are not indicated by geologic mapping, geochemical sampling, or 

aeromagnetic studies. Basalt, volcanic cinders, sand and gravel, and sandstone 

that may be suitable for construction materials occur in the area, but are more 

readily accessible outside the roadless area boundary. 

CHARACTER AND SETTING 

The Rattlesnake Roadless Area is an area of about 

110 sq mi located in Yavapai and Coconino Counties, 

central Arizona. Sedona and Oak Creek, the nearest 

population centers, are located, respectively, at the 

northwest comer and along the western margin of the 

roadless area 

The roadless area boundary mainly follows the rims of 

steep-walled canyons cut into the Mogollon Rim of the 

Colorado Plateaus by Dry Beaver Creek and its main 

tributaries in Jacks, Pine Tank, and Rattlesnake Car,-

yons. The area is skirted by Interstate Highway 17 to 

the east and southeast, by State Highway 179 to the 

southwest and west, and by Schnebly Hill Road (USFS 

road 153) to the north. The canyon mouths mark the 

edge of the Mogollon Rim where its gently westward 

dipping surface falls off abruptly to the Verde Valley, a 

structural basin in the Arizona transition zone floored 

with a thick sequence of deeply dissected lake deposits. 

The maximum altitude in the roadless area is 6834 ft on 

the eroded plateau surface; the lowest altitude, 3480 ft, 

is on Dry Beaver Creek where it flows into Verde Valley. 

The canyon walls in the area expose multicolored sedimentary rocks of Pennsylvanian to Early Permian age 

as much as 2500 ft thick, unconformably overlain by 

basaltic rocks and associated gravels and fluviolacustrine deposits of Tertiary age as much as 500 ft thick. 

The exposed Paleozoic rocks include (from bottom to 

top): distinctive reddish siltstone and sandstone of the 

'With contributions from Goorge H. Billingsley. USGS. 

lower, middle, and upper units of the Supai Formation 

(525 ft), including in the upper unit the gray to greenishgray limestone of the Fort Apache Limestone(?) 

Member of the Supai Formation (about 25 ft); a transition zone of alternating red and gray siltstone and sandstone (550 ft); the grayish thick-bedded, primarily eolian 

crossbedded sandstone of the Coconino Formation (600 

ft); the grayish thin- to medium-bedded sandstone of the 

Toroweap Formation (350 ft); and erosional remnants of 

the lower part of the grayish to buff limestone and 

dolomite of the Kaibab Formation (less than 300 ft). 

Subsurface data indicate that the exposed sedimentary 

rocks are underlain by Cambrian to Pennsylvanian 

sandstone, siltstone, and limestone more than 1000 ft 

thick that lie unconformably above metamorphosed and 

intruded basement rocks of Precambrian age (Earl Huggins, oral. commun., 1983). 

The volcanic rocks mantling the Plateau surface are 

mainly alkali olivine basalt flows that locally overlie 

Tertiary gravels and that were fed by dikes or plugs 

which cut underlying rocks as young as late Tertiary in 

age. Radiometric dating of basaltic flows in the region 

(Damon and others, 1974; Peirce and others, 1979) indicates that volcanic activity was concentrated mainly in 

Miocene and Pliocene time. The volcanic rocks directly 

overlie either eroded Paleozoic strata or Tertiary conglomerates. At lower altitudes, interbedded conglomerates and lacustrine deposits are intercalated with basalt 

flows that record late volcanic eruptions contemporaneous with marginal lacustrine deposition in Lake Verde 

during Pliocene time (Nations and others, 1981). Within 

the roadless area, Lake Verde at its maximum extent 

rose to about the present 5000 ft level. 

101 
During dissection after the lake retreated, a series of 

Quaternary fluvial gravels were deposited in the roadless area Locally, as many as five aggradational epicycles are recorded by terrace gravels and alluvial fans 

that graded to successively higher levels above present 

stream grade. 

The nearly flat lying Paleozoic and Cenozoic rocks in 

the roadless area are cut by a system of near-vertical 

curving normal faults that trend northwest, northsouth, and east-west. Traced southward through the 

area, the northwest-trending and north-south-trending 

faults tend to decrease in displacement and to split into 

a series of curving faults that define both horsts and 

grabens. This progressive decrease in displacement and 

bifurcation into secondary faults suggest that the 

roadless area lies near the margin of a structural subprovince. Downward displacements on bounding faults 

have occurred around the Munds Mountain-Lee Mountain upland. A magnetic high coincides with the differentially elevated crustal block, which in'dicates that 

the block is probably intruded at depth by an igneous 

body of high magnetic susceptibility (Martin, 1983). 

Faulted basalt flows on Horse Mesa, which have a 

potassium-argon age of 6.4 million years (Peirce and 

others, 1979), suggest latest fault movement along the 

north-south-trending Oak Creek Canyon fault zone in 

late Miocene or later time. 

MINERAL RESOURCES 

Based on geologic mapping, geochemical sampling 

and analysis (Gerstel and others, 1983), aeromagnetic 

data (Martin, 1983), and a review of County and Federal 

land records, the roadless area is evaluated as having 

little promise for the occurrence of mineral-resource 

potential. Significant mineral concentrations were not 

observed nor previously reported from the roadless 

area Field observations and geochemical sampling 

along steep-dipping faults and intrusive contacts, and 

the available subsurface information do not suggest extensive mineralization at depth. Concentrations of 

heavy minerals that would suggest potential placer 

102 

deposits or buried upstream source bodies were not detected in outcrop nor indicated by geochemical sampling of the fluvial and fluviolacustrine deposits in the 

roadless area The basaltic flows, cinders, and sand and 

gravel can be used for road metal, concrete aggregate, 

riprap, or cinder block, and some of the sandstone exposed in canyon walls might provide usable building 

stone and flagstone. Similar construction materials, 

however, are more readily accessible and closer to 

markets outside the roadless area boundaries. 

SUGGESTIONS FOR FURTHER STUDIES 

Further mapping and sampling in the roadless area 

offer little promise for establishing any significant 

mineral-resource potential. 

REFERENCES 

Damon, P. E., Shafiqallah, M., and Leventhal, J. S., 1974, K/Ar 

chronology for the San Francisco volcanic field and rate of erosion of the Little Colorado River, in Karlstrom, T .. V., Swann, 

G. A., and Eastwood, R. L .. eds., Geology of orthern Arizona 

with notes on archaeology and paleoclimate: Geological Society 

of America Guidebook for Rocky Mountain Section Meeting, 

Flagstaff, Arizona, pt. 1, p. 221-235. 

Gerstel, W. J., Day, G. W., and McDanal, S. K., 1983, Analytical 

results for 178 stream·sediment, 98 heavy-mineral-concentrate, 

27 rock, and 11 water samples from t he Rattlesnake and Wet 

Beaver Roadless Areas, Coconino and Yavapai Counties, 

Arizona: U.S. Geological Survey Open File Report 83-339, 156 p. 

Karlstrom, T.N.V., Billingsley, G. H., and McCoily, Robert, 1983, 

Map showing geology and mineral resource potential of the 

Rattlesnake Roadless Area, Yavapai and Coconino Counties, 

Arizona: U.S. Geological Survey Miscellaneous Field Studies 

Map MF - 1567 -A, scale 1:24,000. 

Martin, R. A., 1983, Aeromagnetic interpretation of the Rattlesnake 

Roadless Area, Yavapai and Coconino Counties, Arizona: U.S. 

Geological Survey Miscellaneous Field Studies Map 

MF-1567-B. 

ations, J. D., Hevly, H. H., Blinn, D. W., and Landye, J. J., 1981, 

Paleontology, paleoecology, and depositional history of the 

Miocene-Pliocene Verde Formation, Yavapai County, Arizona: 

Arizona Geological Society Digest 13, p. 133- 149. 

Peirce, H. W., Damon, P. E., and Shafiqallah, M., 1979, An 

Oligocene(?) Colorado Plateau edge in Arizona: Tectonophysics, 

v. 61, p. 1-24. 
RINCON WILDERNESS STUDY AREA, ARIZONA 

By CHARLE H . THORMAt , U.S. GEOLOG I AL S RVEY, and 

MIC HAEL E. LA E U. . B REA OF MI " 

SUMMARY 

On the basis of geologic and geochemical investigations by the USGS and examination of mineralized prospects by the USBM, in 1977, the Rincon 

Wilderness Study Area has little promise for the occurrence of mineral or energy 

resources. A few prospects and small exploratory mines in four widely separated 

areas exist, but no record of mineral production was found. Geochemical 

anomalies in these four areas are weak and no resource potential was identified. 

CHARACTER AND SETTING 

The Rincon Wilderness Study Area includes about 98 

sq mi of the Coronado National Forest in the Rincon 

Mountains east of Tucson, Arizona. The area is 

horseshoe-shaped, encompassing the Saguaro National 

Monument on its north, east, and south sides. Mica 

Mountain (8666 ft) and Rincon Peak (8482 ft), the 

highest peaks in the Rincon Mountains, are about 1 mi 

inside the Monument. Much of the study area lies on the 

rugged flanks of the mountains, but it extends to less 

rugged terrain to the south, along Happy valley to the 

east, and into the Redington Pass area, the broad saddle 

between the Rincon and Santa Catalina Mountains to 

the north. The Rincon Mountains lie within the Basin 

and Range province, about 100 mi south of the Colorado 

Plateau province. North- to northwest-trending mountains and valleys typify this part of the Basin and 

Range province. 

The geology of the Rincon Mountains is complex. 

Rocks range in age from about 1.8 billion years old 

(Precambrian) to about 0.5 million years old (Cenozoic). 

The core of the Rincon Mountains, which includes most 

of the Saguaro National Monument as well as parts of 

the wilderness study area, is underlain by igneous and 

metamorphic rocks chiefly of Precambrian and Tertiary 

ages, hereafter referred to as the core rocks. Most of the 

study area, which flanks the mountains, is underlain by 

a terrain of sedimentary, metamorphic, and igenous 

rocks of Precambrian through mid-Tertiary age, hereafter referred to as the cover rocks. Separating the cover 

and core rocks is the Santa Catalina fault which dips 

gently away from the center of the mountains. Development of the Santa Catalina fault is interpreted to have 

begun in late Mesozoic-early Tertiary time when the 

cover rocks were pushed northeastward over the core 

rocks. 

In mid-Tertiary time, the present form of the Rincon 

Mountains was attained as the result of doming of the 

core area This caused the cover rocks to slide off the 

high part of the dome reactivating the Santa Catalina 

fault, an already established zone of weakness. Subsequent erosion has left the cover rocks exposed primarily 

on the flanks of the mountains. The cover rocks are cut 

by many low- and high-angle faults due to the two 

periods of deformation, late Mesozoic-early Tertiary and 

mid-Tertiary. Mountain ranges in the southwestern 

United States having many of the same geologic features as the Rincon Mountains are generally referred to 

as metamorphic core complexes. 

Valley-fill gravel deposits were deposited in the basin 

areas surrounding the Rincon Mountains uplift from 

about 15 million years ago until the present. Locally 

these valley deposits are faulted against the cover 

rocks, along high-angle faults. 

MINERAL RESOURCES 

There is little promise for the occurrence of mineral or 

energy resources in the Rincon Wilderness Study Area. 

Geochemical investigations during the study included 

the collecting and analyses of stream-sediment and rock 

samples. Anomalous amounts of beryllium, copper, 

manganese, molybdenum, lead, and silver were detected 

in some stream-sediment samples, but because most of 

these samples are interspersed with samples containing 

only background values they are not considered indicative of significant mineralization. In four small 

areas, however, samples containing anomalous values 

103 
104 

D 

D 

S A G U A R 0 

NATIONAL 

MO U.'v!E 'T 

0 

X Mica Mtn 

8,666' 

Approximate 

boundary 

Rincon Peak 

xB.4B2' 

MILES 

5 

EXPLANATION 

Core unit of metamorphic and 

intrusive granitic rocks 

Cover unit of sedimentary, 

igneous, and metamorphic 

rocks 

Valley-fill gravel deposit 

Pluton Youtcy Ranch (Tertiary) 

!{(:}A)}:] Mineralized areas discussed in text 

Contact 

Fault--Bar and ball on downthrown 

side 

Santa Catalina Fault 

Figure 28.- Rincon Wilderness Study Area, Arizona 
are clustered. Analyses of rock samples confirmed that 

the sources for the anomalous metal values were weakly 

mineralized zones that had already been examined by 

prospectors, as evidenced by numerous small diggings 

(areas A-D, on map). In each instance the mineralized 

rocks occur along or very near to the Santa Catalina 

fault or one of the smaller faults related to it. As a result 

of this study it was concluded that the anomalous geochemical samples are not considered as indicating 

mineral-resource potential. 

Mountain ranges in the southwestern United States 

referred to as metamorphic core complexes, such as the 

Rincon Mountains, differ geologically from areas known 

to contain mining districts. No metamorphic core complexes are known to have large metallic ore deposits. 

The known areas of anomalous concentrations of 

metals in the Rincon Mountains are small and the concentration of metals weak and erratic. The surface signs 

of mineralization are largley restricted to four locales in 

which some prospects exist: east of Colossal Cave, 

southwest of the Rincon Mountains (area A); north of 

Happy Valley, east of the mountains (area B); between 

Roble and Y outcy Canyons, northeast of the mountains 

(area C); and near Italian Trap, north of the mountains 

(area D). Very little primary sulfide mineralization is 

present, and signs of alteration are restricted to narrow 

zones along faults and fractures. The geochemical 

anomalies are weak; sites at which anomalous values of 

copper, molybdenum, or silver were obtained are mainly 

controlled by faults. 

Nonmetallic mineral resources occur in deposits that 

are small and remote. Sand and gravel deposits in the 

main drainages are similar to larger deposits that occur 

closer to nearby highways and cities. Limestone and 

marble present in some of the metamorphic rocks are 

too impure and too broken for use as dimension stone. 

Use of this marble as decorative rock is limited by the 

distance to available markets. Limestone suitable for 

making cement is not likely to be found in large quantities within the Rincon Wilderness Study Area Closely 

spaced fractures in the granitic rocks make them of lit· 

tle value for building stone. 

The likelihood for occurrences of energy resources in 

the study area is remote. The abundant granitic rocks of 

the core area and the intense faulting of the cover rocks 

leave the study area with a completely unfavorable 

situation for oil and gas accumulations, and a history of 

later thermal activity in the study area further reduces 

the chances for the preservation of such accumulations. 

The kinds of rocks in which coal deposits could occur are 

not known in the Rincon Mountains. Although uranium 

mineralization occurs 1- 2 mi northeast of the study 

area, such mineralization is unlikely within the study 

area Known deposits occur along or close to low-angle 

faults that strike and dip away from the study area No 

geothermal potential was identified in the study area 

and no hot springs or evidence of ancient hot springs occur in the Rincon Mountains. The youngest volcanic 

rocks are too old to be viewed as signs of available heat 

at shallow depths. 

REFERENCE 

Thorman, C. H., Drewes. Harald, and Lane, M. E .. 1978. Mineral 

resources of the Rincon Wilderness Study Area. Pima County, 

Arizona; U.S. Geological Survey Bulletin 1500. 62 p. 

105 
106 

JJJ OQQ ' 

MAP 

8 

LOCATION 

boundary 

0 4 

MILES 

EXPLANATION 

Geologic terrane with substantiated 

mineral-resource potential and 

probable Uranium potential 

Geologic terrane with substantiated 

mineral-resource potential CJ Geologic terrane with probable 

mineral-resource potential 

Fe Iron 

u Uranium 

~ Mine or deposit 

X Mineral occurrence 

X' Mine 

Tapeats Sandstone 

{Cambrian) 

I':I)J:;(l ~:::·::~:::'·,;:;~~~ow''' Proterozoic) 

Apache Group {Middle 

"""-'..<...l..o."'"'"" Proterozic) 

Granite {Middle Proterozoic) u...>..:..l..>..;~ 

- -- Contact 

---Fault 

Figure 29.- Sierra Ancha Wilderness, Arizona 
SIERRA ANCHA WILDERNESS, ARIZONA 

By CHESTER T. WRUCKE, 1 U.S. G EOLOGICAL SURVEY, and 

THOMAS D . LIGHT, U .S . B REAU OF MI ES 

SUMMARY 

Mineral surveys conducted in 1978 show that the Sierra Ancha Wilderness 

has demonstrated resources of uranium, asbestos, and iron; probable and 

substantiated resource potential for uranium, asbestos, and iron; and a probable 

resource potential for fluorspar. Uranium resources occur in vein and stratabound deposits in siltstone that underlies much of the wilderness. Deposits of 

long-staple chrysotile asbestos are likely in parts of the wilderness adjacent to 

known areas of asbestos production. Magnetite deposits in the wilderness form 

a small iron resource. A fluorite resource may exist in the northern part of the 

wilderness east of a notable flourite deposit that is located in a comparable 

geologic setting 1.4 mi west of the wilderness boundary. No fossil fuel resources 

were identified in this study. 

CHARACTER AND SETTING 

The Sierra Ancha Wilderness occupies an area of 

about 33 sq rni in the mountain region of central Arizona, about 75 rni northeast of Phoenix. The wilderness 

is located in the Sierra Ancha, a northerly trending 

mountain range that has a flat-topped crest along much 

of its length, and cliffs, steep slopes, and broad benches 

on its flanks. Higher parts of the range are thickly 

forested and rise to altitudes of 7000 to 7700 ft above 

the deeply dissected regions to the east and west. Most 

of the wilderness is situated on the eastern side of the 

Sierra Ancha, where the range descends precipitously to 

altitudes of 3000 to 4000 ft along Cherry Creek, located 

immediately east of the wilderness boundary. State 

Highway 288 traverses the Sierra Ancha region from 

the north and south, 0.2 to 3 mi west of the wilderness. 

The wilderness and surrounding areas are underlain 

principally by a layered sequence of sedimentary and 

igneous rocks of Middle Proterozoic age (Bergquist and 

others, 1981). These rocks rest unconformably on Middle Proterozoic granites that form the basement 

throughout most of the region. The oldest of the Middle 

Proterozoic stratified sequences is the Apache Group, 

1

WiLh conLribuLions from James K. OLLOn. Andrew f. hride. Joel R. Bergquist.. Paul K. 

Theobald. Jnrnes S. Duval. and Dolores M. Kulik (Wilson). USGS. 

about 1300 ft in thickness, which comprises in ascending order the Pioneer Formation, the Dripping Spring 

Quartzite, the Mescal Limestone, and an unnamed 

basalt. The Troy Quartzite, which is the youngest Pr<r 

terozoic sedimentary formation, rests unconformably 

on the Apache Group and is about 1000 ft thick. 

Diabase, 1150 million years old, intruded the Apache 

Group and the Troy Quartzite mostly as sills. Dikes are 

numerous but insignificant in volume. Sills are individually as thick as 1200 ft and aggregate about half the 

volume of the host strata Where diabase was emplaced 

in the Mescal, the original dolomite of the formation 

was converted almost completely to limestone. In the 

noncarbonate formations, a narrow selvage of hornfels 

was commonly formed adjacent to thick sills. 

The Tapeats Sandstone of Cambrian age occurs as 

erosional remnants on the Proterozoic rocks at two 

localities on the crest of the Sierra Ancha The sandstone is the youngest geologic unit in the vicinity of the 

wilderness, other than Cenozoic gravels and a few 

Quaternary landslide deposits. 

The subhorizontal attitude of most strata in the 

wilderness reflects the location of the Sierra Ancha in 

the Colorado Plateau structural province. However, the 

stratified rocks locally record significant disruption, 

largely from the effects of inflation by the diabase and 

the uplift of some blocks more than others. The Cherry 

Creek monocline east of the wilderness and the Sierra 

Ancha monocline to the west represent deformation 

107 
before and during emplacement of the diabase. Additional displacements occurred along a few faults during 

Cenozoic time. 

MINERAL RESOURCES 

The Sierra Ancha Wilderness contains resources of 

uranium, asbestos, iron, and possibly fluorspar. Field 

studies in the wilderness were conducted by the USBM 

and the USGS in 1978 (Otton and others, 1981). 

Uranium was discovered in the Sierra Ancha region in 

1950, and in the period 1953-60 a total of 2185 tons of 

ore averaging 0.24 percent U30 8 was produced from 14 

mines. Most of the production was from the Red Bluff 

area, 2.5 mi southwest of the wilderness (outside of the 

area studied), and from the Workman Creek area west of 

the wilderness. Three uranium mines, the Big Buck, 

Donna Lee, and Horseshoe, have had production and 

are located in the wilderness; they accounted for 291 

tons of ore averaging 0.14 percent U308• As of 1979, exploration was being continued in several localities. 

Uranium deposits in the Sierra Ancha region occur in 

carbonaceous siltstone in the upper member of the Dripping Spring Quartzite. This rock underlies nearly all of 

the wilderness. Most of the uranium oc.curs as uraninite 

in near-vertical veins and disseminated along favorable 

stratigraphic zones laterally adjacent to the veins. The 

most extensive uranium deposits overlie diabase sills or 

are located near major dikes of diabase. 

Most of the wilderness has resource potential for 

uranium, and several areas in or adjacent to the wilderness have demonstrated uranium resources in areas of 

substantiated resource potential. Demonstrated 

resources with an average grade of 0.05-0.1 percent 

U30 include 4 to 8 million lbs U30 8 along both sides of 

Workman Creek within 2.5 mi of the wilderness, 2 to 6 

million lbs U30 8 at the Donna Lee mine along Bull Canyon inside the wilderness, and 1 to 5 million lbs U30 8 at 

the Big Buck mine in the wilderness about 2.5 mi eastnortheast of Aztec Peak. Areas underlain by the Dripping Spring Quartzite contiguous to these localities, 

and the area centered about 1.5 mi east-northeast of 

McFadden Horse Mountain, have substantiated 

uranium resource potential. Uranium deposits in these 

areas probably range in grade from 0.01 to 0.3 percent 

U30 8 and in size from 100,000 to 2.0 million lbs U30 8• An 

area of probable resource potential underlies the central 

part of the wilderness, where specific geologic sites for 

uranium are difficult to identify because of the great 

depth of burial of the Dripping Spring Quartzite. 

Asbestos, in the form of long fiber, low-iron chrysotile, has been produced in the Sierra Ancha region since 

1913. As much as 50 to 85 percent of the fibers in these 

108 

deposits are textile length (more than 1/8 in.). The only 

asbestos production in the wilderness has been from the 

Pueblo mine, which probably produced several tens of 

tons of fiber, as did the Lucky Strike just north of the 

Pueblo mine but outside the wilderness. The Reynolds 

Falls mine, just west of the wilderness, furnished 

several hundred tons of asbestos, and a few thousand 

tons of fiber were produced from the American Ores 

mine, located 1 mi west of the southwest comer of the 

wilderness. An area of substantiated asbestos resource 

potential borders a large-scale discordant diabaseMescal Limestone contact beneath Center Mountain. If 

this contact is characterized by numerous steps or other 

irregularities over broad areas, a few deposits with contents of 200 to 10,000 tons of long-staple asbestos 

would be likely. If irregularities are widely spaced and 

of short lateral extent at this or other discordant contacts, many separate occurrences of 10 to 50 tons, and 

exceptionally as much as 200 tons, can be expected. A 

number of small areas of probable asbestos resource 

potential exist in the Sierra Ancha Wilderness, and one 

area of substantiated resource potential occurs in the 

area around Asbestos Point. 

Iron occurs in a few small deposits in the wilderness 

and adjacent areas. A magnetite-bearing horizon on the 

southern and eastern flank of Zimmerman Point has 

about 15 million tons of demonstrated resources averaging 26.5 percent iron in an area of substantiated iron 

potential (Cerro de Pasco Corp., written commun., 

1979). Magnetite beds at the Pueblo and Lucky Strike 

asbestos mines have been estimated by Colorado Fuel 

and Iron, Inc. to contain about 6 million tons of 

demonstrated resources averaging 40-60 percent iron 

(B. B. Kyle, oral commun., 1978). Although these 

deposits and others suggested by magnetic anomalies 

occur in areas of substantiated iron resource potential, 

they are regarded as having little promise for the 

recovery of iron. 

Fluorspar mined during the period 1976- 78 from the 

Mack mine on the McFadden fault, about 1.4 mi west of 

the wilderness, totalled approximately 30,000 tons of 

ore that averaged between 60 and 90 percent CaF 2· A 

probable resource potential for fluorspar exists along 

the McFadden fault in the wilderness. Scattered occurrences of copper and anomalous concentrations of 

barite, lead, bismuth, tin, tungsten, and molybdenum 

found in concentrates from stream sediment in the 

Sierra Ancha are not associated with known resources 

(Tripp and others, 1980). 

Hydrothermal alteration and contact metasomatism 

associated with the diabase were important in the 

development of most of the known mineral deposits in 

the Sierra Ancha The genetic relationship of diabase 

and uranium mineralization is suggested by (1) proximity of diabase to uranium deposits, (2) similar ages of 
uraninite in veins and zircons in diabase, and (3) high 

temperatures of formation for the deposits. Syngenetic 

uranium in the carbonaceous siltstone in the upper 

member of the Dripping Spring Quartzite was mobilized 

and redeposited in fractures by hydrothermal fluids 

driven by heat from the diabase. The asbestos deposits 

formed where the Mescal Limestone was subjected to 

karstification and silicification prior to deposition of the 

Troy Quartzite and was subsequently serpentinized by 

heat and fluids from the diabase. Deposition of asbestos 

occurred generally within 25ft above or below a diabase 

sill in veins developed where small-scale thrust and 

bedding-plane faults opened near discordant steps as 

diabase shouldered aside the adjacent sedimentary 

strata. The relationship of iron deposits to diabase is 

evident from magnetite stockworks formed by pyrometasomatic replacement of carbonate rock adjacent to 

sills and by the partial to complete conversion of sedimentary hematite in the Apache Group to magnetite by 

contact metamorphism during diabase intrusion. 

The origin of the fluorspar deposits is uncertain. They 

occupy the McFadden fault, which formed during 

emplacement of the diabase. 

SUGGESTIONS FOR FURTHER STUDY 

The general geology and mineral resources of the 

Sierra Ancha Wilderness are moderately well known. 

However, careful investigations of the structural 

geology and stratigraphy in areas where discordant 

diabase intrusions transect favorable strata would provide information useful for making projections of possible concealed uranium and asbestos resources, some of 

which could be substantial. Additional geochemical and 

geophysical surveys may be helpful in defining the 

sources of the anomalous concentrations of barite, lead, 

bismuth, tin, tungsten, and molybdenum observed in 

the wilderness. 

REFERENCES 

Bergquist, J. R., Shride, A. F., and Wrucke, C. T., 1981 , Geologic map 

of the Sierra Ancha Wilderness and Salome Study Area Gila 

County, Arizona: U.S. Geological Survey Miscellaneous Field 

Stuclies Map MF - 1162-A, scale 1:48,000. 

Otton, J. K., Light, T. D., Shride, A. F., Bergquist. J. R., Wrucke, 

C. T., Theobald, P. K., Duval, J. S., and Wilson, D. M .. 1981. Map 

showing mineral resource potential of the Sierra Ancha Wilder· 

ness and Salome Study area Gila County. Arizona: U.S. Geolog· 

ical Survey Miscellaneous Field Study Map MF·ll62- H, scale 

1:48,000. 

Tripp, R. B., Barton, H. N., egri, J. C .. and Theobald. P. K., 1980. 

Mineralogical map showing the clistribution of minerals in the 

heavy·mineral concentrate of stream sediments in the ierra 

Ancha Wilderness and Salome Study Area Gila County. 

Arizona: U.S. Geological Survey Miscellaneous Field Stuclies 

Map MF- 1162- E, scale 1:62,500. 

109 
110 

111 °30' 

35° 

30' 

\. 

\ 

0 

D 

"' 

MILES 

EXPLANATION 

ARIZONA 

• 

MAP LOCATION 

3 

Geologic terrane with probable 

geothermal resource potential 

Figure 30.-Strawberry Crater Roadless Areas, Arizona 
STRAWBERRY CRATER ROADLESS AREAS, ARIZONA 

By EDWARD W. WOLFE, U . . GEOLOGICAL R EY, and 

THOMAS D. LICHT, U.S . B REA OF MI E 

SUMMARY 

The results of a mineral survey conducted in 1980 in the Strawberry Crater 

Roadless Areas, Arizona, indicate little promise for the occurrence of metallic 

mineral or fossil fuel resources in the area The area contains deposits of cinder, 

useful for the production of aggregate block, and for deposits of decorative 

stone; however, similar deposits occur in great abundance throughout the San 

Francisco volcanic field outside the roadless areas. There is a possibility that the 

Strawberry Crater Roadless Areas may overlie part of a crustal magma 

chamber or still warm pluton related to the San Francisco Mountain 

stratovolcano or to basaltic vents of late Pleistocene or Holocene age. Such a 

magma chamber or pluton beneath the Strawberry Crater Roadless Areas 

might be an energy source from which a hot-, dry-rock geothermal energy 

system could be developed, and a probable geothermal resource potential is 

therefore assigned to these areas. 

CHARACTER AND SETTING 

The Strawberry Crater Roadless Areas are located in 

Coconino Coun ty, Arizona, approximately 20 mi northeast of Flagstaff, Arizona Together the two roadless 

areas encompass 15.5 sq mi in the northeastern portion 

of the Coconino National Forest. The Strawberry Crater 

Roadless Areas are accGssible from U.S. Highway 89 by 

several interconnecting USFS roads. 

The eastern San Francisco volcanic field was previously studied by Moore and Wolfe (1976). The area, in 

the sou them part of the Colorado Plateau, is underlain 

by largely basaltic Quaternary lavas and cinder cones 

that overlie nearly horizontal Permian Kaibab Lime-

!'ltone or Triassic siltstone or sandstone of the Moenkopi 

Formation. Holocene basaltic cinders from the eruption 

of Sunset Crater mantle much of the area Locally, 

basaltic ash has been reworked to form small dunes. 

Tree-ring dating (Smiley, 1958) indicates that the lavas 

and cinders of the Sunset Crater eruptions are less than 

1000 years old. 

The Strawberry Crater flow consists of blocky 

basaltic andesite dated at less than 100,000 years old 

(Damon and others, 1974). The cone, built largely of agglutinated basaltic andesite spatter, was breached by 

the flow. Subsequently a small dacite vitrophyre plug 

was emplaced within the breached cone. In addition to 

resting on older Quaternary basalt, Strawberry Crater 

and its lava flow overlie the east edge of the rhyodacite 

of Deadman Mesa, which erupted from the O'Leary 

Peak silicic center and has been dated at about 0.17 m.y. 

(million years) old (P. E. Damon and M. Shafiqullah, 

unpub. data, 1980). 

There has been no mining in the Strawberry Crater 

Roadless Areas, and exploration and mining activity in 

the general vicinity of Strawberry Crater have been 

limited to cinder and pozzolan deposits. Cinder deposits 

within 5 mi of the roadless areas were being mined in 

1980. o other commodities are known to occur in the 

areas. 

MINERAL RESOURCES 

All rocks exposed in the Strawberry Crater Roadless 

Areas are relatively unaltered; there is no evidence of 

mineralization. Semiquantitative spectrographic analyses of samples of flow and pyroclastic units give values 

appropriate for unaltered basaltic rocks (Wolfe and 

Hahn, 1982) and show no indication of concealed metallic mineral resources. 

The Strawberry Crater Roadless Areas contain 

deposits of cinder suitable for the production of aggregate block and deposits of decorative stone; similar 

deposits occur in great abundance throughout the San 

Francisco volcanic field outside the roadless areas. 

111 
The Strawberry Crater Roadless Areas are within a 

region of the San Franciso volcanic field that has probable resource potential for geothermal energy. The 

youngest volcanic vents of the San Francisco field are in 

the general vicinity of Strawberry Crater. These include 

Sunset Crater, which is less than 1000 years old, the 

rhyolite of Sugarloaf (K-Ar age is approximately 0.22 

m.y.), and the dacitic to rhyolitic O'Leary Peak center 

(K-Ar ages of approximately 0.17 and 0.24 m.y.) (K-Ar 

ages from Damon and others, 197 4, and P. E. Damon 

and M. Shatiqullah, unpub. data, 1980). Strawberry 

Crater itself erupted less than 0.1 m.y. ago (Damon and 

others, 1974). Strawberry Crater, O'Leary Peak, Sugarloaf, and the exposed conduit system for the San Francisco Mountain stratovolcano, which erupted largely 

between 1.0 and 0.4 m.y. ago, form an alinement that 

coincides closely with a distinct linear aeromagnetic low 

(Sauck and Sumner, 1970); a common volcano-tectonic 

control for these vents is suggested (Wolfe and Hoover, 

1982). If an intrusive complex related to these alined 

vents and to the coincident aeromagnetic low contains 

residual magmatic heat or is partly molten, it may comprise a potential source of geothermal energy. Stauber 

(1982) suggested that one of several possible explanations for low compressional wave velocity approximately 6.5 to 22 mi below San Francisco Mountain 

would be the presence of partly molten rock. In addition, magnetotelluric soundings show local anomalously 

low resistivities at depth near Sunset and Strawberry 

Craters (Ware and O'Donnell, 1980). Possibly these 

anomalies reflect locally high lower crustal 

temperatures. 

SUGGESTIONS FOR FURTHER STUDIES 

Additional geophysical studies to elucidate the electrical and magnetic characteristics of the crust beneath 

112 

the eastern part of the San Francisco volcanic field 

would contribute to evaluation of geothermal resources. 

The most definitive information, however, will be obtained only when and if holes suitable for heat-flow 

studies are drilled into the Precambrian basement. 

REFERENCES 

Damon. P. E., Shafiqullah, M .. and Leventhal, J. .. 1974. K-Ar 

chronology for the San Francisco volcanic field and rate of erosion of the Little Colorado River, in Karlstrom, T. . V.. wann, 

G. A .. and Eastwood, R. L .. eds .. Geology of northern Arizona, 

Part 1. Regional Studies: Geological Society of America. Rocky 

Mountain Section, p. 221-235. 

Moore, R. B., and Wolfe, E. W .. 1976, Geologic map of the eastern an 

Francisco volcanic field, Arizona: U. . Geological Survey 

Miscellaneous Investigations Series 1- 953. scale 1:50,000. 

Sauck, W. A .. and Sumner. J . S .. 1970, Residual aeromagnetic map of 

Arizona: University of Arizona. Department of Geosciences, 

scale 1:1.000,000. 

Smiley, T. L.. 195 . The geology and dating of unset Crater. 

Flagsta:ff, Arizona. in New Mexico Geological Society, 9th Field 

Conference. Guidebook of the Black Mesa Basin: p. 1 6-190. 

Stauber, D. A .. 1982. Two-dimensional compressional wave velocity 

structure under an Francisco volcanic field, Arizona. from 

teleseismic P residual measurements: Journal of Geophy ical 

Research,v. 87,p.5451-5459. 

Ware, R. H .. and O'Donnell, J. E .. 19 0. A magnetotelluric survey of 

the San Francisco volcanic field. Arizona: U .. Geological urvey 

Open-File Report 0-1163. 44 p. 

Wolfe. E. W .. and Hahn. D. A., 1982, Geology and geochemical 

analyses of the Strawberry Crater RoadJe_ Areas, Coconino 

County. Arizona: U.S. Geological Survey Miscellaneous Field 

Studies Map MF -1394-A. scale 1:24,000. 

Wolfe. E. W .. and Hoover. D. B.. 1982, Geophysical map of the 

Strawberry Crater Roadless Areas, Coconino County. Arizona: 

U.S. Geological Survey Miscellaneous Field Studies Map 

MF - 1394- B. scale 1:24,000. 

Wolfe. E. W .. and Light, T. D .. 1982, Mineral resource potential map 

of the Strawberry Crater Roadless Areas, Coconino County, 

Arizona: U.S. Geological Survey Miscellaneous Field Studies 

Map MF- 1394- C, scale 1:24,000. 
SUPERSTITION WILDERNESS, ARIZONA 

By DO ALD W . PETER 0 , 1 U .S. GEOLOG ICAL S RVEY , and 

jiMMI E E. ji1 KS, .. BUREA OF MINES 

SUMMARY 

On the basis of geologic studies and mineral evaluations made between 1973 

and 1977, most of the Superstition Wilderness and adjoining areas are judged to 

have little promise for occurrence of mineral resources. However, two areas in an 

east-trending zone near the southern margin of the area, marked by spotty occurrences of mineralized rock, prospect pits, and a band of geochemical 

anomalies that coincides with alined magnetic anomalies, are considered to have 

probable mineral-resource potential. This zone lies within about 6 mi of two productive mines in Arizona's great copper belt, and the trend of the zone is parallel 

to many of the significant mineralized structures of this belt. A small isolated 

uranium anomaly was found in the northeastern part of the wilderness, but no 

evidence of other energy resources, such as petroleum, coal, or geothermal, was 

found. 

CHARACTER AND SETTING 

The Superstition Wilderness in south-central Arizona 

includes about 194 sq mi; an additional contiguous area 

of about 50 sq mi was included in the study for a total of 

about 244 sq mi. The Superstition Mountains rise as a 

spectacular range front above the adjacent desert to the 

south and west and provide a scenic treat to travelers on 

U.S. Highway 70. Arizona State road 88 skirts the 

northern boundary of the wilderness and offers hints of 

the ruggedly dissected landscape that makes up the interior of the wilderness. Altitudes range from 1660 to 

6266 ft; local relief between canyon bottoms and ridge 

tops ranges from a few hundred to a thousand feet, and 

the relief between the desert and the summit of the 

Superstition Mountains is 3500 ft. 

The wilderness is in a region of highly diverse rock 

types and complex geologic structure. Rocks range in 

age from Middle Proterozoic to Quaternary and include 

metamorphic, sedimentary, and both intrusive and extrusive igneous rocks. The geology of the eastern half of 

the wilderness differs distinctly from that of the western half. The eastern half includes mainly Proterozoic 

rocks of different types that have been pervasively 

1

Wilh contributions from D. L. Gaskill. M. L. Sorensen. W. E. Yeend. W. R. Miller. J. M. 

Mot.ooka. J . C. Wynn. K. L. Stark , N. H. &meson, and G. D. J oh.npeer. USG , and F. E. 

Williams, H. C. Meeves, L. S. Griffilhs, and J .A.T. Fallin, U BM. 

faulted. The rocks include schist and granite of Proterozoic age unconformably overlain by Middle Proterozoic 

sedimentary rocks (sandstone, quartzite, shale, conglomerate, and limestone), all intruded by massive sills 

and dikes of diabase. These, in turn, are unconformably 

overlain by isolated remnants of Paleozoic sedimentary 

rocks. The Proterozoic and Paleozoic rocks have been 

extensively faulted on an intricate scale chiefly by 

discontinuous high-angle normal faults of various orientations. Fault blocks have been tilted in diverse directions; the attitude of strata within individual fault 

blocks is relatively uniform, whereas attitudes vary 

widely from one block to another. These rocks are locally overlain by volcanic rocks of Tertiary age. 

The western half of the wilderness consists chiefly of 

Tertiary volcanic rocks of many different types. The 

most abundant are thick deposits of ash-flow tuff; these 

are overlain, underlain, and intruded by rhyolitic, 

dacitic, and basaltic lavas. The volcanic rocks were 

erupted from many different vents that lie within or 

near the wilderness, and, as is characteristic of volcanic 

source areas, the rocks are locally highly contorted and 

bear complex relationships with one another. The roots 

of one or more collapsed calderas that are the source of 

the voluminous ash-flow tuff may lie within the wilderness. Spectacular canyons have been cut into the 

volcanic rocks, and in some places erosion has carved intricate and fantastic forms for which the Superstition 

Mountains are famous. 

113 
11 1°30' 

33° 

30' 

114 

MAP LOCATION 

' ' . 

D Geologic terrane with 

resource potential 

Cu Copper 

Au Gold 

Pb Lead 

Ag Silver 

Zn Zinc 

X Mineral occurrence 

11 1°15' 

Approximate boundary 

< ~ 

~ ) < ... 

Cu , Pb , Zn , " < 

Au 

0 

M ILES 

EXPLANATION 

probable mineral-

/' /'-

-I _/_ 

5 

Volcanic rocks (Tertiary ) 

Sedimentary rocks (Paleozoic and 

Granite (Proterozoic) 

Ys Schist (Proterozoic) 

Contact 

Proterozoic) 

Fault--Bar and ball on downthrown side 

Figure 31.- Superstition Wilderness, Arizona 
The USBM, at intervals from 1973 to 1977, examined 

mining claims, prospects, and the few accessible mine 

workings showing evidence of mineralization. The 

USGS, at intervals from 1975 to 1977, carried out 

reconnaissance geologic mapping and geochemical sampling for analyses. Aeromagnetic mapping and a gravity survey were also carried out. Analytical results were 

compiled by Motooka and others (1978), and gravity 

results by Wynn and Manydeeds (1978). 

MINERAL RESOURCES 

The southern and eastern boundaries of the area 

studied are within 6 mi of large copper mines; the mines 

of the Globe, Miami, and Superior areas, which have 

had copper and precious-metal production exceeding 

$2 billion, lie within 20 mi of the wilderness. In spite of 

this proximity and intensive prospecting throughout 

terrane that resembles the geology around the major 

mineral deposits, little mining activity has resulted 

within and adjacent to the wilderness. 

Legal records reveal that no mining claims have been 

patented or mineral leases effected within the wilderness or the adjoining areas. Notices of claims filed 

through the years indicate a low level of prospecting activity during recent years, and most claims have not 

been maintained. 

Abundant pits, shafts, and adits dot an east-west 

zone along the sou them margin of the wilderness. 

Material found on dumps shows that the workings encountered appreciable mineralized ground, particularly 

in two areas designated here as the JF area (SE part of 

wilderness) and the Peralta Canyon area (SW part of 

wilderness). Valid claim have been maintained in the 

areas and although almost all workings are inaccessible 

and could not be examined both areas have a probable 

mineral-resource potential. In the JF area, hydrothermal alteration and copper, lead, zinc, and silver 

mineralization are found in both schist and granite in an 

elongate zone extending from about 1.5 mi south of the 

JF Ranch for about 4 mi in an east-northeast direction 

toward Iron Mountain; the vaguely defined zone is as 

much as 1.5 mi wide and lies both within and outside the 

wilderness. 

In the Peralta Canyon area, mineralized ground in an 

east-northeast trending zone from 1 mi west of the 

mouth of Peralta Canyon eastward for about 4 mi has 

been explored by several small operations. Alteration 

and mineralization of base and precious metals occur 

both in Proterozoic granite and Tertiary volcanic rocks, 

and they are associated, at least in part, with an eastnortheast trending range-front fault. A few claims are 

maintained, but no recent exploration activity is known. 

A small amount of mineralization evidently occurs 

along a siliceous vein in a mine near the western margin 

of the wilderness, about 2 mi southeast of the community of Goldfield. The workings are inaccessible. 

An important control of ore deposits in the GlobeMiami mining district (6-20 mi east of the wilderness) is 

postulated to be the east-northeast trending contact 

between Proterozoic schist and granite (Peterson, 1962). 

Granitic stocks of Late Cretaceous or early Tertiary age 

intruded this ancient zone of weakness, carrying mineralizing fluids that solidified to form the important ore 

deposits. A reconnaissance of the geology of the area 

undertaken as part of this study showed that the contact between the ancient schist and granite extends 

westward across the southern part of the wilderness. A 

band of geochemical anomalies with high values of copper, lead, zinc, silver, and other metals extends across 

the southern part of the wilderness and straddles the ancient contact. An east-west series of magnetic low 

anomalies is also alined roughly along the contact. No 

large intrusive bodies of younger Cretaceous or Tertiary 

age were found in proximity to the contact, although a 

north-trending dike swarm has intruded schist just 

north of the contact in an area just west of Iron Mountain (JF area). These dikes could be outliers of a larger 

concealed intrusive body. The possibilities are intriguing because of the alteration and mineralization in the 

JF area Owing to these combined factors, the two areas 

along the southern margin of the wilderness are designated as having probable mineral-resource potential. 

Another possibility for undiscovered minerals would 

be a deposit concealed beneath the Tertiary volcanic 

rocks. The only hint of such a deposit is a tongue-like 

geochemical anomaly extending north-northwest from 

the Peralta Canyon area and no resource potential is 

identified. 

Anomalously high values of uranium and thorium 

were detected in a number of rock and stream-sediment 

samples near the northeastern comer of the wilderness 

(Peterson and Jinks, 1983). 

Although the Superstition Mountains are well known 

for legends of lost gold, the general geologic environment holds little promise for an important gold deposit 

that could have been found using the techniques of 19th 

century prospecting. The Lost Dutchman mine can likely be relegated to the store of folk tales that extend and 

embellish historical reality. 

SUGGESTIONS FOR FURTHER STUDIES 

Most of the wilderness holds little promise for identification of mineral resources. The areas indicated as 

having probable mineral-resource potential will need 

115 
detailed geologic mapping and exploration to determine 

the feasibility of realizing this potential. 

REFERENCES 

Motooka. J. M .. Sanzalone, R. F. , and Curtis, C. A., 1978, Analyses of 

rock and stream sediments of the Superstition Wilderness, Arizona: U.S. Geological Survey Open-File Report 78-483. 

116 

Peterson, D. W., and Jinks, J. E .. 1983, Mineral resource potential 

maps of the Superstition Wilderness and contiguous roadless 

areas, Maricopa, Pinal, and Gila Counties, Arizona: U.S. 

Geological Survey Open-File Report 83- 472. scale 1:24.000. 

Peterson, . P., 1962, Geology and ore deposits of the Globe-Miami 

district, Arizona: U.S. Geological Survey Professional Paper 342, 

151 p. 

Wynn, J. C., and Manydeeds. S. A., 1978, Principal facts for gravity 

stations in and adjacent to the Superstition Mountains, Gila. 

Pinal, and Maricopa Counties, Arizona: U.S. Geological urvey 

Open-File Report 78- 566, 10 p. 
SYCAMORE CANYON PRIMITIVE AREA, ARIZONA 

By LYMA C. H FF, U.S. GEOLOCI AL RVEY , and 

R . C . R AABE, U.S. B REA OF MI 1 E 

SUMMARY 

On the basis of a mineral survey made by the USGS and USBM in 1965, the 

Sycamore Canyon Primitive Area has little promise for the occurrence of 

mineral commodities. 

CHARACTER AND SETTING 

The Sycamore Canyon Primitive Area, which occupies about 7 4 sq mi, lies about 24 mi southwest of 

Flagstaff, Arizona. The margin of this primitive area 

corresponds to the rim of deeply eroded Sycamore Canyon. To the southeast, beyond the canyon rim, lies an 

upland within the Coconino National Forest. To the 

northwest, also beyond the canyon rim, lies a similar 

upland within the Kaibab National Forest. These 

uplands near the head of the canyon have an elevation 

of about 6700 ft above sea level. In its lowest part, 

where Sycamore Creek leaves the primitive area at its 

southern end, the area has an elevation of 3600 ft. 

Through much of the area the canyon is more than 1700 

ft deep. 

The rocks in Sycamore Canyon consist almost entirely of flat-lying sedimentary rocks of Paleozoic age. 

Many of the formations that crop out in the Grand Canyon ational Park also crop out in Sycamore Canyon 

and form similar beautiful cliffs. 

The Paleozoic sedimentary rocks include thick formations of limestone, siltstone, and sandstone. Above 

these is a thin layer of mudstone and sandstone of early 

Mesozoic age, which is in tum overlain locally by gravel 

and basalt flows of Tertiary and Quaternary age. The 

alluvial sand and gravel deposits along the narrow flood 

plain of Sycamore Creek are also of Quaternary age. The 

basaltic igneous rocks present are located mostly near 

the head of the canyon. They are flows and dikes peripheral to the volcanic complex centering around San Francisco Mountain to the north. 

Access to Sycamore Canyon is limited to hiking trails 

which wind down from the canyon rim to the narrow 

lowland along Sycamore Creek. Vistas are similar to 

that along the Kaibab Trail at Grand Canyon but on a 

smaller scale. Kelsey Spring and other springs in the 

northern part of the canyon provide fresh water near 

good camping sites. During late summer much of the 

flow of Sycamore Creek is underground and good 

sources of water in the lower part of the canyon are difficult to find. 

MINERAL RESOURCES 

o evidence of mineral deposits was discovered in 

this area. The sedimentary beds are cut by numerous 

small faults but none of these are mineralized. The rocks 

are well expo ed so that if any mineral deposits were located in the area they would almost certainly be noticed. 

The only mining claims located in the area are near 

the southern end where two partners excavated the clay 

fill in a cave close to Sycamore Creek in the belief that 

that is where the renegade Apache Indian Geronimo 

buried treasure. This cave, which is limestone, and its 

clay filling were examined carefully and concluded to be 

entirely natural. 

To help evaluate the area for mineral resources, sediment samples were collected along Sycamore Creek and 

its tributaries. These were analyzed for traces of the ore 

metals without finding any local concentrations. In addition, a scintillometer was used to test rocks in the area 

without finding any abnormal radioactivity. 

o oil wells have been drilled in the area and it is 

unlikely that any drilled would be successful. Geologic 

structures favorable for accumulating oil are lacking 

and geologic mapping indicates that Precambrian crystalline rocks unsuitable for oil underlie the area at relatively shallow depth. 

SUGGESTIONS FOR FURTHER STUDIES 

Further study of this primitive area offers little promise for the discovery of any hidden mineral deposits. 

117 
35°05' 

35•oo· 

118 

112°05' 

QTb ? 

0 

>- 2 

SYCAMORE. (3 

BAc- N 

0 

112•oo· 

MILES 

EXPLANATION 

111 °55' 

Approximate boundary 

ore 

• 

MAP LOCATION 

5 

c==:J Basalts (Quaternary and Tertiary) 

B Sedimentary rocks (Mesozoic and Paleozoic) 

Contact 

Figure 32.-Sycamore Canyon Primitive Area, Arizona 
REFERENCE 

Huff, L. C., Santos, Elmer, and Raabe, R. G., 1966, Mineral resources 

of the Sycamore Canyon Primitive Area, Arizona: U.S. 

Geological Survey Bulletin 1230-F, 19 p. 

119 
120 

0 

MILES 

EXPLANATION 

D Sedimentary rocks (Quaternary and Tertiary ) 

D Volcanic rocks (Tertiary) 

Sedimentary rocks (Permian ) 

10 

Contact 

Fault--Bar and ball on downthrown side 

Mine 

Figure 33.-West Clear Creek Roadless Area, Arizona 
WEST CLEAR CREEK ROADLESS AREA, ARIZONA 

By G EORGE E. ULRIC H, U . . GEOL Gl AL S RVEY, and 

A LA M. BIEL KI , U .. B REAU OF Mit E 

SUMMARY 

Results of USGS geologic, geochemical, and aeromagnetic studies and USBM 

review of mineral records and prospect examination for the West Clear Creek 

Roadless Area, Arizona, indicate that there is little likelihood of the occurrence 

of mineral or energy resources. No concentrations of minerals were identified 

within the boundary of the area A small manganese deposit occurs 1- 3 mi east 

of the area but does not extend into the area Slightly anomalous values for certain trace metals were found in samples taken within the area, but do not indicate the presence of metallic resources. Gypsum, basaltic cinders, and sandstone 

occur in the area, but similar materials are available and have been quarried outside the area where they are much more readily accessible. 

CHARACTER AND SETTING 

The West Clear Creek Roadless Area includes approximately 53 sq mi in Yavapai and Coconino Counties in 

central Arizona, about 70 mi north of Phoenix. The area 

lies on the southwestern margin of the Colorado Plateau 

and includes part of the Verde valley, one of several 

northwest-linear basins in the Arizona transition zone 

separating the Basin and Range and Colorado Plateaus 

physiographic provinces. Interstate 17 connecting 

Phoenix and Flagstaff crosses Verde Valley 10 mi west 

of the roadless area and affords a view of the westfacing escarpment of the plateau margin notched by the 

prominent canyon of West Clear Creek. 

The roadless area boundary closely follows the rim of 

the steep-walled canyon of West Clear Creek and its 

tributaries. The perennial stream within the canyon 

drops 3000 ft over a distance of 36 mi from its head at 

the juncture of Willow and Clover Creeks to its confluence with the Verde River. Together with its 

tributaries, it drains an area of about 240 sq mi. The 

maximum altitude of the area, approximately 7000 ft 

above sea level, occurs at the eastern end, on the top of 

the plateau. The topographic relief increases about 100 

ft at the eastern end, to a maximum of 1800 ft toward 

the west as the canyon deepens across the Plateau 

margin. The relief decreases abruptly at the western 

boundary where West Clear Creek flows onto the broad 

open floor of the Verde River valley. 

Paleozoic and Mesozoic rocks are exposed in the 

precipitous walls of the canyon and include upper 

Paleozoic sedimentary strata having a cumulative 

thickness of about 1700 ft and remnants of Triassic 

rocks in the northeastern corner of the roadless area 

The Paleozoic formations, in ascending order, are the 

impressive "red rocks " of the Supai Formation (650 ft 

of siltstone, sandstone, and minor limestone), the lightgray crossbedded Coconino Sandstone (700 ft), and the 

ledgy limestones of the Kaibab Formation (as much as 

350 ft). In the middle part of the canyon, west of the 

Cash Tank fault, these rocks were deeply eroded more 

than 10 million years ago, creating an old valley at least 

1300 ft deep which crossed the direction of the modern 

westerly course of West Clear Creek. This paleovalley 

was partly filled by as much as 300 ft of coarse conglomerate chiefly derived from the valley walls. Beginning 

about 11 million years ago (Pierce and others, 1979), extensive volcanic eruptions, primarily basaltic, produced 

pyroclastic deposits and lava flows that filled and overtopped the remaining space within the old valley, 

reaching a maximum thickness of about 1500 ft . Basinfilling sediments of the Tertiary Verde Formation were 

deposited in the western part of the roadless area during 

and following the volcanic activity. After deposition of 

the Verde Formation had ceased, extensive erosion by 

the present river system began; it has cut as much as 

1500 ft into the plateau. 

The structural setting is one of gentle westward dips 

in the sedimentary rocks and steeply dipping normal 

faults. Most of the faults trend north to northwest, but 

121 
two of them, the Cash Tank and Toms Creek faults, are 

unusual in that they strike northeasterly and can be 

traced for more than 3 mi. The Cash Tank fault is also 

notable for its large throw, 240-360 ft, and is reflected 

in both the gravity and aeromagnetic data The Toms 

Creek fault parallels the aeromagnetic contours in the 

area and lies on a trend which, if extended to the northeast, would coincide with the breccia zone described by 

Jones and Ransome (1920) in the Long Valley manganese district. 

MINERAL RESOURCES 

On the basis of geologic mapping, geochemical sampling, an aeromagnetic survey, and review of the county 

and federal land records, the roadless area is considered 

to have little likelihood for the occurrence of hidden 

mineral resources. No metallic mineral occurrences are 

known within the area 

Mineralized areas, mining claims, and mining activities are limited to the Long Valley manganese district 

1-3 mi east of the roadless area. The Last Chance mine 

near the head of Iron Mine Draw, is within the Long 

Valley district but mineralization does not appear to extend into the roadless area 

The Verde Formation occurs at the western extremity 

122 

of the roadless area and is quarried for gypsum about 

2 mi west of the area; however, this formation does not 

contain evaporite deposits within the roadless area 

Basalt and basaltic cinder deposits along the canyon 

rim have uses for road metal, concrete aggregate, 

riprap, and cinder blocks, and the Coconino Sandstone 

exposed in the canyon can be used as building- and 

flagstone but similar construction materials are more 

readily available outside the area 

SUGGESTIONS FOR FURTHER STUDIES 

Further study of the roadless area offers little promise 

for the identification of hidden mineral deposits. 

REFERENCES 

Jones, E. L. and Ransome, F. L .. 1920, Deposits of manganese ore in 

Arizona: U.S. Geological Survey, Bulletin 710- D, p. 125- 128. 

Pierce, H. W., Damon, P. E., and Shafiqullah, M., 1979, An 

Oligocene(?) Colorado Plateau edge in Arizona: Tectonophysics, 

V. 61, p. 1-24. 

Ulrich, G. E .. and Bielski, A. M., 1983, Mineral resource potential map 

of West Clear Creek Roadless Area. Yavapai and Coconino Counties. Arizona: U.S. Geological Survey Miscellaneous Field 

Studies Map MF - 1555-A, scale 1:24,000 (in press). 
WET BEAVER ROADLESS AREA, ARIZONA 

By GEORGE E. ULRICH,' US. GEOL C l AL R EY, and 

ALA N M. BIEL KI , U .. B REA OF MI ES 

SUMMARY 

On the basis of field studies by the USGS and the USBM in 1982 there is little 

promise for the occurrence of mineral or energy resources in the Wet Beaver 

Roadless Area, Arizona No significant concentrations of metals were indicated 

by geochemical sampling or aeromagnetic data within the area Basaltic cinders 

and sandstone have been quarried for construction materials near the area but 

are readily available and more accessible outside the precipitous canyons of Wet 

Beaver Creek and its tributaries. 

CHARACTER AND SETTING 

The Wet Beaver Roadless Area includes 15.4 sq. mi of 

the Coconino National Forest in Coconino and Yavapai 

Counties, central Arizona, about 85 mi north of 

Phoenix. Montezumas Castle National Monument is 

4 mi southwest of the area's western boundary. The 

roadless area lies on the southwestern margin of the Colorado Plateau and near the eastern margin of the Verde 

valley, one of several linear basins in the Arizona Transition Zone that separates the Basin-and-Range and Colorado Plateaus physiographic provinces. Interstate 17 

connecting Phoenix and Flagstaff crosses Verde valley 

2 mi northwest of the roadless area, and access to the 

area is easiest from the Sedona interchange to the USFS 

Ranger Station from which only foot traffic is allowed 

into the roadless area. Two well-marked trails climb 

from Wet Beaver Creek onto the basalt-capped surface 

of the Mogollon Rim within 2 mi of the Ranger Station. 

The roadless area boundary closely follows the rim of 

the steep-walled canyon of Wet Beaver Creek and its 

tributaries cut into the gently westward sloping surface 

of the Colorado Plateau. The perennial stream within 

the canyon drops 2100 ft over a distance of 13 mi from 

its head at the juncture of Brady and Jacks Canyons in 

the east to the intersection with Casner Canyon on the 

western edge of the roadless area. Wet Beaver Creek 

continues another 12 mi on the broad floor of Verde 

valley before it joins the Verde River near Camp Verde. 

Together with its tributaries, Wet Beaver Creek drains 

an area of 101 sq mi above the western boundary of the 

1

Wit.h conLributions (Tom J. u1.annc Bywaters. U ,s. 

roadless area. Perennial springs below Hog Hill discharge 1200 to 1500 gallons of water per minute into 

Wet Beaver Creek (Twenter and Metzger, 1963). The 

maximum altitude within the roadless area, just east of 

Hog Hill, is 6470 ft. The lowest point, at 4000 ft, is the 

stream bed of Wet Beaver Creek near the western 

boundary. Topographic relief within the roadless area 

ranges from 1200 ft near the mouth of the canyon at 

Casner Butte, to approximately 150 ft at the eastern 

boundary. 

The rocks exposed by the downcutting of Wet Beaver 

Creek include, in ascending order, the spectacular red 

sandstones and siltstones of the upper Supai Formation, (550 ft) in the western part of the canyon, the lightgray and yellowish-gray crossbedded Toroweap and 

Coconino Sandstones, undivided, (600 ft) exposed in 

most of the canyon, and the gray ledgy limestones and 

dolomites of the Kaibab Formation (280 ft) in the eastern part. These sedimentary rocks, all of Early Permian 

age, are unconformably overlain by 300 to 1500 ft of 

Tertiary basaltic rocks and are intruded by basaltic 

dikes and at least one basaltic plug. The unconformity 

truncates increasingly older rocks from east to west and 

is commonly marked by a thin conglomerate or gravel 

with clasts of the Permian rocks described above. 

The structural setting is one of variable local clips and 

a gentle regional clip to the east within the sedimentary 

rocks. ormal faults offset volcanic and sedimentary 

units, clip steeply, and strike mainly northwest or north. 

Blocks of Permian strata between faults are generally 

upthrown on the west and tilted downward toward the 

east. The net displacement for all faults mapped within 

the main canyon is approximately 1300 ft down to the 

123 
J40 111°45' 

45' 

/,; 

.g 1 r 

~ ~ 

124 

~ G Sedona 

~terchangc 

\)-le\ 

i:-1ontezurnas 

Ca le at•onal 

rvfonumt•rt 

Ranger 

StatiO I" 

/To 

L.-

17 

(' 

(' 

"' .L. 

0 

Flagstaff 

\ ~ (,..... ........ , ',~ _..,..., ) '-"' I ,_, 

' '~ /~ ~App "" roximate '\ ~ roadless boundary 

\~ 

~l 

MILES 

EXPLANATION 

Sedimentary rocks 

Basaltic rocks 

Contact 

Fault 

5 

MAP LOCATION 

F1gure . 34 .- Wet Beaver Roadless Area, Arizona 

111 °30' 
west. The density of faults increases locally near areas 

of basaltic vent deposits. 

MINERAL RESOURCES 

On the basis of geologic mapping, geochemical sampling, an aeromagnetic survey, and review of the county 

and federal land records, the roadless area is considered 

to have little promise for the occurrence of mineral 

resources. There are no known mineral occurrences 

within the roadless area. Basalt and basaltic cinder 

deposits along the canyon rim have a potential for road 

metal, concrete aggregate, riprap, and cinder blocks, 

and the Coconino Sandstone exposed in the canyon may 

be used as building and flagstone but similar construction materials are more readily available outside the 

roadless area o energy resources were identified in the 

study. 

SUGGESTIONS FOR FURTHER STUDIES 

Further study of the roadless area offers little promise 

for the identification of hidden mineral deposits. 

REFERENCES 

Twenter, F. R., and Metzger, D. G., 1963. Geology and ground water 

in Verde Valley-Mogollon Rim Region, Arizona: U.S. Geological 

Survey Bulletin 1177, 132 p. 

Ulrich, G. E., Bielski. A. M., and Bywaters, J. S., 19 3. Mineral 

resource potential map of the Wet Beaver Roadless Area, Coconino and Yavapai Counties, Arizona: U.S. Geological Survey Miscellaneous Field Studies ReportMF- 1558- A, scale 1:24,000. 

125 
126 

11 

31 ° 

55' 

31 ° 

45' 

OTs 

OTs 

0 

MILES 

EXPLANATION 

Geologic terrane with substantiated 

mineral -resource potential D Geologic terrane with probable 

mineral-resource potential 

Cu Copper Ag Silver 

Au Gold w Tungsten 

Pb Lead u Uranium 

M o Molybdenum 

~ Mine or deposit 

8 

QTs 

psum8 

ARIZON: 

MAP LOCATION 

5 

Quaternary and Tertiary 

sedimentary rocks 

Cretaceous granitic rocks 

Cretaceous sedimentary rocks 

Paleozoic sedimentary rocks 

Proterozoic granitic rocks 

and schist 

Contact 

Fault 

Figure 35.- Whetstone Roadless Area, Arizona 
WHETSTONE ROADLESS AREA, ARIZONA 

By CHE'TER T. WRUCKE, 1 • • GEOLOG ICAL S RVEY , and 

R OBERT A. M CCOLLY, U.S. B REA Of' MI E 

SUMMARY 

A mineral survey conducted by the USGS and the USBM in 1981 has shown 

that areas in and adjacent to the Whetstone Roadless Area have a substantiated 

resource potential for copper, lead, gold, silver, and quartz, and a probable 

mineral-resource potential for copper, silver, lead, gold, molybdenum, tungsten, 

uranium, and gypsum. Copper and silver occur in a small vein deposit in the 

southwestern part of the roadless area Copper, lead, silver, gold, and 

molybdenum are known in veins associated with a porphyry copper deposit in a 

reentrant near the southern border of the roadless area. Vein deposits of 

tungsten and uranium are possible in the northeast part of the roadless area 

near areas of known procl.uction of these cornmocl.ities. Demonstrated resources 

of quartz for smelter flux extend into the roadless area from the Ricketts mine. 

Areas of probable potential for gypsum resources also occur within the roadless 

area. No potential for fossil fuel resources was identified in the study. 

CHARACTER AND SETTING 

The Whetstone Roadless Area comprises about 57 sq 

mi in the Basin and Range province of southeastern 

Arizona, about 40 rni southeast of Tucson and 25 mi 

north of the border with Mexico. The principal physiographic feature of the roadless area is a prominent 

north-northeast-trending ridge about 9 mi long that 

forms the crest of the Whetstone Mountains and culminates in several peaks about 7100 to 7700 ft in altitude, no one of which stands out significantly compared 

to the others. Some lower slopes and many of the higher 

areas in the mountains expose well-defined layered rock 

sequences, a few of which, especially near the ridge 

crest, form bold exposures many hundreds of feet in 

length, giving an impression of bedrock structure of 

marked simplicity and continuity. This is the general 

appearance of the range from the vicinity of Benson, the 

nearest town, which is situated about 6 mi northeast of 

the roadless area 

Bedrock in the roadless area and surrounding parts of 

the Whetstone Mountains consists of Proterozoic igneous and metamorphic rocks and an overlying stratigraphic succession of Paleozoic and Mesozoic strata. 

'With contributions from David C. ScoLL. USBM. and R. ScoLL Werschky. Viki Bankey. 

M. Dean Kleinkopf. Mortimer H. SJ.aalz. and Augusws K. AnnsLrong. USGS. 

The Paleozoic and Mesozoic rocks have been intruded 

by Mesozoic granitic masses. Published geologic maps 

of the area are by Creasey (1967) and Hayes and Raup 

(1968). 

The oldest rocks in the area are muscovite-biotitequartz schist of Early Proterozoic age and quartz monzonite and alaskite of Middle Proterozoic age. The 

metamorphic rocks formed from shales and silty shales 

that were regionally metamorphosed near the end of the 

Early Proterozoic Era and intruded by quartz monzonite about 1400- 1450 million years ago. Alaskite that 

also intruded the schist may be genetically related to 

the quartz monzonite. 

Resting unconformably on the Proterozoic rocks are 

sedimentary deposits that range in age from Cambrian 

to Permian. Middle Cambrian sandstone and quartzite 

recorded the beginning of Paleozoic sedimentation in 

southeastern Arizona, and represent deposition by advancing seas that beveled the Proterozoic basement. 

The overlying limestones and dolomites were deposited 

from the Late Cambrian into the Late Pennsylvanian in 

an open marine environment, whereas carbonate strata 

of Late Pennsylvanian to Late Permian age originated 

under tidal, supratidal, and marine conditions. Gypsum 

beds of Late Permian age record a supratidal environment. The Paleozoic rocks aggregate about 8000 ft in 

thickness. 

127 
Sandstone, shale, limestone, and conglomerate of 

Late Cretaceous age were deposited on an unconformity 

of great local relief that had been carved into the 

Paleozoic rocks. Deposition of the Mesozoic strata was 

marine and nonmarine in a prograding delta near the 

margin of a shallow sea that advanced northwestward 

into southeastern Arizona from Mexico. The Cretaceous 

stratified succession is about 8800 ft thick. 

The youngest Mesozoic rocks in the roadless area are 

granodiorite in sills and a small stock, and intrusive 

rhyodacite in irregular sill-like masses. These bodies 

were emplaced into the Paleozoic and Mesozoic strata 

about 7 4 million years ago. They are the youngest rocks 

in the Whetstone Mountains, other than a Tertiary(?) 

dike near the south end of the range, and Cenozoic 

gravels that crop out mainly around the base of the 

mountains. 

The principal structural feature of the Whetstone 

Mountains is a southwest-dipping homocline of Paleozoic and Mesozoic strata Steep faults and thrust faults 

in these rocks generally have displacements of a few 

hundred feet or less and do not significantly disturb the 

homoclinal pattern of the strata The homocline and 

faults probably represent deformation mainly during 

the Laramide orogeny of Late Cretaceous and Early 

Tertiary age. Additional deformation probably occurred 

during Basin and Range faulting in the Neogene. 

MINERAL RESOURCES 

The Whetstone Roadless Area has a substantiated 

resource potential for copper, gold, silver, and quartz 

and a probable resource potential for lead, copper, 

silver, gold, molybdenum, tungsten, uranium, and gypsum. Fluorite and mercury occur in or near the area but 

no resource potential was identified (Wrucke and others, 

1983; McColly and Scott, 1982). Mining activity in the 

Whetstone Mountains dates from the 1870s, but no 

mines have yielded ore since the 1960's. 

Copper ore containing minor amounts of silver was 

mined from a vein deposit in quartz-rich sandstone at 

the Copper Plate mine in the 1950's, and the mine contains demonstrated resources of 2000-4000 tons of lowgrade copper and occurs in an area of substantiated 

mineral-resource potential. 

Copper also is known in Mine Canyon just outside the 

roadless area The copper occurs in a porphyry-type 

deposit in granodiorite and in vein and replacement 

sulfide deposits in granodiorite and skarn at nearby 

mines. The area of the porphyry deposit as well as the 

vein deposits has substantiated mineral-resource potential, based on demonstrated resources of 32 million tons 

of 0.28 percent copper and 0.01 percent molybdenum 

(DeRuyter, 1957). Records dating from 1918 show that 

128 

mines in the vein deposits have produced at least 

136,048 lbs of copper, 900,000 lbs of lead, and small 

amounts of silver and gold. A probable mineral-resource 

potential for copper, lead, silver, gold, and molybdenum 

exists around the area of substantiated resource potential. This determination is based on the assumption that 

copper mineralization extends beyond the area explored 

by drilling and mining, and on geophysical evidence 

that the granodiorite widens at depth. 

Quartz was produced for smelter flux during the 

1950's from the Ricketts mine, located outside the 

roadless area, north of Middle Canyon. Demonstrated 

resources of 5000- 6000 tons for each vertical foot of 

quartz exist in that part of the quartz body that extends 

for a distance of 800 ft westward into the roadless area 

and is shown on the map as an area of substantiated 

quartz resource potential. 

Tungsten has been mined sporadically since about 

1900 from an area 1 mi north of Middle Canyon. Most of 

the production was from veins at the Chadwick mine 

outside the roadless area, although the James mine 

within the roadless area has recorded production. All of 

the ore-grade deposits were exhausted prior to 1960, 

and there is little promise of additional deposits near the 

surface. A probable resource potential for tungsten in 

this area is based on the possibility that tungsten veins 

occur at depth. 

High-grade fluorspar has been produced at the Lone 

Star mine, on the north side of Middle Canyon. 

Although the mine is about 1000 ft outside the roadless 

area the fluorite vein system might extend into the 

roadless area at depth. The mine is believed to have 

been the largest single producer of fluorspar in Arizona 

Although the workings are now inaccessible, a probable 

mineral-resource potential for fluorite is assigned to this 

area 

Uranium deposits occur in veins in Proterozoic quartz 

monzonite and alaskite on the northeastern flank of the 

Whetstone Mountains. High scintillometer readings, 

chemical values for uranium, and the production of 

uranium at the Old Windmill No. 1 mine in Cottonwood 

Canyon indicate that additional resources exist at the 

mine. Demonstrated resources of 4 7 tons of uraniumbearing rock containing as much as 0.094 percent 

uranium occur at the Star No. 1 (Bluestone) prospect 

north of Middle Canyon. However, the concentration of 

uranium in the mine areas and elsewhere is spotty. The 

northern part of the Whetstone Mountains has a probable resource potential for uranium. 

Gypsum occurs in Permian sedimentary rocks near 

the south end of the Whetstone Mountains, outside the 

roadless area, and these same Permian rocks occur 

within the roadless area, indicating a probable resource 

potential for gypsum. 

A gold deposit at the Gold Crystal prospect in Middle 
Canyon outside, but within a few hundred feet of the 

roadless area has about 3000 tons of demonstrated lowgrade gold resources to a depth of 100 ft, and a small 

area of substantiated resource potential extends into 

the roadless area. 

Mercury (as cinnabar) was found in heavy-mineral concentrates during sampling in the vicinity of Middle Canyon and Montosa Canyon. The mercury shows no clear 

relationship to any of the known mineral resources in the 

area No mercury resource potential was identified. 

Most of the known mineral deposits in the Whetstone 

Mountains were formed by hydrothermal processes that 

can be related to igneous events. The copper deposits in 

the southern and western parts of the mountains are 

best developed in and adjacent to Cretaceous gran<r 

diorite, leaving little doubt of a genetic tie between 

these deposits and the Cretaceous intrusive rocks. A 

genetic relationship between the uranium, tungsten, 

and fluorite veins and the Proterozoic quartz monzonite 

and alaskite is suggested by the close spatial association of the mineral deposits to these igneous rocks. 

Moreover, the trace-element suite uranium, fluorine, 

tungsten, beryllium, niobium, and yttrium is in both the 

host igneous rocks and the vein deposits. This relationship is consistent with a model for mineralization in 

which the uranium, tungsten, and beryllium were carried in solution as fluoride complexes during a late 

phase of the igneous event. The quartz body located between the quartz monzonite and alaskite probably is of 

Proterozoic age, whereas the mercury mineralization 

most likely was Cretaceous or younger. 

SUGGESTIONS FOR FURTHER STUDY 

The geology of the Whetstone Mountains is known in 

some detail, but the mineral deposits are understood 

only in a general way as a result of this investigation. 

Detailed study of the Proterozoic rocks would lead to a 

better understanding of the fluorite, tungsten, and 

uranium mineralization and enhance the possibility for 

finding additional occurrences of these commodities. 

Study of the Cretaceous igneous rocks would aid in 

understanding the copper mineralization. Detailed ge<r 

chemical sampling and geologic mapping could provide 

information on the source and setting of the mercury 

occurrences. 

REFERENCES 

Creasey, S.C., 1967, Geologic map of the Benson quadrangle, Cochise 

and Pima Counties, Arizona: U. . Geological Survey Miscellaneous Investigations Map I- 470, scale 1:4 ,000. 

DeRuyter, V. D., 1979, Geology of the Granitic Peak tock area, 

Whetstone Mountains, Cochise County, Arizona: Tuc on. Uni· 

versity of Arizona, M.S. thesis, 121 p. 

Hayes, P. T., and Raup, R. B., 1968, Geologic map of the Huachuca 

and Mustang Mountains, southeastern Arizona: U .. Geological 

Survey Miscellaneous Investigations Map 1- 509, scale 1:4 .000. 

McColly, R. A., and Scott, D. C .. 1982, Mineral investigations of the 

Whetstone Roadless Area, Cochise and Pima Counties, Arizona: 

U.S. Bureau of Mines Open· File Report MLA 129- 2, 22 p. 

Wrucke, C. T., McColly, R. A., Scott, D. C., Werschky, R .. , Bankey, 

Viki, Kleinkopf, D. M. , taatz. M. H., and Armstrong. A. K.. in 

pre s. Mineral resource potential map of the Whetstone Roadless 

Area, Cochise and Pima Counties. Arizona: U.S. Geological 

Survey Miscellaneous Field Studies Map MF- 1614- A. 

129 
130 

32° 

25' 

32° 

20' 

110°05' 

MAP LOCATION 

0 2 

M ILES 

EXPLANATION 

Alluvium (Holocene and Pleistocene) ~ Latite member, Galiuro Volcanics 

(Miocene and Oligocene) Basalt (Tertiary) 

- -- Contact 

Rhyolite member, Galiuro Volcanics 

1 (M. d 01. ) FC!Ut 1ocene an 1gocene 

Figure 36.-Winchester Road.less Area, Arizona 
WINCHESTER ROADLESS AREA, ARIZONA 

By WILLlAMj . K EITH, 1 • • G EOLOGI ,AL S RV EY, and 

TERRY j. KRETDLER, U.S. B REA Of MI NE 

SUMMARY 

Results of geologic, geochemical, geophysical, and mining activity and production surveys in the Winchester Roadless Area in 1981 indicate little promise 

for the occurrence of metallic and nonmetallic or energy resources in the area. 

Volcanic rocks cover the area to a thickness of 1000 to 2000 ft and possibly 

more, thus preventing inspection and evaluation of the underlying rock. 

CHARACTER AND SETTING 

The Winchester Roadless Area, located in northwestern Cochise County, Arizona, consists of 22 sq mi 

of Coronado National Forest in the Winchester Mountains. The area lies approximately 15 mi northwest of 

Willcox, Arizona. Access to the boundary of the roadless area by county and ranch roads (with permission 

from the owners) is good on all but the west side, where 

roads generally end more than 1 mi from the boundary. 

Within the area the terrain is steep and rugged, with 

many vertical cliffs. Altitudes in the area range from 

about 5000 ft on the eastern flank of the mountains to 

7631 ft at the summit of Reiley Peak. Heavy growth of 

manzanita inhibits accessibility at higher altitudes. Intermittent streams have incised steep-walled canyons 

into the volcanic rocks. 

This study consisted of (1) field checking and modification of the existing geologic maps of the area (Creasey 

and others, 1961, 1981), (2) field examination of all 

mines, prospects, and mineralized areas in and adjacent 

to the Winchester Roadless Area, (3) sampling of bedrock and stream sediments from drainage basins for 

geochemical analysis; and (4) examination and interpretation of available aeromagnetic and gravity data The 

results have been published by Keith and others (1982). 

Rocks of the Winchester Roadless Area consist of a 

sequence approximately 1000 to 2000 ft thick of silicic 

ash-flow tuffs and lava flows capped by basaltic lava 

flows. The silicic volcanic rocks are assigned to the 

Galiuro Volcanics (Cooper and Silver, 1964). The 

Galiuro Volcanics is divided into four members, two of 

which occur in the Winchester Roadless Area The lower 

or latite member consists of undifferentiated lava flows 

'With contribut.ions from R<mny A. Martin. USGS. 

and tuffs that range from latite to rhyolite in composition. This member is limited to the central and eastern 

parts of the area and clips approximately 30 o northwest. 

The upper or rhyolite member consists of rhyolitic lava 

flows, dikes, and ash-flow tuffs. The rhyolite member is 

found in the central and western parts of the area and 

appears to thicken to the west. The Galiuro Volcanics, 

considered to be of Oligocene and Miocene age (Creasey 

and Krieger, 1978) is capped by younger basalt which 

consists of black vesicular lava flows and is confined to 

the central and western parts of the roadless area 

MINERAL RESOURCES 

Twenty-eight sample sites were selected as representative of the drainage basins in and around the Winchester Roadless Area The sites were sampled for rock, 

stream sediment, and panned concentrates. Samples 

were analyzed for 31 elements by six-step semiquantitative emission spectrography and for two additional 

elements (zinc and gold) using atomic absorption or colorimetry. The results of the analyses indicate a generally high concentration of lanthanum, niobium, lead, 

and tin in the panned concentrates. The lanthanum and 

niobium occur in zircon, sphene, and other minerals that 

weather out of the Galiuro Volcanics and have no significance for the assessment of resource potential. The tin 

and lead anomalies, which are from drainage basins near 

the boundary of the roadless area, are probably related 

to human contamination in areas where springs have 

been developed and where there has been a large 

amount of human traffic (hunters, picnickers, or 

ranchers). 

Geophysical data (gravity, magnetic, and audiomagnetotelluric) indicate no significant features that 

131 
can be confidently interpreted as being directly related 

to mineral deposits. The Galiuro Volcanics have generally lower magnetic susceptibilities than the overlying 

basalt. A magnetic high along the southern border of 

the roadless area possibly reflects an underlying extension of the Precambrian intrusive rocks exposed to the 

south that have high magnetic susceptibility but are 

not known to be mineralized. A broad magnetic low in 

the northwest corner of the roadless area probably 

reflects a thin basaltic cover over a thick section of 

rocks with low magnetic susceptibility (probably an 

extension of the Galiuro Volcanics). Therefore, these 

magnetic anomalies do not in themselves indicate the 

presence of significant mineralization. Reconnaissance 

gravity data show a broad gravity low over the central 

roadless area, which probably indicates the area where 

ash-flow tuffs and lava flows are at their maximum 

thickness. Resistivity contrasts between audiomagnetotelluric soundings just south of the roadless 

area suggest the possibility of a northwest-trending 

fault along the west face of the Winchester Mountains. 

Low resistivities at depth for two soundings and an entire low-resistivity section for another sounding plus 

low magnetic intensity suggest that the rocks may have 

been altered along the postulated fault, although there 

is no surface evidence of mineralization. 

The Winchester mining district lies approximately 3 

to 4 mi south of the southern boundary of the roadless 

area. The district was originally worked for silver in the 

1870 's, but has had little or no activity since the 1920's 

(Keith, 1973). Gold mineralization southeast of the roadless area occurs in a sliver of Paleozoic limestone in fault 

contact with Precambrian granite but geologic evidence 

indicates that this feature does not extend into the 

roadless area at the surface. Geophysical data suggests 

132 

that it may extend into the roadless area in the subsurface, buried under a thick pile of Tertiary volcanic rocks. 

A search of the Cochise County records revealed that 

no mining claims have been located in or near the roadless area The only prospect in the roadless area was a 

small pit near the center of sec. 17, T. 12 S., R. 22 E. No 

mineralization was evident in the pit, which had been 

dug into volcanic rock. 

Pan concentrates of stream-sediment samples in or 

near the Winchester Roadless Area assayed no significant gold and silver values. 

Geologic, geochemical, geophysical, and mines and 

prospects surveys of the Winchester Roadless Area indicate that there is little promise for the occurrence of 

any metallic or nonmetallic resources. 

REFERENCES 

Cooper, J. R., and Silver, L. T., 1964, Geology and ore deposits of the 

Dragoon quadrangle, Cochise County, Arizona: U.S. Geological 

Survey Professional Paper 416, 196 p. 

Creasey, S. C., Jackson, E. D., and Gulbrandsen, R. A., 1961 , Reconnaissance geologic map of parts of the an Pedro and Aravaipa 

Valleys, south-<:entral Arizona: U.S. Geological Survey Mineral 

Investigations Field Studies Map MF-238, scale 1:1 25,000. 

Creasey, S. C., Jinks, J. E., Williams, F. E., and Meeves, H. C., 1981, 

Mineral resources of the Galiuro Wilderness and contiguous further planning areas, Arizona, with a section on Aeromagnetic 

survey and interpretation, by W. E. Davis: U. . Geological 

Survey Bulletin 1490. 94 p. 

Creasey, S. C., and Krieger, M. H., 1978, Galiuro Volcanics, Pinal, 

Graham, and Cochise Counties, Arizona: U.S. Geological Survey 

J ournal of Research, v. 6, no. 1, p. 11 5-131. 

Keith, S. B., 1973, Index of mining properties in Cochise County, 

Arizona: Arizona Bureau of Mines Bulletin 187, 98 p. 

Keith, W. J., Martin, R. A., and Kreidler, T. J., 1982, Mineral resource 

potential of the Winchester Roadless Area, Cochise County, Arizona: U.S. Geological Survey Open-File Report 82-1028, 7 p. 

A R K A N s A s 

e 2,3 

4 5 • 6 

e ' 

. s o Hot Springs 

0 100 

MILES 

Location of areas studied. 

134 
ARKANSAS 

Map 

Na. Name of Area 

4 Bell Star East and West Roadless Areas 

5 Belle Starr Cave Wilderness Study Area 

8 Black Fork Mountain Roadless Area, Arkansas and Oklahoma 

9 Caney Creek Wilderness 

6 Dry Creek Wilderness Study Area 

7 Little Blakely Roadless Area 

2 Richland Creek Roadless Area 

3 Richland Creek Wilderness Study Area 

1 Upper Buffalo Wilderness and Buffalo Addition Roadless 

Area 

135 
136 

0 

H k y 

I( ob 

MILES 

<. 

0 

> 

<. 

u "' 

0 

a: 

EXPLANATION 

- Geologic terrane with substantiated Ed 

coal resource potential and 

probable gas resource potential 

94°10' 

flm P '$? 

e r 

8~ 

• ARKANSAS 

MAP LOCATION 

5 

Sedimentary rocks (Pennsylvanian) 

Figure 37.-Bell Star East and West Roadless Areas, Arkansas. 
BELL STAR EAST AND WEST ROADLESS AREAS, ARKANSAS 

By MARY H . MILLER U.S. GEOLOG IC L S RVEY, and 

LYLE E. H ARRIS, U.S. B REA OF Mr E 

SUMMARY 

On the basis of mineral and geologic surveys in 1981-82, it was concluded 

that Bell Star East and West Roadless Areas, Arkansas, have inferred 

resources of coal in areas of substantiated coal resource potential from the 

Lower Hartshorne coal bed at depths of 2000 to 4000 ft below the surface. These 

areas also have a probable potential for natural gas from the Atoka and Hall 

Formations at depths as much as 6000 ft below the surface. No metallic mineral 

resources were identified in the roadless areas. 

CHARACTER AND SETTING 

Bell Star East and West Roadless Areas cover about 

18 sq mi in the Ouachita National Forest, Sebastian and 

Scott Counties, Arkansas. Access to the areas is by 

USFS Road 158 and by primitive, privately owned dirt 

roads that cut across private land. 

Bell Star East and West Roadless Areas occupy the 

center and part of the north flank of the east-west trending Poteau syncline (Reinemund and Danilchik, 1957). 

The Pennsylvanian Savanna and McAlester Formations are exposed in the roadless areas, and the Pennsylvanian Atoka Formation and Hartshorne Sandstone 

are exposed on the outer flanks of the syncline (Haley, 

1966; Haley and Hendricks, 1968). 

MINERAL RESOURCES 

There are no mines within the roadless areas; one coal 

prospect was found near West Creek in Bell Star West 

Roadless Area Coal has been produced from the Lower 

Hartshorne coal bed in the McAlester Formation about 

2.25 mi north and about 1 mi south of the roadless 

areas. This coal bed, which underlies the roadless areas 

at depths of 2000 to 4000 ft, contains 4 7.5 million short 

tons of inferred coal resources (Reinemund and Danilchik, 1957; Haley and others, 1980; Harris, 1981) and 

the roadless areas are classified as having substantiated 

coal resource potential. The Lower Hartshorne coal bed 

in the roadless areas also could contain coal bed gas 

(Harris, 1981) although no coal bed gas resources were 

identified. 

Natural gas has been produced from the Mansfield 

field about 3 mi north of the roadless areas, and minor 

quantities from the Waldron syncline, about 4.5 mi 

southeast of the roadless areas. These wells produce 

from the Pennsylvanian Atoka Formation at depths as 

much as 6000 ft (Haley and others, 1980; W. M. Caplan, 

oral commun., 1982). There is a probable potential for 

natural gas in the roadless areas. 

The Savanna and McAlester Formations contain 

stone, sand, and gravel useful to the construction industry, but these materials occur in abundance outside 

the roadless areas. 

SUGGESTIONS FOR FURTHER STUDY 

Drilling to determine thickness and continuity of the 

Lower Hartshorne coal bed would be necessary to completely evaluate the resource potential for coal in the 

roadless areas. 

The potential for natural gas in the Atoka Formation 

within the roadless areas can be proved or disproved 

only by exploratory drilling. 

REFERENCES 

Haley, B. R., 1966, Geology of the Barber quadrangle, Sebastian 

County and vicinity, Arkansas: Arkansas Geological Conunission I. C. 20-C, 76 p. 

Haley, B. R., and Hendricks, T. A., 1968, Geology of the Greenwood 

quadrangle, Arkansas-Oklahoma: U.S. Geological Survey Profes· 

sional Paper 536-A, 15 p. 

137 
Haley, B. R., Earhart, R. L., and Stroud, R. B., 1980, Mineral 

resources of the Belle Starr Caves Wilderness Study Area, Sebastian and Scott Counties. Arkansas: U.S. Geological Survey Open· 

File Report 80-356, 19 p. 

Harris, L. E., 1981, Mineral resources of Belle Starr East RARE II 

Further Planning Area and Belle Starr West RARE II Further 

Planning Area, Scott and Sebastian Counties, Arkansas: U.S. 

Bureau of Mines Open-File Report MLA 27- 81 , 25 p. 

138 

Miller, M. H., Smith, M. C., and Harris, L. E .. 1983, Mineral resource 

potential and geologic map of the Bell tar East and West Roadless Areas, Sebastian and Scott Counties, Arkansas: U.S. Geological Survey Miscellaneous Field Studies Map MF- 1579. 

Reinemund, J. A., and Danilchik, Walter. 1957, Preliminary geologic 

map of the Waldron quadrangle and adjacent areas. Scott County, Arkansas: U.S. Geological Survey Oil and Gas Investigations 

Map OM- 192, scale: 1:48,000. 

140 

Rocks of Atokan age 

(Pennsylvanian) 

of Lower Hartshorne 

coal bed 

Outcrop of Lower 

coal bed 

94°15' 

Rocks 

Rocks of Atokan age 

(Pennsylvanian) 

Oh~ 

0 

MILES 

EXPLANATION 

D Geologic terrane with probable 

oil and gas potential 

--- Contact 

2 

Figure 38.- Belle Starr Cave Wilderness Study Area, Arkansas. 

ARKANSAS 

• 

MAP LOCATION 
BELLE STARR CAVE WILDERNESS STUDY AREA, ARKANSAS 

By B YD R. HALEY U.S. GE LOGICAL R\ EY, and 

RAYMOND B. TRO D , .S. B UREA OF MI E 

SUMMARY 

A mineral survey of the Belle Starr Cave Wilderness Study Area conducted in 

1977 concluded that there is little promise for the occurrence of metallic mineral 

resources in the area There is a probable resource potential for small quantities 

of natural gas. A coal bed that underlies the area contains demonstrated coal 

resources of about 22.5 million tons in a bed that averages less than 28 in. thick. 

Despite its contained coal, this area is not shown as having a coal resource 

potential. 

CHARACTER AND SETTING 

The Belle Starr Cave Wilderness Study Area covers 

an area of about 9.4 sq mi in parts of Sebastian and 

Scott Counties, west-central Arkansas. Rock Creek is 

an intermittent stream that has its headwaters in the 

southwestern part of the area and flows northeastward 

in a valley that, at its maximum, is about llOO ft 

deep and 2 mi wide. The forest-covered valley walls are 

a series of slopes underlain by shale, and some bluffs 

as much as 40 ft high formed by the more resistant 

sandstone. 

The rocks in the study area are sedimentary and are 

gently folded into the Poteau Syncline. They consist of 

shale, sandstone, and siltstone, a few thin coal beds of 

limited extent, and one coal bed (Lower Hartshorne) of 

wide extent. All of the rocks at the surface are part of 

the Des Moinesian Series of Middle Pennsylvanian age. 

MINERAL RESOURCES 

The Lower Hartshorne coal bed extends under the 

study area and has been mined at the surface and in the 

subsurface north and south of the study area Assuming 

an average thickness of the coal at 2 ft (it may be more), 

there is a demonstrated resource of 22.6 million short 

tons of coal under the Belle Starr Cave Wilderness 

Study Area Demonstrated coal resources are estimated 

separately for beds more than 28 in. thick and for beds 

less than 28 in. thick. Beds more than 28 in. thick are 

considered as areas of substantiated coal resource 

potential, but because the Lower Hartshorne coal bed 

more than likely averages less than 28 in. thick, no coal 

resource potential is shown on the map. 

Natmal gas was discovered in 1902 about 3 mi north 

of the study area. Wells drilled since that date have produced gas from sandstone reservoirs of Atokan age to 

depths of about 6000 ft. The southern limit of that gas 

field (Mansfield) has not been established by dry holes, 

and shows of gas have been reported from wells drilled 

through similar Atokan rocks about 7 mi southeast of 

the study area Because these Atokan age rocks are 

present at depth underneath the study area, the area 

has been assessed to have a probable resource potential 

for small volumes of gas. 

Some of the sandstone in the area could be used as 

flagstone or aggregate and some of the shale could be 

used in the brick industry. Stone of equal quality is 

present elsewhere in west-central Arkansas. 

There is little promise for the occurrence of metallic 

mineral resources according to the data derived from 

geochemical studies of outcropping rocks and stream 

sediments (Haley and others, 1980). 

REFERENCE 

Haley. B. R .. Earhart. R. L .. and troud. R. B., 1980. Mineral 

Resources of the Belle Starr Caves Wilderness tudy Area 

Sebastian and Scott Counties. Arkansas: U .. Geological Survey 

Open-file Report 80- 356, 18 p. 

141 
34° 

40' 

142 

l I T • L I . I .. 

( 08084 \.__ j Approximate road less Mississippian and Pennsylvanian 

:1 - - - - - - - - "\ 1 boundary sedimentary rocks .L r- I --~------ r- -, 

I BLACK I FORK -

M 0 u 0 [ I TAIN 

- - - - - ..._ .JIII'!!!"- ......... -----1 - .r ..... - - 'l 

gp ~ - -- -- _..:.--- -, - -------.. - - I G) - ----

N 

-

1 

<rr 

.... ,< 2,f 

~~~ o,< 

,_ 

-J 

OKLAHOMA ARKANSAS 

I 

MAP LOCATION I 

0 5 

MILES 

Figure 39.-Black Fork Mountain Roadless Area, Arkansas and Oklahoma 
BLACK FORK MOUNTAIN ROADLESS AREA, ARKANSAS AND OKLAHOMA 

By MARY H. MILLER, ' U.S. GEOLO !CAL S R EY 

SUMMARY 

On the basis of a mineral survey in 1982, the Black Fork Mountain Roaclless 

Area has little promise for the occurrence of metallic mineral resources. Stone 

and sand and gravel suitable for construction purposes occur in the Jackfork 

Sandstone and the Stanley Shale which also occur outside the roaclless area 

Although the potential for gas and oil is unknown and no resource potential was 

identified, some investigators believe that there is a possibility for the occurrence of gas and oil in the roaclless area. 

CHARACTER AND SETTING 

Black Fork Mountain Roaclless Area covers about 21 

sq rni in the Ouachita National Forest in Polk County, 

Arkansas and LeFlore County, Oklahoma Access to 

the area is principally via U.S. Highway 270 and USFS 

roads. 

The north flank of Eagle Gap syncline makes up 

Black Fork Mountain. The area is bounded on the north 

and south by high-angle thrust faults, and the stratigraphic displacement may be as much as 25,000 ft 

(Seely, 1963). Formations exposed in the roaclless area 

are the Pennsylvanian Atoka Formation, the Pennsylvanian and Mississippian Jackfork Sandstone, and the 

Mississippian Stanley Shale (Seely, 1963). 

MINEIV.;tL RESOURCES 

Between 1900 and 1918, impsonite, a nearly infusible 

asphaltic pyrobitumin with a high-fixed carbon content, 

was mined from a deposit near Page, Oklahoma for its 

vanadium content (Ham, 1956). Although this material 

is present in the roaclless area in fissures and along a 

bedding plane in the Jackfork Sandstone, no resource 

potential was identified. 

'With coolribut.ions by Marjorie C. Smith, USGS. 

Good-quality rock for construction purposes occurs in 

the Jackfork and Stanley Formations throughout the 

roaclless area 

Most of the area is leased for gas and oil, and 

although no oil and gas potential was identified, some 

investigators believe there is a possibility for the occurrence of gas and oil in this area from rocks of Arbuckle 

(Cambrian and Ordovician) age or younger (C. G. Stone, 

oral commun., 1983). 

SUGGESTIONS FOR FURTHER STUDY 

Deep exploratory drilling to determine the gas and oil 

potential seems desirable. 

REFERENCES 

H'IID, W. E .. 1956, Asphaltite in the Ouachita Mountains: Oklahoma 

ueological Survey Mineral Report 30, 12 p. 

Miller, M. H., and rnith, M. C., 1983, Mineral resource potential map 

of Black Fork Mountain, Polk County, Arkansas, and LeFlore 

County, Oklahoma: U.S. Geological Survey Map MF- 1599, scale 

1:50,000. 

Seely. D. R .. 1963. Structure and stratigraphy of the Rich Mountain 

area, Oklahoma and Arkansas: Oklahoma Geological urvey 

Bulletin 101, 173 p. 

143 
34° 

25' 

144 

94°05 ' 

ARKANSAS 

MAP LOCATION 

-

Mn 

X 

0 

MILES 

EXPLANATION 

Geologic terrane with substantiated 

minera l-resource potential 

Manganese 

Mineral occurrence 

D 

Liid 

2 

X 

Stanley Shale (Mississippian) 

Arkansas Novaculite (Mississippian 

and Devonian) 

Formations older than Arkansas 

Novaculite (Paleozoic) 

Contact 

Fault 

Figure 40.-Caney Creek Wilderness, Arkansas. 
CANEY CREEK WILDERNESS , ARKANSAS 

By GEORGE E. ERICK E , 1 U .S. G EOLOGl AL R EY, and 

MAY ARD L. Du , JR . , U.S. BUREA OF MI NE 

SUMMARY 

Metallic and nonmetallic mineral resources identified in the Caney Creek 

Wilderness during a study in 1978, include many small manganese deposits in 

areas of substantiated manganese resource potential and moderate to large 

deposits of novaculite, tripoli, shale, and slate. Small amounts of hand-sorted 

manganese-oxide ore have been recovered from several of the manganese 

deposits during sporadic mining activity from the late 1880's to the mid-1950 's. 

Additional manganese resources remain in the known deposits, but the amount 

in any given deposit is small. Large resources of novaculite, tripoli, shale, and 

slate are in the wilderness but even larger resources exist in this region outside 

the wilderness and nearer to markets. No energy resources were identified in 

this study. 

CHARACTER AND SETTING 

The Caney Creek Wilderness extends over an area of 

22.5 sq mi in the Cossatot Mountains, a southern segment of the Ouachita Mountains of west-central Arkansas. The area is elongate, being about 8 mi long and 

3-3.5 mi wide. Located in Polk County, Arkansas, the 

northwest corner of the wilderness is 12 air miles 

southeast of Mena, the county seat. The wilderness is 

accessible by State Route 375 from Mena and by State 

Route 246 from U.S. Highway 71, south of Mena The 

area is encircled by unimproved roads, and the interior 

is accessible by a well-maintained trail along Caney 

Creek and an unmaintained trail that follows a former 

road along Short Creek. 

The wilderness encompasses three prominent eastwest ridges and the intervening valleys of Caney and 

Short Creeks, which drain westward into the Cossatot 

River. Altitudes range from 940 ft at the confluence of 

Caney Creek and the Cossatot River to 2320 ft at Buckeye Mountain, the highest peak in the wilderness. The 

crests of the three principal ridges slope gently westward from altitudes of 2000- 2300 ft in the east to 

1500- 1700 ft in the west. 

The wilderness is in a region of deformed Paleozoic 

sedimentary rocks having an aggregate thickness of 

'WiLh contribul.ions from S.H. Patterson. USGS. and D. K. Harrison. USBM. 

8000-9000 ft. Six formations crop out in the wilderness. 

From oldest to youngest these are Ordovician Bigfork 

Chert and Polk Creek Shale, Silurian Blaylock Sandstone and Missouri Mountain Shale, Devonian and 

Mississippian Arkansas Novaculite, and Mississippian 

Stanley Shale. The highly resistant, ridg~forming 

Arkansas Novaculite, about 900 ft thick, is the dominant formation in the wilderness. The Stanley Shale is 

about 6000 ft thick, and is by far the thickest formation 

in this region. Only the lower part of this formation is 

exposed in the wilderness. The Arkansas Novaculite 

and Stanley Shale were of particular interest in our 

study because at many places in western Arkansas 

these formations contain mineral deposits, chiefly 

manganese-oxide and tripoli in the Arkansas Novaculite 

and bedded barite in the Stanley Shale. The novaculite 

is also the source of the famed Arkansas wetstones. 

The Paleozoic sedimentary rocks were intensely d~ 

formed during late Paleozoic orogeny, which produced 

tightly folded anticlines and synclines. The repetition of 

formations across the wilderness is the result of erosion 

of these folds. 

Our investigations included reconnaissance geochemical sampling of stream sediments and rocks, field 

checking and modifying existing geologic maps, examination and sampling of prospects, and a search of courthouse records for mining claims in the wilderness. This 

report is based on the results of these investigations 

(Ericksen and others, in press). 

145 
MINERAL RESOURCES 

Manganese oxide is the only mineral commodity that 

has been produced from the wilderness. Most of the 

manganese deposits are in the northeastern section of 

the wilderness where deposits were first prospected in 

the late 1880 s; a few deposits are scattered westward 

along Short Creek valley. Prospect workings on the 

lower north slope of Tall Peak, opened by the Arkansas 

Development Company in 1887-1889, consisted of two 

adits, the longest of which was 100 ft. Other prospect 

workings were opened on Buckeye Mountain at this 

time. Additional prospecting was done in the Buckeye 

Mountain-Tall Peak area during World Wars I and II, 

when some manganese oxide was mined, but most of the 

work in this area apparently was done during the 1950's 

in response to the U.S. stockpile purchase program. 

Aerial photographs taken in the mid-1950's and courthouse records indicate that most prospecting and mining of manganese along Short Creek was done during 

the stockpile purchase program. 

The total tonnage of manganese oxide produced from 

the wilderness is not known, but to judge from incomplete production records it could not have been 

more than a few hundred tons. Manganese oxide resources exist in small deposits, and it is possible that 

additional resources exist in yet-to-be-found deposits in 

the wilderness. However, it is unlikely that any undiscovered deposits are larger or richer than the identified 

deposits. 

Th mangane e deposit of the Caney Creek Wilderness occur chiefly in the upper of the three major units 

that comprise the Arkansas Novaculite, and near the 

top of the lower unit. All are of secondary origin, having 

formed as local concentrations of manganese oxides 

deposited from ground water that had previously 

leached the manganese from manganese-bearing carbonate minerals in the novaculite and perhaps other 

Paleozoic formations. The deposits consist of the 

manganese oxide minerals pyrolusite, hausmannite, 

lithiophorite, and cryptomelane occurring chiefly as irregular masses and short veins within linear zones of 

fractured and brecciated novaculite. A few occurrences 

are in other formations near the contact with the 

novaculite. Deposits that have been prospected are commonly a few tens of feet to about a hundred feet long 

and a few feet to 10 or 20 ft wide. Masses of high-grade 

manganese ore are rarely more than a few feet in maximum dimensions. 

Relatively pure manganese oxide ore ranges from 

about 29 percent to 40 percent manganese, and it is 

146 

estimated that most of the hand-sorted ore shipped 

from the wilderness contained about 40 percent manganese. The manganese ore also contains small amounts of 

copper, zinc, nickel, and cobalt. The total content of 

these metals in most ore is less than 1 percent, but 

samples collected in the present study show maximum 

values of 1.5 percent copper, 0.3 percent zinc, 0.2 percent nickel, and 0.3 percent .cobalt. Such values suggest 

that these metals are potential byproducts of the 

manganese resources. There is a substantiated potential 

for manganese resources in the area 

ovaculite suitable for whetstones occurs in the 

Arkansas Novaculite. Several thousand tons of tripoli, a 

weathering product of the Arkansas Novaculite, was 

mined from an open cut about 600ft south of the southeastern margin of the wilderness. This deposit extends 

into the wilderness to the east, where it has been prospected. Small amounts of slate have been mined from 

the Missouri Mountain Shale in Polk County, outside 

the wilderness. However, the slate in this formation and 

in other formations in and near the wilderness is 

relatively low grade, and no slate has been mined in 

Polk County since the 1950's. Some of the shale in the 

Stanley Shale is suitable for heavy clay products and 

brick, and slaty material from the Bigfork Chert will 

bloat with heat, so that it might be suitable for lightweight aggregate. Although deposits of novaculite, 

tripoli, shale, and slate occur in the wilderness, large 

resources of these materials occur widely in the 

Ouachita Mountains outside the wilderness. 

SUGGESTIONS FOR FURTHER STUDIES 

Known manganese oxide deposits should be mapped 

and core drilled, and a search for other deposits be 

made. New manganese oxide deposits would be expected to occur chiefly in the upper and lower units of 

the novaculite, and might best be located by detailed 

geochemical sampling. The most favorable areas for 

finding such deposits are the northern and northeastern 

part of the wilderness where the identified deposits 

occur. 

REFERENCES 

Ericksen, G. E., Patterson, S. H .. Dunn, M. L., and Harrison, D. K., in 

press, Mineral resources of the Caney Creek Wilderness, Polk 

County, Arkansas: U.S. Geological Survey Bulletin 1551. 

93°45' 

• ARKANSAS 

MAP LOCATION 

35oL-------------------------- 00' ------------------------L-------------------------------------------~ 

D 

148 

0 

MILES 

EXPLANATION 

Geologic terrane with probable 

natural gas potential B 

2 

Rocks of Des Moinesian age 

Rocks of Atokan age 

Contact 

Figure 41.-Dry Creek Wilderness Study Area, Arkansas. 
DRY CREEK WILDERNESS STUDY AREA, ARKANSAS 

By BOYD R . H ALEY, U. S. GEOLOG ICAL SURVEY and 

R AYMO D B. STRO D, U .S . BUREAU OF Mr E 

SUMMARY 

A mineral evaluation study of the Dry Creek Wilderness Study Area indicated 

that the area has a probable resource potential for natural gas and little promise 

for the occurrence of other mineral commodities. 

CHARACTER AND SETTING 

The Dry Creek Wilderness Study Area covers an area 

of about 10 sq mi in parts of Logan, Scott, and Yell 

Counties, Arkansas. Dry Creek, an intermittent stream 

that has its headwaters in the extreme southeastern 

part of the area, flows to the northwest through a canyon that at its maximum is about 800ft deep and 1.5 mi 

wide. The study area is entirely within this canyon and 

extends over nearly all of the drainage basin of Dry 

Creek. The results of a mineral survey of the area were 

published by Haley and others (1980). 

The rocks in the area consist of shale, sandstone, and 

orne iltstone and are folded into the Poteau Syncline. 

Most of the rocks are of Atokan age with rocks of Des 

Moine ian age (both Middle Pennsylvanian) capping the 

hills on the south side and east end. 

MINERAL RESOURCES 

Geochemical studies indicate that the study area has 

little promise for the occurrence of metallic mineral 

resources. Coal is not known to be present in the area 

Sandstone suitable for use in construction occurs in 

the study area, but equal quality sandstone occurs 

elsewhere. 

Less than 100,000 cu ft/day of natural gas is being 

produced from one well about 4 rni north of the area 

Two wells drilled south of that well and one well drilled 

about 8 mi southeast of the area were reported as dry 

holes. Small quantities of natural gas may be present in 

the rocks under the Dry Creek Wilderness Study Area 

and the area has a probable gas resource potential. 

REFERENCE 

Haley, B. R .. Earhart, R. L .. and Stroud, R. B .. 1980, Mineral 

resources of the Dry Creek Wilderness Study Area. Logan, Yell, 

and Scott Coun ties. Arkansas: U .. Geological Survey Open-File 

Report 0-355, 13 p. 

149 
150 

34 

38' 

0 

'-------' 

MILE 

EXPLANATION 

Bigfork Chert (Ordovician) 

Womble Shale (Ordovician) 

Blakely Sandstone (Ordovician) 

Mazarn Shale (Ordovician) 

--- Contact 

Fault 

'X' Mine 

Figure 42.-Little Blakely Roadless Area, Arkansas. 

ARKANSAS 

• 

MAP LOCATION 
LITTLE BLAKELY ROAD LESS AREA, ARKANSAS 

By MARY H . MILLER, .S . GEOLOG ICAL R\ EY, and 

R O BERT H. W OOD II, . . B REA F MI NE 

SUMMARY 

Based on geologic and geochemical surveys in 1981, Little Blakely Roadless 

Area has little promise for the occurrence of metallic mineral resources or for the 

occurrence of oil and gas. Quartz crystal occurs in the Blakely Sandstone and 

the Womble Shale (Engel, 1951). 

CHARACTER AND SETTING 

Little Blakely Road.less Area covers about 9 sq mi of 

the Ouachita National Forest in Garland County, 

Arkansas. Access to the western, northern, and 

southern portions of the roadless area is by boat from 

Lake Ouachita Access to the eastern parts of the area is 

by unimproved logging roads. 

Strata in the Ouachita Mountains are folded, overturned, and thrust faulted toward the north (Haley and 

others, 1979). Formations exposed in the Little Blakely 

Road.less Area are the Mazam Shale and Blakely Sandstone of Early Ordovician age, the Womble Shale of 

Early and Middle Ordovician age, and the Bigfork 

Chert of Middle Ordovician age (Haley and others, 

1979). 

MINERAL RESOURCES 

Quartz crystal has been mined from this region for 

more than 50 years. Although crystal occurs in the 

Womble Shale, Crystal Mountain Sandstone (outside 

the area), and the Blakely Sandstone, only the Blakely 

Sandstone has produced significant amounts of crystal 

from or near the road.less area Mines were operated in 

sees. 11 and 12, T. 1 S., R. 21 W. on theW. T. Beard 

property. Although the quartz crystal occurs in the 

road.less area, these quartz crystal-bearing formations 

are exposed over large areas outside of the area 

Phosphate occurs in the Mazam and Womble Shales 

and in the Bigfork Chert in Garland County (C. G. 

Stone, written commun., 1982), and phosphate and 

vanadium are present in wavellite in the Bigfork Chert 

near Avant and Mountain Pine, Arkansas (C. G. Stone, 

written commun., 1982; Foster and Schaller, 1966). 

Although the Mazam and Womble Shales and the Bigfork Chert crop out in the roadless area, it is unlikely 

that the size of the phosphate occurrences or the size 

and vanadium content of wavellite occurrences are sufficient for either to be identified as having resource potential (J. B. Cathcart, oral commun., Jan. 1983). 

Although some gas has been produced from the 25-1 

Weyerhaeuser well in the Ouachita Mountains core area 

in southeastern Oklahoma, core areas, including the 

area of Little Blakely Roadless Area (Caplan, 1963; 

Haley and others, 1979), have little promise for the occurrence of oil or gas (Goldstein, 1975; Miller and 

others, 1983). 

Geochemical analyses of stream-sediment and rock 

samples from Little Blakely Roadless Area indicate 

that there is no significant mineralization in the rock 

formations exposed within the roadless area (Miller and 

others, 1983). 

A Bouguer gravity map of Arkansas (Hendricks and 

others, 1981) shows no anomalies in the roadless area 

SUGGESTIONS FOR FURTHER STUDIES 

Although quartz crystal probably will continue to be 

discovered in formations in the region, such deposits 

within the Little Blakely Road.less Area would not be 

sufficiently unique to justify additional study of the 

roadless area Deposits of phosphate and vanadium 

elsewhere that have greater significance make it unlikely that either of these commodities will soon be 

sought from the Little Blakely Roadless Area. Exploration for oil and gas in . this region appears unlikely to 

meet with significant positive results. 

151 
REFERENCES 

Caplan, W. M., 1963, Oil and gas possibilities in the Ouachita Mountain Region of Arkansas: Fort Smith Geological Society Second 

Regional Field Conference Guide Book, p. 31-37. 

Engel, A.E.J., 1951, Quartz crystal deposits of western Arkansas: 

U.S. Geological Survey Bulletin 973-E, p. 173-260. 

Foster, M. D., and Schaller, W. T., 1966, Cause of colors in wavellite 

from Dug Hill, Arkansas: The American Mineralogist. v. 51. 

p. 422- 428. 

Goldstein, A., Jr., 1975, Geologic interpretation of Viersen and 

Cochran 's 25-1 Weyerhaeuser Well, McCurtain County. 

Oklahoma: Oklahoma Geological Survey Geology otes, v. 35, 

no. 57, p. 169-181. 

152 

Haley, B. R., Stone, C. G., and McFarland, J. D., lll, 1979, A 

guidebook to the second geological excursion on Lake Ouachita: 

Arkansas Geological Commission Guidebook, 23 p., 1 map. 

Hendricks, J. D., Keller, G. R., and Hildenbrand, T. G., 1981, Bouguer 

gravity map of Arkansas: U.S. Geological Survey Geophysical 

Investigations Map GP- 944, scale 1:500,000. 

Miller, M. H., Keefer, E. K., and Wood, R. H., II, 1983, Map showing 

geology and mineral resource potential of the Little Blakely 

Roadless Area. Garland County, Arkansas: U.S. Geological 

Survey Miscellaneous Field tudies Map MF- 1562, cale 

1:24,000. 
RICHLAND CREEK ROADLESS AREA, ARKANSAS 

By MARY H. MILLER , .S . GEOLO !CAL SUR EY, and 

R OBERT H. W OOD II, U . . B REA OF MI E 

SUMMARY 

On the basis of geologic and mineral surveys made in 1981, Richland Creek 

Roadless Area, Arkansas, has little promise for the occurrence of metallic mineral resources, gas and oil, or oil shale. The Boone Formation of Mississippian 

age and the Everton Formation of Ordovician age, both known to contain zinc 

and lead deposits in northern Arkansas, underlie the roadless area. The presence 

or absence of zinc and lead deposits in these formations in the subsurface can be 

neither confirmed nor ruled out without exploratory drilling. Most of the 

Richland Creek Roadless Area is under lease for oil and gas; however two wells 

drilled near the eastern boundary of the area did not show contained gas or oil. 

CHARACTER AND SETTING 

Richland Creek Roadless Area covers about 15 sq mi 

in the Ozark National Forest, Newton and Searcy Counties, Arkansas. Access to the area is by USFS roads. 

trata in the area of Richland Creek are nearly horizontal. A normal fault extending across the southern 

part of the area displaces beds a maximum of 280 ft 

(Glick and Frezon, 1965). Formations exposed in the 

roadless area are Mississippian carbonates, sandstones, 

and shales; and Pennsylvanian sandstones, siltstones, 

and shales. Beds in the subsurface include Devonian or 

Silurian limestones, and Ordovician shales, sandstones, 

and carbonates (Glick and Frezon, 1965; Haley and 

others, 1980). 

MINERAL RESOURCES 

No mining districts lie in or adjacent to the Richland 

Creek Roadless Area. About 4700 tons of zinc and lead 

concentrates were produced during World War I from 

the Cave Creek district, about 3 mi north of the roadless 

area (McKnight, 1935). Zinc and lead deposits in the 

Cave Creek district are related to faults and fractures in 

the Boone Formation. The Boone Formation underlies 

the roadless area, and faults are present in the southern 

part of the roadless area The Everton Formation, zincand lead-bearing in northern Arkansas, probably is 

buried 800-1500 ft below the surface. The resource 

potential of these formations cannot be assessed without exploratory drilling. The zinc and lead contents of 

surface samples analyzed in this study are very low and 

there is little or no promise for the occurrence of zinc 

and lead resources in surface or near surface rock units. 

No potential for zinc and lead resources was identified 

along the fault zone in the southern part of the area 

The Batesville Sandstone, Fayetteville Shale, and 

Pitkin Limestone of Mississippian age and the middle 

and upper units of Morrowan age may be possible reservoir rocks for natural gas, and the Fayetteville Shale 

and middle and upper Morrowan units may be sources 

of shale oil. Shales from the Fayetteville Shale and from 

the middle unit of Morrowan age are somewhat petroliferous, but Fischer assays of shale samples do not show 

commercial oil concentrations (Haley and others, 1980). 

No resource potential for gas and oil was identified in 

this study. 

SUGGESTIONS FOR FURTHER STUDIES 

Deep exploratory drilling along the fault in the 

southern part of Richland Creek Roadless Area will confirm the presence or absence of zinc and lead deposits. 

Exploratory drilling for natural gas is necessary to 

ascertain its presence or absence. 

153 
93°05' 

35° 

50' 

154 

35° 45' 

0 

L 

• 

ARKANSAS 

MAP LOCATION 

93°00' 

/ '-.: ,.- \ 

--~ Approximate roadless boundary-/ 

08001J 

,.. 

( 

/ 

~ 

\ 

'\ 

l 

\ 

"'\ 

\ 

\ 

~~ 

\ 

' l 

,...... 

92°55' 

Approximate 

boundary 

, '\ ~, ______ J ) 

0 2 

MILES 

EXPLANATION 

Alluvium (Quaternary) 

Morrowan sedimentary rocks (Pennsylvanian) 

Sedimentary rocks (Mississippian) 

Contact 

Figure 43.-Richland Creek Roadless Area, Arkansas. 
REFERENCES 

Glick, E. E .. and Frezon, S. E., 1965, Geologic map of the Snowball 

quadrangle, ewton and Searcy Counties, Arkansas: U.S. 

Geological Survey Geologic Quadrangle Map GQ-425. scale 

1:62,500. 

Haley, B. R .. Stroud, R. B., and Earhart, R. L., 1980, Mineral 

resources of the Richland Creek Wilderness study area. Newton 

and Searcy Counties, Arkansas: U.S. Geological Survey OpenFile Report 80-354, 29 p. 

McKnight, E. T., 1935, Zinc and lead deposits of northern Arkansas: 

U.S.Geological Survey Bulletin 853, 311 p. 

Miller, M. H., and Wood, R. H .. II. 1983, Geology and mineral 

resource potential map of the Richland Creek Roadless Area. 

ewton and Searcy Counties, Arkansas: U. . Geological urvey 

Miscellaneous Field Studies Map MF - 1525, scale 1:24,000. 

155 
156 

93°00 ' 

35° 

50' 

• 

ARKANSAS 

MAP LOCATION 

X 

Sun on 

IPI 

lo< ~(' 

0 

If' I 

MILES 

/ 

Stump 

MolJit ... un 

IPI 

EXPLANATION 

2 

Lower Pennsylvanian rocks 

Pitkin Limestone (Mississippian) 

Contact 

Fault--Bar and ball on 

downthrown side 

-<?- Dry well 

Figure 44 .-Richland Creek Wilderness Study Area, Arkansas. 

93°55' 

PI 

T.D . 1,108 feet 
RICHLAND CREEK WILDERNESS STUDY AREA, ARKANSAS 

By BOYD R . HALEY , U.S . GEOLOGI AL S RVEY, and 

RAYMO DB. STRO D, U.S. B REA OF MI E 

SUMMARY 

A mineral survey of the Richland Creek Wilderness Study Area indicated that 

the rocks in the area have little promise for the occurrence of energy or metallic 

mineral resources. 

CHARACTER AND SETTING 

The Richland Creek Wilderness Study Area covers an 

area of about 5 sq mi in parts of Newton and Searcy 

Counties, Arkansas. Richland Creek flows eastward 

through the study area in a narrow steep-sided valley 

that is about 1 mi wide and 1000 ft deep. The forestcovered valley walls are a series of shale slopes and 

sandstone bluffs. The bluffs are as much as 100 ft high. 

The resource potential of the area was evaluated and the 

results published by Haley and others (1980). 

The rocks exposed at the surface in the study area are 

sedimentary, dip south at about 100 ft)mi, and are of 

two ages: limestone and subordinate amount of shale of 

the Pitkin Limestone of Late Mississippian age are 

found along Richland Creek; and, above the Pitkin, 

shale, sandstone, siltstone and some limestone of Morrowan or Early Pennsylvanian age are found. 

1 he Pan American Petroleum Corporation U.S.A. No. 

1 well drilled about 0.5 mi east of the study area penetrated limestone, shale, and chert of Mississippian age, 

limestone of ilurian age, and limestone and sandstone 

of Late Ordovician age. 

MINERAL RESOURCES 

Geochemical studies of the outcropping rocks and 

stream sediments in the study area indicate that these 

rocks have little promise for the occurrence of metallic 

mineral resources. Lead, zinc, and manganese whose 

common ore minerals are galena, sphalerite, and psilcmalene have been mined from older rocks (Mississippian 

Boone Formation, Orodvician Cason Shale, and Fernvale Formation) to the north and east of the study area, 

but were not noted in the samples of these formations 

where they were penetrated by the Pan American Petroleum Corp. U.S.A. No. 1 well. 

There is little promise for the occurrence of natural 

gas within the area because the Pennsylvanian age 

rocks have been breached by erosion and the other 

potential reservoir (Devonian to Middle Ordovician) 

rocks were reported as dry in the U.S.A. No. 1 well. 

Some of the sandstone and limestone could be used 

for commercial purposes but equal or better quality 

stone is present in more accessible parts of northern 

Arkansas. 

REFERENCE 

Haley. B. R .. Earhart, R. L., and Stroud, R. L., 1980, Mineral 

resources of the Richland Creek Wilderness Study Area. ewton 

and Searcy Counties, Arkansas. 1980: U.S. Geological Survey 

Open-file Report 80-354, 29 p. 

157 
158 

35° 

55' 

35 

50' 

I 

ARKANSAS 

MAP LOCATION 

'\( 

C'lve 

Mountain 

r1 

I I 

I 

oaoo3 I 

___ _. I 

0 

MILES 

EXPLANATION 

n Pennsylvanian rocks 

D Mississippian rocks 

--- c ontact 

2 

Figure 45.-Upper Buffalo Wilderness and Buffalo Addition Roadless Area, Arkansas. 
UPPER BUFFALO WILDERNESS 

AND BUFFALO ADDITION ROADLESS AREA, ARKANSAS 

M ARY H . MILLER, U.S. GEOLOG I L S R EY, and 

MIC HELLE K. ARMSTRONG , .S. B REA OF MI E 

SUMMARY 

On the basis of geologic and geochemical surveys by the USBM in 1977 and 

1979, and by the USGS in 1982, the Upper Buffalo Wilderness and Buffalo 

Addition Roadless Area in northwestern Arkansas have little promise for the 

occurrence of metallic mineral or energy resources. 

CHARACTER AND SETTING 

The Upper Buffalo Wilderness and Buffalo Addition 

Roadless Area (referred to here as study area) covers 

about 19 sq mi in the Ozark National Forest, Newton 

County, Arkansas. Access to the area is by Arkansas 

State Highways 16 and 21 and by USFS roads. Interior 

access is difficult because of 40-80 ft bluffs at about 

1900 ft. 

Strata in the area are nearly horizontal, and no faults 

have been mapped in the study area. Formations exposed in the study area consist of Mississippian and 

Pennsylvanian limestone, sandstone, and shale. Ordovician carbonate rocks are present in the subsurface (Morrison, 1971; Zachry and Haley, 1975). Interpretation by 

several investigators (Smith, 1978; Konig, 1974; Kirk 

and Walters, 1968) of lineaments shown on LANDSAT 

imagery indicate that zinc-lead deposits in the PoncaBaxley district to the north of the area coincide with a 

northeast-trending lineament. It is thought that this 

lineament reflects a major fracture or shear zone in the 

Earth's crust that functioned as a channelway for fluid 

migration (Konig, 1974). Another similar lineament 

crosses the area coincident to part of the Upper Buffalo 

River (Kirk and Walters, 1968). 

MINERAL RESOURCES 

There are no mines or prospects within the study area; 

however, the nearby Ponca-Baxley and Little Buffalo 

districts produced about 7200 tons of zinc and lead concentrates intermittently from the time of the Civil War 

through World War I (McKnight, 1935). Ores in these 

districts are associated with fractures and minor faults 

in the Mississippian Boone Formation. The Boone crops 

out in the northern part of the area and underlies the entire study area. 

No metal-bearing minerals were observed during geologic mapping, and analyses for zinc and lead contents 

in surface rock and sediment samples from the study 

area are not anomalous (Miller and others, 1983). No 

drilling information is available so an assessment of the 

mineral-resource potential for zinc and lead or other 

metals in the Boone Formation and the underlying 

Ordovician Everton Formation (McKnight, 1935; 

Smith, 1978; Konig, 1974; Kirk and Walters, 1968) cannot be made at this time. 

SUGGESTIONS FOR FURTHER STUDIES 

Exploratory drilling into the Boone Formation and 

(or) the Everton Formation will be necessary to evaluate 

the mineral-resource potential of zinc and lead in the 

study area 

REFERENCES 

Kirk, J. .. and Walters, R. L., 1968, Preliminary report on radar 

lineaments in the Boston Mountains of Arkansas: Compass. v. 

45,no.2, p. 122- 127. 

Konig. R. H .. 1974, Relationship of geomorphic anomalies on ERTS 

imagery to the distribution of mineralization in northern Arkan· 

sas jabs.]: Geological Society of America, Abstracts with Programs. p. 110. 

McKnight, E. T .. 1935. Zinc and lead deposits of northern Arkansas: 

U.S. Geological Survey Bulletin 853, 311 p. 

Miller, M. H .. Smith. M. C .. Armstrong, M. K., and Dunn. M. L.. Jr., 

1983. Geologic and mineral resource potential map of Upper Buf· 

falo Wilderness and Buffalo Addition Roadless Area. ewton 

County, Arkansas: U.S. Geological urvey Map MF- 1578, scale 

1:24,000. 

159 
Morrison, J. D., 1971, Bedrock geology of the Ponca quadrangle, 

Newton County, Arkansas: University of Arkansas, unpublished 

M.A. thesis, 198 p. 

Smith, D. A., 1978, Lead-zinc mineralization in the Ponca-Boxley 

area: University of Arkansas, unpublished M.A. thesis, 169 p. 

Stroud, R. B., Arndt, R. H., Fulkerson, F. B., and Diamond, W. G .. 

1969, Mineral resources and industries of Arkansas: U.S. Bureau 

of Mines Bulletin 645,418 p. 

160 

Zachry, D. L., and Haley, B. R .. 1975, Stratigraphic relationships between the Bloyd and Atoka Formations (Pennsylvanian) of 

northern Arkansas, in Headrick, K. N., and Wise, 0 . A., eds., 

Contributions to geology of the Arkansas Ozarks: Arkansas 

Geological Commission, p. 96- 106. 

162 

c A L 

122° 

. 2 

e 3 

6 . 5 

8, :1 e 7 

11 10 C/) e 14 13 12 g . 15 ...... . 16 

0 18 e 19 ;:?, e 17 • (\) 

~ 

e 20 o e 21 e 22 

25 

• e 26 

38° 

San 

Francisc 

0 

e 23 

100 

MILES 

I 

e 24 

F 0 R N I 

120° 

. 4 

e 55 e 58 

e64 

72 e 

Los Angeles 0 34° 

Location of areas studied. 

e 67 

• e 68,69 • 70 

71 tl'73 

74 s 65 

e 75 

e 76 

A 
CALIFORNIA 

Map 

No. arn e of Area 

76 Agua Tibia Primitive Area 

52 Andrews Mountain, Mazourka, and Paiute Roadless Areas 

72 Arroyo Seco Roadless Area 

23 Bald Rock and Middle Fork Feather River Roadless Areas 

41 Benton Range Roadless Area 

25 Black Butte and Elk Creek Roadless Areas 

47 Blanco Mountain and Black Canyon Roadless Areas 

22 Bucks Lake and Chips Creek Roadless Areas 

46 Buttermilk Roadless Area 

75 Cactus Spring Roadless Area 

17 Caribou Wilderness and Trail Lake Roadless Area 

36 Carson-Iceberg Roadless Areas 

19 Chanchelulla Roadless Area 

2 Condrey Mountain Roadless Area 

51 Coyote Southeast and Table Mountain Roadless Areas 

69 Cucamonga Roadless Areas 

61 Cypress Roadless Area 

31 Desolation Valley Wilderness 

71 Devil Canyon-Bear Canyon Primitive Area 

49 Dinkey Lakes Roadless Area 

59 Domeland Wilderness, Dorneland Addition, and Woodpecker 

Roadless Areas 

32 East part of the Raymond Peak Roadless Area 

24 East Yuba and West Yuba Roadless Areas 

37 Emigrant Basin and Hoover Wildernesses and adjoining 

roadless areas 

13 Fisher Gulch Roadless Area 

33 Freel and Dardanelles Roadless Areas 

55 Golden Trout Wilderness 

28 Granite Chief Wilderness study area 

12 Granite Peak Roadless Area 

53 High Sierra Primitive Area 

21 1shi, Mill Creek, Polk Springs. and Butt Mountain Roadless 

Areas 

50 John Muir Wilderness 

48 Kaiser Wilderness 

54 Kings River, Rancheria. Agnew, and Oat Mountain Roadless 

Areas 

10 Lake Eleanor Roadless Area 

43 Laurel-McGee and Wheeler Ridge Roadless Areas 

14 Lost Creek Roadless Area 

3 Marble Mountain Wilderness 

40 Minarets Wilderness and adjacent areas 

63 Miranda Pine, Horseshoe Springs, Tepusquet Peak. La Brea, 

Spoor Canyon, Fox Mountain, and Little Pine Roadless 

Areas 

Map 

No. arne of Area 

34 Mokelumne Wilderness and adjacent roadless areas 

58 Moses and Dennison Peak Roadless Areas 

6 Mount Eddy and Castle Crags Roadless Areas 

45 Mount Raymond Roadless Area 

5 Mount Shasta Wilderness study area 

27 North Fork of the American River Wilderness study area 

orth Fork Smith River Roadless Area, California and 

Oregon 

8 Orleans Mountain Roadless Area (B5079) 

9 Orleans Mountain Roadless Area (C5079. B5079) 

67 Pleasant View Roadless Area 

29 Pyramid Roadless Area 

7 4 Raywood Flat Roadless Areas 

30 Rubicon Roadless Area 

11 Salmon Trinity Alps Wilderness 

73 San Gorgonio Wilderness 

65 San Jacinto Wilderness 

44 San Joaquin Roadless Area 

66 San Rafael Primitive Area 

62 Santa Lucia Wilderness, and Garcia Mountain, Black Moun· 

tain. La Panza. Machesna Mountain, Los Machos Hills, Big 

Rocks, and Stanley Mountain Roadless Areas 

60 Scodies Roadless Area 

64 Sespe-Frazier, Diablo, Matilija. Dry Lakes, Sawmill-Badlands, 

Cuyama, Antimony, and Quatal Roadless Areas 

68 Sheep Mountain Wilderness Study Area and Cucamonga Wil· 

derness and Additions 

77 Sill Hill, Hauser, and Caliente Roadless Areas 

26 Snow Mountain Wilderness Study Area 

4 South Warner Wilderness 

70 Sugarloaf Roadless Area 

35 Sweetwater Roadless Area, California and evada 

16 Thousand Lakes Wilderness 

7 Timbered Crater Roadless Area 

38 Tioga Lake, Hall Natural Area, Log Cabin· addlebag, and 

Horse Meadows Roadless Areas 

39 Tuolumne River Roadless Area 

57 Ventana Wilderness 

56 Ventana Wilderness Additions and the Black Butte, Bear 

Mountain, and Bear Canyon Roadless Areas 

15 Weaver Bally Roadless Area 

42 White Mountains and Birch Creek Roadless Areas, California 

and Nevada 

18 Wild Cattle Mountain and Heart Lake Roadless Areas 

20 Yolla Bolly-Middle Eel Wilderness and Big Butte-Shinbone, 

East Fork, Murphy Glade, and Wilderness Contiguous 

Roadless Areas 

163 
164 

33 

22' 

30" 

0 

117°00' 

Approximate boundary 

\ ' 

~ 

MAP LOCATION 

5 

MILES 

Figure 46.-Agua Tibia Primitive Are~ California 
AGUA TIBIA PRIMITIVE AREA, CALIFORNIA 

By WILLIAM P. lRWI , U.S. G EOLOGICAL S RVEY and 

' 

HORACE K. THURBER, U.S. B REA OF Mr E 

SUMMARY 

The Agua Tibia Primitive Area in southwestern California is underlain by 

igneous and metamorphic rocks that are similar to those widely exposed 

throughout much of the Peninsular Ranges. Evidence of deposits of metallic or 

nonmetallic minerals was not seen during our study in 1969, nor is the presence 

of such deposits indicated from analysis of numerous stream-sediment samples 

and an aeromagnetic survey. No record of past or existing mineral claims was 

found. 

CHARACTER AND SETTING 

The Agua Tibia Primitive Area covers about 43 sq mi 

of the Cleveland National Forest, about 40 mi north of 

San Diego, California. The principal topographic 

feature of the primitive area is Agua Tibia Mountain, 

which rises 2500 ft higher than the adjacent lowland 

and merges with Palomar Mountain to the southeast 

beyond the boundary of the area. Most of Agua Tibia 

Mountain is covered by dense brush, but small stands 

of timber are present at the crest of the mountain and 

at the bottom of the canyons. 

In the spring of 1969, the USGS spent 2 man-months 

in the area to assess the mineral potential (Irwin and 

others, 1970). Geologic traverses were essentially 

restricted to roads, trails, and streams, because of the 

general cover of dense brush. Pertinent published and 

unpublished maps that cover part of the region were 

compiled along with the reconnaissance mapping to aid 

in a geologic evaluation of the mineral potential of the 

primitive area. To detect the presence of any concealed 

mineral deposits, samples of stream sediments were 

collected along the various creeks that head in the 

mountain. As an additional aid in evaluating the mineral potential, an aeromagnetic survey was made and 

was interpreted by Andrew Griscom of the USGS. A 

search for records of past or existing mining claims 

within the primitive area was made in the assessor's 

and recorder's offices of San Diego and Riverside County Courthouses by the USBM, but none was found. 

The Agua Tibia Primitive Area is in the Peninsular 

Ranges geologic province, which is characterized by 

northwest-trending mountain ranges that consist mostly 

of plutonic and metamorphic rocks of Mesozoic age. The 

plutonic rocks are much more abundant than the 

metamorphic rocks in the Agua Tibia region and mostly 

range from granite to gabbro. Varieties of granitic rocks, 

mainly granodiorite with subordinate tonalite, occupy a 

much greater area of outcrop on Agua Tibia Mountain 

than the gabbro. The metamorphic rocks of the region include schist, amphibolite, and calc-silicate granulite, and 

probably represent Jurassic or older sedimentary and 

volcanic rocks that were metamorphosed by the intrusion of the plutonic rocks during later Jurassic and 

Cretaceous time. Along the southwest side at the base 

of Agua Tibia Mountain, the plutonic and metamorphic 

rocks are cut by the Elsinore fault, which locally is 

marked by a zone of brecciated rock Y4 to Y2 mi wide. 

Although the fault is a major regional structure, the 

amount and sense of displacement are not clearly 

known. Virtually all of the Agua Tibia Primitive Area is 

on the northeast side of the Elsinore fault. On the 

southwest side of the fault, opposite the primitive area, 

some of the plutonic rocks contain sills and dike swarms 

of pegmatite, but little evidence of similar pegmatite 

was seen in the primitive area 

MINERAL RESOURCES 

Evidence of past or present mining activity was not 

seen in the Agua Tibia Primitive Area, but appreciable 

mining has been done nearby in the area southwest of 

the Elsinore fault. Some of the pegmatites have been 

165 
mined for semiprecious gemstones, including tourmaline, kunzite, and beryl, and for lepidolite (lithiumbearing mica). The Pala district, centered about 2 mi 

west of the primitive area, had yielded gemstones and 

lepidolite valued at more than $7 50,000 by 194 7 (Jahns 

and Wright, 1951), and it is estimated that at least an 

equal value has been produced since that time (E. E. 

Foord, U.S. Geological Survey, oral commun., 1982). 

The Rincon district, centered about 4 mi south of the 

primitive area, has yielded beryl valued at less than 

$2000 (Weber, 1963). Gabbro has been mined at the 

Magee quarry just west of the Elsinore fault. It is referred to commercially as "black granite" and is used 

for monuments and facing stone. Total production from 

the Magee quarry probably has not exceeded a few tens 

of thousands of tons. 

To detect the possible presense of concealed 

metalliferous deposits in the primitive area, streamsediment samples were collected along the principal 

creeks. These samples, in addition to samples of typical 

rocks of the area, were analyzed spectrographically; 

both groups of samples were also analyzed by the 

atomic absorption method for their content of gold, copper, lead, zinc, and silver, and by the paper chromatography method for uranium. Essentially all the samples 

were barren of anomalous concentrations of metals and 

minerals. The results of the geochemical sampling give 

166 

little promise for the discovery of mineral resources in 

the Agua Tibia Primitive Area. 

The aeromagnetic survey of the region has been interpreted to show two large positive anomalies, only one of 

which is mostly within the primitive area. The 

anomalies are on opposite sides of the Elsinore fault 

and both are centered over large gabbro bodies. A 

smaller anomaly is centered over gabbro nearby to the 

south. According to Andrew Griscom of the USGS (oral 

commun., 1969) the positive anomalies cover too large 

an ar~a relative to their amplitudes to suggest the 

presence of concealed ore bodies and could be caused by 

the gabbro bodies which commonly contain 2- 3 percent 

magnetite. 

REFERENCES 

Irwin. W. P., Greene, R. C .. and Thurber. H. K. 1970, Mineral 

resources of the Agua Tibia Primitive Area, California: U . . 

Geological Survey Bulletin 1319- A. 19 p. 

Jahns. R. H., and Wright, L. A., 1951. Gem- and li thium-bearing 

pegmatites of the Pala district, an Diego Coun ty. California: 

California Division of Mines and Geology Special Report 7- A. 

72 p. 

Weber, F. H., Jr., 1963, Geology and mineral re ources of an Diego 

County. California: California Division of Mines and Geology 

County Report 3, 309 p. 
ANDREWS MOUNTAIN, MAZOURKA, AND 

PAIUTE ROADLESS AREAS, CALIFORNIA 

By EDW! H . M CK EE, 1 U .S. GEOLOGICAL RVEY and 

STEVE W . SCHMAUCH , U.S. BUREAU OF M l ES 

SUMMARY 

On the basis of a mineral survey carried out in 1979-81, local areas near and 

within the Andrews Mountain, Mazourka, and Paiute Roadless Areas have 

probable and substantiated mineral-resource potential. The principal metallic 

mineral resources in these roadless areas are gold, copper, and silver with lead, 

zinc, and tungsten, as lesser resources. A zone of probable resource potential for 

talc, graphite, and marble is identified in the Mazourka Roadless Area Metallic 

mineralization occurs mostly in vein deposits in silicic and carbonate 

metasedimentary rocks peripheral to Mesozoic plutons and locally in granitic 

rocks as well. There is little promise for the occurrence of fossil fuel resources in 

the roadless areas. 

CHARACTER AND SETTING 

The contiguous Andrews Mountain, Mazourka, and 

Paiute Roadless Areas occupy an area of about 234 sq 

mi in the northern Inyo Mountains, Inyo County, California Big Pine, California is about 6 mi west of the 

north end of the combined study area and Independence 

California is about 6 mi from the southwest comer of 

the study area The terrain is rugged and steep with 

relief of about 7000 ft along the east side of the range. 

Altitudes range from about 3800 ft above sea level in 

Owens Valley near Independence to 11,123 ft above sea 

level at W aucoba Mountain. The climate is arid to 

semiarid with a wide range in temperature controlled 

primarily by altitude. 

The geology of the three roadless areas has been 

studied in detail and is published as maps by Ross 

(1965, 1967) and Nelson (1966, 1971). A compilation and 

summary of these maps is by Langenheim and others 

(1983). 

The rocks in the study area can be divided into major 

groups according to age and type. The oldest are 

sedimentary rocks of Late Proterozoic to Permian age; 

rocks of intermediate age are the granitoid plutonic 

rocks of middle to late Mesozoic age; and the youngest 

are Cenozoic volcanic rocks and surficial deposits. The 

1

With conbibutions from J ames L. Donahoe. USGS and Peter . Gabby and David A. 

LipUln. U BM . 

strata of Late Proterozoic to Permian age represent 

sediments that accumulated in a shallow-marine-shelf 

environment. The total aggregate thickness of these 

strata is at least 35,000 ft but no single section has been 

found that contains more than a small fraction of this 

thickness. The rocks are mostly clastic types made of 

about equal amounts of quartzose (sandstone and shale) 

and carbonate (limestone and dolomite) varieties. They 

are tightly compacted, recemented, and partially 

recrystallized almost everywhere. Locally, a low-grade 

metamorphic mineral assemblage including andalusite, 

sericite, metamorphic biotite, and coarsely crystalline 

calcite and dolomite has developed. 

Mesozoic plutonic rocks make up about half of the 

pre-Cenozoic exposures in the study area and are 

regarded as satellitic parts of the Sierra Nevada 

batholith (Bateman and others, 1963; McKee and Nash, 

1967; Ross, 1969). These plutons intrude and metamorphose the sedimentary rocks of Late Proterozoic and 

Paleozoic age of the region. They generally have steep 

and sharp contacts with the surrounding country rocks 

and contact metamorphic effects extend as far as 2 mi 

from the contacts. Most of the plutonic rock is 

granodiorite but there are significant quartz monzonite, 

monzonite, and diorite plutons as well. The rocks are 

generally medium to coarse grained, porphyritic, and 

nonfoliated. 

Small remnants of upper Cenozoic basalt, mainly lava 

flows and agglomerate occur on the east side of the 

167 
168 

Cu , Pb, Zn .l 

Au, Ag 

f bh 

37° 

00' 

# 0 gl ~ 

"' z 

(/) 

0 5 

MILES 

EXPLANATION 

-

D 

Geologic terrane with substantiated gold and 

tungsten resource potential and probable 

potential for other mineral resources 

Geologic terrane with probable mineralCu 

Au 

Pb 

resource potential 

Copper 

Gold 

Lead 

~ Mine or deposit 

x Mineral occurrence 

~ Mine 

Ag 

w 

Zn 

Silver 

Tungsten 

Zinc 

11s•oo· 

boundary 

Granitic rocks 

Sedimentary rocks 

Contact 

Figure 47.-Andrews Mountain, Mazourka, and Paiute Roadless Areas, California 
range near the mouth of Paiute Canyon and along the 

west front of the range west of Badger Flat. These 

basalts have been isolated by erosion from their sources; 

those on the east from the Saline Range and those on 

the west from vents in Owens Valley. The rocks are 

medium to dark gray, dense to vesicular, and locally 

scoriaceous. 

Sedimentary deposits of Cenozoic age fill the valleys 

adjacent to the Inyo Mountains and within the mountains shallow accumulations floor the major canyons 

and cap the higher alluviated areas. The oldest rocks are 

Tertiary deposits that occur in scattered areas along the 

east side of the range. Quaternary deposits consist of 

older, partly dissected fans, pediment deposits and 

valley fill and younger alluvial fans and other types of 

alluvium presently being deposited. 

Structural features in the northern part of the Inyo 

Mountains represent at least three distinct periods of 

deformation. These structural episodes include deformation that took place before emplacement of the 

plutonic rocks; deformation associated with emplacement of the plutonic rocks; and basin and range faulting 

that is responsible for the present uplift of the Inyo 

Mountains. Preplutonic deformation (pre-middle Jurassic) is characterized by many high-angle normal and 

reverse faults and open north-trending folds. These 

structures predate and postdate regional thrusting of 

the Last Chance thrust, a large fault with about 20 mi 

displacement that thrust upper Proterozoic and lower 

Paleozoic rocks onto upper Paleozoic rocks. Deformation associated with emplacement of the plutonic rocks 

during the middle and late Mesozoic affected almost all 

the upper Proterozoic and Paleozoic formations. This 

deformation is characterized by folds caused by forceful 

emplacement of the plutons and local metamorphic 

fabric in the rock. 

MINERAL RESOURCES 

The northern part of the Inyo Mountains, an area that 

includes the Andrews Mountain, Mazourka, and the 

Paiute Roadless Areas has substantiated resource 

potential in a small area near several existing mines for 

gold and tungsten and probable resource potential for 

silver, lead, zinc, and copper at other places. There is a 

probable resource potential for talc, graphite and 

marble in the Mazourka Roadless Area. The large 

number of mines and prospects throughout the study 

area is an indication of the widespread nature of alteration and mineralization. The suite of elements including 

molybdenum, lead, zinc, and silver with local additions 

of copper, gold, and molybdenum is found in anomalously high concentrations at many places as well. This 

group of elements, indicative of base-metal vein 

deposits formed by hydrothermal systems is what 

might be expected within the geologic framework of the 

northern Inyo Mountains. Hydrothermal solutions 

associated with the large granitoid plutons of the region 

would have found a suitable host for vein deposits in the 

much fractured and faulted Proterozoic and Paleozoic 

metasediments they intruded. The general distribution 

of the enrichment of this suite of metals is peripheral to, 

or within, the plutons. 

There are 51 mining properties in the three roadless 

areas; thirteen of these are mines with some record of 

past production. One of the productive mines is in the 

Andrews Mountains Roadless Area, 10 are in the 

Mazourka Roadless Area, and 2 are in the Paiute Roadless Area The most important are 3 mines along the 

southern boundary of the Mazourka Roadless Area The 

Copper Empire Group (loc. 1) has some mineralization 

along a 3-mi granitic contact zone with demonstrated 

resources of 66,000 tons averaging 1.57 percent copper. 

The Betty Jumbo mine (loc. 2) has two sheelite-bearing 

tactite bodies; one is nearly mined out, the other has 

estimated inferred resources of 53,000 tons averaging 

0.7 percent tungsten trioxide. The Black Eagle mine 

(loc. 3) has a small, demonstrated resource of 11,000 

tons averaging 0.21 oz gold/ton. On the northeast edge 

of the Paiute Roadless Area the Silver Princess nos. 1-4 

(loc. 4) produced some lead, zinc, and silver and has 

probable potential for additional resources of these 

metals. The Custer (Baxter) mine (loc. 5) in the Paiute 

Roadless Area produced a small amount of the same 

metals and more may exist in or near this mine. 

Little promise for the occurrence of significant 

mineral resources exists in the Andrews Mountain 

Roadless Area Weak anomalies in molybdenum, zinc, 

copper, gold, and tungsten were detected in streamsediment samples from one drainage west of Andrews 

Mountain. Four mining properties in the roadless area, 

including the Squaw Flat Nos. 1-4 (loc. 6) which had a 

small production of silver and lead, were determined to 

offer little promise for the occurrence of additional 

resources. 

The Mazourka Roadless Area has substantiated mineral potential for gold and tungsten in the area adjacent 

to the Black Eagle and Betty Jumbo mines that are 

near the southern part of the roadless area There is 

probable resource potential for silver and copper in the 

vicinity of the Copper Empire mine near the mouth of 

Mazourka Canyon. There is also probable resource 

potential for silver with lead and zinc in the northeastern part of the roadless area in the vicinity of The Narrows and areas to the east of The Narrows. There is 

probable resource potential for silver, lead, zinc, copper, 

and gold throughout most of Mazourka Canyon, and at 

169 
several other localities along the west front of the range. 

An area of probable resource potential for talc and 

graphite is located along the east side of Mazourka Canyon about 5 mi from its mouth. 

The Paiute Roadless Area has probable resource 

potential for silver and associated lead and zinc in the 

area around Lead Canyon. This estimate is based on 

high anomalous values of lead, zinc, molybdenum, and 

silver from stream-sediment and heavy-mineral concentrate samples as well as inferred resources in several 

mines and prospects in or near the area Although 

anomalous amounts of molybdenum are ubiquitous in 

samples from the Paiute Roadless Area, no molybdenum resource potential was identified. 

SUGGESTIONS FOR FURTHER STUDIES 

Three mines along the south edge of the Mazourka 

Roadless Area, the Copper Empire Group, Betty 

Jumbo, and Black Eagle mines, have demonstrated 

mineral resources. A drilling program at these sites 

might better define and extend the limits of mineralized 

rock. 

The specific areas of probable mineral-resource potential should be studied in detail to identify the sources of 

the geochemical anomalies detected by stream-sediment 

and (or) panned-concentrate sampling. 

170 

REFERENCES 

Bateman. P. C., Clark, L. C., Huber, N. K., Moore, J. ., and Rinehart, 

C. D., 1963, The Sierra Nevada batholith-a synthesis of recent 

work across the central part: U.S. Geological urvey Professional 

Paper 414- D, p. D1 - D46. 

Langenheim. V. A. M .. Donahoe, J. L., and McKee, E. H., 1983, 

Geologic map of the Andrews Mountain, Mazourka, and Paiute 

Roadless Areas, Inyo County, California: U.S. Geological Survey 

Miscellaneous Field Studies Map MF- 1492- A, scale 1:62,500. 

McKee, E. H., Donahoe, J. L., Blakely, R. J., Schrnauch, S. W., 

Lipton, D. A., and Gabby, P. N., 1983, Mineral resource potential 

map of the Andrews Mountain, Mazourka, and Paiute Roadless 

Area, Inyo Coun ty, California: U.S. Geological Survey 

Miscellaneous Field Studies Map MF- 1492- B, scale 1:62,500. 

McKee, E. H., and Nash, D. B .. 1967, Potassium·argon ages of 

granitic rock in the Inyo batholith, east-eentral California: 

Geological Society of America Bulletin, v. 78, no. 5, p. 669- 680. 

Nelson, C. A., 1966. Geologic map of the Waucoba Mountain 

quadrangle, Inyo County, California: U .. Geological Survey 

Geologic Quadrangle Map GQ-528, scale 1:62,500. 

__ 1971, Geologic map of the Waucoba Spring quadrangle, Inyo 

County, California: U.S. Geological Survey Geological Quad· 

rangle Map GQ- 921, scale 1:62,500. 

Ross, D. C., 1965, Geology of the Independence quadrangle, Lnyo 

County, California: U.S. Geological Survey Bulletin 1181- 0, 64 p. 

__ 1967, Geologic map of the Waucoba Wash quadrangle, Inyo 

County, California: U.S. Geological urvey Geologic Quadrangle 

Map GQ- 612, scale 1:62,500. 

__ 1969, Descriptive petrography of three large granitic bodies in 

the Inyo Mountains, California: U.S. Geological Survey Profes· 

sional Paper 601,47 p. 
ARROYO SECO ROADLESS AREA, CALIFORNIA 

By R OBERT E. POWELL, 1 .S. GEOLO !CAl RVEY, and 

PETER . GABBY, U.S . B REAU F MI NES 

SUMMARY 

On the basis of geologic mapping, a geochemical stream-sediment survey, and 

a survey of mines, quarries, and prospects conducted in 1982, the Arroyo Seco 

Roadless Area has a probable resource potential for small gold occurrences in 

the southern part of the area Sand, gravel, and stone suitable for construction 

materials are found in the roadless area, but similiar or better quality materials 

are abundant and more accessible outside the area. 

CHARACTER AND SETTING 

Situated in the southwestern San Gabriel Mountains 

in Los Angeles County, California, the Arroyo Seco 

Roadless Area encompasses about 8 sq mi within the 

Angeles National Forest. The roadless area includes 

Bear and Little Bear Canyons and most of upper Arroyo Seco between Red Box Gap and Oakwilde Picnic 

Area The roadless area is approximately bounded on 

the north by the Angeles Crest Highway (California 

State Highway 2) and on the south by CCC Ridge and 

the Brown Mountain-Mount Lowe-Mount Markham 

ridge. Altitude within the roadless area ranges from 

1800 ft in Arroyo Seco at Oakwilde Picnic Area to nearly 6000 ft atop Mount Disappointment. This report 

summarizes results presented by Powell and others 

(1983) and Gabby (1982). 

The roadless area is situated in a wedge between the 

San Gabriel fault zone along its northern margin and 

the Sierra Madre fault zone along its western and 

southwestern margin. Both faults are characterized by 

late Cenozoic right-lateral displacement. Crystalline 

units in the area generally trend northwest. The oldest 

rocks consist of pelitic metasedimentary gneiss interlayered with dark-colored Precambrian biotite-quartzfeldspar augen gneiss that originally intruded the 

metasedimentary rocks as porphyritic granodiorite and 

monzogranite. The Precambrian gneiss is intruded by 

the Permian and (or) Triassic Mount Lowe Granodiorite 

of Miller (1926, 1934) that consists of two principal 

phases within the roadless area: monzodiorite with 

coarse-grained hornblende partially rimmed by epidote 

and scattered ovoid alkali feldspar phenocrysts in a fine1

Willl contributions from J onalllan C. MaLti. BreLL F. Cox. and Curtis M. Obi. USC . 

grained matrix of plagioclase, alkali feldspar, and 

quartz; and leucocratic porphyritic monzodiorite with 

ovoid gray alkali feldspar phenocrysts, coarse-grained 

hornblende or clots of biotite, and garnet in a finegrained matrix of plagioclase, alkali feldspar, and 

quartz. The two phases appear to be transitional over a 

few feet. Quartz is generally present within the range of 

5 to 10 percent. Both phases are foliated. Between the 

San Gabriel and Sierra Madre fault zones, these older 

crystalline units are successively intruded by Mesozoic 

syenogranite (Echo Granite of Miller, 1930, 1934, which 

is considered Mesozoic by L. T. Silver, oral commun., 

1977), dark-colored hornblendite, hornblende gabbro 

and diorite, hornblende-biotite-sphene tonalite and 

granodiorite, porphyritic biotite-hornblende monzogranite, and coarse-grained, nonporphyritic biotite monzogranite, all of which are foliated to varying degrees. 

Mafic dikes, probably derived from the mafic Mesozoic 

plutonic units, crosscut the Echo Granite, the Mount 

Lowe Granodiorite, and probably the Precambrian 

gneiss. Along the Angeles Crest Highway west of the 

Sierra Madre fault zone and north of the San Gabriel 

fault zone, coarse-grained, foliated hornblende-biotite 

monzodiorite has been intruded by fine-to mediumgrained, foliated leucocratic biotite monzogranite. 

No producing or developing mines, active or patented 

mining claims, or mineral leases are in the roadless area 

The Dawn mine, just south of the roadless area, produced gold between 1895 and 1950 (Gay and Hoffman, 

1954). An occurrence of molybdenite and copper minerals, reported by Gay and Hoffman (1954) from a prospect at the west end of the roadless area, was not 

located during this study. 

A reconnaissance geochemical survey in the Arroyo 

Seco Roadless Area and vicinity was conducted to 

171 
34° 

15' 

172 

D 

Au 

118°10' 

0 

MILES 

EXPLANATION 

Geologic terrane with probable 

mineral-resource potential 

Gold 

Mine or deposit 

, r 4.-*"') 

M> 

To 

2 

Mou-.t 

Luwlor 

ou 

". 

Box 

' rkt n 

MAP LOCATION 

Quaternary alluvium and colluvium 

Mesozoic igneous rocks 

Permian and (or) Triassic igneous rocks 

Precambrian gneiss 

Mylonite 

Contact 

Fault--Arrows show direction of 

relative movement 

Figure 48.-Arroyo Seco Roaciless Area, California 

m 

01 

0 

., 

118°05' 
determine spatial variations in stream-sediment 

chemistry that might indicate the occurrence of metal 

concentrations. 

MINERAL RESOURCES 

There is an area of probable gold resource potential 

just inside the south edge of the Arroyo Seco Roadless 

Area Sand, gravel, and stone suitable for construction 

materials are found in the roadless area, but similar or 

better quality materials are more abundant and more 

accessible outside the area 

Mineral concentrations have not been observed along 

any of the structures or intrusive contacts mapped 

within the roadless area, nor in any lithologic units 

within the area Neither prominent veining nor extensive alteration has been observed. 

None of the elemental concentrations found in streamsediment samples suggest the presence of resources. 

Most of the analyses fall within ranges that are 

reasonable for nonmineralized igneous and metamorphic rock and derivative stream-sediments. The few 

values that exceed the geochemical background appear 

to be related to common petrologic processes or, in some 

cases, possibly to contamination from litter rather than 

to processes of ore concentration and deposition. 

About 0.5 mi south of the Arroyo Seco Roadless Area, 

gold is found in a pyrite-bearing quartz vein at the 

Dawn mine, where there are demonstrated resources of 

about 1000 tons of gold-bearing rock that averages 

0.046 oz gold/ton. The host rock at the Dawn mine and 

at several reported gold prospects in the vicinity, is the 

distinctive Echo Granite that extends only to the 

southern boundary of the roadless area at Brown Mountain. Thin, fine-grained, generally foliated mafic dikes 

also crosscut the Echo Granite at the Dawn mine. 

Although gold mineralization is spatially associated 

with similar-looking mafic dikes in older rocks elsewhere in the region, no evidence for significant mineralization was found in the vicinity of the roadless area 

other than at the Dawn mine. Very little of the host unit 

is exposed within the roadless area and it is unlikely 

that much of the unit is present, even in the subsurface. 

A probable gold resource potential is assessed to that 

small portion of the granite that extends into the roadless area. 

SUGGESTIONS FOR FURTHER STUDY 

Because of their regional association with gold 

mineralization, the thin and poorly exposed mafic dikes 

in the Echo Granite, the Mount Lowe Granodiorite, and 

the Precambrian gneiss in and around the roadless area 

offer the most promising avenue for additional study of 

the resource potential of the area 

REFERENCES 

Gabby, P. ., 1982, Mineral resources of the Arroyo Seco RARE II 

Area (No. 5012), Los Angeles County, California: U.S. Bureau of 

Mines Open· File Report MLA 104- 82,19 p. 

Gay, T. E., Jr., and Hoffman, S. R., 1954, Mines and Mineral Deposits 

of Los Angeles County, California: California Journal of Mines 

and Geology, v. 50, p. 467- 709. 

Miller, W. J., 1926, Crystalline rocks of the middle-southern San 

Gabriel Mountains, California [abs.]: Geological Society of America Bulletin, v. 37, p. 149. 

__ 1930, Rocks of the southwestern San Gabriel Mountains, 

California [abs.]: Geological Society of America Bulletin. v. 41. 

p. 149- 150. 

__ 1934, Geology of the western San Gabriel Mountains of 

California: Publications of the University of California at Los An· 

geles in Mathematical and Physical Sciences, v. 1, n. 1, p. 1- 114. 

Powell, R. E., Cox, B. F., Matti, J . C., and Gabby, P. ., 1983, Mineral 

resource potential map of the Arroyo Seco Roadless Area. Los 

Angeles County, California: U.S. Geological Survey Mi cellaneous Field Studies Map MF- 1607- A. 

173 
174 

39° 

45' 

I. 

D 

Cr 

Au 

Pb 

Ag 

1- eat•wr F" I 

0 

0 

MILES 

II 

MAP LOCATION 

10 

EXPLANATION 

Geologic terrane with probable 

mineral-resource potential 

Chromium 

Gold 

Lead 

Silver 

Mine 

, , Intrusive rocks (Cretaceous and Jurassic) 

Horseshoe Bend Formation (Permian?) 

Franklin Canyon Formation (Triassic? and 

C 

Upper Paleozoic) 

Calaveras Formation (Pennsylvanian) 

Ultramafic rocks in Melones fault zone 

Shoo Fly Complex (Devonian) 

Contact 

Fault 

Figure 49.- Bald Rock and Middle Fork Feather River Roadless Areas. California 
BALD ROCK AND 

MIDDLE FORK FEATHER RIVER ROAD LESS AREAS, CALIFORNIA 

By M ART I L. ORE E , 1 U .. GEOLO !CAL SU RVEY, and 

A LA R . B EHLER , . B RE OF MI E. 

SUMMARY 

The results of a mineral-resource assessment of the Bald Rock and Middle 

Fork Feather River Roadless Areas conducted during 1980-82 indicate several 

areas within the Middle Fork Feather River Roadless Area that have probable 

mineral-resource potential. A probable potential for placer gold exists at various 

localities, both in areas covered by Tertiary volcanic rocks and in small streams 

that drain into the Middle Fork of the Feather River. A probable potential for 

small deposits of chromite exists in tracts underlain by ultramafic rocks in the 

Melones fault zone. A probable potential for lead-silver deposits is recognized at 

the east end of the Middle Fork Feather River Roadless Area There is little 

promise for the occurrence of coal, oil, gas, or geothermal energy resources in the 

roadless areas. 

CHARACTER AND SETTING 

The Bald Rock and Middle Fork Feather River 

Roadless Areas are in the Plumas National Forest on 

the west slope of the Sierra Nevada, 5 to 28 mi south to 

southwest of Quincy, California The Bald Rock Roadless Area consists of about 6 sq mi in Butte County, and 

the Middle Fork Feather River Roadless Area comprises about 46 sq mi in Butte and Plumas Counties, 

California The roadless areas are alined along the Middle Fork of the Feather River and several tributary 

drainages. The canyon bottom of the Middle Fork is 

classified as a National Wild and Scenic River and, 

although included within the roadless areas, was not 

authorized by the USFS to be evaluated during the 

mineral-resource survey. 

The roadless areas are in the northern part of the 

western Sierra Nevada metamorphic belt. Steeply dipping faults divide the region into four north- to 

northwest-trending belts of Paleozoic and Mesozoic 

metasedimentary and metavolcanic rocks that have 

been intruded by Mesozoic granitoid plutons and partially covered by Cenozoic volcanic rocks (Hietanen, 

1973, 1976, 1981a, 1981b). The easternmost part of the 

Middle Fork Feather River Roadless Area is underlain 

bv t.hP ~h()() Flv Comolex. a metasedimentarv unit of 

1

Wit.h oontribul.ions from Andrew Griscom and Henry Piet.ropaoli. USGS. 

pre-Late Devonian age. The rocks of the Shoo Fly are 

bordered on the west by ultramafic rocks coincident 

with the Melones fault zone. West of the Melones fault 

zone are several sequences of upper Paleozoic and lower 

Mesozoic metasedimentary and metavolcanic rocks. 

The easternmost of these is the Calaveras Formation, a 

dominantly metasedimentary unit that has been determined to be Pennsylvanian in age in this region 

(Hietanen, 1981a, p. 17). West of the Calaveras is the 

Franklin Canyon Formation, a series of mostly metavolcanic rocks considered to be late Paleozoic and 

Triassic(?) in age. The westernmost sequence within the 

roadless areas is the Horseshoe Bend Formation of Permian(?) age, consisting of interbedded and possibly tectonically interleaved metasedimentary, metavolcanic, 

and ultramafic rocks. The various metasedimentary, 

metavolcanic, and ultramafic rock units were intruded 

by granitoid plutons during middle and late Mesozoic 

time. The area was elevated, eroded, and partially covered by volcanic deposits by late Tertiary time. In 

places, the Tertiary volcanic rocks cover lower Tertiary 

stream-bed deposits that locally contain placer gold. 

The geology of the roadless areas has been summarized 

by Sorensen and Pietropaoli (1982). 

The results of spectrographic and chemical analyses 

of rock, stream-sediment, and pan-concentrate samples 

(Sorensen and others, 1982) show local, slightly 

anomalous values for barium, bismuth, gold, molyb175 
denum, silver, tin, and tungsten. Aeromagnetic and 

gravity maps of the roadless areas were prepared as an 

aid in the evaluation of the mineral-resource potential. 

Examination of the aeromagnetic map (Andrew 

Griscom, unpub. data, 1982) indicates that most of the 

magnetic anomalies occur over the fault-bounded ultramafic bodies, and that the magnetic expression of the 

other rock units is generally one of low-amplitude 

anomalies and relatively smooth magnetic field. The 

gravity map (Oliver and others, 1982) displays a large 

gravity low associated with the granitoid plutons and a 

gravity gradient between the Shoo Fly Complex and the 

Calaveras Formation. Neither the aeromagnetic nor the 

gravity data provide any specific information for the 

identification of additional mineral-resource potential. 

The Bald Rock and Middle Fork Feather River 

Roadless Areas are near the northern end of the principal zone of placer gold deposits of the western Sierra 

Nevada Tertiary and Quaternary placer deposits in and 

near the roadless areas have been mined by hydraulic 

and drift methods since the mid-19th century and currently are the focus for recreational gold panning and 

dredging. Chromite has been mined since World War I 

from small deposits in ultramafic rocks within the 

Melones fault zone (Rynearson, 1953). In areas underlain by the Calaveras, Franklin Canyon, and Horseshoe 

Bend Formations, prospects have been claimed on the 

basis of reports of chromite, copper, gold, and silver. 

Although many of these prospects are mentioned in 

reports of the State Mineralogist, production records 

were not located for any and it is assumed that production, if any, from these deposits was minimal. 

MINERAL RESOURCES 

A probable potential for the occurrence of placer gold 

resources exists west of the Melones fault zone where 

Tertiary volcanic rocks are exposed over approximately 

2 sq mi and may overlie Tertiary auriferous stream 

deposits. Haley (1923) concluded that an early Tertiary 

stream probably trended northwest near the present 

location of Onion Valley Creek. Thus upper Tertiary 

volcanic rocks at the southeast comer of the Middle 

Fork Feather River Roadless Area may overlie concealed auriferous stream deposits, as may similar 

volcanic rocks exposed 5 mi to the northwest. Small unmapped remnants of Tertiary stream deposits may be 

present along the probable trends of Tertiary stream 

courses as determined by Haley (1923, pl. 7), so a probable potential for placer gold resources in Tertiary 

stream deposits is recognized near Hartman Bar, in 

Bear and Onion Valley Creeks, and southeast of Claremont Peak. 

176 

Gold is reported present in sediments collected from 

small streams that drain into the Middle Fork of the 

Feather River (Sorensen and others, 1982), including 

Bachs, Claremont, and Onion Valley Creeks, as well as 

drainages near Hansons and Hartman Bars. The presence of gold in many of the analyzed samples indicates a 

probable potential for placer gold resources, but the 

steep gradient of the drainages from which the samples 

were collected suggests that any such deposits are probably very small. 

A probable resource potential for small, low- to 

medium-grade deposits of chromite exists near the 

eastern end of the Middle Fork Feather River Roadless 

Area where approximately 6 sq mi are underlain by 

ultramafic rocks within the Melones fault zone. Small 

deposits in these rocks near the Middle Fork of the 

Feather River have produced approximately 1000 long 

tons of chromite since World War I. It is probable that 

any new deposits will be small (less than 50 long tons), 

pod-shaped, and confined to shear zones within the 

ultramafic rocks of the Melones fault zone. 

A probable potential for low-grade lead-silver deposits 

exists at the east end of the Middle Fork Feather River 

Roadless Area Analyses of four rock samples collected 

there show slightly anomalous values for lead and silver 

and indicate low-grade mineralization. The sample localities form a linear that trends north-northwest through 

the Five Bear mine. 

The Bald Rock and Middle Fork Feather River Roadless Areas have little promise for the occurrence of coal, 

oil, gas, or geothermal energy resources. 

SUGGESTIONS FOR FURTHER STUDIES 

Lower Tertiary stream deposits may be present 

beneath upper Tertiary volcanic rocks at two localities 

near Onion Valley Creek in the Middle Fork Feather 

River Roadless Area The presence or absence of these 

potentially auriferous deposits can best be determined 

by drilling through the relatively thin cover of volcanic 

rocks. 

Small unmapped remnants of Tertiary stream deposits may be present near Hartman Bar, in Bear and 

Onion Valley Creeks, and southeast of Claremont Peak. 

The presence or absence of these potentially auriferous 

deposits can best be determined by detailed geologic 

mapping at a much larger scale than that of the present 

study. 

Undiscovered chromite deposits are best sought by 

detailed geologic mapping of faults and shear zones in 

ultramafic rocks within the Melones fault zone. 
REFERENCES 

Haley, C. S .. 1923, Gold placers of California: California State Mining 

Bureau. Bulletin 92, 167 p. 

Hietanen, Anna, 1973, Geology of the Pulga and Bucks Lake 

quadrangles, Butte and Plumas Counties, California: U.S. 

Geological Survey Professional Paper 731,66 p. 

__ 1976, Metamorphism and plutonism around the Middle and 

South Forks of the Feather River, California: U.S. Geological 

Survey Professional Paper 920, 30 p. 

__ 1981a, Geology west of the Melones fault between the Feather 

and orth Yuba Rivers, California: U.S. Geological Survey Professional Paper 1226- A, 35 p. 

__ 1981b, The Feather River area as a part of the Sierra evada 

suture system in California: U.S. Geological Survey Professional 

Paper 1226- B, 13 p. 

Oliver, H. W., Robbins, S. L., Rambo, W. L., and ikora, R. F., 19 2, 

Bouguer gravity map of California, Chico sheet: California Divi· 

sion of Mines and Geology, scale 1:250,000. 

Rynearson, G. A., 1953, Geological investigations of chromite in 

California: California Division of Mines, Bulletin 134,321 p. 

Sorensen, M. L., Griscom, Andrew, and Buehler. A. R .. in pres , 

Mineral resource potential map of the Bald Rock and Middle 

Fork Feather River Roadless Areas, Butte and Plumas Counties, 

California: U.S. Geological Survey Miscellaneous Field Studies 

MapMF- 1427- B. 

Sorensen, M. L .. and Pietropaoli, Henry, 1982, Geologic map of the 

Bald Rock and Middle Fork Feather River Roadless Areas, Butte 

and Plumas Counties, California: U.S. Geological urvey Miscellaneous Field Studies Map MF- 1427- A, cale 1:62,500. 

Sorensen, M. L., Pietropaoli, Henry, and Peterson, J. A., 19 2, 

Geochemical analyses of rock and strean1-sediment sample from 

Bald Rock, Bucks Lake, Chips Creek, and Middle Fork Feather 

River Roadless Areas, Butte and Plumas Counties. California: 

U.S. Geological Survey Open-File Report 2- 776,52 p. 

177 
178 

MAP LOCATION 

GOLD CROWN 

GOLD 

GOLD 

0 

Ben•or llo J; ..., Sprin~' t· 

3 

MILES 

D 

Au 

EXPLANATION 

Geologic terrane with substantiated 

mineral-resource potential 

Geologic terrane with probable 

mineral-resource potential 

Gold 

Ag Silver 

w Tungsten 

~ Mine 

118°30' 

\\ 

MINE 

Basalt (Tertiary) 

Granitic rock (Mesozoic ) 

Metamorphic rock (Mesozoic 

and Paleozoic) 

Contact 

Figure 50.-Benton Range Roadless Area, California 
BENTON RANGE ROADLESS AREA, CALIFORNIA 

By EDWIN H . M KEE, 1 U.S . GEOLO l AL S R EY and 

RIC HARD L. RAI S, U .S. B REAU OF MI NE 

SUMMARY 

On the basis of a mineral survey in 1980-81, two parts of the Benton Range 

Roadless Area are considered to have mineral-resource potential. The central 

and southern part of the roadless area, near several nonoperating mines, has a 

probable potential for tungsten and gold-silver mineralization in tactite zones. 

The central part of the area has a substantiated resource potential for gold and 

silver in quartz veins. 

CHARACTER AND SETTING 

The Benton Range Roadless Area covers about 

17.5 sq mi at the southern end of the Benton Range at 

the north end of Owens Valley. The area is approximately 33 mi southeast of Mono Lake and 27 mi north 

of Bishop, California There is easy access to the area 

from Benton Hot Springs, California, located on State 

Highway 120. 

The Benton Range is composed of about equal 

amounts of metamorphic, plutonic, and volcanic rocks 

(McKee and Donahoe, 1981). The southern part of the 

area consists mostly of metamorphic rocks of Paleozoic 

age that are part of a large pendant engulfed in 

Mesozoic granitic rocks of the Sierra Nevada batholith. 

The central and northern part of the area is composed 

mostly of granitic rocks that are also part of this 

batholith. The granitic rocks are mostly coarse grained 

porphyritic granodiorites but include a variety of compositional and textural types. A swarm of felsic and 

dioritic dikes of uncertain, but possibly Mesozoic age, 

intrudes the metamorphic and granitic rocks on the 

western side of the roadless area Tertiary basalt lava 

flows lie on the eroded Mesozoic granitic rocks in the 

northern part of the area. 

MINERAL RESOURCES 

Tactite, formed at the contact between intrusive and 

calcareous metasedimentary rocks, locally contains the 

tungsten mineral scheelite. In mines outside but near 

1

WiLh contributions by James L. Donahoe. USGS. 

the roadless area large amounts of scheelite have been 

mined in the past. In addition to scheelite, the tactite 

zones have yielded small quantities of gold and silver in 

sulfides. The geologic environment (tactite) in the 

sou them part of the roadless area is similar to areas 

with production nearby and therefore has a probable 

potential for resources of tungsten and some gold and 

silver. 

ative gold, and gold and silver sulfides, occur in 

quartz veins and small shear zones in metamorphic and 

granitic rocks outside and locally within the roadless 

area. Numerous porphyritic felsic dikes as much as 30ft 

thick occur near the Gold Crown mine on the west edge 

of the area These are associated with quartz veins that 

contain gold and silver minerals, and small amounts of 

these metal-bearing minerals are disseminated in the adjacent metamorphic country rocks. The vicinity of the 

Gold Crown mine has a substantiated resource potential 

for gold and silver. Other areas within or near the 

roadless area contain abandoned mines and have probable resource potential for gold and silver on the basis of 

geologic features, geochemical anomalies, and evaluation of existing mines. 

A reconnaissance geochemical study is published in 

Donahoe and Chaffee (1982) and a mineral-resource appraisal by Donahoe and others (1982). 

SUGGESTIONS FOR FURTHER STUDIES 

Detailed mapping and geochemical sampling for 

tungsten, gold, and silver in the central and southern 

part of the roadless area might indicate targets for 

shallow drilling exploration. Although this area has 

179 
been heavily prospected for nearly 100 years exploration has been confined to panning and surface sampling. 

REFERENCES 

Donahoe, J. L., Chaffee, M. A., Fey, D. L., Hill, R. H., and Sutley, 

S. J ., 1982, Geochemical anomaly map of the Benton Range Further Planning (RARE II) area, Mono County, California: U.S. 

Geological Survey Miscellaneous Field Studies Map 

MF - 1317- B, scale 1:62,500. 

180 

Donahoe, J. L., McKee E. H., Rains, R. L., Barnes, D. J., Carnpbeil, 

H. W., Denton, D. K .. Jr., Iverson, S. R., Jeske, R. E., and Stebbins, S. A., 1982, Mineral resource potential map of the Benton 

Range Roadless Area, Mono County, California: U.S. Geological 

Survey Misceilaneous Field Studies Map MF- 1317- C, scale 

1:62,500. 

McKee, E. H., and Donahoe, J. L., 1981, Geologic map of the Benton 

Range Further Planning (RARE II) Area, Mono County, California: U.S. Geological Survey Misceilaneous Field Studies Map 

MF- 1317- A, scale 1:62,500. 
BLACK BUTTE AND ELK CREEK ROADLESS AREAS, CALIFORNIA 

By H E RY . 0HLI , 1 U.S. GEOLOGICAL RVEY , and 

R . j. SPEAR, U.S. B REA OF MINE 

SUMMARY 

A mineral investigation conducted by the USGS and the USBM in 1980-81 in 

the nearly contiguous Black Butte and Elk Creek Roadless Areas of northern 

California, indicates that small parts of both roadless areas have a probable 

mineral-resource potential for small manganese-copper- or chromite-type 

deposits. There is little promise for the occurrence of energy resources in the 

areas. 

CHARACTER AND SETTING 

The Black Butte and Elk Creek Roadless Areas each 

comprise approximately 40 sq mi in Mendocino National Forest, Mendocino, Glenn, and Lake Counties, 

California, and are nearly contiguous. The roadless 

areas are in the eastern part of the northern California 

Coast Range and are characterized by northwesttrending ridges separated by steep-sided valleys. 

Altitudes range from 1500 ft to 6100 ft, commonly with 

gradients of 1000 ft/mi. The steep slopes are covered by 

brush, grassland, oak, and conifer forests. Access to the 

areas is by California State Highway 261 from Covelo 

and by a county road from Potter Valley to Lake Pillsbury. USFS Route M1 connects these two roads along a 

north-south trend. 

The Black Butte and Elk Creek Roadless Areas are 

underlain by metamorphosed and highly deformed 

rocks ranging in age from Middle Jurassic to early Late 

Cretaceous (about 160 to 96 million years ago), assigned 

to the Franciscan assemblage. Isolated lenticular 

masses of serpentinite occur along faults in the area 

The rocks of the Franciscan assemblage are divided into 

four structural units based on different lithologies, 

degrees of metamorphism, and styles of deformation. 

The Central belt melange of the Franciscan assemblage is the structurally lowest unit, consisting primarily of argillite and thin-bedded metasandstone that 

are regionally metamorphosed to pumpellyite and lawsonite grade. Following, or perhaps during regional 

metamorphism, the argillite and metasandstone were 

1

Wilh contributions from Robert J. McLaughlin, USGS. 

extensively sheared and chaotically mixed with scattered blocks of mafic metaigneous rocks, manganiferous 

metachert, limestone, and high-grade glaucophane 

schist. These blocks range in length from inches to 50 or 

more feet. Fossils from metamorphosed blocks within 

the melange unit are Late Jurassic (140 million years 

ago) to early Late Cretaceous (96 million years ago) in 

age, indicating that regional metamorphism and the 

mixing together of rocks in the melange occurred less 

than 96 million years ago. 

The metasandstone and argillite of Sanhedrin Mountain overlies the Central belt melange in the southwest 

part of the area Intercalated with metaclastic rocks of 

the unit are thick lenses of metachert and mafic metavolcanic rock. The rocks of Sanhedrin Mountain have 

been modified texturally to low-grade slate and phyllite, 

and the sandstones typically are metamorphosed to 

lawsonite grade. This unit has been assigned a midCretaceous age (Etter, 1979; Jordan, 1974) although no 

fossils have been found. 

To the east of Sanhedrin Mountain is another unit of 

metamorphosed sandstone and argillite, referred to as 

the metasandstone and argillite of Hull Mountain. The 

Hull Mountain rocks are weakly to moderately modified 

texturally, and contain metamorphic mineral assemblages similar to the Sanhedrin Mountain unit. Both 

units locally contain intercalated radiolarian metachert 

and mafic igneous rocks with sheared contacts. The 

Hull Mountain unit also contains rare unsheared gabbroic rocks with intrusive contacts. The Hull Mountain 

unit has less abundant metachert than the Sanhedrin 

Mountain unit, and the metaclastic rocks locally include 

prominent quartz-pebble metaconglomerate and 

metagrit. Fossils indicate a middle Cretaceous (about 

181 
182 

39° 

40' 

39 

30' 

D 

Cr 

Cu 

Mn 

Pt 

r-- 1 IY;Q I .......... 

l .......... Black Butte ~ 

o51o2 I 

Porson 

Cr, Pt -, 

GRAVELLY 

Butt X ~- ~ 

/~ cr·e"- - / COPPER 

J CITY r'./ Mn , Cu PROSPECT 

( • Cr. Pt 

• 

M AP LOCATION 

VALLEY X' J:_ ·e Plllsb.;ry 

0 5 

MILES 

EXPLANATION 

Geologic terrane with probable 

mineral-resource potential 

Chromium 

Copper 

Manganese 

Platinum 

Mine 

D Franciscan Assemblage 

(Cretaceous and Jurassic ) 

Coast Range Ophiolite 

(Jurassic ) 

Contact 

Fau lt 

• • • Thrust fault --Sawteeth on 

upper plate 

Figure 51.- Black Butte and Elk Creek Roadless Areas, California 
96-110 million years ago) age for the metasandstone 

and argillite. 

The metasandstones and metavolcanic rocks of Black 

Butte and Bald Mountain are the structurally highest 

rocks of the map area These rocks overlie the metasandstone and argillite of Hull Mountain and the Central belt melange along a low-angle thrust fault. The 

metasandstone and metavolcanic rocks of Black Butte 

and Bald Mountain are extensively modified texturally 

to schist or phyllite, and they contain lawsonite. 

Serpentinite occurs in lenticular masses along highangle and low-angle faults in the roadless areas. Most 

notably, serpentinite occurs at Blue Banks, the Devils 

Rock-Barley Lake area, along Elk Creek, and in the Bennet Valley-Eden Valley areas, and on Brushy Mountain. 

Samples collected for geochemical analysis in the 

roadless areas included panned stream sediment and 

mineralized and nonmineralized bedrock. Geochemical 

analyses of these samples, using quantitative and semiquantitative spectrographic, atomic absorption and fire 

assay techniques, were then used in evaluating the 

metallic-resource potential of the roadless areas (Ohlin 

and others, 1983). 

MINERAL RESOURCES 

Metallic element concentrations above average 

crustal abundance are locally present in all bedrock 

units of the Black Butte and Elk Creek Roadless Areas, 

and small parts of each area have a probable mineralresource potential, mainly for manganese-copper and 

chromite deposits. 

Minor manganese mineralization is associated with 

metachert and metavolcanic rocks in the Elk Creek 

Roadless Area. Three occurrences of manganese mineralization within the Sanhedrin Mountain structural unit 

have been prospected, but they are 0.5 to 3.0 mi outside 

the Elk Creek Roadless Area Two of these prospects, 

Consolidated Claims and Gravelly Valley, are reported 

to have produced less than 150 tons of manganese ore 

(Trask and others, 1943). No production is known from 

the Impassable Rock prospect. At the Consolidated 

Claims and Impassable Rock prospects the manganese 

mineralization is associated with metachert or metaigneous rocks. Manganese carbonates were reported at 

Impassable Rock (Trask and others, 1943). At the 

Gravelly Valley occurrence manganese oxide mineralization is concentrated along bedding in folded metachert or along faults and fractures cutting the metachert. Copper, nickel, zinc, cobalt, molybdenum, and 

gold are associated with the manganese, in trace 

amounts. The Sanhedrin Mountain rocks extend into 

the Elk Creek Roadless Area and are considered to have 

a probable potential for manganese and copper. 

At the Copper City prospects, 4 mi east of Black 

Butte Roadless Area, veinlets of specular hematite and 

minor blue and green copper staining (azurite and 

malachite) were observed in slightly manganiferous 

metatuff and metachert of the Black Butte structural 

unit. Eric (1948) reported disseminated cuprite in these 

rocks and possibly this extends into the roadless area 

There has been no known production but the area is 

assessed a probable resource potential for manganese 

and copper. 

Minor chromite mineralization and trace amounts of 

platinum group metals are associated with the lenticular masses of serpentinite that occur along faults in 

the roadless areas. The serpentinite is considered to 

have a probable mineral-resource potential for chrornite 

and associated platinum group elements. 

Two springs along northwest-trending faults alined 

with Sanhedrin Creek discharge hydrogen sulfide gas. 

Although these springs were not studied in detail, they 

show no obvious evidence of geothermal potential. Heat 

flow measurements, from three explorations wells in 

and near the roadless areas, are normal for the region 

(Lachenbruch and Sass, 1980). No evidence of any oil or 

natural gas resource potential was identified in this 

study. 

SUGGESTIONS FOR FURTHER STUDIES 

No further mineral-resource investigations are recommended for areas within the boundaries of the Elk Creek 

or Black Butte Roadless Areas. However, 20 rni to the 

south of the roadless areas is the Geysers-Clear Lake 

geothermal area Between Lake Pillsbury 3 rni south of 

the Elk Creek Roadless area, and Clear Lake, numerous 

thermal springs discharge along the Bartlett Springs 

fault zone (in part the Hot Springs shear zone of Etter, 

1979). Investigation of geothermal resource potential 

and of the potential for other hydrothermal base- and 

precious-metal mineralization along this fault zone 

should be initiated. 

REFERENCES 

Eric, J. H .. 1948, Tabulation of copper deposits in California, in 

J enkin , 0. P., ed., Copper in California: California Division of 

Mines Bulletin 144, p. 199-387. 

Etter. . D .. 1979, Geology of the Lake Pillsbury area, northern Coast 

Ranges, California: University of Texas at Austin, Ph.D thesis, 

314 p. 

Jordan, M. A .. 1974, Geology of the Round Valley, Sanhedrin Moun· 

tain area, northern California Coast Ranges: University of Texas 

at Austin. Ph.D thesis, 17 4 p. 

Lachenbruch, A. H., and Sass, J. H., 19 0, Heat flow and energetics 

of the San Andreas Fault Zone: Journal of Geophysical Research, 

v. 85. no. Bll. p. 6185- 6222. 

183 
Ohlin, H. ., McLaughlin, R. J., Oscarson, R. L., Peterson, D. M., 

Weed, R.B., and Spear, J. M., 1983, Mineral resource potential 

map of the Black Butte and Elk Creek Road.less Areas, Mendocino, Lake, and Glen Counties, California: U.S. Geological 

Survey Miscellaneous Field Studies Map MF- 1544- A. 

184 

Trask, P. D., Wilson, I. F., and Simons, F. S., 1943, Manganese 

Deposits of California-A summary report (including tabulated 

data on manganese properties of California), in Jenkins, 0 . P., 

ed., Manganese in California: California Division of Mines and 

Geology Bulletin 125, p. 125. 
BLANCO MOUNTAIN AND 

BLACK CANYON ROADLESS AREAS, CALIFORNIA 

By MICHAEL F. DIGG LE , 1 .S. GEOLOG I AL RVEY and 

RICHARD L. RAI S U .S. BUREA OF Mr E 

SUMMARY 

The mineral survey of the Blanco Mountain and Black Canyon Roadless 

Areas, conducted in 1980 and 1981 indicated that areas of probable and 

substantiated mineral-resource potential exist only in the Black Canyon 

Roadless Area Gold with moderate amounts of lead, silver, zinc, and tungsten, 

occurs in vein deposits and in tactite. The nature of the geolgic terrain indicates 

little likelihood for the occurrence of energy resources in the roadless areas. 

CHARACTER AND SETTING 

The Blanco Mountain and Black Canyon Roadless 

Areas occupy 27 and 48 sq mi, respectively, in the 

southern White Mountains about 10 mi east of Bishop, 

California They are bounded on the west by Owens 

Valley, on the east by Fish Lake Valley, and are accessible from secondary roads off U.S. Highway 395 and the 

road to the research station on Mount Bancroft. A 

geologic map of roadless areas in the White Mountains 

is presented by McKee and others (1982). Personnel 

from the USGS carried out a geochemical sampling program in 1980 and the results and interpretation are included in Diggles and others (1982) and Diggles (1983). 

An aeromagnetic and gravity study was also conducted. 

The USBM evaluated mines, prospects, and other 

known mineral deposits in 1980 and 1981. A summary 

of the results of these studies and an evaluation of the 

mineral-resource potential is presented by Diggles and 

others (1983), by Schmauch and others (1982), and in unpublished data by R. L. Rains. 

The two roadless areas are underlain primarily by 

Late Proterozoic through Cambrian strata consisting of 

a carbonate-sandstone-shale sequence. These strata are 

metamorphosed to marble, quartzite, and phyllite; in 

many places, quartz veins are common. Mesozoic plutonic rocks of the Inyo batholith occur in three bodies. 

A large granite body extends into the eastern edge of 

the Blanco Mountain Roadless Area with a smaller 

body located west of it. Another small granitic body is 

'Wi!.h conUibut.ions from Steven W. Schmauch. U BM . 

exposed in Redding Canyon in the Black Canyon 

Roadless Area Tertiary volcanic rocks are exposed in 

the northern Blanco Mountain Roadless Area 

The structural history of the roadless areas is marked 

by three periods of deformation. Prior to emplacement 

of the batholithic rocks, a thrusting event displaced 

younger Cambrian strata over older Cambrian rocks 

which elsewhere in the White Mountains are found in 

conformable sequences. Emplacement of the Mesozoic 

plutons locally deformed much of the older rock. Tertiary through Holocene basin-and-range faulting is 

responsible for the present steep, rugged topography. 

Mining activity in the Black Canyon Roadless Area 

dates back to the early 1860's; no claims were filed in 

the Blanco Mountain Roadless Area until about 1900. 

In the Black Canyon Roadless Area there is one mine 

which produced 11 tons of ore containing gold, silver, 

and copper; this and five additional properties within 

the roadless area contain 49,600 tons of demonstrated 

resources as determined by a mineral-deposit survey by 

the USBM. 

MINERAL RESOURCES 

In the Black Canyon Roadless Area, gold associated 

with veins of quartz, and lead, silver, and zinc in 

calcareous rocks are the major types of metal deposits 

which must be assessed. Tungsten is also known to be 

present in contact zones between granitic and calcareous rocks. 

A single area with substantiated mineral-resource 

potential was identified in Redding Canyon on the 

185 
186 

118°30' 118°00' 

37° 

30' 

Oll. en 

= &J 

Bi loo 

MAP LOCATION 

0 10 

MILES 

EXPLANATION 

Geologic terrane with substantiated 

mineral-resource potential D Geologic terrane with probable 

mineral-resource potential 

Au Gold w Tungsten 

Pb Lead Zn Zinc 

Ag Silver 

~ Mine or deposit 

X Mineral occurrence 

~ Mine 

Surficial deposits (Quaternary) 

fttTr:='*':'l 

;{j;~j{£1% Volcanic rocks (Tertiary) 

~-(,'/-(,' ,_ ,.,., Plutonic rocks (Mesozoic) 

Sedimentary rocks (Paleozoic 

L__ __ _, and Proterozoic ) 

--- Contact 

Figure 52.- Blanco Mountain and Black Canyon Roadless Areas, California 
western side of the Black Canyon Roadless Area Goldbearing quartz veins are present in the Gray Eagle mine 

inside the roadless area and the Little Gem mine, outside, but near, the roadless area Tungsten-bearing 

skarn deposits outside the roadless area in this canyon 

occur at the Mirage-Mariposa mine. This type of deposit 

forms when hot, mineral-bearing fluids from intruding 

magma react with calcareous country rock and form the 

tungsten mineral scheelite. The contact zone from the 

Mirage-Mariposa mine extends into the Black Canyon 

Roadless Area A geochemical survey in the mouth and 

interior of Redding Canyon showed slightly anomalous 

amounts of tungsten and moderately anomalous 

amounts of gold. An area of substantiated resource 

potential for gold and tungsten surrounded by an area 

of probable potential, is based on geologic and geochemical information, and the resources estimated at the 

Gray Eagle mine. 

At the upper end of Redding Canyon, on the east edge 

of the Black Canyon Roadless Area, the Hope Group of 

claims includes the Carol-J mine in the roadless area 

and the Hope mine just outside the roadless area Lead, 

silver, and minor zinc and gold were produced from 

these properties. Slightly anomalous gold and lead 

values were found during the geochemical survey. An 

area of probable resource potential occurs on the east 

edge of the Black Canyon Roadless Area for lead, silver, 

and zinc resources. 

South of Silver Canyon, relatively anomalous 

amounts of gold, silver, lead, and barium were found 

during the geochemical survey. Barite in small veins is 

present in the Barite Queen prospect. Samples from 

Black Canyon were anomalous in lead, silver, and gold. 

Silver and gold occur in quartz veins in shear zones at 

the Black Beauty mine, outside the area. The Hall Extension prospect, inside the area, contains lead and 

silver in a fault-terminated quartz vein. Based on 

available data, there is little promise for the occurrence 

of resources in these areas. 

In the northwestern part of the Blanco Mountain 

Roadless Area a contact zone between granitic rocks 

and calcareous strata may be the source of geochemical 

anomalies of tungsten found in this survey. The Blizzard Extension prospect within the area contains gold 

in small quartz veins. This property is along an igneoussedimentary contact. Based on available information, 

there seems to be little likelihood of the occurrence of 

gold resources. 

Tertiary basalt caps cover older stream gravels in the 

eastern part of the Blanco Mountain Roadless Area. 

Small amounts of gold have been produced from these 

gravels outside the area at the Blue Bird Nos. 1-3 

claims, but there seems little promise for resources inside the roadless area 

The nature of the geologic terrain suggests little 

likelihood of the occurrence of energy resources in the 

roadless areas. 

SUGGESTIONS FOR FURTHER STUDIES 

In the Redding Canyon area detailed geologic mapping might better define the extent of gold mineralization. Detailed stream-sediment sampling and analysis 

of heavy-mineral concentrations could better define 

tungsten resource potential. 

REFERENCES 

Diggles, M. F., 1983. Maps and interpretation of geochemical 

anomalies in the White Mountains, Blanco Mountain, Birch 

Creek, and Black Canyon Roadless Areas, White Mountains, 

California and Nevada: U.S. Geological Survey Miscellaneous 

Field Studies Map MF - 1361-B. scale 1:62,500. 

Diggles, M. F., Dellinger. D. A., Sutley, S. J .. Fey, D. L., and Hill, 

R. H., 1982, Chemical data for samples of rock, stream-sediment, 

and dense-mineral concentrate in the White Mountains, Blanco 

Mountain, Birch Creek, and Black Canyon Roadless Areas, 

White Mountains, California and evada: U.S. Geological 

Survey Open-File Report 82-984, 188 p., scale 1:62,500. 

Diggles. M. F .. Blakely, R. J., Rains, R. L .. Schmauch, S. W., Hom, 

M. C .. Lipton, D. A., Gabby. P. N., Barnes, D. J., and Neumann, 

T. R .. 1983, Mineral resource potential of the Blanco Mountain 

and Black Canyon Roadless Areas, White Mountains, California: 

U.S. Geological Survey Miscellaneous Field Studies Map 

MF- 1361-C, scale 1:62,500. 

McKee, E. H., Diggles, M. F., Donahoe. J. L., and Elliott, G. S., 1982, 

Geologic map of the White Mountains Wilderness and Roadless 

Areas. California and evada: U.S. Geological Survey Miscellaneous Field Studies Map MF- 1361-A, scale 1:62,500. 

Schmauch, S. W .. Lipton, D. A., Gabby, P. .. Barnes, D. J .. and 

Horn, M. C., Mineral investigations of the Blanco Mountain 

RARE II Area (No. 5059), lnyo and Mono Counties. California: 

U.S. Bureau of Mines Open-File ReportMLA 146-82, 12 p. 

187 
18 

40° 

oo· 

Approximate roadless boundary 

MAP LOCATION 

0 5 

M ILES 

EXPLANATION 

D 

Au 

Geologic terrane with probable 

mineral-resource potential 

Gold 

Mine or deposit 

Mine 

Glacial deposits (Quaternary) 

Volcanic rocks (Tertiary) 

Granitoid rocks (Mesozoic) 

Ultramafic rocks (Jurassic 

to Devonian) 

- Calaveras Formation (Pennsylvanian) 

Contact 

Figure 53.-Bucks Lake and Chips Creek Roadless Areas, California 
BUCKS LAKE AND CHIPS CREEK ROADLESS AREAS, CALIFORNIA 

By MARTI L. SORE SE 1,

1 U.S. GEOLOGICAL R E , and 

j . MITCHELL LI E, U.S. B REA OF MI E 

SUMMARY 

The results of a mineral-resource assessment of the Bucks Lake and Chips 

Creek Roadless Areas conducted during 1980- 82 indicate several areas with 

mineral-resource potential. In the Bucks Lake Roadless Area, demonstrated and 

inferred low-grade lode gold resources exist at and near the Shenandoah mine. 

Demonstrated and inferred placer gold resources occur at the Bud Lee, Fales 

Hill, and Monte Cristo mines within the Bucks Lake Roadless Area A probable 

placer gold resource potential exists in the Bucks Lake Roadless Area in areas 

covered by Quaternary glacial deposits. In the Chips Creek Roadless Area, 

demonstrated and inferred low-grade copper-gold-lead-zinc-silver resources exist 

at and near the Belden mine. An area of substantiated placer gold resource 

potential in the Chips Creek Roadless Area is located around the Lotts and Morris mines, and areas of probable placer gold resource potential exist in Quaternary glacial gravel around the Snows mine and along Yell ow Creek. An area of 

probable placer gold resource potential exists between the Lotts and Morris 

mines and the Snows mine where auriferous (gold-bearing) Tertiary stream 

deposits may exist beneath Tertiary volcanic rocks. A similar area of probable 

placer gold resource potential exists beneath Tertiary volcanic rocks in the 

northwest comer of the Chips Creek Roadless Area. No other metallic mineral or 

any energy resources were identified in this study. 

CHARACTER AND SETTING 

The Bucks Lake and Chips Creek Roadless Areas are 

on the west slope of the Sierra Nevada approximately 

20 mi west of Quincy, California The Bucks Lake Roadless Area consists of 30 sq mi in Plumas National 

Forest. The Chips Creek Roadless Area comprises 70 sq 

mi in Lassen and Plumas National Forests. The two 

areas are separated by California Highway 70 and the 

canyon of the North Fork of the Feather River. 

two roadless areas encompass part of one of the faultbounded belts. This belt consists mainly of metasedimentary rocks of Pennsylvanian age (Sorensen and 

Pietropaoli, 1982). 

The Bucks Lake and Chips Creek Roadless Areas are 

in the northern part of the western Sierra Nevada 

metamorphic belt. Steeply dipping faults subdivide this 

metamorphic belt into four north- to northwesttrending belts of Paleozoic and Mesozoic metasedimentary and metavolcanic rocks that have been intruded by 

Mesozoic granitoid plutons and partially covered by 

Cenozoic volcanic rocks (Hietanen, 1973, 1981a, b). The 

'With cootributions from Andrew Griscom and Henry Pietropaoli. USGS. and Scott A. 

tebbins and Donald E. Graham. U BM . 

A mineral-resource study of the Bucks Lake and 

Chips Creek Roadless Areas (Sorensen and others, 1983) 

was conducted during 1980-82. The USGS did reconnaissance geologic mapping in selected areas, fieldchecked published geologic mapping, collected and 

analyzed rock and stream-sediment samples (Sorensen 

and others, 1982), and conducted a geophysical study of 

the roadless areas. The USBM studied the mines and 

prospects in and near the roadless areas and collected 

and analyzed samples from mines, prospects, mineralized areas, and major streams. 

The Bucks Lake and Chips Creek Roadless Areas are 

near the northern end of the principal zone of placer gold 

deposits of the western Sierra Nevada Tertiary and 

Quaternary placer gold deposits in and near the roadless 

areas have been mined by hydraulic and drift methods 

at various times since 1850 when gold was discovered at 

189 
Rich Bar on the East Branch of the North Fork of the 

Feather River. Claims have been filed in and near the 

roadless areas for lode deposits of chromite, copper, 

gold, lead, silver, and zinc, but with the exception of 

limited production from one lode gold deposit (Shenandoah mine) within the Bucks Lake Roadless Area and 

two lode gold deposits (Edman and Megowen mines) adjacent to the Bucks Lake Roadless Area. very little production is recorded for any of these metals from 

deposits within or immediately adjacent to the roadless 

areas. At the time of this study, the Callahan Mining 

Corporation was conducting an evaluation of the 

Shenandoah mine within the Bucks Lake Roadless 

Area. and placer gold was being mined from a gravel bar 

at the Bud Lee mine. Current mining activity within the 

Chips Creek Roadless Area consists of assessment work 

and recreational gold parming and dredging on Chips 

and Yell ow Creeks. 

MINERAL RESOURCES 

Demonstrated and inferred lode gold resources exist 

at and near the Shenandoah mine in the Bucks Lake 

Roadless Area The Shenandoah mine has produced 95 

oz of gold from a zone of irregular bunches and stringers 

of quartz with occasional kidney-shaped enlargements 

(Averill, 1928, p. 295-296). Sampling data of the USBM 

indicate the presence of approximately 7500 tons of 

demonstrated and inferred resources averaging 0.19 

oz/ton gold at the Shenandoah mine. The mineral potential of the Shenandoah mine is currently being evaluated by the Callahan Mining Corporation (R. D. 

Thomas, Callahan Mining Corp., written commun., 

1981). 

The Bud Lee, Fales Hill, and Monte Cristo placer gold 

mines in the Bucks Lake Roadless Area are developed 

on Tertiary auriferous gravel deposits. The Bud Lee 

mine, currently being worked, has demonstrated and inferred resources consisting of an estimated 89,000 cu yd 

of Tertiary river gravels having an average assay value 

of $0.27/cu yd. The operator reports recovering an 

amount of gold equivalent to an average of $10/cu yd 

from local, high-grade parts of the deposit. At the Fales 

Hill mine, gold has been recovered from deposits in 

deeply weathered bedrock, where the gold was concentrated during earlier hydraulic mining operations. 

Approximately 154,000 cu yd of demonstrated and inferred gold-bearing resources are at the Fales Hill mine, 

but there are difficulties in extracting gold from the 

weathered bedrock. Approximately 56,000 cu yd of 

demonstrated and inferred gold-bearing gravel 

resources are at the Monte Cristo mine. Nearby exposures of Tertiary river deposits suggest that any exten190 

sions of the Monte Cristo deposit will contain very little 

gold. 

Quaternary surficial deposits in the Bucks Lake 

Roadless Area may contain gold reworked from Tertiary stream deposits. An area of glacial deposits in the 

eastern part of the Bucks Lake Roadless Area has probable resource potential for reworked placer gold. 

Demonstrated and inferred resources of copper, gold, 

lead, and silver exist in a vein at the Belden mine in the 

Chips Creek Roadless Area Production is not recorded 

for this deposit, but 6400 to 15,000 tons of low-grade 

resources averaging 0.08 oz/ton gold, 0.52 oz/ton silver, 

0.52 percent copper, and 1.69 percent lead are present at 

the Belden mine. Additional resources may occur along 

strike or at depth in the vein. 

An area around Mt. Hope that contains the Lotts and 

Morris mines has a substantiated potential for placer 

gold deposits. These mines contain demonstrated and 

inferred resources of 188,000 cu yd of auriferous Tertiary stream gravels. 

A probable resource potential for placer gold deposits 

exists in an area around the Snows mine, southwest of 

the Lotts and Morris mines. The deposit is not exposed 

at present, but the operators were reported to have been 

working in gravel with a high gold content when operations were halted due to a cave-in (Lindgren, 1911, 

p. 96). 

A probable resource potential for placer gold is 

recognized in the area between the Lotts, Morris, and 

Snows mines, where Tertiary stream deposits mined at 

those properties are probably present beneath Tertiary 

volcanic rocks. Similarly, a probable resource potential 

for placer gold exists in the northwest corner of the 

Chips Creek Roadless Area. where Tertiary volcanic 

rocks may overlie a concealed extension of the deposits 

mined at the Lotts and Morris properties. 

A probable resource potential for placer gold deposits 

is present along Yellow Creek near the east boundary of 

the Chips Creek Roadless Area Panned concentrates of 

stream sediments collected during this study contained 

as much as 100 parts per million gold (Sorensen and 

others, 1983). Tertiary auriferous gravel deposits 

traversed by Yell ow Creek north of the roadless area 

have contributed reworked placer gold to the Yellow 

Creek drainage (Haley, 1923, p. 102). The presence of 

this gold is disclosed by chemical analysis and strongly 

suggested by numerous mining claims along Yell ow 

Creek just north of the North Fork of the Feather River. 

Quaternary surficial deposits may contain gold reworked from Tertiary stream deposits. Glacial deposits 

north of Chambers Peak are considered to have a probable resource potential for reworked detrital gold. 

Claims are recorded for copper and chromite deposits 

in the roadless areas, but the results of the present 
study suggest that there is little promise for the occurrence of resources of these minerals. No potential for oil, 

gas, coal, or geothermal resources was identified within 

the study area 

SUGGESTIONS FOR FURTHER STUDIES 

Early Tertiary stream deposits may be present 

beneath late Tertiary volcanic rocks between the Snows 

and Lotts mines and north of these properties in the 

Chips Creek Roadless Area The presence or absence of 

these potentially auriferous deposits can best be determined by drilling through the relatively thin cover of 

volcanic rocks. 

REFERENCES 

Averill, C. V ., 1928, District reports of mining engineers, Redding 

field division, Plumas County, in Report 24 of the State 

Mineralogists: California Division of Mines and Geology, 

p. 261-316. 

Haley, C. S., 1923, Gold placers of California: California tate Mining 

Bureau Bulletin 92, 167 p. 

Hietanen, Anna, 1973. Geology of the Pulga and Bucks Lake 

quadrangles, Butte and Plumas Counties, California: U.S. Geological Survey Professional Paper 731,66 p. 

__ 1981a, Geology west of the Melones fault between the Feather 

and North Yuba Rivers, California: U.S. Geological urvey Professional Paper 1226-A, 35 p. 

__ 1981b, The Feather River area as a part of the ierra Nevada 

suture system in California: U.S. Geological Survey Professional 

Paper 1226-B, 13 p. 

Lindgren, Waldemar, 1911, The Tertiary gravels of the Sierra evada 

of California: U.S. Geological Survey Professional Paper 73, 

226 p. 

Sorensen, M. L., Griscom, Andrew, Linne, J. M., Stebbins, . A., and 

Graham, D. E., 1983, Mineral resource potential map of the Chips 

Creek and Bucks Lake Creek Roadless Areas, Butte and Plumas 

Counties, California: U.S. Geological Survey Miscellaneous Field 

Studies Map MF-1419-B, scale 1:62,500. 

Sorensen, M. L., and Pietropaoli, Henry, 1982, Geologic map of the 

Chips Creek and Bucks Lake Roadless Areas, Butte and Plumas 

Counties, California: U.S. Geological Survey Miscellaneous Field 

Studies Map MF- 1419- A, scale 1:62,500. 

Sorensen, M. L., Pietropaoli, Henry, and Peterson, J. A., 1982, 

Geochemical analyses of rock and stream sediment samples from 

Bald Rock, Bucks Lake, Chips Creek, and Middle Fork Feather 

River Roadless Areas, Butte and Plumas Counties, California: 

U.S. Geological Survey Open-File Report 82- 776, 52 p., 2 maps, 

scale 1:62,500. 

191 
192 

37° 

30' 

MOUNT TOM 

Approximate 

boundary 

BASIN 

MOUNTAIN 

o--

MT 

HUMPHYRES 

;'! .:;:. :: ::. ~"::= 

.. ~ 

1/ :-;.. IJ :u lfcJ 

q-:--'/ Unconsolidated 

'\ Quaternary 

deposits 

0 5 

MILES 

Figure 54.-Buttermilk Roadless Area, California 

118°20' 

Bisho p 

MAP LOCATION 
BUTTERMILK ROADLESS AREA, CALIFORNIA 

By EDWI H . M CK EE, U.S. GEOLOGICAL SURVEY, and 

STEPHE R . IVERSON, U.S. BUREA OF MI ES 

SUMMARY 

The results of geologic, geochemical, and mining activity and production 

surveys made in 1980 in the Buttermilk Roadless Area indicate little or no 

promise for the discovery of metallic or energy resources in the area (McKee and 

Iverson, 1982). Glacial till and other types of surficial alluvium cover the 

bedrock to a depth of tens and probably hundreds of feet preventing examination and evaluation of possible minerals that might be present in the bedrock. 

No mining claims are known to be in the area and the nearest mining activity is 

too far removed to reasonably project mineralization into the buried bedrock of 

the roadless area The glacial till has little promise for placer deposits because 

the eroded debris has had little or no sorting and concentration by natural 

hydraulic action. 

CHARACTER AND SETTING 

The Buttermilk Roadless Area is on the eastern side 

of the Sierra Nevada about 12 mi west of Bishop, California It is contiguous with the John Muir Wilderness 

on its west side. The roadless area is 1.5 sq mi and lies at 

elevations between 7700 and 8700 ft above sea level. 

Easy access to its eastern boundary is by an unimproved dirt road that leads to McGee Creek, a major 

water source for Bishop. 

The Buttermilk Roadless Area is covered entirely by 

unconsolidated Quaternary deposits including glacial 

till from at least three glacial periods recognized in the 

Sierra Nevada, and younger talus and alluvial-fan 

deposits. Bedrock is at an unknown depth beneath these 

surficial deposits but it is probably several tens to hundreds of feet beneath the surface. Outcrops of Triassic 

and Cretaceous granitic and Triassic or older mafic 

metavolcanic rock occur within about one half mile of 

the roadless area but the highly faulted nature of the 

eastern front of the Sierra Nevada make projection of 

the depth of bedrock beneath alluvium very speculative. 

The glacial deposits are unsorted piles of rock rubble 

transported to their present site by flowing glaciers. As 

such, they contain a wide size range and variety of rock 

types. Glacial deposits classified as belonging to the 

Sherwin, Tahoe, and the Tioga Glaciations consist of 

rem.mants of moraines and other glacial detritus. The 

talus includes rock glaciers and some reworked till or 

modified moraine deposits; the alluvial fans are the 

debris that accumulated where a significant flattening 

in slope occurs and alluvium gathers. Less steep parts 

of the roadless area are covered with variable thicknesses of talus and alluvial fans that are younger than 

the glacial till deposits. 

MINERAL RESOURCES 

Examination of the Buttermilk Roadless Area and 

sample analyses failed to reveal any indication of 

metallic, nonmetallic, or energy resources. The entire 

area is covered by a considerable thickness of glacial 

debris and bedrock which might prove a target for exploration is at variable depths probably measured in 

tens or hundreds of feet. Analyses of gravel samples 

taken where gold or other heavy metals would tend to 

accumulate contain no valuable heavy minerals. Glacial 

till which comprises most of the surficial deposits in the 

area is not particularly good as host for placer deposits 

because of the lack of natural hydraulic action to concentrate minerals of differing specific gravity. 

SUGGESTIONS FOR FURTHER STUDIES 

Further study of the roadless area offers little promise 

for the identification of hidden mineral deposits. Bedrock exposures are no closer than about 0.5 mi from the 

193 
roadless area and have no known mineral deposits so 

that subsurface exploration does not seem warranted. 

REFERENCE 

McKee, E. H., and Iverson, S. R., 1982, Mineral resources of the Buttermilk Roadless Area, Inyo County, California: U.S. Geological 

Survey Open-File Report 82-380, 10 p. 

194 
CACTUS SPRING ROADLESS AREA, CALIFORNIA 

By jO ATHA C. MAITI, 1 U .S. GEOLOGICAL R EY, and 

L CIA K UIZO , U.S. BUREAU OF MINE 

SUMMARY 

Geologic, geochemical, and geophysical studies by the USGS in 1980-82, 

together with a review of historic mining and prospecting activities by the 

USBM, indicate that the Cactus Spring Roadless Area has little promise for the 

occurrence of mineral or energy resources. Marble bodies occur in the northern 

part of the roadless area and are possible resources for building stone, crushed 

and quarried aggregate, and lime and magnesium for Portland cement and industrial applications. No resource potential was identified for the marble 

because the quantity and quality of the resources was not established. 

CHARACTER AND SETTING 

The Cactus Spring Roadless Area is located in the 

Santa Rosa Mountains, about 25 mi southeast of Palm 

Springs and about 10 mi south of Palm Desert, California The roadless area consists of about 30 sq mi within 

the San Bernardino National Forest, and includes 

rugged mountainous terrain covered with coniferous 

forest and dense chaparral as well as rolling high-desert 

terrain that supports a blend of desert scrub and pinonjuniper woodland. Topographic relief within the roadless area ranges from about 4000 ft to about 7600 ft; 

prominent summits in the vicinity include Martinez 

Mountain (6562 ft) and Toro Peak (8716 ft). Two major 

stream drainages bisect the roadless area: Horsethief 

Creek flowing northwestward into Deep Canyon, and an 

unnamed perennial stream flowing southeastward 

through Martinez Canyon. Access to the roadless area 

is limited because it is almost entirely surrounded by 

rugged ground that has no roads and few established 

trails. One foot trail that does provide access originates 

near California State Highway 7 4 at the northwest 

corner of the roadless area 

The Cactus Spring Roadless Area is underlain by 

plutonic igneous rocks and metamorphosed sedimentary rocks. The crystalline units have been deformed 

during at least two major events (Sharp, 1979): a period 

of intense ductile shearing that stretched and squeezed 

the rocks and produced foliated and layered fabrics 

(mylonitic fabrics); and a period of brittle deformation 

1

Wilh contributions from BreLL r. Cox. Robert E. Powell. Bradley Erskine. Eduardo A. 

Rodriguez. Scot.L E. Carson. and Curtis M. Obi. USG . 

during which different rock types were juxtaposed by 

large-scale lateral movements on thrust faults. Valley 

areas within the roadless area locally are mantled by 

Quaternary deposits of sand and gravel, and landslides 

are developed on some hillslopes. 

The oldest rocks in the roadless area consist of 

metasedimentary units that include biotite schist and 

phyllite, gneiss, metaquartzite, and calcareous and 

dolomitic marble. These rocks represent ancient accumulations of clay, silt, sand, and calcareous sediment 

that were deposited in the sea, probably during the 

Paleozoic Era or during Precambrian time. During the 

Mesozoic Era, the lithified sedimentary rocks were intruded by large plutonic bodies of granitic magma 

High temperature and pressure associated with these 

igneous events converted the sedimentary rock to 

schist, phyllite, metaquartzite, gneiss, and marble by 

metamorphic processes that partially melted the sedimentary rocks, folded and sheared-out the sedimentary 

layering, and produced new mineral assemblages. The 

igneous bodies produced during these events include 

various types of granitic rock (monzogranite, granodiorite, tonalite, and quartz diorite) that occupy much of 

the Cactus Spring Roadless Area. Although these 

plutonic and metamorphic events provided a geologic 

setting within which mineralizing systems could have 

operated to produce mineral deposits in the Cactus 

Spring Roadless Area, we did not observe geologic 

evidence for mineral concentrations or deposits. 

Toward the end of these plutonic and metamorphic 

events, some rocks in the region were subjected to intense ductile shearing that stretched and squeezed the 

195 
196 

Is 

gr 

116°30' 

Surficial deposits 

Landslide deposits 

Granitoid rocks 

ms Metasedimentary rocks 

0 

M ILES 

EXPLANATION 

Rocks deformed by ductile shearing 

5 

Contact 

Fault 

• • Thrust fault--Sawteeth on 

upper plate 

Mine 

Figure 55. - Cactus Spring Road.less Area, California 
rocks, resulting in a variety of deformational fabrics. 

Rocks in the southwest part of the road.less area 

generally escaped this deformation, or only were affected mildly by it. However, northeastward toward 

Horsethief Creek, the rocks progressively display increasing evidence of shearing. In the deformed zone, the 

rocks are strongly foliated, culminating in mylonitic 

fabrics that largely obscure the original plutonic or 

metamorphic appearance of the rocks. The most intensely deformed rocks are represented by a narrow belt 

of dark-colored, fine-grained mylonite that occurs along 

the south flank of Horsethief Creek. Northeast of 

Horsethief Creek, toward Sheep Mountain, the rocks 

also are foliated and mylonitized, although not so intensely as the mylonite along Horsethief Creek. There is 

no evidence that mineral deposits were produced within 

the Cactus Spring Road.less Area during this period of 

ductile shearing. 

After the period of ductile deformation, rocks in the 

roadless area were cut by low-angle thrust faults that 

broke the rocks into brittle slabs or plates and carried 

these plates laterally. Some thrust-fault-bounded plates 

may have been displaced only a short distance. However, other plates may have been displaced a few miles 

or even a few tens of miles laterally, as suggested by 

relationships on Martinez Mountain where a thrustfaulted plate of relatively undeformed granitic rock 

overlies a plate of highly deformed granitic and 

metasedimentary rocks. Mineral deposits apparently 

were not produced within the Cactus Spring Road.less 

Area during this period of thrust faulting. Instead, 

rocks that may have been mineralized during earlier 

geologic events merely were redistributed within the 

mountain range by movements on the thrust faults. 

A reconnaissance geochemical survey of stream sediment in the Cactus Spring Road.less Area was conducted to identify spatial variations in stream-sediment 

chemistry that might reflect local concentrations of ore 

minerals in bedrocks drained by the streams. The 

patterns of chemical composition determined by the 

geochemical survey do not indicate significant mineralization within the road.less area Most of the analyses fall 

within ranges that are reasonable for nonmineralized 

crystalline rocks and derivative stream sediment; few 

elemental values are anomalous with respect to average 

geochemical abundances for the road.less area An aerial 

magnetic survey of the roadless area (U.S. Geological 

Survey, 1982) did not reveal any abnormal patterns of 

rock magnetism and thus provides no indication of 

mineral resources. 

Our investigation of historic mining and prospecting 

activity indicates that no mineral production has come 

from the Cactus Spring Road.less Area, no mines and 

prospects exist in the area, and only three currently inactive claims have been filed within the boundaries of 

the road.less area 

MINERAL RESOURCES 

Geologic, geochemical, and geophysical investigations, together with a review of prospecting and mining 

activities, indicate that the Cactus Spring Road.less 

Area has little promise for the occurrence of mineral or 

energy resources. 

Although geologic mapping within the road.less area 

has identified geologic environments potentially favorable for mineralization, we did not observe evidence of 

mineral concentrations or mineral deposits within these 

environments. Small-scale occurrences of tungsten in 

tactite (skarn) settings have been identified elsewhere in 

the Santa Rosa Mountains, where bodies of metasedimentary rock have been engulfed by granitic rock. 

However, we did not observe evidence for tungsten 

mineralization in metasedimentary rocks of the road.less 

area Bodies of marble (metamorphosed limestone and 

dolomite) occur within the road.less area in the belt of 

metasedimentary rock north of Horsethief Creek. The 

marble units are possible resources for crushed aggregate, building stone, and lime and magnesium for Portland cement and industrial applications. The marble has 

variable magnesium content, ranges from pure carbonate to carbonate containing nodules of silica and 

clots of calc-silicate minerals, and includes relatively 

thick monolithologic carbonate units as well as thin lenticular units that are interlayered complexly with noncarbonate metasedimentary rocks. Because the marble 

units have variable quantity, composition, quality, 

thickness, and extent, detailed mapping and sampling 

would be needed to assess the resource potential of this 

commodity. 

Generally low concentrations of metallic and nonmetallic elements in stream sediments sampled within 

the road.less area indicate that elemental abundance 

generally fall within background ranges expected for 

nonmineralized rocks. 

Aeromagnetic patterns do not point to the existence 

of economic concentrations of magnetic minerals. 

Within the boundaries of the road.less area, prospecting activities have been limited and short lived, no production has been reported, and no deposits of metallic or 

radioactive minerals have been discovered. The three 

currently inactive claims within the road.less area were 

filed for marble deposits similar to those that occur at 

the Dolomite mine. Two of the claims do not contain 

marble and the third contains marble units that are thin 

extensions of the marble occurring at the Dolomite 

mine; no carbonate resources were identified. 

197 
SUGGESTIONS FOR FURTHER STUDIES 

The results of the mineral-resource survey indicate 

that further study of the roadless area for mineral and 

energy resources is not warranted. In the event that 

future mineral resource investigations are contemplated, it is recommended that the terrane of marble be 

mapped and sampled carefully in order to evaluate the 

quantity and quality of the carbonate resources. 

198 

REFERENCES 

Matti, J. C., Cox. B. F ... Powell, R. E .. and Ku.izon, Lucia, in press, 

Mineral resource potential map of the Cactus Spring Roadless 

Area. River ide County. California: U.S. Geological Uivey 

Miscellaneous Field Studies Map MF- 1650- A. scale 1:24.000. 

Sharp. Robert V .. 1979, Some characteristics of the eastern Penin· 

sular Ranges mylonite zone. in peed, Robert, and Sharp, 

Robert, Analysis of actual fault zones in bedrock: U.S. Geological 

SUIVey Open·file Report 79- 1239. p. 25 - 267. 

U.S. Geological SUivey, 1982, Aeromagnetic map of the Cactus 

Spring Further Planning Area. California: U.S. Geological 

SUIVey Open-file Report 82-945. 
CARIBOU WILDERNESS AND TRAIL LAKE ROADLESS AREA, CALIFORNIA 

By ALISO B. TILL,

1 U.S. GEOLOG I AL S RVEY and 

' 

EDWARD L. M CH GH, .S. B REA OF MI E 

SUMMARY 

A mineral survey of the Caribou Wilderness and Trail Lake Roadless Area 

conducted in 1979 revealed no indications of a potential for mineral or fossil fuel 

resources in the areas. The wilderness is in the Cascade volcanic province, a setting locally favorable for geothermal resources, but no geothermal resource 

potential was identified in the wilderness or roadless area. 

CHARACTER AND SETTING 

The Caribou Wilderness and Trail Lake Roadless 

Area are part of Lassen National Forest, in northeast 

California They are adjacent to the east boundary of 

Lassen Volcanic National Park and together are 

roughly 8.5 mi from north to south and 6 mi from east 

to west, a total of about 34 sq mi. Susanville, California, 

the nearest population center, is 25 mi to the east. Redding, California is 65 mi to the west. 

Caribou Wilderness and Trail Lake Roadless Area lie 

within the southernmost part of the Cascade Range. 

The wilderness and roadless area are near the juncture 

of three major geologic provinces: the Cascade volcanic 

province, the Modoc plateau volcanic province, and the 

Sierra Nevada province of metamorphic and plutonic 

rocks. Geologic units within the area may be assigned to 

the High Cascade Volcanic series of Macdonald (1966), 

the post-Miocene rocks that form the crest of the 

Cascade Range. Oldest units of the High Cascade series 

are deeply eroded block-faulted lavas assigned a latest 

Pliocene age by Macdonald (1964). The lavas of the 

Caribou Wilderness and Trail Lake Roadless Area are 

less deeply eroded, less pervasively block faulted, and 

are probably Pleistocene to Holocene in age. The 

wilderness is a high plateau of Pleistocene basaltic 

andesite flows and basalt buttes. A thin veneer of 

glacial and lacustrine deposits occupies the central 

valley of the plateau. A Holocene basaltic cinder cone 

and flows that emanated from it sit on the north end of 

the plateau. The Trail Lake Roadless Area is on the east 

flank of the Caribou Wilderness. Rocks exposed there 

'Wit.h contributions from Cloywn M. Rumsey. USBM . 

are the Pleistocene basaltic andesite which forms the 

high plateau of the Caribou Wilderness. Northwest of 

Silver Lake the wilderness and roadless area are physically separated by a vertical fault scarp as much as 

150ft high. 

A light-medium-gray porphyritic basaltic andesite is 

the major unit in the wilderness and the only unit in the 

roadless area It is a thick composite unit which includes flows and a subordinate volume of cinders 

erupted from numerous vents. The most prominent 

vents within the wilderness are North Caribou and 

South Caribou. Lavas erupted from Red Cinder overlie the basaltic andesite and are medium dark gray, 

sparsely porphyritic and glomeroporphyritic, and commonly platey and vesicular. Abundant red cinders cap 

the peak itself. The basaltic andesite and the basalt of 

Red Cinder have been glaciated. Both units are cut by 

near vertical faults trending roughly north south. A 

series of steep, talus-sided flat-topped buttes from 1/3-

to 1/2-mi in diameter and as high as 300 ft are found in 

the central valley of the wilderness. They are composed 

of glassy olivine basalt, sit on the basaltic andesite, and 

were erupted along a roughly north-south trending line 

which is parallel to the vertical faults which cut the 

basaltic andesite. The general shape, limited lateral extent, glassy texture, and jointing perpendicular to the 

margins of the buttes are characteristics strongly suggestive of subglacial origin. The glacial deposits in the 

central valley of the wilderness consist of a thin veneer 

of ground moraine that is locally overlain by lacustrine 

deposits. The flows that emanate from Black Butte, a 

prominent cinder cone on the north boundary of the wilderness, are the youngest in the area The flows are 

blocky, generally unvegetated, reddish gray, and 6 to 

30ft thick. 

199 
200 

40° 

35' 

40° 

30' 

r 

Butt~ 

Lak< 

121 °15' 121 °10' 

'To Reddmg 

Lake 

Bogar J B II 

l.J p r St.,ph s Meadow 

Approximate boundary 

A5095 Approximate 

J... roadless 

,/ /f--"boundary 

K.l. ~,[_rai l Lake 

/ ' 0 X 

Nortn Cartbou 

South Caobou 

0 2 

MILES 

EXPLANATION 

\A5095 

( 

J 

D Quaternary and Tertiary basalt 

D Tertiary basaltic andesite 

Contact 

Fault--Bar and ball on downthrown side 

MAP LOCATION 

Figure 56.-Caribou Wilderness and Trail Lake Roadless Area. California 
MINERAL RESOURCES 

Geologic mapping, geochemical sampling, and 

aeromagnetic surveys by the USGS and field assessment by the USBM have found little promise for the occurrence of metallic mineral or energy resources in the 

Caribou Wilderness and Trail Lake Roadless Area 

Cinders, suitable for road metal, are locally abundant 

but difficult to access relative to more plentiful deposits 

outside of the wilderness. Hot springs, mineral sublimates from fumaroles, or other surface features indicating geothermal resource potential were not found. 

The wilderness is 1 mi northeast of the Morgan Springs 

Geothermal Resource Area (KGRA) that adjoins the 

south side of Lassen Volcanic National Park and more 

than 100 hot springs are known 7-15 mi west of the area 

(Waring, 1968, p. 20-21). Although known geothermal 

resources occur in the vicinity of Lassen Volcanic National Park, drilling is necessary to assess the geothermal resource potential of the Caribou Wilderness and 

Trail Lake Roadless Area 

No mining claims have been located, and no mines or 

prospects are known within the area studied. Mining for 

gold has occurred in Mesozoic granitic rocks in the Diamond Mountain gold district, 25 mi to the southeast, 

and in Mesozoic rhyolitic tuffs at Hayden Hill, 36 mi 

northeast of the wilderness and roadless area Copper 

was mined 27 mi southeast of the area in the Plumas 

copper belt. Host rocks for these deposits are older than 

rocks of the Caribou Wilderness. In Lassen Volcanic 

National Park, the Supan Sulphur Works 15 rni 'West of 

the wilderness produced a small amount of sulfur before 

1900 (Lydon, 1957, p. 616). The sulfur was deposited 

from hot gasses or water released at the Earth's surface. 

No sulfur was identified in the wilderness and roadless 

area 

Volcanic cinders have been mined from at least 14 

sites within 10 mi of the wilderness. Most were used as 

road building material, railroad ballast, or as lightweight aggregate in concrete. Several million cubic 

yards of good quality cinders are available within the 

wilderness at Black Butte, Red Cinder, and other 

smaller cones, but abundant cinders are available at 

sources outside these areas. 

Large volumes of basalt and andesite within the areas 

studied are potential sources of stone for construction 

uses. Quarries throughout the region have yielded 

undetermined quantities of stone, mostly used for road 

building and stone sources outside the wilderness, are 

sufficient to meet future needs. 

SUGGESTION FOR FURTHER STUDIES 

Further study of the wilderness and roadless area is 

not likely to identify mineral resources. The geologic 

setting is favorable for geothermal resources, but regional studies and drilling would be necessary to identify geothermal resource potential. 

REFERENCES 

Kane, Phillip. 1982, Pleistocene glaciation in Lassen Volcanic a· 

tiona! Park: California Geology, v. 35. no. 5, p. 95- 105. 

Lydon, P. A .. 1957, Sulfur and sulfuric acid, in Wright, L. A .. editor. 

Mineral co=odities of California: California Division Mines 

Bulletin 176. p. 613- 622. 

Macdonald. G. A., 1964. Geology of the Prospect Peak quadrangle, 

California: U.S. Geological Survey Geologic Quadrangle Map 

GQ-345, scale 1:62,500. 

__ 1966, Geologic map of the Harvey Mountain quadrangle, 

Lassen County, California: U.S. Geological Survey Geologic 

Quadrangle Map GQ- 443, scale 1:62,500. 

Till, A. B., McHugh, E. L., and Rumsey, C. M., 1983, Mineral resource 

potential of the Caribou Wilderness and Trail Lake Roadless 

Area, Lassen and Plumas Counties, California: U.S. Geological 

Survey Open-File Report 83-481. 

U.S. Geological Survey, 1978, Lands valuable for geothermal 

resources, northern California: Office of Area Geologist, 

Conservation Division, scale 1:500,000. 

Waring. G. A., 1968, Thermal springs of the United States and other 

countries of the world- A su=ary: U.S. Geological Survey Professional Paper 492, 383 p. 

Williams, Howe!. 1932, Geology of the Lassen Volcanic National 

Park, California: University of California, Department of Geological Sciences Bulletin, v. 21, no. 8, p. 195- 385. 

201 
202 

120°00' 

} 

0 10 

MILES 

EXPLANATION D Geologic terrane with probable 

mineral-resource potential 

D Granitic and metamorphic 

rocks (Cretaceous) 

Cu 

Au 

Pb 

M o 

Ag 

w 

u 

Zn 

~ 

Copper 

Gold 

Lead 

Volcanic and associated 

sedimentary rocks 

Molybdenum --- Contact 

Silver ---Fault 

Tungsten 

Uranium B Area discussed in text 

Zinc 

Mine or deposit 

Figure 57.-Carson-Iceberg Roadless Areas, California 
CARSON-ICEBERG ROADLESS AREAS, CALIFORNIA 

By WILLIAM j. K EITH , 1 U.S. G EOLOG ICAL S RVEY, and 

MICHAEL S . MILLER, .. BUREA OF MI E 

SUMMARY 

Areas of probable mineral-resource potential for base and precious metals, 

molybdenum, tungsten, and uranium were identified in 1979- 81 by the USGS 

and the USBM in the Carson-Iceberg Roadless Areas, California. During the 

mineral-resource study existing geologic mapping was modified and supplemented with new mapping; geophysical studies were conducted in the form of 

gravity and aeromagnetic surveys; stream-sediment and rock samples were collected in all of the drainage basins and chemically analyzed; and the USBM personnel conducted studies of mines, prospects, and known mineralized areas. o 

evidence of fossil fuel resource potential was found in the study. 

CHARACTER AND SETTING 

The Carson-Iceberg Roadless Areas form a roughly 

circular area of 343 sq mi in Alpine and Tuolumne Counties, California The roadless areas are bisected by the 

northwest-trending boundary of the Stanislaus and 

Toiyabe National Forests which coincides with the crest 

of the Sierra Nevada The Carson-Iceberg Roadless 

Areas are bounded approximately on the east by the 

Mono-Alpine County boundary; on the south by California State Highway 108; on the west by the west boundary of the Dardanelles Cone 15-minute quadrangle, and 

on the north by California State Highway 4 and the 

East Fork of the Carson River. The area is quite rugged 

containing many peaks over 10,000 ft in altitude and at 

least one that reaches 11,462 ft (Sonora Peak). 

The oldest rocks in the roadless areas are Cretaceous 

granitic gneisses and undivided metamorphic rocks. 

These are either surrounded by or included in plutonic 

rocks of Mesozoic age. The plutonic rocks are mostly 

granodiorite, although small bodies of alaskite, tonalite, 

and adamellite occur locally. 

Tertiary and Quaternary age volcanic rocks and 

minor interbedded sedimentary rocks intrude and overlie the older rocks. 

'Wit.h contributions from Mouricc A. Chaffee and Donald Plou ff. USG . 

MINERAL RESOURCES 

There are four areas (A-D, on map) in the CarsonIceberg Roadless Areas that have probable mineralresource potential. These areas of probable potential are 

discussed in order of their importance. 

The obel Canyon drainage basin in the northern part 

of areas C4- 986 and C5-986 (area A , on map) contains 

geochernically anomalous concentrations of silver, 

arsenic, lead, and copper in stream sediments. It contains both plutonic and volcanic rocks, including 

younger silicic volcanic rocks which are strongly favorable host rocks. This area also contains a zone of intense 

hydrothermal alteration as indicated by the presence of 

an iron-barium-strontium-cobalt alteration suite, 

silicification, argillization, and strong bleaching and 

pyritization. A fault in Nobel Canyon is probably one of 

the feeders for alteration and mineralization in the area 

Further south in area A, sediment from a stream 

draining the Highland Lakes contains anomalous 

amounts of silver, copper, lead, zinc, iron, and barium. 

Sediments from streams draining Iceberg Peak, at the 

southern end of the strip, contain anomalous concentrations of silver, copper, cadmium, molybdenum, barium, 

and strontium. Although there are no known mineral 

deposits in this area, it has been heavily prospected in 

the past, and trace amounts of placer gold can still be 

found in various creeks in the area 

Area A extends northward, outside the roadless 

areas, into the Silver Mountain mining district which 

has many inactive gold and silver mines and prospects. 

203 
Area B contains drainage basins with anomalous concentrations of lead, arsenic, silver, antimony, bismuth, 

tin, beryllium, boron, and molybdenum. Favorable rock 

types in this area consist of metamorphic rocks and 

granitic rocks. The rocks contain many areas of shearing and quartz veining and are largely hydrothermally 

altered. The area has been extensively prospected. The 

Hilltop mine, on the west edge of the area. has demonstrated resources of 720,000 tons containing an estimated 0.17 oz gold/ton. The mineral resources in this 

area would most likely be precious-metals in veins or 

porphyry molybdenum-tungsten-type deposits. 

Drainage basins in area C contain anomalous 

amounts of copper, lead, silver, arsenic, and antimony 

and also minor amounts of alteration and shearing. 

There is a probable potential for vein-type precious 

metal resources. 

Area D contains only minor amounts of alteration, 

shearing, and anomalous amounts of molybdenum, tin, 

and tungsten. Resources here would probably be molybdenum or tungsten of the quartz vein or pegmatite type. 

Areas of probable uranium potential are shown where 

the geologic environment would support the presence of 

uranium oxide. Uranium is concentrated in the basal 

sedimentary rocks of the largely volcanic Miocene 

Relief Peak Formation which is widespread in the 

204 

roadless areas. The uranium was probably leached from 

the overlying Miocene Eureka Valley Tuff also largely 

of volcanic origin. A mine south of the roadless area produced 45,000 lbs of uranium oxide from 1963 to 1966 in 

areas of similar geologic environment and age. 

SUGGESTIONS FOR FURTHER STUDIES 

Areas A and B contain combinations of geologic and 

geochemical indicators strong enough to warrant further study of these two areas. However, the location of 

these areas, the limited access, and the fact that these 

areas are used extensively for recreation, probably 

preclude larg~7scale exploration attempts. 

REFERENCES 

Keith, W. J., Dohrenwend. J. C., Giusso, J. R., and John, D. A., 1982, 

Geologic map of the Carson-Iceberg and Leavitt Lake Roadless 

Areas, central Sierra evada, California; U.S. Geological Survey 

Miscellaneous Field Studies Map MF- 1416- A, scale 1:62,500. 

Keith, W. J., Chaffee, M. A., Plouff, D., and Miller, M. S., 1982, 

Mineral resource potential of the Carson-Iceberg Roadless Areas, 

central Sierra Nevada, California; U.S. Geological Survey 

Miscellaneous Field Studies Map MF- 1416- B, scale 1:62,500. 
CHANCHELULLA ROADLESS AREA, CALIFORNIA 

By D O ALD F. H BER,' U .S. GEOLO !CAL UR EY , and 

SCOIT A. STEBBINS, U. . B REA OF Mr E 

SUMMARY 

On the basis of a mineral survey in 1980-82, there seems to be little likelihood 

for the occurrence of mineral resources in the Chanchelulla Roadless Area, 

California, except for a demonstrated resource of about 7200 tons containing 

0.084 oz gold/ton, 0.84 oz silver/ton, and accessory copper at the Chanchelulla 

prospect. This prospect is located on a northwest-trending quartz vein. 

Limestone and small amounts of magnetite occur in the area but on the basis of 

available data no resources are identified. No potential for energy resources was 

identified. 

CHARACTER AND SETTING 

The Chanchelulla Roadless Area occupies an area of 

about 18.6 sq mi in the Klamath Mountains about 8 mi 

southeast of Hayfork, California Altitude above sea 

level ranges from 2850 ft on the north, along East Fork 

Hayfork Creek, to 6399 ft on Chanchelulla Peak, near 

the center of the roadless area 

The roadless area is underlain by sedimentary rocks 

in the northwest and northeast. The remainder of the 

roadless area is underlain by mafic and ultramafic 

rocks. The sedimentary rocks were accreted to the 

North American continent by plate-tectonic processes 

between 230 and 185 million years ago (Early Triassic 

to Early Jurassic). The mafic and ultramafic rocks were 

intruded between 160 and 170 million years ago (Middle 

Jurassic). The sedimentary rocks in the roadless area 

are all in fault contact with the mafic and ultramafic 

rocks. 

Streams draining the roadless area were sampled, and 

representative samples of the rock types in the area 

were collected. Samples from all mines and prospects 

were collected and analyzed to check the nature of the 

mineralized rock. The rock sample analyses were used to 

establish background values to compare with the 

stream sediment analyses, and evaluated in terms of 

geologic setting and resource significance. 

Mining in the Klamath Mountains began in 1848 with 

the discovery of gold in the Trinity River and has continued intermittently since then. The gravels of the 

'With contributions from ScoLL C. elson and Luis A. F'rnticelli. USC . 

East Fork of Hayfork Creek, just north of the roadless 

area, have been mined using various placer techniques. 

The Midas mine 3 mi south of the roadless area, was one 

of the largest gold producers in Shasta County during 

the early part of the century. Various prospects and 

claims have been located in or near the roadless area 

Within the roadless area the prospects include the 

Chanchelulla and the Potato Creek. Near the boundaries 

of the roadless area the prospects include the Iron Chief, 

the Deer Lick Springs, and the High Channel. 

MINERAL RESOURCES 

Lode gold and silver are present in the roadless area 

at the Chanchelulla prospect. The prospect was discovered in 1929 and produced 1 oz of gold and 14 oz of 

silver in 1958. Demonstrated resources of over 7200 

tons are estimated from a quartz vein 1.5 ft thick, 480 ft 

northwest-southeast along strike and 120 ft down dip. 

Actual exposure of the vein is 240 ft along strike. The 

quartz vein contains 0.084 oz gold/ton, 0.84 oz silver/ 

ton, and accessory copper, and the gold and silver contents appear to be persistent throughout. Copper might 

be recovered as a co-product. 

No other quartz veins similar to the one at Chanchelulla prospect were found in the roadless area during 

this study, nor have they been found by prospectors 

who have extensively explored this region since the 

1850's. This activity makes the occurrence of additional 

lode gold-silver deposits at the surface very unlikely. 

Quartz veins with gold and silver that do not crop out 

205 
fa,, 

:::._~ HIGH CHANNEL ..#'/----~ -o --

PROSPECT -=-=-=-- % ""'x -=-=-=-=-=-- ~ 

~ =-=-=-=-=-=-::\ ) d l-=-=-=-=-=-=-=-=-=-= IRON 

123° QQ ' 

_/ 

05220 

l

-, ---1-

1 I I 

CHIEF PROSPEC T I I. J I --- -- ,-- I' X I I .., J- ~ L . .-."' 

\/ 

X 

'I 

/ 

/ 

/ 

.. ~heit•H""• / ~~a,.\. ____ ,.. .. __ , ·r....,. 

I 

lA . pprox1mate 

roadless boundary 

'- /---19 

\ 

206 

/ 

-

0 

~ Mine or deposit 

x Mineral occurrence 

2 

MILES 

EXPLANATION 

1------1 

'------' 

Sedimentary rocks (Lower 

Jurassic to Lower Triassic) 

Limestone (Permian) 

Mafic rocks (Middle Jurassic) 

Ultramafic rocks (Middle Jurassic) 

--- Contact 

• • 

Fault--Bar and ball on 

downthrown side 

Thrust fault--Sawteeth 

on upper plate 

Figure 58.-Chanchelulla Road.less Area, California 

Sugarloaf 

X PPak 

MAP LOCATION 
might possibly be present in the roadless area, but 

because there are no indications to narrow the search for 

these occurrences, they would be difficult to locate by 

present-day methods. There seems, therefore, little 

likelihood for the occurrence of gold resources beyond 

the Chanchelulla prospect, based on available data 

Placer gold has been recovered from the gravels of the 

East Fork of Hayfork Creek, just north of the roadless 

area, notably from the High Channel prospect. Placer 

gold has also been recovered from many places along 

the Hayfork Creek and a portion of this creek runs along 

the western margin of the roadless area This reach of 

the creek is a steep-walled, narrow canyon that contains 

small amounts of sand and gravel. Small, portable, 

underwater suction-dredge operations may recover 

small amounts of gold from the sand and gravels that 

are present. Because the analyses of stream-sediment 

samples from streams that drain the roadless area do 

not show significant amounts of gold, the placer gold 

recovered from Hayfork Creek was probably derived 

from sources outside the roadless area 

The background levels for chromium, nickel, and 

cobalt are fairly high throughout the Cha'lchelulla 

Roadless Area, but are consistant with their occurrence 

as common minor elements in mafic and ultramafic 

rocks. Some concentration was noted in stream sediments as chromium, nickel, and cobalt minerals are 

highly resistant to, and may be concentrated by, weathering processes. Small amounts of platinum-group 

elements also are common in mafic and ultramafic 

rocks. Where detected in stream-sediment samples, the 

platinum-group element values do not exceed the background levels. Like placer gold, the platinum-group 

elements recovered from the Hayfork and East Fork of 

Hayfork Creeks were probably derived from other 

sources outside the roadless area. 

Magnetite occurs at the Iron Chief prospect, in a prospect pit in a saddle east of Chanchelulla Peak and on the 

north slope of Chanchelulla Peak, but not enough 

magnetite is present to identify a resource for iron. 

The Potato Creek prospect is a deposit that contains 

approximately 13 million tons of limestone. There is little likelihood that this deposit constitutes a resource 

because this limestone is too far from present and anticipated markets. Other limestone bodies that occur 

throughout this region are closer to main roads. 

The Deer Lick Springs prospect, just outside the 

roadless area on the east, is located on a group of mineral springs that have been developed as therapeutic 

baths. There are three undeveloped mineral springs just 

north of Deer Lick Springs along Browns Creek, two of 

which are inside the roadless area. There is little 

likelihood for use of these three springs because the 

volumes of flow are small and the well-developed therapeutic baths at Deer Lick Springs meet the anticipated 

usage. 

REFERENCE 

Huber, D. F., elson, S. C .. Fraticelli, L.A., and Stebbins, S. A .. 1983, 

Mineral resource potential map of the Chanchelulla Roadless 

Area, Trinity County, California: U.S. Geological Survey Open· 

File Report 83-506. 

207 
208 

0 2 

MILES 

EXPLANATION 

- Geologic terrane with substantiated 

mineral-resource potential D Geologic terrane with probable 

mineral-resource potential 

Cr Chrom ium 

Cu Copper 

Au Gold 

Ag Silver 

Zn Zinc 

~ Mine or deposit 

i Graphitic schist (Black schist) 

Greenschist 

lnterlayered black schist 

------ and greenschist 

Metamorphosed serpentinite 

--- Contact 

--- Fault 

• 4 Thr~st fault 

Figure 59.-Condrey Mountain Roadless Area, California 
CONDREY MOUNTAIN ROAD LESS AREA, CALIFORNIA 

By R. G. COLEMA , 1 U.S. GEOLOG ! AL S RVEY, and 

R ON MAYERLE, U .. B UREA OF Mr E 

SUMMARY 

A mineral-resource study carried out by the USGS and the USBM in 1980 and 

1981 indicate that the Condrey Mountain Roadless Area has areas of probable 

resource potential for copper, zinc, gold, and silver in the westernmost extremities of the area Although there are no presently exposed chromite concentrations in the serpentinite bodies within the roadless area, the possibility that 

chromite occurs in the subsurface within these bodies should not be overlooked 

and they are shown as areas of probable chromite resource potential. No potential for energy resources was identified in the study. 

CHARACTER AND SETTING 

The Condrey Mountain Roadless Area lies along the 

crest of the Siskiyou Mountains in northern California, 

about 30 mi northwest of the town of Yreka The area is 

accessible by State Highway 96, often called the 

Klamath River Highway. Access to the roadless area is 

afforded by unpaved roads leading from the villages of 

Seiad Valley and Klamath River. The roadless area extends along the Siskiyou Divide, a physiographic feature ranging from 6000 to 7000 ft in altitude which 

marks the natural boundary between Oregon and California in this region. 

Geologic and geophysical studies carried out by the 

USGS in 1980 and 1981 were supplemented by detailed 

investigations of mines, prospects, and mineralized 

areas by the USBM. The results of these investigations 

are the basis for this report. 

The Condrey Mountain Roadless Area is underlain by 

Jurassic metamorphic rocks exposed in a structural 

dome, whose core consists of highly deformed metasedimentary and metavolcanic rocks known as the Condrey 

Mountain Schist (Coleman, Helper, and others, 1983). 

The most abundant rock type is a fine-grained gray to 

black graphitic schist whose parent rock was probably a 

graywacke containing abundant organic debris. The 

metavolcanic rocks are laminated greenschists which 

probably represent metamorphosed volcanogenic 

sedimentary rocks. Distinctive thin units locally interlayered with the greenschist and graphitic schist ex-

'With coo!J'ibut.ions from R. Jachens and D. miLh, USGS. 

tend north and south from the vicinity of the Blue 

Ledge mine. They consist mainly of quartz and muscovite with minor amounts of barite, and have been referred to as "silver schist. " The " silver schist" parent 

rock was probably silicic volcanic rock. These schists 

are often associated with copper and zinc mineralization, as at the Blue Ledge mine. 

Tabular and lens-shaped bodies of metaserpentinite 

are present within the schist and consist mainly of antigorite with minor amounts of magnetite and brucite. 

No concentrations of chromite were observed in these 

bodies. 

Geochemical studies carried out during the course of 

this assessment delineated the previously known mineralization in the Blue Ledge mine area A copper-zinc 

geochemical anomaly was found in the drainage basin of 

Joe Creek, which contains the Blue Ledge mine. No 

other geochemical anomalies were found. 

Aeromagnetic studies supplemented geologic and 

geochemical investigations of the roadless area Prominent magnetic anomalies reflect the locations and 

shapes of the metaserpentinite bodies within the Condrey Mountain Schist. Although the metaserpentinites 

are potentially favorable hosts for chromite, there are 

no presently exposed concentrations of chromite within 

the area 

The only recognized mining district of importance 

near the roadless area boundaries includes the Blue 

Ledge mine and zones of associated mineralization 

which may extend into the roadless area The Blue 

Ledge mine, last active in 1930, lies outside the western 

boundary of the roadless area Production records from 

209 
Hundhausen (1947) for the years 1917-20 and 1930 

report that 11,151 tons of copper-zinc ore were shipped 

from the mine during those years. Most of the mineralization is found within the drainage basin of Joe Creek, a 

tributary of Elliot Creek. Throughout the greenschist 

exposure in the Joe Creek drainage, thin layers of 

"silver schist", usually less than about 10ft thick, contain copper and zinc sulfide minerals. At the Blue Ledge 

mine itself, lenses of copper-zinc ore associated with 

"silver schist" are reported to be several hundred feet 

long with a maximum thickness of over 12 ft. The actual 

ore zone is reported to have been about 5 ft thick, and 

consists mainly of massive sulfides in the following 

order of abundance: pyrrhotite, pyrite, chalcopyrite, and 

sphalerite. Minor amounts of galena and covellite are 

present, and it is considered that gold and silver are contained within the copper sulfide minerals. The ore 

bodies appear to have been stratabound (that is, concordant with original sedimentary layering), but metamorphism and deformation have obscured the original 

relationships. The mineralization appears to pre-date 

metamorphism, and is most likely related to the formation of the "silver schist" as a silicic volcanic rock. 

Based on the regional structural grain, and the fact that 

altered "silver schist" is present in the roadless area, 

massive sulfide zones may also extend into the roadless 

area 

MINERAL RESOURCES 

The westernmost part of the Condrey Mountain 

Roadless Area has probable resource potential for copper, zinc, gold, and silver in stratabound sulfide 

deposits. Copper and zinc sulfide minerals in small areas 

of substantiated resource potential are associated with 

the "silver schist" outside the boundary of the roadless 

area, and ore-bearing zones may extend into the roadless area Small amounts of gold and silver may occur 

within the copper sulfide minerals. An indication of 

210 

demonstrated resources in the known areas of substantiated potential is given by the estimate calculated by 

Shenon (1933), and is considered to be approximately 

correct: 250,000 tons of ore, with average copper, 

4.4 percent; average gold, 0.125 oz/ton; average silver, 

5.6 oz/ton; and average zinc, 2.0 percent. 

Although no chromite concentrations are presently 

exposed, unexposed parts of the metaserpentinite 

bodies within the roadless area may contain chrornite. 

The metaserpentinite bodies are shown on the map as 

areas of probable chrornite resource potential. If improved subsurface exploration techniques become available in the future, chrornite concentrations in such 

bodies may be found. 

SUGGESTIONS FOR FURTHER STUDY 

The common association of the " silver schist" and 

copper-zinc mineralization suggests the two are genetically related. Further study of favorable lithologies in 

the westernmost part of the roadless area are warranted 

to refine the estimate of resource potential. 

REFERENCES 

Coleman, R. G., Helper, M. D., and Donato, M. M. , 1983, Geologic 

map of the Condrey Mountain Roadless Area, Siskiyou County, 

California U. S. Geological Survey Miscellaneous Field Studies 

Map MF- 1540-A. 

Coleman, R. G., Mayerle, Ron, J achens, R. C., and Smith, D. B., 1983, 

Mineral resource potential of the Condrey Mountain Roadless 

Area, Siskiyou County, California U.S. Geological Survey OpenFile Report 83- 497. 

Hundhausen, R. J., 1947, Blue Ledge copper-zinc mine, Siskiyou 

County, California U. S. Bureau of Mines Report of Investigations 4124, 16 p. 

Shenon, P. J., 1933, Copper deposits in the Squaw Creek and Silver 

Peak districts and at the Almeda Mine, southwestern Oregon 

with notes on the Pennell and Farmer and Banfield prospects: 

U.S. Geological Survey Circular 2, 34 p. 
COYOTE SOUTHEAST AND 

TABLE MOUNTAIN ROADLESS AREAS, CALIFORNIA 

By E DWI H. M CK EE, 1 U.S. GEOLOG ICAL S UR EY , and 

D O ALD 0 . CAPSTICK, U .. B REA OF Mr E 

SUMMARY 

On the basis of a mineral survey in 1982 the contiguous Coyote Southeast and 

Table Mountain Roadless Areas have one area of probable and two areas of 

substantiated mineral-resource potential. Mineral occurrences in these areas are 

in tactite deposits with tungsten as the most important metal; copper, 

molybdenum, and gold may occur in small amounts in the same deposits. One 

area in the southwestern part of the Coyote Southeast Roadless Area has 

anomolous amounts of uranium in stream-sediment samples but no resource 

potential was identified. The geologic terrane precludes the occurrence of fossil 

fuel resources. 

CHARACTER AND SETTING 

The Coyote Southeast and Table Mountain Roadless 

Areas include about 90 sq mi along the eastern front of 

the Sierra Nevada in Inyo County between Big Pine and 

Bishop, California The two roadless areas are in a 

region of relatively low relief east of the main crest of 

the Sierra Nevada Altitudes range from about 12,000 ft 

above sea level at several places in the roadless areas to 

about 4000 ft in the Owens Valley near Bishop. An extensive level area, called Coyote Flat, exists at about 

10,000 ft in the southwest part of the Coyote Southeast 

Roadless Area The climate is semiarid and vegetation 

sparse, as the area is in the rainshadow of the Sierra 

Nevada crest. Access to the Coyote Southeast Roadless 

Area is from the north by a steep four-wheel-drive road. 

State Highway 168 to Lake Sabrina and South Lake 

give access to the southern parts of the Table Mountain 

Roadless Area 

The geology of the region, including the two roadless 

areas, was mapped in detail by Bateman (1965), and a 

new geologic map using Bateman's report and more recent information was compiled by Elliott and McKee 

(1982). A tabulation of chemical analyses determined as 

part of a geochemical study was published by Elliott 

and others (1982). 

The eastern Sierra Nevada records a complex history 

involving Paleozoic shallow-marine sedimentation, late 

'With conlributions from Maurice A. Chaffee and Geoffrey S. Elliott.. USGS. 

Paleozoic and Mesozoic deformation, Mesozoic granitic 

plutonism, and late Tertiary and Quaternary igneous 

activity and faulting. The rocks can be divided into four 

major groups according to age and type: (1) lower 

through middle Paleozoic metasedimentary rocks consisting of marble, quartzite, pelitic, hornfels, schist, and 

chert; (2) upper Paleozoic metavolcanic rocks; (3) granitic rocks that were intruded in late Triassic to late 

Cretaceous time; and (4) basaltic and andesitic intrusives and extrusives of Miocene age. These Miocene 

volcanic rocks were erupted on ancestral Basin and 

Range topography from feeder dikes controlled in many 

places by high-angle Basin and Range faults. 

The largest body of metasedimentary rocks in the 

roadless areas, called the Bishop Creek pendant, covers 

approximately 20 sq mi and includes about 6500 ft of 

strata which range in age from early Ordovician to 

Devonian. Other, smaller bodies include the Big Pine 

Creek pendant and scattered uncorrelated metamorphic 

rocks. Triassic to upper Cretaceous granitic rocks of the 

Sierra Nevada batholith underlie most of the Coyote 

Southeast and Table Mountain Roadless Areas. The 

batholithic rocks are mostly granodiorite but include 

hornblende gabbro, quartz diorite, quartz monzonite, 

granite and alaskite. 

MINERAL RESOURCES 

The Coyote Southeast Roadless Area contains one 

211 
212 

MAP LOCATION 

-

D 

Cu 

Au 

Mo 

Approximate 

0 

MILES 

EXPLANATION 

Geologic terrane with substantiated 

mineral-resource potential 

Geologic terrane with probable 

mineral-resource potential 

Copper 

Gold 

Molybdenum 

w Tungsten 

x Mineral occurrence 

'X' Mine 

5 

Alluvium 

r- .... ~ l' .(. 

(..).,. < ' .,. ..... < I. ..I Volcanic rocks 

, ...... ....-\ ,_, ,', ~'r,--;;. Granitic rocks 

Metasedimentary rocks 

Contact 

Figure 60.-Coyote Southeast and Table Mountain Road.less Areas, California 
area of probable and two areas of substantiated mineralresource potential, but all the known mineral deposits 

are small and low-grade and any undiscovered deposits 

are also likely to be small and low grade. 

The geologic setting of the roadless areas is similar to 

that of the nearby Pine Creek tungsten mine, suggesting that the areas have a potential for mineralized tactite deposits. The most important metal in such 

deposits is tungsten; gold, silver, copper, and molybdenum are of secondary importance. Consequently, the 

metamorphic rocks in the roadless areas were searched 

for tactites and for evidence of prospecting. Rock, 

stream-sediment, and panned concentrate samples were 

evaluated for tungsten, gold, silver, copper, and 

molybdenum and for other elements that might indicate 

the presence of mineralized tactities. 

No mineralized tactite deposits of significance were 

identified. Analysis of samples and evaluation of the 

Waterfall property on the boundary of the Coyote 

Southeast Roadless Area indicate a probable resource 

potential for tungsten mineralization over an area 

extending eastward and south from the prospect. 

Tungsten-bearing tactite occurs in two areas of substantiated resource potential in the Coyote Southeast 

Roadless Area One area contains the abandoned Chipmunk mine (outside the area) and the Brown prospects. 

The other area contains the Marble mines directly outside the east boundary of the Coyote Southeast Roadless Area, and the Middle Fork Shannon prospect 

within the roadless area Substantiated resource potential for low-grade and small tungsten deposits exists 

around these properties. Numerous other small, lowgrade tungsten occurrences were found within the 

Coyote Southeast Roadless Area but no resource potential was identified. 

One area in the southwestern part of the Coyote 

Southeast Roadless Area has anomalous amounts of 

uranium in stream-sediment samples, probably from 

small veins in the granitic and metamorphic rocks of 

this area These veins, if present, would be dispersed 

over a wide area and would contain a small amount of 

total uranium; no resource potential for uranium was 

identified. 

SUGGESTIONS FOR FURTHER STUDIES 

Further study of these roadless areas offers little 

promise for the identification of hidden mineral deposits 

due to the small and discontinuous nature of the mineralized tactite occurrences. More detailed geochemical 

sampling of rocks and eroded material in the areas with 

metamorphic rock might reveal additional small 

tungsten resources at or near the surface in tactite 

deposits. 

REFERENCES 

Bateman, P. C., 1965, Geology and tungsten mineralization of the 

Bishop district, California: U.S. Geological Survey Professional 

Paper 4 70, 208 p. 

Elliott, G. S., Chaffee, M. A., and Capstick, D. 0., 1983, Mineral 

resource potential map of the Coyote Southeast and Table Moun· 

tain Roadless Areas, lnyon County. California: U.S. Geological 

Survey, Miscellaneous Field Studies Map MF- 1426- B. scale 

1:62,500. 

Elliott, G. S., and McKee, E. H., 1982, Geologic map of the Coyote 

Southeast and Table Mountain Roadless Areas, California: U.S. 

Geological Survey Miscellaneous Field Studies Map 

MF- 1426- A, scale 1:62,500. 

Elliott, G. S., Diggles, M. F., Chaffee, M. A., Fey, D. L., Sutley, S. J., 

Hill, R. H., and Van Gaalen, Glen, 1982, Chemical analyses of 

samples of rock and stream sediment, and norunagnetic heavy· 

mineral concentrate, Coyote SE and Table Mountain Roadless 

Areas, lnyo County. California: U.S. Geological Survey Open·File 

Report 82- 996, 116 p. 

21 3 
34° 

15' 

214 

117°40' 

S 4 IV 

41o 

I.J 

Mount 

San AntoniO 

X 

0 

\\ 

l 

MILES 

5 

117°25' 

I 

) 

Approximate / \~ roadless 

\ / "' ~/' MAP LOCATION 

EXPLANATION D Geologic terrane with probable 

mineral-resource potential 

Au Gold 

Pb Lead 

Ag Silver 

w Tungsten 

Zn Zinc 

~ Mine or deposit 

~ Mine 

··:-·::-:. ·:· · .. ::. ·: . .-....... . :·.·::.:.:- . Surficial sedimentary deposits 

Granitoid rocks 

Metamorphic rocks 

Contact 

Fault--Arrows show direction of 

relative movement 

.............. ._.... Thrust fault--Sawteeth on upper plate 

Figure 61.-Cucamonga Roadless Areas, California 
CUCAMONGA ROADLESS AREAS, CALIFORNIA 

By D OUGLAS M. MORTO , 1 U.S. GEOLOGIC L R EY, and 

THOMA j . P ETER , U. . BUREA OF M I ES 

SUMMARY 

On the basis of geologic, geochemical, and geophysical surveys in 1972-82, 

and an investigation of mines, prospects, and mineralized areas in 1980, the 

Cucamonga Roadless Areas have two areas of probable mineral-resource potential. An area of probable mineral-resource potential for low-grade tungsten and 

gold resources is located in the northern part of the roadless areas, and an area 

of similar potential for small deposits of silver, lead, and zinc is located in the 

southwestern part of the roadless areas. There is little promise for the occurrence of other mineral or any energy resources in the area. 

CHARACTER AND SETTING 

The Cucamonga Roadless Areas are located about 10 

mi northwest of San Bernardino and about 10 mi northeast of Pomona, California The Cucamonga Roadless 

Areas comprise about 37.5 sq mi that surround the existing Cucamonga Wilderness in the Angeles National 

Forest in the southeastern San Gabriel Mountains. The 

area consists of rugged mountainous terrain, including 

Telegraph and Cucamonga Peaks, and is chiefly drained 

by San Antonio Canyon, Cucamonga Creek, and Lytle 

Creek. Relief is considerable with altitudes ranging 

from about 2500 to 7500 ft. Access to the roadless areas 

is by dirt roads that lead from the foothill communities 

to the south, and paved roads which border the roadless 

areas on the east and west. 

The roadless areas are situated at the eastern end of 

the San Gabriel Mountains in the eastern part of the 

Transverse Ranges Province of Southern California 

This geomorphic-geologic province is east-oriented, contrasting with the prominent northwest orientation of 

the other geologic-geomorphic provinces in California 

The roadless areas are underlain by a wide variety of 

metamorphic and plutonic rocks. The older metamorphic rocks are considered to be of Precambrian age, with 

younger ones both of Mesozoic and of probable Paleozoic age. Plutonic rocks are both of Mesozoic (Cretaceous) and of Tertiary (Miocene) age. Many faults cross 

the area and occur near its boundaries. The oldest of the 

'With contributions by Eduardo A. R<Xirigucz. Curtis M. Obi. and Robert W. Simpson. Jr .. 

USGS. 

faults, the Vincent Thrust, a major structural discontinuity of probable Mesozoic age, lies interior to the 

mountain ranges, and has been segmented by younger 

faults. Reverse faults of the Cucamonga fault zone, 

located near the south margins of the roadless areas, 

have uplifted the San Gabriel Mountains. Major strikeslip faults occur within and adjacent to the roadless 

areas. Landslides are common throughout the eastern 

San Gabriel Mountains. Surficial alluvial deposits occur 

along all major drainages. 

A geochemical survey of stream sediments from 48 

localities in the Cucamonga Roadless Areas was conducted for 31 elements to determine if spatial variations 

in stream-sediment chemistry reflect any concentrations of ore minerals. 

No significant systematic patterns of anomalous element concentrations were noted. Most of the analyses 

fall within ranges that are reasonable for nonmineralized crystalline rocks and sediments derived from them. 

MINERAL RESOURCES 

Data obtained from the investigations all suggest 

that although most of the Cucamonga Roadless Areas 

have little promise for the occurrence of mineral 

resources two areas have probable mineral-resource 

potential. During the investigations, a few localized 

zones of mineralized rock were found, but, with one exception, geologic environments favorable for the occurrence of mineral deposits have not produced extensive 

zones of mineralization. Cataclastic rocks above the 

215 
Vincent Thrust in the northern part of area B5174 have 

a probable mineral-resource potential for low-grade 

tungsten and gold. The Blue Diamond tungsten prospect, in the northwest part of the area, is within these 

highly deformed rocks and has an estimated 16,000 tons 

of demonstrated and inferred resources averaging 0.16 

percent tungsten trioxide (W03). 

Gamet-€pidote tactite occurs locally where carbonate 

metamorphic rocks are engulfed, or partly so, by quartz 

diorite. The Blew Jordam and California-Hercules prospects, minor occurrences of silver-lead-zinc mineralization associated with calc-silicate rock and tactite, are 

located in an area of probable mineral-resource potential 

near the upper part of the South Fork of Lytle Creek. 

Other occurrences of calc-silicate and tactite rock have 

rarely observable blebs of sulfide minerals. No tungsten 

mineralization was noted within the calc-silicate tactite 

rock. In Cascade Canyon, a local metasomatized part of 

this carbonate sequence contains a small amount of 

!azurite (lapis lazuli). In the vicinity of the !azurite 

occurrence, a leucocratic granitic rock intrusive into carbonate rock locally contains pink-corundum of non-gem 

quality. No potential was identified in the area of these 

occurrences. The lower parts of some perched and elevated alluvial sand and gravel deposits in San Antonio 

Canyon, Cucamonga Canyon, and Lytle Creek drainages have been prospected, and a few mined on a small 

scale, for placer gold, however no potential for resources 

was identified. 

A few stream-sediment samples from the Barrett and 

Cascade Canyon areas have anomalous values of gold. 

These areas are spatially related to metamorphosed carbonate rock and quartzite. A few anomalous values for 

gold in samples from upper Day Canyon, the South 

Fork of Lytle Creek, and Falling Rock Canyon are also 

related to these rocks. Gold values in samples from the 

north side of Icehouse Canyon are spatially related to 

cataclastic gneiss. 

In Coldwater Canyon, high gold and tungsten values 

are probably related to cataclastic rock in the vicinity of 

the Vincent Thrust, which is apparently the site of gold 

and tungsten mineralization farther to the west in the 

San Gabriel Mountains (Evans, 1982). 

A few somewhat high chromium and nickel values for 

some isolated samples from near the mouth of the South 

216 

Fork of Lytle Creek, and somewhat high chromium 

values for samples from Icehouse Canyon may be related to pyroxene or other mafic minerals in the metamorphic rocks. 

Because the Cascade, Barrett, Kerkhoff, and Icehouse 

Canyon areas have long been the sites of human activity, contamination of the geochemical samples should 

be considered. Lead contamination is possible in 

sediments from all the major drainages in the eastern 

San Gabriel Mountains. 

The results of the geochemical survey are compatible 

with the geologic evidence, all of which suggests a probable resource potential for low-grade gold and tungsten 

in rock above the Vincent Thrust, and for small tonnages of silver-lead-zinc in tactite pods in the small area 

near the head of the South Fork of Lytle Creek. 

An interpretation of an aeromagnetic survey of the 

Cucamonga Roadless Areas in 1979 showed magnetic 

anomalies and patterns (R. W. Simpson, Jr., unpub. 

data, 1979) closely related to magnetic variation in rock 

units, but indicated no unknown areas of mineralresource potential. 

REFERENCES 

Evans, J. G., 1982, Geology of the Sheep Mountain Wilderness tudy 

Area and the San Bernardino Counties, Caliiomia. in Mineral 

Resources of the Sheep Mountain Wilderness Study Area and 

the Cucamonga Wilderness and additions, Los Angele and an 

Bernardino Counties, Caliiomia: U.S. Geological Survey Bulletin 

1506 A, p. 5-28. 

Morton. D. M .. Rodrequez, E. A., Obi, C. M .. Simpson, R. W., and 

Peters, T. J., in press, Mineral resource potential map of the 

Cucamonga Roadless Area. San Bernardino County, Caliiomia: 

U.S. Geological Survey Miscellaneous Field Studies Map 

MF-1646-A. 

Peters, T. J ., 1983, Mineral investigation of the Cucamonga RARE II 

Area (nos. B5174 and C5174), San Bernardino County, Caliiomia: 

U.S. Bureau of Mines Open-File Report MLA 44-83, 16 p. 

Zilka. N. T., and Schmauch, S. W., 1982. Economic appraisal of 

mineral resources of the Cucamonga Wilderness and additions. 

San Bernardino County, Caliiomia. in Mineral resources of the 

Sheep Mountain Wilderness Study Area and the Cucamonga 

Wilderness and additions, Los Angeles and San Bernardino 

Counties, Caliiomia: U.S. Geological Survey Bulletin 1506-E, 

p. 85-92. 
CYPRESS ROADLESS AREA, CALIFORNIA 

By GEORGE L. K E EDY,

1 U.S. GEOLO !CAL RVEY and 

D O ALD 0. CAPSTIC K , . . B RE OF Mr E 

SUMMARY 

Mineral surveys of the Cypress Roadless Area, located in the southern part of 

the Sierra Nevada, California, were conducted in 1980-82. On the basis of these 

investigations, the eastern part of this roadless area has probable resource 

potential for gold with associated silver in quartz veins. This area has been 

extensively prospected since the late 1800's. The geologic terrane precludes the 

occurrence of energy resources. 

CHARACTER AND SETTING 

The Cypress Roadless Area comprises 3 sq mi of Sequoia National Forest in the southern Sierra Nevada, 

approximately 30 mi east-northeast of Bakersfield, 

Kern County, California Isabella Lake is 5 mi north of 

the area and the nearest communities are Bodfish and 

Lake Isabella Access to the roadless area is by Piute 

Mountain Road, which parallels the west and south 

sides of the roadless area, and by unimproved jeep roads 

from the north in Myers and Bodfish Canyons. 

The area is characterized by its rugged and steep terrain, and altitudes range from 3900 ft in Myers Canyon 

to 6437 ft on the ridge crest that approximates the 

southern border of the area The Cypress Roadless Area 

contains the largest of only nine known groves of Piute 

cypress, Cupressus neuadensis Abrams. 

The mineral-resource evaluation of the roadless area 

(Kennedy and others, 1983) was based on reconnaissance field checking of a previously published geologic 

map, geochemical analyses of rock, stream-sediment, 

and heavy-mineral concentrate samples (Chaffee and 

others, 1983), and an examination of mines, prospects, 

and mineralized areas (Capstick, 1983). Geophysical 

surveys were not done for this study. 

The geology of the roadless area is typical of the 

Sierra Nevada Intensely deformed metamorphic rocks 

of sedimentary and volcanic origin occur as roof pendants scattered throughout an intrusive country rock 

composed predominantly of granitic rocks of the Sierra 

Nevada batholith. 

1

Wit.h contributions from M. A. Chaffoo. J. F. Seitz. and J. L. Harner. USGS. 

Metamorphic rocks are exposed in the western half of 

the roadless area They are predominantly quartzite and 

mica schist, and are referred to as the Kernville series of 

Miller (1931). Similar metasedimentary rocks nearby 

contain fossil mollusks that are about 215 to 175 million 

years old (Late Triassic to Early Jurassic in age). 

In the northwest part of the roadless area, the Kernville series has been intruded by a small pluton of mafic 

igneous rock that is assigned to the Summit gabbro of 

Miller and Webb (1940). Contact metasomatism of carbonate rocks in the Kernville series along this contact 

has resulted in the formation of limited amounts of 

tactite. The Tripoli tungsten prospect is located in this 

tactite. 

The dominant rocks of the Sierra Nevada batholith 

are lighter colored granitic rocks of varying composition. Those in the Kern River area are assigned to the 

Isabella granodiorite of Miller (1931) and are about 80 

million years old (Late Cretaceous in age). Rocks of this 

type comprise the eastern half of the roadless area Surface exposures are normally deeply weathered and covered by a veneer of grus. A shallowly eastward dipping 

system of quartzofeldspathic to milky-quartz dikes and 

veins occurs in the granodiorite in a north-trending fault 

system, and is the probable source of precious metals in 

the area 

The contact between the metamorphic rocks of the 

roof pendant and the Isabella granodiorite occurs in a 

north-trending gradational zone of mixed metamorphic 

and granitic rocks through the central part of the 

roadless area Contacts elsewhere are more sharply 

defined, but are often obscured by weathering and surficial debris. 

Mining activity in the region dates to the 1850's, 

when gold was discovered in the Kern River area By 

217 
35° 

35' 

218 

MAP LOCATION 

Au 

Ag 

Bald Eagle 

Peak 

0 

MILE 

EXPLANATION 

Geologic terrane with probable Isabella granodiorite 

Summit gabbro 

Kernvil le series 

mineral-resource potential 

Gold 

Silver 

Mine 

Figure 62.-Cypress Roadless Area California 

() 

')> 

z 

-<. 

0 

z 

118°25' 
the middle 1860's, substantial amounts of gold were being produced from four local mining districts, none very 

far from the present roadless area Total production of 

gold and silver from these districts since 1880 has been 

estimated at several million dollars (Troxel and Morton, 

1962). Several claims and (or) mines in the roadless area, 

among them the Pickwick mine near Bodfish Peak 

(presently known as the Devils Hole prospects?), appear 

to have had limited, but unrecorded production in the 

past. None is presently active. The Glen Olive mine, 0.3 

mi southeast of the roadless area was located about 

1888 and produced an estimated $500,000 worth of gold 

by 1914; considerably less has been produced since. The 

mine was operated almost continuously until its closing 

in 1942. In 1982, the mine appeared to be under preparation for renewed operation. 

Tungsten has been mined in Kern County in the 

southern Sierra Nevada since 1905. Production, never 

great, was both intermittent and modest until 1950, 

when the importation of Chinese tungsten stopped. Additional sources were sought and encouraged by price 

supports from the U.S. Government. Most of the southem Sierran mines and prospects were discovered in the 

period 1951-56, but most were abandoned when price 

supports were withdrawn in 1957 (Troxel and Morton, 

1962, p. 294-295). The Tripoli prospect is the only 

tungsten prospect in the roadless area 

Uranium was discovered in 1954, 5 mi west-northwest 

of the roadless area in what is now known as the Kern 

River uranium area (MacKevett, 1960). About 189 tons 

of ore were produced from small secondary deposits 

localized in fracture systems in granitic rocks. 

MINERAL RESOURCES 

The Cypress Roadless Area is a small part of an areally extensive geologic terrain that locally has yielded 

small amounts of tungsten, base-metal, and uranium 

minerals along with substantial amounts of gold and 

associated silver over the past 100 years. On the basis of 

the geologic reconnaissance, a geochemical survey of 

rock and stream-sediment samples, and examination of 

mines and prospects, the eastern part of the roadless 

area is regarded as having probable resource potential 

for small deposits of lode gold with associated silver in 

veins. 

Lode gold has been produced from several mines 

along the ridge of Isabella granodiorite that extends 

through, and to the southeast of, the roadless area At 

the Glen Olive mine just outside of the area, free-milling 

gold was produced from two quartz veins that strike 

northwest and dip to the northeast (Troxel and Morton, 

1962, p. 151). These may be part of, or related to, the 

shallowly eastward dipping system of quartzofeldspathic to milky-quartz dikes and veins that crop out in 

Isabella granodiorite below Bodfish Peak on the east 

side of Myers Canyon. These gold-bearing dikes and 

veins are in a north-northwest-trending fault system 

through the center of the roadless area At least 30 adits 

have explored this system within the roadless area; a 

few may have had limited, but unrecorded, production. 

One, the Pickwick mine, probably had production before 

1916. Analyses of samples from these workings suggest 

a sporadic distribution of the gold, a characteristic apparently shared by similar prospects and mines in the 

region. 

At the Fairview(?) mine in the northeast comer of the 

roadless area are workings consisting of a 450-ft long 

(haulage?) tunnel, caved raise, and caved incline shaft. A 

limited production, although unrecorded, is suggested 

by the extent of these workings. 

Anomalous concentrations of gold and silver were 

recovered from stream-sediment and heavy-mineral concentrate samples from Myers Canyon, in the roadless 

area, and from areas draining Isabella granodiorite outside of the roadless area However, the steep terrain, 

extensive bedrock exposures, and lack of gravel accumulations in Myers Canyon precludes accumulation 

of placer resources in the roadless area 

Metamorphic rocks of the Kernville series in roof 

pendants east and west of the roadless area have yielded 

small amounts of tungsten and base-metal minerals. 

Scheelite, a tungsten mineral, occurs in small amounts 

in limited tactite deposits at the Tripoli prospect, in the 

northwest part of the roadless area The occurrence is in 

the contact zone between the Kernville series and the 

Summit gabbro that intruded it. Samples from this 

prospect assayed 0.25 to 0.5 percent scheelite, but the 

amounts of mineralized rock are very small and no 

resource potential was identified. There has been no 

recorded production from this prospect (Troxel and 

Morton, 1962, p. 324). 

No tactite was observed in the mixed zone of metamorphic and granitic rocks in Myers Canyon. Streamsediment and heavy-mineral concentrate samples from 

areas draining exposures of the Kernville series contain 

slightly anomalous concentrations of elements constituting a suite that might be related to tungsten 

mineralization, but the anomalous metals do not appear 

to have been derived from sources in the roadless area. 

The Isabella granodiorite locally contains abnormal 

amounts of uranium in the Kern River uranium area 5 

219 
mi west-northwest of the roadless area, but these concentrations do not appear to extend into the roadless 

area 

SUGGESTIONS FOR FURTHER STUDIES 

Because the Cypress Roadless Area is small and has 

been extensively prospected since the late 1800's, it is 

unlikely that further studies would refine understanding of the mineral-resource potential of this area 

REFERENCES 

Capstick, D. 0., 1983, Mineral investigation of the Cypress RARE II 

area (No. A5213), Kern County, California; U.S. Bureau of Mines 

Open-File ReportMLA 64-83. 

220 

Chaffee, M. A., Fey, D. L., Hill, R. H., and Sutley. . J., 1983, 

Geochemical maps showing distributions of anomalous element 

concentrations and of anomalous drainage basins, Cypress Roadless Area, Kern County, California; U.S. Geological urvey Miscellaneous Field Studies Map MF- 1532- B, scale 1:24,000 (in 

press). 

Kennedy, G. L., Chaffee. M. A., Seitz, J. F., Hamer, J. L .. and 

Capstick. D. 0 .. 1983, Mineral resource potential map of Cypress 

Roadless Area, southern Sierra evada, California: U.S. Geological Survey MiscellaneousField Studies Map MF- 1532- A, scale 

1:24,000 (in press). 

MacKevett. E. M., Jr., 1960, Geology and ore deposits of the Kern 

River uranium area, California, in Contributions to the geology of 

uranium: U.S. Geological Survey Bulletin 1087- F, p. 169- 222. 

Miller, W. J., 1931, Geologic sections aero the southern Sierra 

Nevada of California; California University, Department of 

Geological Sciences Bulletin, v. 20, no. 9, p. 331 - 360. 

Miller, W. J .. and Webb. R. W., 1940, Descriptive geology of the Kernville quadrangle, California; California Journal of Mines and 

Geology, v. 36, p. 343- 378. 

Troxel, B. W .. and Morton, P. K.. 1962, Mines and mineral resources 

of Kern County, California; California Division of Mines and 

Geology County Report 1, 370 p. 
DESOLATION VALLEY WILDERNESS, CALIFORNIA 

By F. C . W. DODGE, U.S. GEOLOGICAL SURVEY , and 

P. V. FILLO, U . . BUREA OF Ml E 

SUMMARY 

A mineral survey of the Desolation Valley Primitive Area, now Desolation 

Valley Wilderness, conducted in 1966, disclosed the presence of a small 

mineralized area with demonstrated gold resources. Geologic terranes 

elsewhere in the area show little potential for the occurrence of mineral 

resources. 

CHARACTER AND SETTING 

The Desolation Valley Wilderness covers an area of 

101 sq mi in El Dorado County, California, near the 

southwestern shore of Lake Tahoe. Topographically, 

the area is dominated on the east by peaks and subsidiary spurs of the main crest of the Sierra evada and 

on the west by the crest of a parallel-trending range 

with altitudes ranging from about 6500 to nearly 

10,000 ft. Pleistocene glacial erosion was largely 

responsible for shaping surface features of the area. 

Igneous rocks of the Sierra evada batholith, remnants of metamorphic rocks, and younger surficial 

deposits underlie the wilderness. The oldest rocks consist of a thick sequence of metamorphosed sedimentary 

and volcanic deposits, at least some of which were 

deposited in the Early Jurassic. This entire sequence 

was buried, folded , and intruded by plutonic bodies 

before the Late Cretaceous. Prolonged erosion since intrusive emplacement has unroofed the batholith, and 

repeated uplift has elevated the mountains to their 

present heights. During the late Cenozoic, lavas were 

extruded over an extensive part of the batholith; however, only two small patches of the resulting volcanic 

rocks remain within the wilderness. The youngest 

geologic units within the area are Quaternary glacial 

moraines, lacustrine deposits, talus, stream gravels, 

and soils, all in small scattered deposits. 

A mineral survey of the Desolation Valley Primitive 

Area was made in 1966 in accordance with the 

Wilderness Act of 1964 (Dodge and Fillo, 1967). The 

area surveyed is not identical with the Desolation 

Valley Primitive Area as originally defined, because 

modifications of the boundary were proposed for the 

area to be considered for wilderness status. The USGS 

made a reconnaissance of the geology of the area, field 

checked existing geologic maps, and carefully examined areas considered possibly favorable for mineral 

deposits. During field studies, samples of fresh, altered, 

or mineralized rocks and panned stream-sediment concentrates were collected and subsequently analyzed. 

The USBM conducted a search in the El Dorado County recorder's office, which showed that three groups of 

unpatented claims were located in the area and that all 

were subsequently abandoned. 

It is reasonable to assume that the area was 

thoroughly prospected after the mid- 19th century 

discoveries of the Mother Lode to the west and the 

Comstock Lode to the east; however, no productive 

mineral deposits have been discovered in, or immediately adjacent to, the area, and only a few claims have 

been filed in the area. 

MINERAL RESOURCES 

A small area in the wilderness south of Gilmore Lake 

in the east- central part of the area contains significant 

amounts of gold and must be regarded as having a 

demonstrated gold resource. In this mineralized area, 

hornfelsic metavolcanic rocks contain sulfide minerals 

and gold in veinlets occupying small fractures and in 

disseminated grains. Of 48 samples taken in an area of 

about 2000 by 150 ft, 15 contained 1 ppm or more in 

gold- the richest containing 46 ppm or about 1.5 troy 

oz/ton of rock. Insofar as known from surface outcrops, 

the deposit is low grade, and the gold is erratically 

distributed; however, further exploration is necessary 

221 
222 

38° 

55' 

38° 

50' 

120°15' 

Approximate boundary 

MAP LOCATION 

0 

R r. 

I H H) 

Rut • r 

Plutonic rocks 

89 / 

__ /'\/ Metavolcanic 

rocks 

L \K 

Plutonic rocks 

D on 

>'yr d Pk y 

5 

MILES 

EXPLANATION 

~ Mine or deposit 

Figure 63.-Desolation Valley Wilderness. California 

120°05' 

L A !{ I 

I '\/I() 
to better assess the potential for discovery of significant quantities of gold. 

Geologic terranes elsewhere in the area show no evidence favorable for mineral-resource discovery. Tactite 

bodies, which are important hosts for tungsten 

minerals in other parts of the Sierra Nevada, are small 

and do not contain important concentrations of 

valuable minerals. Pegmatites and massive quartz 

veins are exceedingly rare, and those observed are not 

mineralized. Granitic rocks that are stained with iron 

oxide were found to have no enrichment of base or 

precious metals appreciably greater than the unstained 

counterparts. 

No buried placer deposits are believed to occur within 

the area. Glacial erosion has stripped any remnants of 

Tertiary stream channels that formerly may have been 

present. Panned concentrates of Holocene stream sediments do not contain concentrations of valuable 

metallic minerals or metals. 

SUGGESTIONS FOR FURTHER STUDIES 

Exploratory drilling is necessary before the resource 

potential of gold-bearing rocks south of Gilmore Lake 

can be assessed. Any additional study of the wilderness 

offers little likelihood of discovery of additional mineral 

deposits. 

REFERENCE 

Dodge. F. C. W .. and Fillo. P. V .. 1967. Mineral resources of the 

Desolation Valley primitive area of the ierra evada. Cal.ifornia: 

U.S. Geological Survey Bulletin 1261- A, 27 p. 

223 
X 

224 

0 

Mineral occurrence 

117°55' 

3 

MILES 

EXPLANATION 

Granitic rocks (Pre-Tertiary) 

Gneiss (Pre-Tertiary ) 

Quartz diorite complex (Pre-Tertiary) 

Contact 

--- Fault 

Figure 64.-Devil Canyon-Bear Canyon Primitive Area, California 
DEVIL CANYON-BEAR CANYON PRIMITIVE AREA, CALIFORNIA 

By DWIGHT F. C ROWDER, 1 U .S . G EOLOG ICAL S RVEY and 

' 

P AU L V . FILLO U .S. BUREAU F MI ES 

SUMMARY 

A mineral-resource survey made in 1966 concluded that there is little promise 

for the occurrence of metallic resources in the Devil Canyon-Bear Canyon 

Primitive Area, California This conclusion was based on chemical analyses of 

fractured, altered, and mineralized rocks in this area, of soils over such rocks, of 

stream sediments, and of heavy minerals from stream sediments. 

CHARACTER AND SETTING 

The Devil Canyon-Bear Canyon Primitive Area, 

located about 10 mi northeast of Pasadena in the 

Angeles National Forest, Los Angeles County, California, is an area about 8 mi long by 6 mi wide. Located on 

the south slope of the San Gabriel Mountains overlooking the Los Angeles metropolis, the 48 sq mi area is 

bounded on three sides by California Highways 2 and 

39, both paved, and on the fourth side by an improved 

but unpaved road that is closed to the public. Few trails 

exist in the primitive area. 

On the north border of the area, the crest of the San 

Gabriel Mountains rises to an altitude of 8038 ft at 

Waterman Mountain. Devils Canyon and Bear Creek 

run south around Twin Peaks, the dominant crags in the 

north-central part of the area; 6000 ft below, these canyons join the major stream of the area, the West Fork of 

the San Gabriel River. Because the West Fork is cutting 

channels more rapidly than its branches, these tributaries descend over waterfalls and through narrow 

gorges on their way to join the West Fork. Dikes of 

resistant rocks that occur in streams cause falls and 

rapids. Excellent rock exposures are found in all stream 

valleys because of the rapid erosion. 

Most of the Devil Canyon-Bear Canyon Primitive 

Area is underlain by a variety of old crystalline rocks 

similar to those that form much of the rest of the San 

Gabriel Mountains; these rocks are cut locally by darkcolored dikes. The primitive area lies between two major 

fault zones: the San Andreas fault zone, 5 mi to the 

north and well outside the area, and the San Gabriel 

fault zone, near the south boundary of the area Broken 

'With contributions from W. H. Raymond. USG . Abstracted from a report by Crowder 

11967) by H. E. Hodgson. 

and altered rocks are found associated with the San 

Gabriel fault. Although some gneisses occur in the 

southwest comer of the area and an intrusive complex 

crops out in the San Gabriel fault zone and in the northeast comer of the area, the area is primarily underlain 

by granitic rocks that are part of a once-molten mass 

that solidified deep in the Earth. This mass may have 

produced mineralizing emanations, but any deposits 

that may have formed were removed by the deep erosion that has since exposed these rocks. The gulches and 

stream valleys are partly floored by sand and gravel 

deposits composed of a heterogeneous mixture of rocks 

and mineral grains from the rock now exposed within 

the area 

The only significant mining activity in the vicinity of 

the primitive area has been placer mining for gold along 

the East Fork of the San Gabriel River, a few miles from 

the southeast comer of the area (Gay and Hoffman, 

1954, p. 495-6). Debris flows, lack of water, catastrophic floods, and exhaustion of the deposits have 

ended all mining activity. 

To evaluate the mineral-resource potential of the area, 

geologic examinations were made by foot traverses in 

March 1966. Samples of fresh, altered, and mineralized 

rocks, of sand, gravel, and other sediments, and of some 

panned concentrates from stream sediments were collected and analyzed. Results were reported in the following year (Crowder, 1967). 

MINERAL RESOURCES 

There is little promise for the occurrence of metallic 

resources in the Devil Canyon-Bear Canyon Primitive 

Area. This conclusion was based on (1) an evaluation of 

225 
the geology of the area; (2) the absence of significant 

concentrations of metals and ore minerals in deposits at 

the surface, as well as in sheared, broken, and altered 

rocks; and (3) the evaluation of mineral production and 

occurrences in nearby areas. 

Mineral occurrences include antimony, copper, gold, 

molybdenum, and silver found in the southwestern part 

of the area, but they are small and do not constitute a 

mineral resource. 

Rocks in the primitive area that might possibly be 

mineralized by introduced metals are those that are 

fractured, altered, or iron stained. Analyses of these 

rocks and of soils along the north boundary of the area, 

however, indicated no anomalous concentrations of 

metals. The sheared and conspicuously oxidized lenses 

of gneiss in the southwest comer of the area did contain 

anomalous traces of molybdenum and gold. The traces 

of antimony, copper, gold, molybdenum, and silver are 

found chiefly near the contact of the granitic rocks with 

the gneiss in the southwestern part of the area 

Although placer mining for gold has undoubtedly occurred in the West and North Fork drainages, little, if 

any, gold appears to have been mined. Absence of placer 

deposits on the West Fork is significant inasmuch as 

this stream drains the entire primitive area Careful 

panning of the stream gravels in the area produced no 

visible gold, and analyses of the panned concentrates indicated that the stream gravels contain an average of 

0.0002 oz or less gold per ton of gravel. Inasmuch as the 

patches of perched gravels were derived from very near 

the present erosion level, they can be expected to be as 

barren of placer gold as the present stream deposits. 

226 

The only prospect found in the area, the Boatwright 

prospect, consists of a 60-ft adit driven along a quartz 

vein that is 18 in. wide at its widest spot in the surface 

outcrop and less than 1 in. wide at the end of the adit. In 

the surface outcrop the vein occurs as a short segment 

between two faults. Analysis of the quartz vein revealed 

trace amounts of molybdenum and no detectable gold. 

Near Cogswell Dam, just outside the primitive area, 

sparce copper sulfides occur with quartz and muscovite 

in widely scattered pods. Traces of antimony and silver 

occur with the copper in these pods. In the primitive 

area itself, however, only one broken and sheared pod 

was found within the San Gabriel fault zone. 

SUGGESTIONS FOR FURTHER STUDIES 

Although it has been some years since this investigation was completed, no further study is warranted. The 

geologic setting, the lack of significant concentrations 

of metals and ore minerals, and the absence of mining 

activity in the area preclude the need for additional 

work. 

REFERENCES 

Crowder, D. F., 1967, Mineral resources of the Devil Canyon-Bear 

Canyon primitive area, California: U.S. Geological Survey Bulletin 1230-G, 21 p. 

Gay, T. E., Jr., and Hoffman, S. R., 1954, Mines and mineral deposits 

of Los Angeles County, California: California Division of Mines 

and Geology, v. 50, nos. 3-4, p. 476-709. 
DINKEY LAKES ROADLESS AREA, CALIFORNIA 

F. C. W. D ODGE U.S. GEOLOGIC L URVEY and , 

F. E. F EDERSPIEL, U . . B REAU OF MINE 

SUMMARY 

The results of a mineral survey conducted in 1980, show that parts of the 

Dinkey Lakes Roadless Area have substantiated resource potential for tungsten 

and marble and probable resource potential for quartz crystal gemstones. A 

probable resource potential for geothermal energy exists in one small area No 

potential for other metallic mineral or energy resources was identified in this 

study. 

CHARACTER AND SETTING 

The Dinkey Lakes Roadless Area occupies an area of 

about 184 sq mi on the western slope of the Sierra 

Nevada, California, about 50 mi northeast of the city of 

Fresno. Altitudes in the roadless area range from over 

10,500 ft to less than 6500 ft. Small lakes and alpine 

meadows dot the area's rugged mountainous terrain, 

much of which is covered with forests of pine and fir. 

The spectacular scenery is typical of glaciated regions of 

the Sierra Nevada California State Highway 168 provides access to the roadless area from the southwest 

and passes near its northern boundary. Several paved 

and dirt roads branch from State Highway 168, providing access to margins of the area 

Much of the roadless area is underlain by granitic 

rocks extensively mantled with glacial debris; however, 

remnants of pregranitic rocks are locally present. A 

variety of metasedimentary rocks, principally quartzite, 

schist, marble, and hornfels, occur in a roof pendant in 

the southwest part of the area and as scattered inclusions south of the pendant. These rocks were metamorphosed and locally metasomatized during intrusion of 

plutonic rocks. Metavolcanic rocks, chiefly of rhyolite or 

rhyodacite composition, occur along the northeastern 

boundary of the area in a second roof pendant. Ages of 

the metamorphic rocks are not known with certainty, 

but based on regional setting and lithologic correlations, the metasedimentary rocks are believed to be 

Paleozoic or early Mesozoic, and the metavolcanic 

rocks, early or middle Mesozoic. 

Numerous bodies of plutonic rocks ranging in composition from gabbro to granite are separated by sharp, 

steeply dipping or vertical contacts. The oldest plutonic 

rocks, believed to be Jurassic, are included in the 

metavolcanic roof pendant. Most of the granitic rocks in 

the southwest third belong to an Early Cretaceous sequence. Granitic rocks in the northwestern two-thirds of 

the roadless area belong to a Late Cretaceous sequence. 

The USGS and USBM conducted field investigations 

during the summer of 1980 to determine the mineralresource potential of the Dinkey Lakes Roadless Area 

Field investigations included a reconnaissance of the 

geology of the area and field checking existing geologic 

maps, comprehensive examination of terrains with possible mineral-resource potential, geochemical sampling, 

and detailed examination of mines, prospects, and mineralized zones. 

The Dinkey Creek mining district in the southwest 

part of the Dinkey Lakes Roadless Area is the only 

district in the area Tungsten production has been 

recorded from two mines. The Rainbow mine has been 

worked by stoping methods intermittently since 1942, 

with total production of about 3000 short-ton units of 

tungsten trioxide concentrate. From 1953 to 1956 the 

Mud Lakes mine yielded about 4,800 short-ton units of 

tungsten trioxide concentrate from an open pit; a substantial portion of the ore body has been removed. 

MINERAL RESOURCES 

There is substantiated resource potential for tungsten 

in the southwestern part of the roadless area Tungsten 

resources are in contact metamorphic deposits along the 

margins of the metasedimentary Dinkey Lakes roof 

pendant and in inclusions in granitic rocks near the 

pendant. Tactite interbedded in the schist unit of the 

227 
228 

119°15' 

37° 

30' 

Peak 

>( 

119°00' 118°45' 

I ok. rh 1!\JS 

'VI<>l 11 

s? /To"'o """ 

~t~ ~ \ ...... Approximate roadless 

~ ~ /-- "V ~ 1\ boundary 

8 ~ ~~ X \\J l ~ 1 Mo mt G \ "'" l \_ \ 

/ \ .sl ~ I I 

jJJ } 

_f ~I, 

Geoth e rmal , 

D 

w 

X 

, ....... - / Quartz (05244 

1 

D ate 

d k p Mo '' t.J 

R < 

0 10 

MILES 

EXPLANATION 

Geologic terrane with substantiated 

mineral-resource potential 

Geologic terrane w ith probable 

mineral-resource potential 

Tungsten 

Mine or deposit 

Mineral occurrence 

Granitic rocks (Cretaceous) 

Metavolcanic rocks (Mesozoic) 

Metasedimentary rocks 

(Mesozoic and (or) Paleozoic) 

Contact 

Figure 65.-Dinkey Lakes Roadless Area, California 
pendant and small inclusions of tactite south of the 

pendant are particularly favorable geologic environments for the occurrence of scheelite (calcium 

tungstate)-rich lenses and shoots. 

The Rainbow, Mud Lakes and Lone Wolf mines, and 

Young Group properties have 164,000, 20,000, 17,000, 

and 800 tons of demonstrated tungsten resources, 

respectively, averaging about 0.13 percent W03; a total 

for the area of approximately 220,000 tons. 

A finely laminated marble unit occurs in the roof 

pendant in the southwestern part of the roadless area 

The gray marble is probably clastic in origin; it is nearly 

pure calcite and chemically meets limestone specifications for portland cement. The marble unit is exposed 

over an area of at least 1300 ft long and 400-600 ft wide; 

it may contain more than 20 million tons of demonstrated limestone resources. Transportation costs 

would greatly limit the distance the material could be 

shipped to major markets. 

Smoky quartz (morion) crystals that occur at a wellknown collecting locality in a 0.25 sq mi area in the 

south-central part of the roadless area are a potential 

semi-precious gemstone resource. Singly and doubly 

terminated smoky-grayish-brown to black quartz crystals are present in numerous miarolitic cavities in lightcolored, garnet-bearing granite. Crystals 6 in. long have 

been found in some of the larger cavities. The area has a 

probable resource potential for quartz crystals. 

Thermal-spring activity in the northeastern part of 

the area is an identified hot-water convection system. 

Reservoir temperatures are estimated to be most likely 

130°F. The system may be adequate for space and process heating; however, electrical generation requires 

significantly greater temperatures and the area is 

assessed as having a probable geothermal resource 

potential. 

Sulfide-bearing quartz samples containing low gold 

and silver values have been collected from a prospect 

adjacent to the southwestern boundary of the area. A 

minor amount of gold (6.48 troy oz) was produced in the 

late nineteenth century from quartz veins that discontinuously outcrop along the margins of a granitic intrusion. No gold or silver resources were identified at this 

locality. 

Although small low-grade placer gold deposits are 

present near the roadless area, none are known to occur 

within the area Sand and gravel resources are abundant 

in the area; however, similar and more accessible 

deposits are available closer to potential markets. 

SUGGESTIONS FOR FURTHER STUDIES 

Most of the scheelite-bearing surface outcrops in the 

roadless area have probably been found; however, subsurface exploration may lead to the discovery of additional tungsten resources in the southwestern part of 

the roadless area. Any further study of the area offers 

little likelihood of identification of other mineral 

resources. 

REFERENCES 

Dodge, F. C. W .. 1982, Geologic map of the Dinkey Lakes Study 

Area, Fresno County, California: U.S. Geological Survey 

Miscellaneous Field Studies Map MF- 1389- A. scale 1:62,500. 

Dodge, F. C. W., Federspiel. F. E., Smith, D. B., Campbell, H. W., 

Scott, D. F., and Spear, J. M., 1983, Mineral resource potential 

map of the Dinkey Lakes Roadless Area, Fresno County, Califor· 

nia: U.S. Geological Survey Miscell.aneous Field Studies Map 

MF- 1389- B, scale 1:62,500. 

229 
230 

36° 

00 ' 

35° 45' 

0 5 

MILES 

EXPLANATION 

Geologic terrane with substantiated 

mineral-resource potential D Geologic terrane w ith probable 

mineral-resource potential 

Cu Copper Sn Tin 

Au Gold w Tungsten 

Pb Lead u Uranium 

Mo Molybdenum Zn Zinc 

Ag Silver 

,_-;,_-;, 

!;~'...'"/'..-' _ Granitic rocks (Mesozoic) 

Metamorphic rocks (Pre-Middle .Jurassic) 

Contact 

Figure 66.-Domeland Wilderness, Dorneland Addition, and Woodpecker Roadless Areas, California 
DOMELAND WILDERNESS , DOMELAND ADDITION AND 

WOODPECKER ROADLESS AREAS, CALIFORNIA ' 

By j OEL R . BERGQ I T 1 U.S. GEOLOG I AL R EY, and 

jAM E M. SPEAR, U .S. B REA OF Mr E 

SUMMARY 

A mineral survey of the Domeland Wilderness and the contiguous Domeland 

Addition and Woodpecker Roadless Areas was made in 1978-80 by the USGS 

and USBM. The study delineated areas of substantiated and probable mineralresource potential. The areas of substantiated resource potential are in the 

Woodpecker Roadless Area where alluvial gravel in Rockhouse Basin and on 

Upper Trout Creek contains small, irregular, low-grade deposits of placer gold. 

There is a probable resource potential for very small deposits of uranium in fractures in granitic rocks west of the South Fork of the Kern River in the Domeland 

Wilderness. Geochemical data indicate a probable potential for a porphyrymolybdenum deposit at the southern end of the Domeland Wilderness, and for 

very small deposits of tungsten, copper-lead-zinc, tin, silver, and molybdenum 

at several places in the wilderness and roadless areas. The geologic terrane 

precludes the occurrence of organic fuel resources. 

CHARACTER AND SETTING 

The Domeland Wilderness, the Domeland Addition, 

and Woodpecker Roadless Areas are in the Sequoia National Forest on the crest of the Sierra Nevada near the 

southern end of the range. The Domeland Wilderness includes 98 sq mi, the Domeland Addition Roadless Area 

5 sq mi, and the Woodpecker Roadless Area 69 sq mi. 

The town of Kernville is 10 mi west of the wilderness at 

the north end of Lake Isabella, and Bakersfield is 45 mi 

southwest. The southern end of the wilderness is accessible by roads leading from California State Highway 

178. Access from the west, north, and east is by state, 

county, and USFS roads that in places parallel the 

boundary of the Woodpecker Roadless Area. 

The South Fork of the Kern River flows south 

through both the Woodpecker Roadless Area and the 

Domeland Wilderness, then west through South Fork 

valley into Lake Isabella The river has cut a steep and 

rugged V -shaped canyon in the wilderness, as deep as 

3000 ft, between Rockhouse Basin and South Fork 

valley. At the northern end of the Domeland Wilderness 

is the Domeland, a unique area of approximately 35 sq 

mi that is characterized by numerous hemispherical to 

'With contributions from William R. Miller and Robert C. Jachens. USGS. and Andrew M. 

Les1.cykoowki. USBM. 

elongate, nearly white, granitic exfoliation domes. The 

domes vary in size from a few hundred feet in diameter 

and 50-100ft high, to approximately 5 mi long, 1-2 mi 

wide, and more than 2000 ft high. The domes are relatively barren of vegetation except for brush and trees 

growing in crevices. 

Altitudes range from about 3000 ft near South Fork 

valley in the southern part of the Domeland Wilderness 

to 9997 ft at Sirretta Peak near the western edge of the 

Woodpecker Roadless Area Lower altitudes support 

desert flora including cacti and Joshua trees. The higher 

altitudes have open coniferous forests of red fir, white 

fir, yellow pine, and Jeffrey pine. The Domeland Wilderness and Woodpecker Roadless Area are crossed by 

numerous hiking trails including the Pacific Crest Trail. 

Metamorphic and plutonic rocks typical of the Sierra 

Nevada underlie the area Older (pre-Middle Jurassic) 

metamorphic rocks were intruded by a succession of 

younger (Mesozoic) granitic plutons of varying composition. The metamorphic rocks occur as roof pendants 

with steeply dipping beds that commonly erode to 

"tombstone" rocks. The metamorphic rocks consist 

mostly of interbedded quartzite, schist, phyllite, and 

marble, with minor amounts of slate and metavolcanic 

rocks. The marble and associated tactites are of particular interest because elsewhere they are host rocks for 

tungsten and other mineral deposits. 231 
Overlying the metamorphic and granitic units are erosional remnants of more recent (late Tertiary) volcanic 

flows of basalt and andesite. 

The area was covered by geologic, geochemical, geophysical, and mineral-occurrence surveys in 1979-80 

(Bergquist and Nitk.iewicz, 1982; J achens, 1983; Miller 

and others, 1983a, b; Miller and McHugh, 1983). 

MINERAL RESOURCES 

There is no recorded production of minerals from the 

wilderness or roadless areas. The closest mining district, the Cove district, is near Kernville approximately 

8 mi west of the southern end of the Domeland Wilderness. Areas along the Kern River near the Cove mining 

district were prospected and mined for placer gold 

beginning in 1851, but by 1855 most mining ceased. 

Gold-quartz veins were discovered in the Cove district 

in 1860. A total of $5 to 8 million in gold was produced, 

mostly before 1883. 

The Kern River uranium area is 17 mi southwest of 

the southern end of the wilderness. Uranium deposits 

discovered there in 1954 occur locally along fractures in 

the granitic rocks. Only about 189 tons of ore were 

reported to have been shipped; the richest shipment was 

46 tons of ore that averaged 0.62 percent uranium oxide. 

There are no patented mining claims in the wilderness 

or roadless areas and only 38 mining claims have been 

located within the Domeland Wilderness. The first mining in Woodpecker Roadless Area was in 1901 when 

gold placers were worked in Rockhouse Basin along the 

South Fork of the Kern River. Between 1901 and 1968, 

34 placer claims were staked along the South Fork of 

the Kern River in Rockhouse Basin. Old placer workings are still in evidence in lower Rockhouse Basin, but 

there is no evidence of recent activity. 

A demonstrated resource of approximately 4.5 million 

cu yds of gold-bearing gravel occurs in fan deposits 

along the South Fork of the Kern River in four areas of 

substantiated gold resource potential in Rockhouse 

Basin. At $500/troy oz of gold, the resources are valued 

at an average of approximately 40 ¢/cu yd. Selective 

mining probably could not produce more than a few tens 

of thousands of cubic yards of gravel averaging more 

than $1/cu yd. 

Gold-bearing gravels on upper Trout Creek in the 

western part of the Woodpecker Roadless Area yielded 

as much as $4.50/cu yd; however, the average grade is 

much lower, just as it is in the gold-bearing gravels in 

Rockhouse Basin. These gravels are in a small area of 

substantiated gold resource potential, but the deposits 

are small in size (only about 1000 cu yds of gravel) and 

are remote. 

232 

Geochemical data indicate a probable resource potential for very small deposits of uranium in the relatively 

inaccessible rugged canyons on the west side of the 

South Fork of the Kern River within the Domeland 

Wilderness. On the basis of the occurrence and production of uranium in the Kern River uranium area 17 mi 

southwest of the wilderness, any uranium deposits in 

the wilderness will probably have no more than a few 

tens of tons of rock averaging as much as 0.5 percent 

uranium oxide. 

At the southern end of the Domeland Wilderness, a 

geochemical suite of base metals and molybdenum indicates an area of probable mineral-resource potential for 

porphyry-type molybdenum mineralization. However, 

the geochemical anomalies are of relatively low 

magnitude and there is a lack of any corroborating 

evidence. 

Small, irregular tactite bodies occur locally at the contacts of metamorphic rocks and granitic rocks. Two 

areas of tactites near Trout Creek in the Woodpecker 

Roadless Area have a probable resource potential for 

small deposits of tungsten and other base-metal 

mineralization. 

Several other areas have probable potential for very 

small vein or tactite-type deposits of tungsten, copperlead-zinc, tin, silver, and molybdenum. These areas were 

identified on the basis of geochemical data, but the low 

magnitudes of the anomalies and the lack of other 

evidence indicates that the occurrences would be small 

and difficult to identify. 

SUGGESTIONS FOR FURTHER STUDIES 

Further studies are not recommended. Additional 

studies might confirm the presence of porphyry-type 

molybdenum mineralization at the southern end of the 

Domeland Wilderness. Further study in other areas is 

unlikely to reveal significant mineral deposits. 

REFERENCES 

Bergquist, J. R., Jachens, R. C., Miller, W. R., Leszcykowski, A. M., 

and Spear, J . M., 1983, Mineral resource potential map of the 

Domeland Wildemess and contiguous roadless areas, Kern and 

Tulare Counties, California: U.S. Geological Survey Miscellaneous Field Studies Map MF- 1395- F, scale 1:48.000. 

Bergquist, J. R., and Nitkiewicz, A. M., 1982, Geologic map of the 

Domeland Wilderness and contiguous roadless areas, Kern and 

'l'ulare Counties, California: U.S. Geological Survey Miscellaneous Field Studies Map MF- 1395-A, scale 1:48,000. 

J achens. R. C., 1983, Geophysical interpretation of the Domeland 

Wilderness and contiguous roadless areas, Kern and Tulare 

Counties. California: U.S. Geological Survey Miscellaneous Field 

Studies Map MF-1395-B, scale 1:48,000. 
Miller, W. R., McHugh, J. B., and Motooka, J. M., 1983a, Maps 

showing distribution of anomalous trace elements in the nonmagnetic fraction of heavy-mineral concentrates and uranium in 

the less than 0.180 = fraction of selected stream sediments, 

Domeland Wilderness and contiguous road.less areas, Kern and 

Tulare Counties, California: U.S. Geological Survey 

Miscellaneous Field Studies Map- 1395-E, scale 1:48,000. 

__ 1983b, Map showing distribution of anomalous trace elements 

in the magnetic fraction of heavy-mineral concentrates, Domeland Wilderness and contiguous road.less areas, Kern and Tulare 

Counties, California: U.S. Geological Survey Miscellaneous Field 

Studies Map MF- 1395- C, scale 1:48,000. 

Miller, W. R., and McHugh, J. B., 1983, Map showing distribution of 

anomalous elements in water, Domeland Wilderness and contiguous road.less areas, Kern and Tulare Counties, California: 

U.S. Geological Survey Miscellaneous Field Studies Map 

MF- 1395- D, scale 1:48,000. 

233 
234 

38° 

40' 

38° 

35' 

To 

Lake Tahoe 

MAP LOCATION 

T 

Be~r v~~ 

0 

119°50' 

Pass 

5 

M ILES 

119°45' 

CLAIM 

T< 

opaz 

EXPLANATION D Geologic terrane with probable 

mineral-resource potential 

Ag Gold 

Au Silver 

w Tungsten 

~ Mine or deposit 

'X' Mine 

Alluvial and glacial deposits (Quaternary) 1-~--i f" "7" l.. 

~., ~ Younger volcanic rocks (Miocene) 

" " 

''1.::: .; !.'tl.- \-\ 

Older volcanic rocks (Miocene ) 

Granitic rocks (Cretaceous ) 

Sedimentary rocks (Mesozoic) 

Contact 

Fault--Bar and ball on 

downthrown side 

Figure 67.-East part of the Raymond Peak Roadless Area, California 
EAST PART OF THE RAYMOND PEAK ROADLESS AREA, CALIFORNIA 

By DAVID A. jOHN, U.S. GEOLOGICAL S RVEY, and 

FRANK E . FEDERSPIEL, .S. B REAU OF Mr ES 

SUMMARY 

Based on a mineral survey in 1979-80, there are demonstrated silver-gold 

resources at five properties within a large area of probable silver-gold potential 

in the east part of the Raymond Peak Roadless Area A small area with probable 

mineral-resource potential for skarn-type tungsten resources occurs at the north 

end of the roadless area The geologic setting precludes the presence of fossil 

fuels and no other energy resources were identified in the study. 

CHARACTER AND SETTING 

The east part of the Raymond Peak Roadless Area, 

Alpine County, California encompasses about 58 sq mi 

along the crest and eastern slope of the Sierra Nevada, 

about 15 mi south of Lake Tahoe. The topography of the 

area is characterized by deeply incised canyons with 

glacially scoured walls. The jagged volcanic pinnacles 

forming Raymond Peak may be seen from miles away 

while traveling along U.S. Highway 395 south of Carson City, evada. The spectacular Ebbetts Pass road 

(California Highway 4) passes just south of the area and 

forms the southeastern boundary. Altitudes range from 

about 5600 ft to more than 10,000 ft on Raymond and 

Hawkins Peaks. Markleeville, the county seat of Alpine 

County, is just east of the area 

The east part of the Raymond Peak Roadless Area, to 

be referred to as the study area, consists of two contrasting geologic environments. Most of the northwestem half is underlain by granitic rocks of the Sierra 

evada batholith. There are 13 granitic plutons, all of 

Late Cretaceous age, exposed in the study area. Except 

for areas where these granitoids intrude calcareous 

metasedimentary rocks, there is no mineral-resource 

potential associated with them. 

Most of the southeastern half of the study area is 

underlain by volcanic rocks of late Tertiary age which 

unconformably overlie the granitic rocks. These rocks 

are part of an extensive volcanic terrain lying primarily 

to the east and to the south of the Raymond Peak Roadless Area. An unusually thick section of volcanic rocks 

(as much as 7000 ft) is preserved near the southeast 

comer of the study area; this is thought to occur 

because of the presence of a nearby eruptive center and 

because of major normal faulting which has downdropped the volcanic rocks relative to the older granitic 

rocks. Most known mineralization in the east part of the 

Raymond Peak Roadless Area is in the volcanic rocks. 

Pleistocene glaciation extensively modified the topography of the study area, and thick glacial deposits cover 

the bottoms of major valleys. 

Mining activity began near the Raymond Peak Roadless Area in the 1850's shortly after the discovery of the 

Comstock lode in Virginia City, Nevada Mining properties in and adjacent to the southeastern part of the 

study area are in the Silver Mountain district. Production from the Silver Mountain district is thought to 

have been less than $300,000 mostly in silver and gold 

in the 1870's (Clark, 1977). The northwest end of the 

study area lies in the Hope Valley district. Small 

amounts of tungsten and gold were produced from two 

mines just outside the area in the 1950's. 

The mineral-resource potential described in this 

report is based on studies conducted during 1979-80. 

Studies included geologic mapping of the area (Armin 

and others, 1982), interpretation of aeromagnetic and 

gravity maps (Plouff, 1983), geochemical sampling of 

stream sediments (S. J. Sutley, unpub. data, 1982), and 

examination of mines and mineralized areas. All of these 

data are summarized in John and others (1983). 

MINERAL RESOURCES 

Two diverse geologic settings, each with different 

types of possible mineral deposits, are present in the 

east part of the Raymond Peak Roadless Area Tertiary 

volcanic rocks in the eastern Sierra Nevada host 

235 
precious-metal (silver-gold) deposits at several localities 

including a number of mines and prospects along the 

southeastern margin of the study area and in the 

Monitor district 2 mi to the east. Metasedimentary 

rocks intruded by granitic rocks of the Sierra Nevada 

batholith host numerous tungsten deposits including 

three small deposits in the Hope Valley district just 

northwest of the area 

Two types of silver-gold mineralization are present in 

Tertiary volcanic rocks near the study area Most of the 

silver-gold mineralization in the Silver Mountain 

district occurs in quartz veins filling shears and fault 

zones in the lower part of the volcanic section. Along the 

edges of these veins, argillic (clay) alteration is superimposed on earlier propylitic alteration, which is a widespread feature throughout the district and in the nearby 

Monitor district. The source of the mineralizing fluids is 

unclear but may be related to nearby unmineralized 

rhyolite intrusions. 

A second type of silver mineralization occurs in the 

Zaca mine (the largest mine in the Monitor district) and 

is apparently genetically related to a rhyolite plug that 

intrudes and hydrothermally alters andesitic rocks 

which had been previously propylitized. Intense argillic 

alteration and silicification are present in the rhyolite, 

and most of the ore occurs in altered rhyolite. 

Three properties within the study area have been 

identified by the USBM as having demonstrated 

resources of silver and (or) gold. These properties are the 

St. Helena prospect with 1,500,000 tons of demonstrated resources averaging 0.01 oz gold/ton and 2.5 oz 

silver/ton; the California-Illinois prospect with 270,000 

tons of demonstrated resources averaging 0.03 oz gold/ 

ton; and the Exchequer mine with 56,000 tons of demonstrated resources averaging 0.04 oz gold/ton. In addition, mineralized zones in the Columbine claim and in 

the IXL mine, which lie just outside of the boundary of 

the study area, probably extend into the study area 

Estimated resources in the Columbine claim are 94,000 

tons of demonstrated resources averaging 0.005 oz gold/ 

ton and 0.5 oz silver/ton and in the IXL mine are 

150,000 tons of demonstrated resources averaging 0.01 

oz gold/ton and 0.93 oz silver/ton and additional 15,000 

tons of demonstrated resources averaging 0.56 oz gold/ 

ton and 48.4 7 oz silver/ton. 

Either or both types of silver-gold mineralization described previously may be present in an area of probable 

resource potential in the southeastern part of the study 

236 

area. Most of the area of probable potential for silver 

and gold is propylitically altered, and there are local 

areas of argillic alteration and silicification similar to 

alteration in the Monitor district. Analyses of geochemical samples indicate anomalous concentrations of many 

elements including silver, copper, molybdenum, lead, 

and zinc throughout much of this area. The hydrothermal alteration, geochemistry, and presence of properties 

with demonstrated silver-gold resources suggest that 

additional silver-gold deposits may be present and the 

area has a probable resource potential. 

Tungsten-skarn mineralization occurs at the Calpine 

and Burnside mines just north of the study area along 

the contact between metasedimentary rocks and a granitic pluton. There is probable mineral-resource potential for tungsten in an area of metasedimentary rocks, in 

part covered by Tertiary volcanic rocks, intruded by the 

same granitic rocks as those at the mines extending into 

the northern part of the study area Structural data suggests that the metasedimentary horizons which contain 

skarn mineralization at the mines extends into this area 

(Parker, 1961). Stream-sediment geochemistry shows 

anomalous concentrations of tungsten and other metals 

in this area which are apparently unrelated to contamination from prior mining activities therefore the 

area is considered to have probable potential for tungsten resources. 

REFERENCES 

Armin, R. A., John, D. A., and Moore, W. J., 1982, Geologic map of 

the east part of the Raymond Peak Roadless Area, Alpine County. California, with Quaternary geology by J. C. Dohrenwend: 

U.S. Geological Survey Miscellaneous Field Studies Map 

MF- 1365-A, scale 1:62,500. 

Clark, W. B., 1977, Mines and mineral resources of Alpine County, 

California: California Division of Mines and Geology, County 

Report 8, 48 p. 

J ohn, D. A., Armin, R. A., Plouff, Donald, Chaffee. M. A., Federspiel, 

F. E., Scott. D. F., and Cather, E. E .. 1983, Mineral resource 

potential of the east part of the Raymond Peak Roadless Area, 

Alpine County, California: U.S. Geological Survey Miscellaneous 

Field Studies Map MF -1365- C, scale 1:62,500. 

Parker, R. B., 1961, Petrology and structural geometry of pre-granitic 

rocks in the Sierra evada, Alpine County, California: Geological 

Society of America Bulletin. v. 72, p. 1789- 1805. 

Plouff, Donald, 1983, Aeromagnetic and gravity maps of the east part 

of the Raymond Peak Roadless Area, Alpine County, California: 

U.S. Geological Survey Miscellaneous Field Studies Map 

MF- 1365- B, scale 1:62,500. 
EAST YUBA AND WEST YUBA ROADLESS AREAS, CALIFORNIA 

B y j OEL R. BERGQU I T, 1 U .. GEOLOGICAL S RVEY and 

' 

WILLIAM W . WHITE, III, U .. B REA F ML E 

SUMMARY 

The East Yuba and West Yuba Roadless Areas, which are located in the 

northern Sierra Nevada, California, have been evaluated on the basis of geologic, 

geochemical, and geophysical investigations by the USGS in 1980-81 and an investigation of mines, prospects, and mineralized area by the USBM in 1981-82. 

Both areas have demonstrated resources of gold and locally associated silver, in 

lode and placer deposits in areas of substantiated gold and silver resource potential. Large areas having a probable gold placer resource potential exist where 

Tertiary gravel deposits lie beneath Tertiary volcanic rocks in the roadless 

areas. There are active lode and placer gold mines in the roadless areas. Two 

areas of substantiated resource potential for small deposits of iron occur in the 

East Yuba Roadless Area Each roadless area has an elongate area of probable 

resource potential for small deposits of chromite. There is little promise for the 

occurrence of energy resources in the roadless areas. 

CHARACTER AND SETTING 

The East Yuba and West Yuba Roadless Areas are 

located on the west side of the crest of the northern part 

of the Sierra Nevada in the California Mother Lode gold 

country. The East Yuba Roadless Area includes 28 sq 

mi in the Tahoe National Forest, Sierra County, California The West Yuba Roadless Area includes about 23 sq 

mi in the Tahoe National Forest in Sierra and Plumas 

Counties. The roadless areas are a few miles north of the 

North Fork of the Yuba River. California Highway 49 

follows the river and links Downieville, located about 2 

mi south of the roadless areas, and Sierra City, located 

about 4 mi southeast of the East Yuba Roadless Area 

Access to and into the roadless areas is provided on all 

sides by graded roads and jeep trails. The site of Poker 

Flat, the gold rush town made famous by Bret Harte s 

book "The Outcasts of Poker Flat, " is on Canyon Creek 

at the northwest edge of the West Yuba Roadless Area 

Altitudes in the roadless areas range from about 4000 

ft to more than 7000 ft. The topography of the areas is 

generally rugged, and at lower altitudes the areas are 

typically cut by rugged ravines and canyons. Cascades 

and small waterfalls are common. The higher areas, in 

the eastern part of the East Yuba Roadless Area, have 

1

With conLribulions from Susan S. Pogtl. USGS. and Douglas F. OLI.. U BM . 

many lakes. At higher altitudes, the areas are generally 

covered by open forests of fir and pine, and at lower 

altitudes, hardwood trees, manzanita, oak, and other 

plants of the chapparal are common. 

The East Yuba and West Yuba Roadless Areas are in 

the northern part of the metamorphic belt of the 

western Sierra Nevada The bedrock in the roadless 

areas is mostly older (Paleozoic) metamorphic rock that 

is locally overlain by younger (Tertiary) volcanic rocks 

and gold-bearing river gravel. The Melones fault zone 

trends northward through the western part of the West 

Yuba Roadless Area and is the contact between two 

metamorphic rock units that include a variety of metamorphosed sedimentary and volcanic rocks. A third 

metamorphic rock unit consists of metamorphosed 

volcanic rocks and is located in the eastern part of the 

East Yuba Roadless Area A few small areas of intrusive granitic rocks occur in the East Yuba Roadless 

Area Overlying all of the metamorphic formations are 

younger (Tertiary), locally thick, deposits of volcanic 

mudflows and lava flows. Locally underlying these 

volcanic rocks are remnants of gold-bearing river gravel 

of Eocene (early Tertiary) age that are now elevated 

above the levels of present-day streams. 

Soon after the discovery of placer gold in 1848, the 

river gravels in the area of Downieville and Sierra City 

were mined. Many placer gold and lode gold mines and 

237 
238 

39 

35' 

To 

lo 

I'll 

1 °4 ' 

Mount 

Washmgtor 

120°40' 

Mt Ewell 

add! back Mt 

MAP LOC ATION 

0 

M ILES 

' I 

L"" 

I 

I 

I 

11 

East Yuba 

05264 - ( ~nlth r. 

" 6 

\"-'' :5 

· 

9 

I ,~ 

Au 

' /''K,"lciJ 

5 

EXPLANATION 

Geologic terrane with substantiated 

mineral-resource potential D Geologic terrane w ith probable 

mineral-resource potential 

Cr Chromium 

Au Gold 

~ Mine or deposit 

Fe 

Ag 

Iron 

Silver 

c=J Volcanic rocks (Tertiary) 

CJ Metamorphic rocks (Paleozoic) 

---Contact 

--- Fault 

2 Location discussed in text 

Figure 68.-East Yuba and West Yuba Roadless Areas, California 
prospects are located within and near the roadless areas 

in gold-bearing Tertiary gravels and have recorded production of at least a few hundred thousand dollars 

(Clark, 1970). Gold that is in part reworked from Tertiary gravels is presently being mined from modern 

creek and river gravels in and near the roadless areas. 

The Poker Flat mining district is located around 

Poker Flat at the north end of the West Yuba Roadless 

Area, and includes mostly placer mines, although a few 

lode mines are also in the district. The area was first 

mined in the gold rush of 1849 for placer gold; hydraulic 

mining continued from the late 1850's through the 

1880's, and lode mining continued through the early 

1900's (Clark, 1970, p. 109). 

Geochemical sampling of stream drainages and many 

rock types within the roadless areas was done in order 

to find possible signs of undiscovered mineral deposits. 

The analytical results are listed in Page and Bergquist 

(1982). 

MINERAL RESOURCES 

There is recorded production of gold and lesser 

amounts of silver from lode and placer mines within the 

roadless areas. Mines located within the roadless areas 

have produced about 12,500 oz of gold from Tertiary 

river gravels and about 21 ,300 oz of gold and 13,400 oz 

of silver from lode deposits. More than 300 active placer 

and lode claims are recorded for the West Yuba Roadless Area and more than 200 for the East Yuba Roadless Area 

In the East Yuba Roadless Area, most of the gold 

resources are in gold-bearing quartz veins and quartzveinlet stockworks in lode mines and prospects, including some in the Sierra City mining district. Clark 

(1970, p. 117) reported that the district was most productive from 1870 to 1914, with additional mining in 

the 1920's and 1930's, and that total estimated production is at least $30 million. Of that total, Clark (1970, 

p. 117) estimated that about $2 million in gold was produced from the Four Hills mine (loc. 1, on map), which is 

adjacent to and partly within the northeast part of the 

East Yuba Roadless Area The Four Hills (loc. 1), Big 

Boulder (loc. 2), Empire (loc. 3), Gold King (loc. 4), Lone 

Star (loc. 5), Sisson (loc. 6), and Willoughby (loc. 7) 

mines are on gold-silver lode deposits and have demonstrated resources. Production records for the Empire, 

Four Hills, and Willoughby mines indicate mined ore 

contained 0.26 to 0.48 oz gold/ton and 0.05 to 1.3 oz 

silver/ton. The Dragonfly (loc. 8), Jay Bird (loc. 9), 

Rebate (loc. 10), Upper Lavezzola Creek (loc. 11), Upper 

Pauley Creek (loc. 12), and Whipoorwill (loc. 13) placer 

properties have demonstrated low-grade gold resources 

in bench gravels. Minor amounts of placer gold are produced from active drainages. 

Two small areas containing about 16 separate occurrences of magnetite (an iron oxide mineral) have a 

substantiated mineral-resource potential for iron in the 

north part of the East Yuba Roadless Area The occurrences are all small and were found in the nineteenth 

century, but there has been no attempt at mining, and 

they are all of low tonnage. 

In the West Yuba Roadless Area, most gold mining 

has been in isolated remnants of Tertiary river gravels 

although there has been some mining of gold in lode 

deposits. Currently, small-scale mining of placer gold in 

active drainages is carried out on a seasonal basis. The 

Downieville mining district is located around and north 

of the town of Downieville. The gold mines in this 

district are in placers in gold-bearing Tertiary gravel 

underlying younger volcanic rocks, and in gold-quartz 

vein lode deposits. The placer gold mines on Craycroft 

Ridge (loc. 15) are in an area of substantiated gold 

resource potential in this district. In the West Yuba 

Roadless Area, the Bummer (loc. 14), CraycroftWideawake (loc. 15), Excelsior (loc. 16), Monte Cristo 

(loc. 17), New California (loc. 18), and Sol Wood (loc. 19) 

mines have demonstrated low-grade placer gold resources in remnants of Tertiary river gravels in areas of 

substantiated gold resource potential. The Bunker Hill 

(loc. 20), Gibraltar (loc. 21), Golden Scepter (loc. 22), 

Herkimer (loc. 23), Telegraph (loc. 24), and Tennessee 

(loc. 25) mines have demonstrated placer gold resources 

in gold-bearing Tertiary gravel. The Buckshot (loc. 26), 

Clark Canyon (loc. 27), Crescent (loc. 28), D-B-K (loc. 29), 

Deep Moon (loc. 30), and Progressive (loc. 31) properties 

have demonstrated resources of gold-bearing bench 

gravels, and most of these are being developed or mined. 

The Poker Flat prospect (loc. 32) has recorded production of about 500 oz of gold from gold-bearing quartz 

veins, and there are additional demonstrated resources. 

All of these mines (locs. 20- 32) occur in Tertiary 

gravels in and around areas of younger volcanic 

deposits. There is probable resource potential for the 

occurrence of additional gold-bearing Tertiary river 

gravels beneath the Tertiary volcanic deposits. 

Four chromite mines 2-4 mi south of the West Yuba 

Roadless Area have produced about 2500 tons of ore 

during World Wars I and II with the Oxford mine having produced most of the ore. Examination and analyses 

of similar host rocks within both roadless areas revealed 

only minor amounts of associated chromite. There is a 

probable potential for small undiscovered deposits of 

chromite in areas along the Melones fault in the West 

Yuba Roadless Area and in the southeast part of the 

East Yuba Roadless Area 

Large volumes of sand and gravel are in Tertiary river 

239 
gravels in the West Yuba Roadless Area, and may be a 

local resource, but abundant quantities exist outside the 

area 

The East Yuba and West Yuba Roadless Areas have 

no indications of potential for oil, gas, coal, geothermal 

energy, or radioactive minerals. 

SUGGESTIONS FOR FURTHER STUDIES 

Specialized geophysical methods could be used to try 

to locate gold-bearing Tertiary river gravels that may 

underlie the Tertiary volcanic rocks. Detailed studies of 

mines within the roadless areas may reveal additional 

data on potential resources. 

240 

REFERENCES 

Bergquist, J. R., White, W. W .. Scott. D. F .. Griscom. Andrew, and 

Page, S. S .. in press, Mineral resource potential map of the East 

Yuba and West Yuba Roadless Areas. Plumas and Sierra Counties, California: U.S. Geological Survey Miscellaneous Field 

Stucties Map MF - 1613-A, scale 1:48,000. 

Clark, W. B .. 1970, Gold ctistricts of California: California Division of 

Mines and Geology Bulletin 193, 186 p. 

Page, S. S.. and Bergquist, J. R., 1982, Geochemical analyses of 

panned heavy- mineral concentrates, stream sediments, and rock 

samples from the East Yuba and West Yuba Roadless Areas, 

Plumas and Sierra Counties, California: U.S. Geological urvey 

Open-File Report 82-825, 116 p. 

White, W. W., 1983, Mineral investigation of the East and West Yuba 

RARE II areas (nos. 5664 and 5172) Sierra and Plumas Counties. 

California: U.S. Bureau of Mines Open-File Report MLA 71 - 83. 
EMIGRANT BASIN AND HOOVER WILDERNESSES AND 

ADJOINING ROADLESS AREAS, CALIFORNIA ' 

By EDWI W. TOOKER, 1 U .. GEOLOGI L S R EY, a nd 

lCH LAST. ZILKA, .S . BUREAU F MI1 ES 

SUMMARY 

Mineral surveys conducted in 1967-1978 led to the conclusion that there was 

little promise for the occurrence of mineral or energy resources in the Emigrant 

Basin Wilderness, whereas the Hoover Wilderness and adjoining roadless areas 

contain areas with probable and substantiated potential for base- and preciousmetal resources. The metal contents in the rocks of the Emigrant Basin are 

generally no greater than the abundance levels that characterize nonmineralized 

regions, as shown by a geochemical survey. In contrast, an area in the southern 

part of the Hoover Wilderness has substantiated resource potential for small 

discontinuous precious-metal deposits along veins. This classification was made 

on the basis of an extension of an area containing known precious-metal 

deposits. Extensions of known, or the possibility of discovery of new, tungsten 

deposits in the Roadless Areas 5-662 and 4-664 indicate parts of these areas 

have probable mineral-resource potential. A mineralized area with probable 

mineral-resource potential for disseminated copper and molybdenum is present 

at the north end of the Hoover Wilderness and in the northeastern part of 

roadless area 4-664. No resource potential for uranium, geothermal, or organic 

fuel energy sources was identified in this study. 

CHARACTER AND SETTING 

The Emigrant Basin and Hoover Wildernesses lie 

along the west and east sides of the crest of the Sierra 

evada in Tuolumne and Mono Counties, California 

These wildernesses, which contain about 412 sq mi of 

generally roadless lands, are located within parts of the 

Stanislaus, Toiyabe, and In yo National Forests. Four 

roadless areas, 4-662, 4-664, 4-666, and 5-662 (also 

known as the Emigrant Basin Primitive Area) lie along 

the northern and eastern sides of the Hoover Wilderness. These areas are bounded by Yosemite National 

Park on the south, by Bridgeport Valley, Mono Lake, 

and tributaries of the East and West Walker Rivers on 

the east, by two paved highways that cross the Sierra 

Nevada at Sonora Pass on the north and Tioga Pass on 

the south, and the headwaters of the Middle Fork of the 

Stanislaus and 'I'uolurnne Rivers on the west. The 

region is one of marked relief and spectacular scenery 

that has been enhanced by glacial erosion. 

1

With contributions from H. T. Morris. H. W. Oliver. M. A. Chaffee. R. H. Hill. W. J. Keith. 

Donald Plouff. J. F. icr.z. and . J. Sutley. USG ; P. V. Fillo and A. M. Lcszcykowski. 

U IJM ; and G. F. Brcm. Cnlifomia State University. ~'ullcrt.on. Calif. 

Field investigations were made by the USGS and 

USBM in the Emigrant Basin Wilderness in 1967 and 

1968 (Tooker and others, 1970), and in the Hoover 

Wilderness and adjoining roadless areas in 1977 and 

1978 (Tooker and Zilka, 1983). Geologic mapping, 

geochemical sampling, and gravity and magnetic 

geophysical surveys were conducted by the USGS, and 

mapping and sampling of the mines and prospects and a 

survey of claim records were made by the USBM. 

The Emigrant and Hoover Wildernesses are in the 

west-central part of the Sierra Nevada, an asymmetrical 

north-trending structural block 400 mi long and 40 to 

80 rni wide having a gently inclined western slope and 

an irregular steep escarpment along its eastern side. 

This block consists chiefly of several batholiths of 

Mesozoic granitic rocks containing roof pendants of upper Paleozoic and lower Mesozoic metasedimentary 

rocks (Bateman and W ahrhaftig, 1966). All of these 

rocks are discontinuously overlapped along the northem borders of the wilderness areas by a partly eroded 

blanket of Tertiary volcanic and sedimentary rocks 

(Slernrnons, 1966). Local areas of pyritized and argillized 

granitic, metasedimentary, and volcanic rocks crop out 

241 
38° 

20' 

38° 

00' 

242 

Approximate boundary 

MAP LOCATION 

0 10 

MILES 

EXPLANATION 

- Geologic terrane with substantiated 

mineral-resource potential 

D Geologic terrane with probable 

mineral-resource potential 

Cu Copper 

Au Gold 

Pb Lead 

Mo Molybdenum 

Ag Silver 

w Tungsten 

Zn Zinc 

~ Mine or deposit 

Altered rocks 

< < .) ') L 

"t ~,. ... ., Volcanic rocks, undifferentiated 

Granitic intrusive (batholith) 

rocks, undifferentiated 

~ Metasedimentary and metavolcanic (roof pendant) rocks, undifferentiated 

Contact 

Figure 69.-Emigrant Basin and Hoover Wildernesses and adjoining roadless areas, California. 
along the northern and eastern sides of the Hoover Wilderness area. Five major geologic events are recorded in 

these rocks: (1) a long period of deposition of marine sediments during the Paleozoic Era (from 230 to 600 m.y. 

(million years) ago); (2) formation of a great synclinal 

basin during latest Paleozoic or earliest Mesozoic time 

that became filled by volcanic and sedimentary debris; 

(3) deformation and intrusion by granitic batholithic 

masses followed by uplift and deep erosion before the 

close of the Mesozoic Era (about 62 m.y. ago); (4) subsequent uplift, tilting and faulting, preceeded and accompanied by volcanism in the late Cenozoic (9 to 26 m.y. 

ago); and (5) carving of present topography by erosion 

and Quaternary glaciation (about 1 m.y. ago). 

MINERAL RESOURCES 

The Sierra Nevada region is well known for the 

Mother Lode gold belt and related placers in the 

foothills along the western side of the Sierra Nevada 

batholith and the Pine Creek roof pendant tungsten 

deposits south of Yosemite Park, on the eastern side of 

the Sierra Nevada. Several small base- and preciousmetal, tungsten, and uranium mines and prospects are 

located in and adjacent to the wildernesses. Records indicate 44 lode and placer claims for tungsten within 

roadless area 5-662, which is located between the 

Emigrant Basin and Hoover Wildernesses, and approximately 1100 mining claims for gold, silver, and 

tungsten, mainly in the southern part of the Hoover 

Wilderness and adjoining roadless areas. The earliest 

claim locations in the Hoover area were made in 1859; 

they were followed by the establishment of the now 

abandoned Tioga and Homer mining districts in 1878 

and 1879. Total production from these areas is not 

known, but more than 42,500 oz gold and 18,000 oz 

silver were produced mainly from the May Lundy mine. 

Limited exploration for precious metals continues in 

this vicinity. 

Mineral occurrences are associated mainly with three 

groups of rocks shown on the map: upper Paleozoic and 

lower Mesozoic metasedimentary and metavolcanic roof 

pendants throughout the Emigrant Basin and Hoover 

Wildernesses; the margins of granodioritic Mesozoic 

plutonic bodies in the southern part of the Hoover 

Wilderness; and possibly with Tertiary volcanic rocks 

related to the Little Walker caldera structure in the 

northern part of the Hoover Wilderness. High-angle 

faults provided access channelways for the movement 

of hydrothermal solutions that concentrated the base 

and precious metals and tungsten in these rocks. The 

extensive and complex folding and faulting in the roof 

pendant rocks, particularly in the area of gold deposits, 

is obscured by later batholithic intrusion. Shear faults 

subparallel to bedding in the pendants, and steeply dipping cross faults, which locally offset pendant strata 

and separate plutonic bodies, are the main regional 

structures. 

Gold, silver, and minor base-metal resources are 

located mainly in the southern part of the Hoover 

Wilderness in the region of the May Lundy mine. Early 

plutonic bodies along the eastern margin of the Sierra 

Nevada and their adjacent locally argillized wallrocks 

are the sites of steeply dipping north-northwesttrending gold-bearing veins, which pinch and swell, split 

and branch. They are composed of quartz, brecciated 

host rock, and gold. Pyrite and arsenopyrite are common, and galena, chalcopyrite, sphalerite, and molybdenite are sporadic associated minerals. No known 

precious-metal vein deposits are associated with the 

later Mesozoic plutons along the western side of the 

area The southern part of the Hoover Wilderness contains substantiated resource potential for gold; no gold 

is known to occur in the Emigrant Basin Wilderness. 

The May Lundy mine is estimated to contain demonstrated resources of as much as 140,000 oz of gold. Adjacent mines may also be expected to contain smaller 

amounts of recoverable gold and silver. Only small 

amounts of ore are expected owing to the small size 

limits of the high-grade discontinuous ore shoots in this 

region. 

Tungsten, in the mineral scheelite (CaWO.), and 

associated base-metal minerals occur in discontinuous 

lenses in recrystallized limestone and garnet-epidote 

skarn where they are in contact with granodiorite. A 

number of small mines and prospects were developed in 

the roof pendants located in the westernmost roadless 

area 5-662 and area 4-664, which includes the headwaters of Cherry Creek. These areas have a probable 

tungsten resource potential. 

The main occurrences of tungsten at the southern 

part of the Hoover Wilderness are in sheared carbonate 

beds along or close to the contact with granodiorite and 

these carbonate beds have a small substantiated tungsten resource potential. Where carbonate beds are not 

sheared or in contact with intrusives, they are not 

mineralized. There is only limited promise for occurrence of significant amounts of tungsten in the 

Emigrant Basin and Hoover Wildernesses because of 

the shallow depth for most pendant bodies, the small 

size of the metalliferous skarn zone lenses adjacent to 

plutonic bodies, and the limited amount of limestone or 

dolomite in the pendants. Occurrence of base-metal and 

uranium deposits in areas 5-662 and 4-664 is considered unlikely under existing geologic conditions. 

An argillically altered zone in volcanic rocks on the 

western margin of the Little Walker caldera at the north 

end of the Hoover Wilderness and area 4-664, is intruded by a fine-grained granodiorite plug and is the site 

243 
of strong geochemical anomalies for copper and molybdenum as well as gravity and magnetic geophysical 

anomalies (Tooker and others, 1981). The characteristics of this zone are favorable for the occurrence of 

disseminated (porphyry-type) copper and molybdenum 

at depth, an ore type similar to deposits known in 

western evada (Wallace, 1979). This area has a probable resource potential for copper and molybdenum. 

A geothermal resource potential also exists outside 

the eastern margin of the wilderness, but probably does 

not extend into it. There is no known potential for fossil 

fuel deposits in this region. 

SUGGESTIONS FOR FURTHER STUDIES 

Additional studies of the main parts of the 

wildernesses offer little promise for the discovery of concealed mineral deposits. Geologic and subsurface exploration of the altered area on the west side of the 

Little Walker caldera, and more detailed investigation 

of several other altered and geochemically anomalous 

areas reported by Tooker and Zilka (1983) in the Hoover 

Wilderness may reveal promising areas for exploration. 

244 

REFERENCES 

Bateman, P. C., and Wahrhaftig, Clyde, 1966, Geology of the ierra 

evada, in Bailey, E. H., ed., Geology of northern California 

California Division of Mines and Geology Bulletin 190, 

p.107-172. 

Iemmons, D. B., 1966, Cenozoic volcanism of the central Sierra 

evada, California, in Bailey, E. H .. ed., Geology of northern 

California: California Division of Mines and Geology Bulletin 

170, p. 199-208. 

Tooker, E. W., Morri , H. T., and Fillo, P. V., 1970, Mineral re ources 

of the Emigrant Basin primitive area, California U .. Geological 

Survey Bulletin 1261- G, 70 p. 

Tooker, E. W., Brem, G. F., Chaffee, M. A., and Plouff. Donald, 1981, 

A potential resource target identified in the Hoover Wilderness 

and adjoining RARE II study areas, California U.S. Geological 

urvey Open-File Report 1- 788,7 p. 

Tooker, E. W., and Zilka, . T., 1983, Mineral resource potential map 

of the Hoover Wilderness and adjacent roadless areas, central 

Sierra evada, California: U.S. Geological Survey Miscellaneous 

Field Studies Map MF-1101- D, scale 1:62,500. 

Wallace, A. B., 1979, Possible signatures of buried porphyry-eopper 

deposits in Middle to Late Tertiary volcanic rocks of western 

evada: evada Bureau of Mines and Geology Report 33, 

p. 69- 76. 
FISHER GULCH ROADLESS AREA, CALIFORNIA 

By D O ALD F. H BER , 1 U.S. GEOLOG ! AL SUR EY and ) 

ERIC E. CATHER, .S. B REA OF Ml : E 

SUMMARY 

On the basis of a study in 1980-81, the Fisher Gulch Roadless Area has a 

probable potential for small amounts of placer gold resources in a narrow 

elongate area along the northeast boundary. There is little promise for the occurrence of other metallic, or nonmetallic resources and the geologic terrane 

precludes the occurrence of fossil fuel resources. 

CHARACTER AND SETTING 

The Fisher Gulch Roadless Area occupies an area of 

about 5.2 sq mi near the Trinity Alps in the Klamath 

Mountains, about 10 mi northwest of Weaverville, California Altitude above sea level ranges from 2400 ft on 

the east to 6250 ft on the west. The northern and westem boundaries are shared with the proposed SalmonTrinity Alps Wilderness. 

The roadless area is almost entirely underlain by the 

Salmon Hornblende Schist, a rock that was metamorphosed about 350 million years ago (Devonian). During 

the time from about 230 to 65 million years ago 

(Mesozoic), these rocks were accreted to the North 

American continent by plate-tectonic processes. Overlaying the metamorphic rocks in the northeast part of 

the roadless area are stream sediments in part derived 

from glacial debris. 

Stream-sediment samples from streams that drain 

the roadless area were collected and analyzed. Samples 

of the metamorphic rocks were used to establish 

background values to compare with the streamsediment analyses. The East Wind No. 1 mine sample 

analyses were used to check for mineralization that may 

be still present in the mine. 

Mining has gone on in this area since 1850 with the 

gravels of Canyon Creek and Fisher Gulch, adjacent to 

the roadless area on the east and south, being mined using the various placer techniques. Within the southeast 

part of the roadless area is the East Wind No. 1 mine. 

One mile to the e9.St of the roadless area are the Globe, 

Bailey, and Chloride mines, the largest gold-quartz vein 

mines in the Salmon-Trinity Alps region. 

1

Wit.h contributions from Scou C. Nelson. USG . and J oseph L. Ritchey. USBM . 

MINERAL RESOURCES 

The area of gravels on Canyon Creek, along the northeastern edge of the roadless area has a probable gold 

resource potential although the gravels have been 

extensively mined for placer gold and probably only 

small amounts of gold remain in present-day river 

gravels and bars. Analyses of stream-sediment samples 

from Little Rip stein and Jones Gulches show no significant amounts of gold, suggesting that the gold found in 

Canyon Creek was derived from other drainages outside 

the roadless area 

Analyses of gravels of Fisher Gulch and its tributary 

along the south boundary of the area show small 

amounts of gold. Local prospectors claim that gold nuggets have been recently recovered from Fisher Gulch. 

However, there is little promise for the occurrence of 

placer gold in Fisher Gulch other than the occasional 

nugget and small amounts of fine gold particles similar 

to those that have been recovered, because gravel 

volumes are small. 

Gold-bearing lode samples from the East Wind No. 1 

mine and the presence of small amounts of placer gold in 

the gravels of Fisher Gulch indicate that lode gold exists within the Fisher Gulch drainage area, most of 

which lies within the roadless area However, the East 

Wind No. 1 deposit appears to be mined out because 

both ends of the quartz vein pinch out in the adit, and 

assays of samples from the vein show little gold. A 

stockpile sample assayed 0.25 oz gold/ton, indicating 

that high-grade pockets probably occurred along the 

vein. Exploration along the vein might reveal additional 

pockets. However, because no other mines or claims exist within the roadless area and because extensive past 

exploration and prospecting in the area has been 

245 
246 

40° 123°05' 

55' 

M AP LO CATION 

0 

MILE 

EXPLANATION 

-

Au 

Geologic terrane with probable 

mineral-resource potential 

Gold 

Mine 

~ 

~ 

-

D 

D 

CHLORIDE 

M INE 

.. ,, \ 

£o 1

- / 

Gravels, terraces, and placer 

mine tailings (Quaternary) 

Moraine (Quaternary) 

Tonalite (Cretaceous or 

Upper Jurassic) 

Salmon Hornblende Schist 

(Devonian) 

Contact 

Figure 70.-Fisher Gulch Roadless Area, California 
unrewarding, the area is concluded to offer little promise for the occurrence of additional surface locle gold 

deposits. 

SUGGESTIONS FOR FURTHER STUDIES 

Gold-bearing quartz veins associated with dikes in the 

Salmon Hornblende Schist may be present beneath the 

surface in the roadless area They would be difficult to 

locate by present-day exploration methocls and the gold 

content along the veins is likely to be sporadic as it is in 

mines outside the roadless area Further studies are not 

warranted. 

REFERENCE 

Huber. D. F .. Nelson, S. C., Cather, E. E., and Ritchey, J. L., 1983, 

Mineral resource potential of the Fisher Gulch Roadless Area, 

Trinity County. California: U.S. Geological Survey Open-File 

Report 83-483. 

247 
248 

38° 

50' 

38° 40' 

Cu 

Ag 

w 

Zn 

~ 

M AP LOC ATION 

roadless 

boundary ' 

Echo 

Lakes 

0 

Fallell I rmf 

Lakt> 

MILES 

EXPLANATION 

5 

MINE 

Zn , Cu , Ag 

Pass 

Geologic terrane with probable k};F·:}./j Alluvial and glacial 

mineral-resource potential deposits (Quaternary) 

Copper 

Silver 

Tungsten 

Zinc 

Mine or deposit 

Volcanic rocks (Miocene 

and Oligocene) 

Granitic rocks (Upper 

Cretaceous) 

Metasedimentary and 

metavolcanic rocks 

(Mesozoic) 

Contact 

Fault-- Bar and ball on downthrown 

side 

Figure 71.- Freel and Dardanelles Roadless Areas, California 
FREEL AND DARDANELLES ROADLESS AREAS, CALIFORNIA 

By DAVID A. j OH ,

1 U .S. GEOLO l AL RVEY, and 

Do LA F. SC TT, U. . B REA OF M l E 

SUMMARY 

As a result of the mineral survey of the Freel and Dardanelles Roadless Areas, 

California, made in 1978-80, several areas having demonstrated resources were 

identified: tungsten at the Alpine mine in the Dardanelles Roadless Area; silver 

and copper at the Mountain Top mine in the Freel Roadless Area; and, zinc, 

silver, and copper at the Alhambra prospect just outside of the Dardanelles 

Roadless Area An area along the southeastern margin of the Dardanelles 

Roadless Area has probable mineral-resource potential for tungsten, zinc, silver, 

and copper resources. No potential for energy resources was identified in this 

study. 

CHARACTER AND SETTING 

The Freel and Dardanelles Roadless Areas, Alpine 

and El Dorado Counties, encompass about 60 sq mi in 

the central Sierra Nevada of eastern California, about 5 

mi south of Lake Tahoe. The area consists of rugged 

mountainous topography with altitudes ranging from 

about 6000 ft in the western part of the Dardanelles 

Roadless Area to the 10,881-ft summit of Freel Peak. 

Spectacular views of Lake Tahoe, the Sierra Nevada, 

and western Nevada are possible from these areas. Easy 

access to the areas is possible from California State 

Highway 89 (Luther Pass road), which separates the 

two areas and from California State Highway 88 (Carson Pass)' and U.S. Highway 50 (Echo Summit), which 

form part of the southern and northern boundaries of 

the Dardanelles Roadless Area, respectively. 

Cretaceous granitic rocks of the Sierra Nevada batholith, older metasedimentary and metavolcanic rocks, 

and Tertiary volcanic rocks are exposed ~- the area 

Most of the area is underlain by twelve grarut1c plutons, 

all about 90 to 95 m.y. (million years) old. Freel Peak 

and most of the high peaks in the Freel Roadless Ar_ea 

are composed of granitic rocks. The grani_tic plutons mtrude several small bodies of metasedimentary and 

metavolcanic rocks along the eastern side of the Dardanelles Roadless Area. Most mineral deposits in the 

Freel and Dardanelles Roadless Areas occur where 

marble layers in the metasedimentary rocks are intruded and mineralized by granitic rocks. 

1

With contributions from T. J. Peters. USBM. 

The ridges and peaks at the southern end of the Dardanelles Roadless Area are capped by volcanic rocks of 

late Tertiary age (5 to 26 m.y.). Most of these rocks are 

volcanic mudflows and sediments that probably came 

from the southeast. Stevens Peak, however, is a volcanic neck that may have been a relatively minor source 

for some of the volcanic rocks in the area 

Pleistocene glaciation extensively modified the topography and left widespread glacial deposits. Glacial f~atures especially evident include Grass Lake, a glacial 

lake dammed by debris left by a glacier that once flowed 

from Hope Valley into the Upper Truckee River valley, 

and numerous lateral moraines on the west side of Hope 

Valley that form long step-like benches on the east side 

of the Dardanelles Roadless Area 

Mining activity began in the region in the late 1850'.s, 

shortly after the discovery of the Comstock lode m 

Virginia City, Nevada Mining properties in and adjacent to the Dardanelles Roadless Area are in the Hope 

Valley district. Small quantities of tungsten ore were 

mined at the Alpine mine during the 1940's, and small 

amounts of tungsten and gold were mined from two 

other mines in the district about 4 mi east of the area 

The mineral-resource potential described in this 

report is based on studies conducted during 1978-80. 

Studies included geologic mapping of the area (John and 

others, 1981), interpretation of areomagnetic and gravity maps (Plouff, 1983), geochemical sampling of stream 

sediments, and examination of mines and mineralized 

areas. All of these data are summarized in John and 

others (1983). 

249 
MINERAL RESOURCES 

Two types of mineral resources occur within the 

road.less areas. In the southeastern part of the Dardanelles Road.less Area, base- and precious-metal 

resources occur in skarn zones and in shear zones in 

metamorphic rocks near contacts with granitic rocks. In 

the Freel Road.less Area, silver and copper resources 

occur in a quartz vein in a granitic pluton. 

The USBM identified two properties that have 

demonstrated resources of tungsten, copper, and silver 

within the road.less areas. The Alpine mine, which lies 

just outside the eastern boundary of the Dardanelles 

Road.less Area, contains an estimated 1,700,000 tons of 

demonstrated resources averaging 0.19 percent tungsten trioxide (W03) in a skarn zone that averages 100ft 

thick, 520 ft long and 170 ft in depth. An estimated 

800,000 tons of this resource is in the Dardanelles 

Road.less Area In the Freel Road.less Area, the Mountain Top mine contains an estimated 2000 tons of 

demonstrated resources averaging 0.61 oz silver/ton 

and 1.59 percent copper in an isolated quartz vein in a 

granitic pluton. In addition to these resources within 

the road.less areas, the Alhambra prospect, which lies 

just outside the eastern boundary of the Dardanelles 

Road.less Area, contains an estimated 2,000,000 tons of 

demonstrated resources averaging 1.85 percent zinc, 

0.25 oz silver/ton, and as much as 0.17 percent copper, 

in a shear zone in metamorphic rocks near a contact 

with granitic rocks. 

The southeastern comer of the Dardanelles Road.less 

Area has a probable mineral-resource potential for 

tungsten and (or) other base metals (zinc and copper) 

and silver. This area of probable potential contains the 

Alpine mine and the Alhambra prospect, as well as four 

250 

other prospects for base and precious metals. In the 

area, metamorphic rocks have been intruded by a 

granitic pluton believed to be responsible for the 

mineralization at the Alpine mine and the Alhambra 

prospect, and two other small tungsten mines about 4 

mi east of the road.less area The western part of the area 

of probable potential also includes a ridge covered with 

Tertiary volcanic rocks that aeromagnetic and structural studies suggest is underlain by metamorphic 

rocks, possibly including marble layers similar to those 

that are mineralized at the Alpine mine. The presence of 

nearby known deposits and similar geologic environments suggests that this area has probable mineralresource potential for tungsten, zinc, copper, and silver 

resources. 

Elsewhere in the road.less areas, there is little promise 

for the occurrence of mineral resources. No resource 

potential for oil, gas, coal, or geothermal resources was 

identified in this study. 

REFERENCES 

John, D. A., Armin, R. A., and Moore, W. J., 1981, Geologic map of 

the Freel and Dardanelles Further Planning Areas, Alpine and El 

Dorado Counties, California, with Quaternary geology by J. C. 

Dohrenwend: U.S. Geological Survey Miscellaneous Field 

Studies Map MF- 1322- A, scale 1:62,500. 

John, D. A., Armin, R. A., Plouff, Donald, Chaffee, M. A., Peters, 

T. J., Scott, D. F., Federspiel, F. E., Cather, E. E., and Campbell, 

H. W., 1983, Mineral resource potential map of the Freel and Dardanelles Roadless Areas, Alpine and El Dorado Counties, Califor· 

n.ia: U.S. Geolgical Survey Miscellaneous Field Studies Map 

MF - 1322-C, scale 1:62,500. 

Plouff, Donald, 1983, Aeromagnetic and gravity maps of the Freel 

and Dardanelles Roadless Areas, Alpine and El Dorado Counties, 

California: U.S. Geological Survey Miscellaneous Field Studies 

Map MF- 1322-B, scale 1:62,500. 
GOLDEN TROUT WILDERNESS, CALIFORNIA 

By DAVID A. D ELLI GEl , 1 • • GEOLO I AL R\ EY, and 

I HOLAS T. ZILKA, .S. B REA OF MI E 

SUMMARY 

The mineral survey of the Golden Trout Wilderness, conducted in 1979, 

revealed that four areas in the wilderness have resource potential for tungsten 

and base and precious metals. One, the Mineral King pendant, has substantiated potential for tungsten deposits; the others are designated as having probable resource potential for tungsten and base and precious metals. Demonstrated tungsten resources exist at the Pine Tree mine, a skarn deposit in the 

Mineral King pendant. There is no evidence for the existence of large undiscovered deposits within the wilderness. The geologic terrane precludes the occurrence of organic fuel resources. 

CHARACTER AND SETTING 

The Golden Trout Wilderness occupies 478 sq mi of 

the rugged forested part of the southern Sierra Nevada, 

about 80 mi east-southeast of Fresno. ·rt is bounded on 

the east by Owens Valley, on the north by Sequoia National Park, and on the west and south by USFS 

multiple-use lands. The east side of the area is accessible 

from U.S. Highway 395; the remainder is reached by 

State, County, and USFS roads from the San Joaquin 

Valley. The mineral survey included geologic mapping 

of the area (du Bray and Dellinger, 1981), geochemical 

sampling (Leach and others, 1983a, b), and an aeromagnetic survey (Jachens, 1983); personnel from the USBM 

evaluated known mines and prospects. A summary of 

the results of these studies and an evaluation of mineralresource potential is in Dellinger and others (1983). 

Most of the Golden Trout Wilderness is underlain by 

granitoid plutonic rocks of the Sierra Nevada batholith. 

Pendants of metamorphosed roof rocks and wallrocks 

are preserved between plutons and account for about 10 

percent of the outcrop area The two largest bodies of 

metamorphic rocks in the wilderness are a large unnamed roof pendant on the east slope of the range, 

northwest of Cartago, and the Mineral King roof pend-

'WiUl conlribut.ions by E. A. du Bray. D. L. Leach. H. J. Goldfarb. and H. C. Jachens. 

USG . 

ant. Smaller masses of metamorphic rocks occur 

throughout the wilderness. About 5 percent of the area 

is underlain by young volcanic rocks. 

The major structural features in the wilderness are 

the Kern Canyon fault and the range-front faults near 

the eastern edge of the wilderness. The Kern Canyon 

fault is a major strike-slip fault with at least 8 mi of 

right-slip displacement. Movement on the fault postdates the emplacement of late Cretaceous plutons, but 

the fault does not cut 3.5 rnillion year old basalt in the 

southern part of the wilderness. Its age is thus bracketed between about 80 and 3.5 rnillion years. Kern Canyon, a deep linear valley that enters the wilderness from 

Sequoia National Park, is the topographic expression of 

the fault. High-angle faults along the eastern front of 

the range are the principal structural features 

associated with the uplift and westward tilting of the 

Sierra Nevada block. Uplift probably began about 11 

rnillion years ago and seems to have accelerated about 3 

rnillion years ago. Uplift and westward tilting are still 

occurring; large earthquakes have occurred on extensions of these range-front faults to the north of the 

wilderness in historic times (Owens Valley earthquake, 

1872). Several mineral prospects in the eastern part of 

the wilderness (area C, on map) are located on small 

faults or shears that are probably part of the range-front 

fault system. 

Courthouse records indicate that 143 claims have 

been located within the wilderness; 38 of these were 

found and evaluated by the USBM. Of these, only the 

251 
MAP LOCATION 

Cav• 

0 

MILES 

JorcJr 

1-ft 

Tem I ton 

Mour ldl 

P ak 

10 

::r 

)}', (> 

EXPLANATION 

D 

Geologic terrane with substantiated tungsten 

resource potential and probable resource 

potential for lead, zinc, silver, and bismuth 

Geologic terrane with probable mineralresource potential 

Granitoid and volcanic rocks 

Metamorphic rocks 

Contact 

boundary 

Bi 

Cu 

Au 

Bismuth Fault--Arrows show relative horizontal movement 

Copper 

Gold 

B Area discussed in text 

Pb Lead 

Ag Silver 

w Tungsten 

Zn Zinc 

~ Mine or deposit 

x Mineral occurrence 

Figure 72.-Golden Trout Wilderness, California. 

252 
Pine Tree mine is currently active; 36 prospects have 

been abandoned and Jordan Hot Springs has been 

developed for recreation. 

The Mineral King mining district, now part of Sequoia National Park, adjoins the wilderness on the 

northwest; the Camp Wishon mining district adjoins it 

on the west. Both districts are on pendants of metamorphic rocks that extend into the wilderness, but neither 

has had significant recorded production. Early miners 

sought precious metals in the interior of these pendants, 

but more recent interest has focused on possible tungsten deposits at their margins. 

MINERAL RESOURCES 

Tungsten is the only commodity for which resources 

are known to exist in the Golden Trout Wilderness and 

is also the principal commodity likely to exist in four 

areas of mineral-resource potential. In the western 

United States tungsten is usually found in narrow 

bands of highly altered rock (tactite or skarn) at contacts between granitoid intrusions and metamorphosed 

calcareous sedimentary rocks. These deposits result 

from the reaction between calcareous roof-pendant 

rocks and high-temperature fluids associated with the 

intrusion of granitoid magmas. Deposits formed in this 

manner are common in the Sierra Nevada and Great 

Basin, where they have often been mined for copper, 

molybdenum, lead, or zinc as well as tungsten. All 

known demonstrated tungsten resources within the wilderness are located at the Pine Tree mine, which is 

located just inside the eastern edge of the Mineral King 

roof pendant. 

The Mineral King roof pendant (area A) is the area of 

the wilderness with the greatest promise for the occurrence of small tungsten deposits and contains the only 

known resources. Anomalous concentrations of orerelated elements occur in many geochemical samples 

from throughout the area Ground water from springs 

within a few miles of the Pine Tree mine is anomalously 

acid. While not conclusive evidence for mineralization, 

acid ground water is consistent with the presence of 

metallic sulfide deposits in the ground-water recharge 

area Occurrences of copper, lead, and zinc in sulfides 

are reported in the Mineral King mining district, located 

in the same pendant several miles to the northwest of 

the wildemes.3, and in the Camp Wishon district located 

in a similar pendant west of the wilderness. Fourteen 

abandoned prospects are located in the pendant within 

the wilderness; traces of gold, silver, lead, or tungsten 

are present at some of these. The aeromagnetic survey 

revealed that the part of the Mineral King pendant 

within the wilderness is characterized by a pronounced 

magnetic low with steep magnetic gradients above its 

eastern and western boundaries. This magnetic low 

results from the nonmagnetic character of the metamorphic rocks of the pendant relative to the surrounding 

granitoid bodies and is not in itself either indicative of 

or inconsistent with subsurface mineralization. Modeling of the magnetic data reveals, however, that the 

pendant is about as deep as it is wide and that the 

margins are steeply dipping. Subsurface mineral 

deposits along the margins of the pendant, if they exist, 

may therefore be located at considerable depths. The 

Mineral King pendant area is considered to have substantiated potential for tungsten resources on the basis 

of geologic and geochemical information and known 

resources at the Pine Tree mine. It also has probable 

potential for small deposits of lead, zinc, silver, or 

bismuth. 

The Maggie Mountain area (B), west of the Mineral 

King pendant, is designated as having probable potential for small resources of tungsten, lead, zinc, or silver. 

Geochemical samples from the area contain anomalous 

concentrations of ore-related elements. Rock types 

favorable for mineralization are also present; small 

bodies of metavolcanic and metasedimentary rocks occur within the two large plutons that underlie most of 

the area Five abandoned claims and prospects are 

located in or very near the area; zinc sulfides occur at 

the Galena Cave deposit and minor tungsten mineralization occurs at the Jack Danials deposit. Both of these 

deposits are located just outside the wilderness. No 

known deposits are located within the area 

The eastern range-front area (C) is considered to have 

probable potential for small deposits containing copper, 

silver, gold, or tungsten. The geochemical sampling pn:r 

gram was severely limited by steep terrain in this area, 

but anomalous concentrations of ore-related elements 

were found in some of the samples that were obtained. 

Both metavolcanic and metasedimentary rocks occur 

within the area and the area contains seven abandoned 

claims. Undiscovered deposits, if they exist, probably 

consist of tungsten (scheelite) mineralization at the 

margins of metasedimentary pendants or sulfide mineralization in shear zones in altered metavolcanic rocks. 

The White Mountain area (D) differs from the other 

areas of probable potential in that it is underlain entirely by granitoid rocks. There is, however, evidence for 

hydrothermal alteration and silica enrichment. umerous quartz veins, some containing other potentially ore 

related minerals, are present but there are no known occurrences of mineralization in the area Geochemical 

samples from the area are anomalous in ore-related 

elements, and there is a sharp magnetic anomaly 

253 
associated with the area The magnetic anomaly is partially related to topography, but modeling of the data 

indicates that a region near the top of White Mountain 

contains a concentration of ferrimagnetic minerals. This 

concentration may be related to the geochemical anomaly observed in the same area The geochemical evidence 

indicates that resources of silver, lead, or tungsten may 

exist in the White Mountain area The concurrence of 

the geochemical and aeromagnetic data with the surface 

evidence of hydrothermal alteration gives the area a 

probable resource potential for these elements. 

SUGGESTIONS FOR FURTHER STUDIES 

More detailed geophysical and geochemical studies 

might more closely delineate areas of resources or potential resources, particularly in the Mineral King pendant and White Mountain areas. However, the small size 

of probable deposits indicated by the studies done thus 

far suggest that further studies may not be worthwhile. 

254 

REFERENCES 

Dellinger. D. A., du Bray, E. A., Leach, D. L .. Goldfarb, R. J ., 

Jachens, R. C., and Zilka, N. T., 1983, Mineral resource potential 

map of the Golden Trout Wilderness, southern Sierra evada, 

Caliiomia: U.S. Geological Survey Miscellaneous Field Studies 

Map MF - 1231 - E, scale 1:62,500. 

du Bray, E. A., and Dellinger, D. A., 1981, Geologic map of the 

Golden Trout Wilderness. southern Sierra evada, Caliiomia: 

U.S. Geological Survey Miscellaneous Field Studies Map 

MF- 1231-A, scale 1:48,000. 

Jachens, R. C .. 1983, Map showing aeromagentic interpretation of the 

Golden Trout Wilderness, southern Sierra evada, Caliiomia: 

U.S. Geological Survey Miscellaneous Field tudies Map 

MF-1231-D. 

Leach, D. L., Goldfarb, R. J., and Domenico. J. A., 1983a, 

Geochemical map showing anomalous concentrations of selected 

elements in stream sediments from the Golden Trout Wilderness. 

Caliiomia: U.S. Geological urvey Miscellaneous Field tudies 

Map MF - 1231-C, scale 1:62,500. 

Leach, D. L., Goldfarb, R. J., and Domenico, J. A. , 19 3b, 

Geochemical map showing anomalous concentrations of selected 

elements in heavy-mineral concentrates from the Golden Trout 

Wilderness, Caliiomia: U.S. Geological Survey Miscellaenous 

Field Studies Map MF- 1231- B, scale 1:62,500. 
GRANITE CHIEF WILDERNESS STUDY AREA, CALIFORNIA 

By D AVID . H ARWOOD, . GEOLOG ICAL RVEY , and 

FRANC! E. F EDER PIEL, .S. B REA OF Mr E 

SUMMARY 

On the basis of a mineral-resource survey of the Granite Chief Wilderness 

study area in eastern California, conducted between 1979 and 1981, it is concluded that the area has little promise for the occurrence of precious or base 

metals, oil, gas, coal, or geothermal resources. Sand, gravel, and glacial till 

suitable for construction materials occur in the area, but inaccessability and 

remoteness from available markets preclude their being shown on the map as a 

potential resource. 

CHARACTER AND SETTING 

The Granite Chief Wilderness study area encompasses 57 sq mi near the crest of the Sierra Nevada 6 mi 

west of Tahoe City, California, a major four-season 

recreational center located on the northwest shore of 

Lake Tahoe. The North Fork and the Middle Fork of the 

American River head in deep, glaciated canyons, which 

are interspersed between sharp peaks and ridge crests 

that rise to elevations of 9000 ft. A number of hiking 

and equestrian trails spur off from secondary roads 

located around the perimeter of the study area and from 

a 16- mi segment of the Pacific Crest Trail that lies 

within the area The wilderness study area provides a 

readily accessible back-country retreat from the relatively urban recreational attractions of the Lake Tahoe 

Basin. 

The rugged mountainous terrane of the Granite Chief 

Wilderness study area consists of granitic rocks that intrude a variety of older metamorphosed sedimentary 

and volcanic rocks. The granitic and metamorphic rocks 

are capped by Tertiary volcanic rocks that originated 

from a number of ancient volcanic centers located along 

a major fault system that separates the uplifted Sierra 

Nevada range from the Tahoe Basin to the east. Periodically during the past few million years a series of ice 

caps blanketed the study area. Valley glaciers, 

originating from those ice caps, sculptured the underlying bedrock into scoured and polished canyons separated by sharp-crested ridges and isolated monadnocks. 

The scouring action of the glaciers left little soil on the 

canyon walls and ridges, so vegetation is sparse and 

allows relatively easy and enjoyable cross-country hiking from vista point to vista point. 

Geologic, geochemical, and mines and prospect studies were carried out by the USGS and USBM between 

1979 and 1981 to assess the mineral-resource potential 

of the area 

MINERAL RESOURCES 

Gold and silver have been the principal interests of 

prospectors in the region since the California gold rush 

in 1849. Most production has come from placer and lode 

deposits in the Mother Lode district located 20 mi west 

of the Granite Chief Wilderness study area. No mining 

activity is being conducted currently within the area 

and no record of past production from the area could be 

found; no resource potential has been identified in this 

area. The same country rocks that produced significant 

gold and silver from the Mother Lode district occur 

within the study area, but quartz veins, which were 

hosts for much of the gold produced to the west, are 

sparsely distributed and of minor volume in the study 

area. Placer deposits within the study area show minor 

gold values but the volumes of gravel are small and they 

are not considered to have a resource potential. 

Detailed geologic and geochemical surveys of the area 

have been published by Harwood (1981, 1982) and a 

more detailed evaluation of the mineral-resource potential of the area has been published by Harwood and 

others ( 1982). 

255 
256 

0 5 

M ILES 

EXPLANATION 

§ Volcanic rocks (Tertiary) 

Granitic rocks (Cretaceous and Jurassic) 

Metamorphic rocks (Mesozoic and Paleozoic) 

--- Contact 

- -- Fault 

Figure 73.-Granite Chief Wilderness study area, California 
REFERENCES 

Harwood. D. S., 1981 , Geologic map of the Granite Chief Wilderness 

study area and adjacent parts of the Sierra Nevada. California: 

U.S. Geological Survey Miscellaneous Field Studies Map 

MF- 1273-A, scale 62,500. 

__ 1982, Geochemical maps of the Granite Chief Wilderness study 

area, California: U.S. Geological Survey Miscellaneous Field 

Studies Map MF - 1273-B, scale 95,000. 

Harwood, D. S., Federspiel, F. E .. Cather, E. E., and Scott, D. F .. 

1982, Mineral resource potential map of the Granite Chief Wilderness study area. Placer County, California: U.S. Geological 

Survey Miscellaneous Field Studies Map MF- 1273-C, scale 

62,500. 

257 
258 

~ 

,, '----~~~~~~:~~:: .= : 

J 

/ 

0 2 

MILES 

EXPLANATION 

Surficial deposits (Quaternary) 

Granitic rocks (Jurassic) 

Ultramafic rocks (Jurassic or older) 

Metasedimentary and metavolcanic rocks 

(Triassic, Upper and Middle Paleozoic) 

Abrams Mica Schist (Devonian) 

Salmon Hornblende Schist (Devon ian) 

Contact 

Fault 

• • • Thrust fault--Sawteeth on upper plate 

~ U Plunging, overturned antiform 

Figure 74.-Granite Peak Roadless Area, California. 

MAP LOCATION 
GRANITE PEAK ROADLESS AREA, CALIFORNIA 

By DO ALD F. H UBER, 1 U.S. GEOLOGI AL S R EY and 

H RACE K. TH URBER , U .S. B REA OF MI E 

SUMMARY 

On the basis of mineral surveys conducted in 1968-70 and 1980- 81 in the 

Granite Peak Roadless Area, there seems little likelihood for the occurrence of 

mineral or energy resources. 

CHARACTER AND SETTING 

The Granite Peak Roadless Area occupies an area of 

about 5 sq mi in the southern part of the Trinity Alps of 

the Klamath Mountains, about 12 mi north-northeast of 

Weaverville, California Altitude above sea level ranges 

from 2900 ft on the southwest, at the Stuart Fork of the 

Trinity River, to 8091 ft on Granite Peak, near the 

center of the area The northern boundary is shared by 

the proposed Salmon-Trinity Alps Wilderness. 

The eastern three quarters of the roadless area is 

underlain by ultramafic and granitic rocks and the 

western quarter is underlain by metamorphic rocks. The 

metamorphic rocks were probably thrust under the 

ultramafic rocks about 350 million years ago 

(Devonian). During the time from about 230 to 65 

million years ago (Mesozoic), the granitic rocks intruded 

the ultramafic rocks. Also during this time the 

metamorphic and ultramafic rocks were accreted to the 

North American Continent by plate-tectonic processes. 

Rock and stream-sediment samples collected during 

1968- 70 and stream-sediment sample collected during 

1980-81 were analyzed. All streams draining the roadless area were sampled and representative samples of 

the rock types in the area were collected. Background 

values were established for each element and anomalous 

1

Witll contributions from Scot.L C. Nelson. USGS. 

values were examined within their geologic settings and 

evaluated for their significance. 

MINERAL RESOURCES 

There is no history of mining activity within the 

roadless area, although it probably has been extensively 

examined by prospectors since the 1850's when mining 

began in the Trinity Alps area The results of the 

geochemical survey do not indicate the presence of 

mineralized rock at the surface. Such geochemically 

anomalous values as were found are attributed to differences in sampling and do not reflect accumulation of 

resources. There is little promise for the occurrence of 

mineral or energy resources in the area 

REFERENCES 

Hotz, P. E., Thurber, H. K., Marks, L. Y., and Evans, R. K., 1972, 

Mineral resources of the Salmon-Trinity Alps Primitive Area. 

Caliiornia. with a section on An aeromagnetic survey and inter· 

pretation. by Andrew Griscom: U.S. Geological Survey Bulletin 

1371- B, 267 p. 

Huber, D. F., and Nelson, S. C., 1983, Mineral resource potential of 

the Granite Peak Roadless Area. Trinity County, Caliiornia: U.S. 

Geological Survey Open·File Report 83-489. 

259 
260 

-

w 

118°50' 

0 

MILES 

EXPLANATION 

Geologic terrane with probable 

mineral-resource potential 

Tungsten 

Mine or deposit 

x M ineral occurrence 

boundary MAP LOCATION 

3 

B , 

' 

I' 

Granitic rocks 

Metavolcanic rocks 

Metasedimentary rocks 

Contact 

Figure 75.-High Sierra Primitive Area, California 
HIGH SIERRA PRIMITIVE AREA, CALIFORNIA 

By j AMES G . M OORE, U . . GEOLOG ICAL RVEY , and 

L AWR E CE Y. M ARK .. B URl:: OF MI. E " 

SUMMARY 

On the basis of a mineral-resource survey in 1970, the High Sierra Primitive 

Area was found to have an area of probable mineral-resource potential for 

tungsten. A small demonstrated tungsten resource is present on the Obelisk 

claims near the contact of limy metasedimentary rock and granitic rock in the 

northwest part of the area, and additional small deposits may be expected to 

occur to the south, in a similar geologic setting. 

CHARACTER AND SETTING 

The High Sierra Primitive Area includes about 40 sq 

mi in Sierra and Sequoia National Forests in the central 

Sierra evada. It is adjacent to the west boundary of 

Kings Canyon ational Park. The area is extremely 

rugged and the canyons of the Kings River are among 

the deepest in the United States. Total relief in the area 

is 8880 ft. o roads and few trails occur in the area, and 

river crossings are hazardous. 

Granitic rock forms the dominant bedrock of the area. 

Occurring as many granitic plutons, generally elongate 

in a northwesterly direction, the granitic bedrock is 

primarily Cretaceous in age. Metamorphic bedrock 

forms discontinuous masses between the granitic 

plutons. The metamorphic rocks are intruded by, and 

hence older than, the granitic rocks. In the western part 

of the area the metamorphic rocks are dominantly of 

sedimentary origin; they include rocks that were 

originally shale, siltstone, quartzite, and limestone. In 

the center and northeastern part of the area metamorphic rocks which were originally of volcanic origin occur; they include andesite to rhyolite tuffs and breccias 

and sediments derived from volcanic materials. 

Field investigations were conducted during the summer of 1970 by teams from the USGS and the USBM 

(Moore and Marks, 1972). The USGS team mapped 

the geology, and collected and analyzed 47 streamsediment samples. The geological work was augmented 

by analysis of a 1970 aeromagnetic survey by H. W. 

Oliver. The USBM team investigated mining claims 

and prospects within the area. Because the Garnet Dike 

mine, 7 mi west of the primitive area, was a major 

source of tungsten during World War II, tungsten occurrences are of particular interest. 

MINERAL RESOURCES 

Analysis of stream sediments and bedrock samples 

do not indicate the presence of any previously unknown 

deposits of possible commercial value at the bedrock 

surface. Magnetic anomalies detected by the aeromagnetic survey can be explained as topographic effects of normally magnetized rocks. 

The Obelisk unpatented mining claims are in the 

northwest part of the primitive area and extend out of 

the area to the north. The claims are near the contact 

between granodiorite and limy metasedimentary rock. 

About 30 tons of ore was produced between 1953 and 

1958, and in 1955, 4 tons were mined and handsorted to 

obtain 70 lbs of concentrate containing 57 percent W05 

(tungsten oxide). The property was explored by diamond drilling in 1956, and a demonstrated resource of 

about 8000 tons of tactite containing an average of about 

1 percent W05 is estimated for the Obelisk 1 claim. 

The only other prospect in the area, the Middle Fork 

prospect, is 3.5 mi south-southeast of the Obelisk 

claims and within a continuation of the same metasedimentary mass. This prospect contains small quantities 

of metals in sheared quartzite. 

The presence of the tungsten deposit at the Obelisk 

claims and the presence of similar limy metasedimentary rocks to the south suggests that an area of probable mineral-resource potential for tungsten extends to 

the south. 

261 
SUGGESTIONS FOR FURTHER STUDIES 

Tungsten deposits of the type found at the Obelisk 

claims generally occur near the contact of granitic rock 

and limy metasedimentary rock. Hence, prospecting 

for possible additional deposits may be guided by this 

relationship. It is noteworthy that the only two prospects in the area occur in rather accessible areas, including the brink of the canyon (Obelisk) and the bottom (Middle Fork). Small additional deposits may be 

262 

expected at other places, but accessibility is generally 

extremely difficult due to steep terrain. 

REFERENCES 

Moore, J. G .. and Marks, L. Y., 1972, Mineral resource of the High 

Sierra Primitive Area. California: U. . Geological urvey 

Bulletin 1371 - A, 40 p. 
ISHI, MILL CREEK, POLK SPRINGS, AND 

BUTT MOUNTAIN ROADLESS AREAS, CALIFORNIA 

By j OCELY A. PETER 0 ,

1 U .. GEOLO .!CAL S R EY, and 

D AVID K. D E TON , JR . , U .S. B REA OF M I E 

SUMMARY 

Mineral surveys of the Ishi, Mill Creek, Polk Springs, and Butt Mountain 

Roadless Areas conducted in 1980 and 1982 indicated little promise for the occurrence of mineral resources in much of the areas. Portions of Deer and Mill 

Creeks are considered to have probable resource potential for small amounts of 

gold. The geologic setting precludes the occurrence of energy resources and no 

other metallic mineral resources were identified. 

CHARACTER AND SETTING 

The Ishi, Mill Creek, Polk Springs, and Butt Mountain Roadless Areas occupy approximately 50 sq mi in 

an area about 25 mi north of Chico, California, and 25 mi 

south of Mount Lassen. The areas are characterized by 

dense brush or forest covering a rugged topography in 

the southernmost part of the Cascade volcanic province. 

In late Tertiary and Quaternary time the Ishi, Mill 

Creek, Polk Spring, and Butt Bountain Roadless Areas 

were buried beneath extensive pyroclastic deposits and 

lava flows. Subsequent erosion has exposed a few small 

outcrops of a prevolcanic basement of Mesozoic and (or) 

Paleozoic metamorphosed volcanic rocks in the bottoms 

of the deepest drainages, and, in the northwestern part 

of the area sandstones of the Cretaceous Chico Formation. Most of the area is covered by the Tuscan Formation which consists of as much as 2000 ft of Pliocene 

andesite tuff breccia volcanic mud flows and minor thin 

tuffs and mafic lava flows (Peterson, Bradley, Johnson, 

and Lydon, 1982). These rocks dip gently to the 

southwest across the area Locally overlying the Tuscan 

Formation are remnants of Quaternary andesitic and 

basaltic flows. A few small mafic plugs intrude the mud 

flows and lava flows. 

Within the Tuscan Formation are several bleached 

areas that may be the result of hydrothermal alteration, 

1

Wit.h contributions from Robin B. Fiebclkom and Karen A. Johnson. USGS. and Eric E. 

Cather. ll arry W. Campbell. and Peter . Gabby. U BM. 

but there are no visible sulfide minerals in these areas 

and geochemical analyses (Peterson, Bradley, and 

Johnson, 1982) indicate no unusual concentrations of 

trace elements. 

River terrace gravels in the Polk Springs Roadless 

Area were mined for gold, and quartz-vein-bearing 

metavolcanic and metasedimentary rocks in the Mill 

Creek Roadless Area have been prospected for gold. 

MINERAL RESOURCES 

The metamorphic units underlying the Tuscan Formation contain quartz veins that range in size from 

microscopic to several inches thick. These quartz veins 

are thought to be the source of gold found in old river 

terraces on Deer and Ditch Creeks near Polk Springs. 

Prospecting in this area began in the mid-19th century 

and assessment work was done on three properties as 

recently as 1981 (Peterson and others, 1983). Three of 

the claims visited in 1982 had been mined hydraulically 

in the past but appeared to be inactive at the time of the 

visit. A lode claim on Mill Creek northeast of Black 

Rock was filed at the Tehama County Courthouse. This 

claim could not be located in 1982, but it is thought to 

be in the vicinity of the Mesozoic rocks which are known 

to contain quartz veins. 

On the basis of the mineral-resource survey, portions 

of Deer and Mill Creeks are designated as having probable mineral potential for small amounts of gold. 

263 
264 

40° 

15' 

40° 

00' 

Approximate 

roadless boundary 

121 °45' 

y"i,_ ~o''\l 

.-.' I ~ttddle ,... (),~" /., 

I -'iL_ ~ / Black 

''" p I { Butte 

lshi ..1 ' 

s5098rl ' ,..;.,-\ ,,., 

I ,... ¥- ..., 

/ 0 ee 

-

Fork 

Turner 

Moun tarn 

121 °30 ' 

.--Mill Creek 

/ , ,I 05284 

,_J' I 

r / _,_,_- -- ~ ;f, 

~ ~ ~--r /c ~ ~ ~~ Black '.( 

Rock 

,..-l 

J 

'" .}. J Polk Springs 'l · p, tk s,,"',,)e 

) 05097 \ ::J 

r Ar 

e"¥- .·. ''·· .•• -·-- I 

,} f1 l-- - ....., _I J 

Is hi j- Brush1,Avlo nrarn 

85098 '--,.; 

0 

) 

J 

; 

) 

MILES 

EXPLANATION 

5 

( Butt~-~ \ 1 

-,.., 

Mou urn r 

/ ./'/ 

I I 

'--'r. 

Butt Mountain 

05100 

Humboldt Peak 

MAP LOCATION 

Geologic terrane with probable 

mineral-resource potential 

Quaternary and Tertiary volcanics 

Cretaceous sandstone 

Au Gold 

Mesozoic and(or) Paleozoic 

greenstone 

Contact 

Figure 76.- lshi, Mill Creek, Polk Springs, and Butt Mountain Roadless Areas. California 
REFERENCES 

Peterson, J. A., Bradley, Robin, and Johnson, K. A., 1982, Maps 

showing geochemical analyses of the Ishi, Mill Creek. Polk 

Springs, and Butt Mountain Further Plarming Areas, Tehama 

and Plumas Counties, California: U.S. Geological Survey 

Miscellaneous Field Studies Map MF- 1340-B, scale 1:62,500. 

Peterson, J. A. Bradley, Robin, Johnson, K. A., and Lydon, P. A., 

1982, Geologic maps of the Ishi, Mill Creek, Polk Springs, and 

Butt Mountain Further Plarming Areas, Tehama and Plumas 

Counties, California: U.S. Geological Survey Miscellaneous Field 

Studies Map MF - 1340-A, scale 1:62,500. 

Peterson, J. A. , Fiebelkorn, R. B., Johnson, K. A., Cather, E. E., 

Campbell, H. W .. Denton, D. K., Jr., and Gabby P. ., 19 3. 

Mineral resource potential map of the lshi, Mill Creek, Polk 

Springs, and Butt Mountain Roadless Areas, Tehama and 

Plumas Counties, Californi a: U.S. Geological Survey 

Miscellaneous Field Studies Map MF- 1340-C, scale 1:62,500. 

265 
266 

37° 

oo· 

36° 

45' 

30' 

M 

Lak• 

( rOIL1/t:'f.i 

1 UCKY STRIKE PROSPECT 10 LAMBERT MINE 

2 HARD POINT M INE II TUNGSTEN MINE 

3 PICK AND SHOVEL MINE 12 ALTA MINE 

4 SCHEELORE MINE 13 GABLE LAKES MINE 

5 NICOLL HILTON 14 HANGING VALLEY 

CREEK MINE AND MINE 

FILIPELLI PROSPECT 15 SONNY BOY MINE 

6 PHELPS HILTON 16 MOLY BLUE 

CREEK MINE PROSPECTS 

7 ROUND VALLEY 17 SNOW WHITE 

PEAK PROSPECT PROSPECTS 

PINE CREEK MINE 18 REX MONTIS MINE 

9 BROWNSTONE MINE 

0 20 

MILES 

EXPLANATION 

Geologic terrane with substantiated 

mineral-resource potential D 

D Geologic terrane with probable 

mineral-resource potential 

Co Cobalt Ni Nickel 

Cu Copper Ag Silver 

Au Gold w Tungsten ~ 

Pb Lead Zn Zinc X' 

M o Molybdenum 

MAP LOCATION 

Plutonic and volcanic 

rocks 

Metamorphic rocks 

Contact 

Mine or deposit 

Mine 

Figure 77.-John Muir Wilderness, California 
JOHN MUIR WILDERNESS, CALIFORNIA 

By DAVID A. D ELLINGER U.S. GEOLOGT AL R EY, and 

FREDERICK L. j O H 0 , U.S. B REA OF MINE 

SUMMARY 

The mineral survey of the John Muir Wilderness, conducted between 1969 

and 1978, revealed eight areas of probable and substantiated potential for the 

occurrence of mineral resources. Tungsten, with accompanying resources of 

gold, copper, silver, and molybdenum, is found along contacts between granitic 

rocks and metamorphosed calcareous sedimentary rocks; it is estimated that 

more than 1 million tons of demonstrated tungsten resources exist in areas of 

substantiated resource potential within the wilderness. Resources of gold, 

silver, lead, copper, zinc, molybdenum, and cobalt, occur in small deposits not 

associated with tungsten; however, the known deposits of these commodities 

are small and the possibility of the occurrence of larger ones is unlikely. The 

geologic setting precludes the presence of fossil fuel resources. 

CHARACTER AND SETTING 

The John Muir Wilderness, situated about 200 mi 

north of Los Angeles and the same distance eastsoutheast of San Francisco, occupies 755 sq rni in the 

rugged southern part of the Sierra Nevada It surrounds 

the northern end of Kings Canyon National Park and 

extends south-southeast along the eastern boundaries 

of both Kings Canyon and Sequoia National Parks, following the crest of the Sierra Nevada Thus, most of the 

steep eastern face of the Sierra Nevada from Mammoth 

Lakes to Cirque Peak, about 85 mi distant, lies within 

the wilderness. This area is one of the highest, most 

spectacular regions in the Sierra Nevada; much of the 

wilderness is above 10,000 ft in altitude, and Mount 

Whitney, the highest point in the contiguous United 

States (14,494 ft), lies on the boundary with Sequoia National Park. 

The northwestern part of the area was examined for 

mineral potential in 1969 as part of the USFS Sierra 

Demonstration Project (Lockwood and others, 1972). At 

that time, known deposits were visited and evaluated, 

stream-sediment and bedrock samples were collected 

and analyzed, and the resulting data were interpreted 

on the basis of existing geologic mapping. During the 

period 1975- 78, the USGS and the USBM undertook 

fieldwork expressly for the purpose of evaluating the 

mineral-resource potential of the John Muir Wilderness. 

The USGS conducted an aeromagnetic survey and a 

program of stream-sediment sampling and analysis, 

while the USBM estimated the extent of resources at 

known deposits within the wilderness. Geologic mapping of the area had been nearly complete before fieldwork was begun; the remainder was accomplished in 

1976 through 1978. A generalized geologic map of the 

area was compiled by du Bray (1981), and the results of 

the stream-sediment sampling program were presented 

by Dellinger and others (1982). Results of the aeromagnetic survey and evaluation of known resources were 

summarized by du Bray and others (1982). 

Most of the wilderness is underlain by granitic 

plutons of the Sierra Nevada batholith, but metamorphic and volcanic rocks underlie about 20 percent of the 

area The metamorphic rocks were originally sedimentary and volcanic rocks of Paleozoic and Mesozoic age; 

they were metamorphosed during the emplacement of 

the granitic rocks, which began in early Mesozoic time 

(Triassic), but occurred mostly at the end of the 

Mesozoic Era (Cretaceous). Uplift and westward tilting 

of the Sierra Nevada block from 90 to 65 million years 

ago (Late Cretaceous) resulted in rapid erosion of rock 

overlying the granitic bodies. Periodic eruption of 

volcanic rocks during the last 12 million years and 

widespread glaciation during the Pleistocene Epoch (2 

million to 10,000 years ago) brought about the present 

landform of the wilderness. Uplift, which accelerated 

about 3 million years ago, is still occurring along faults 

on the eastern edge of the Sierra Nevada, and alpine 

glaciers persist in the highest parts of the range. 

Mining in the John Muir Wilderness began in about 

267 
1864 in the Kearsarge district, west of the town of Independence. The district yielded gold and silver, but grade 

and continuity of ore were insufficient to sustain profitable operations, and most mines were closed by 1883. 

The Mammoth district, located at the northern end of 

the wilderness, yielded gold and silver from 1878 

through the early 1900's. In 1916, deposits of scheelite, 

a tungsten-bearing mineral, were discovered in the Pine 

Creek area, west of Bishop. The Pine Creek mine, just 

outside the wilderness, began operation in 1918; it has 

been the largest tungsten producer in the United States 

during recent years, but was not operating at the time 

of this report. Deposits associated with the mine form 

the nation's largest tungsten reserves. Scheelite has 

also been discovered and mined in the Mount Morrison 

area in the northeastern part of the wilderness and in 

several small bodies of calcareous metamorphic rocks in 

the southeastern part of the wilderness. 

MINERAL RESOURCES 

Tungsten is the principal metallic commodity found 

in the John Muir Wilderness. More than 1 million tons 

of tungsten resources in areas of substantiated tungsten potential are estimated to occur in the wilderness. 

We feel there is a possibility for the occurrence of 12 individual deposits in the area About 80,000 tons are considered to be in 5 deposits of more than 1000 tons, 

average grade 0.27 percent W03; about 910,000 tons to 

be in 6 deposits of more than 1000 tons, average grade 

0.36 percent W03; and about 16,000 tons to be in 1 

deposit, average grade 1.0 percent W03• More detailed 

information about individual deposits has been presented by du Bray and others (1982). 

Tungsten, with associated gold, silver, copper, and 

molybdenum, is found in narrow bands of highly altered 

rock (tactite or skarn) at contacts between granitic 

intrusions and metamorphosed calcareous sedimentary 

rocks at the margins of metamorphic pendants. More 

than half of all known tungsten resources within the wilderness are located in mines and prospects of the Mount 

Morrison pendant in the northeastern part of the wilderness. Nearly all the rest are located in deposits of the 

Pine Creek pendant, west of Bishop. The parts of the 

Mount Morrison and Pine Creek pendants that lie 

within the wilderness are classified as having substantiated mineral-resource potential. Four other areas contain small pendants with calcareous metasedimentary 

rocks that have associated geochemical anomalies; the 

Mount Humphreys, Mount Pinchot, Lookout Point, 

and Mount Agassiz areas are considered to have probable mineral-resource potential, but it is unlikely that 

they contain resources of the same magnitude as the 

larger pendants to the north. 

268 

Resources of gold, silver, lead, copper, zinc, molybdenum, cobalt, and possibly uranium occur in small 

deposits not associated with tungsten. Gold-silver 

deposits, some with associated lead, copper, and zinc, 

occur in two geologic environments: (1) discontinuous 

quartz veins and fault gouge in metavolcanic rock, 

granite, and granodiorite and (2) shear zones containing 

quartz veins and siliceous zones in altered latite and 

marble. Mines or prospects in the wilderness with more 

than 1000 tons of demonstrated resources of this type 

include the Rex Montis mine in the Oak Creek pendant, 

the Pick and Shovel mine in the Mount Izaak Walton 

area, and the Lucky Strike prospect in the Mount Morrison pendant. Molybdenum occurs in pods and veins in 

siliceous zones in granodiorite at the Moly Blue prospect south of Mount Humphreys. A probable cobalt 

resource potential for small cobalt deposits exists north 

of Mount Agassiz. The Mount Morrison pendant and 

Mount Agassiz areas are considered to have substantiated and probable resource potential, respectively, on 

the basis of possible tungsten mineralization discussed 

above as well as these non-tungsten deposits. The Oak 

Creek pendant, Mount Izaak Walton, and Mount Humphreys areas are classified as having probable mineralresource potential; however, known demonstrated resources in these areas are small relative to important 

deposits of these commodities elsewhere in the United 

States (less than 10,000 tons each at the gold-silver 

deposits and about 30,000 tons at the Moly Blue molybdenum deposit). 

The geochemical and geophysical surveys of the John 

Muir Wilderness did not reveal any large unknown mineral deposits. The aeromagnetic survey indicates that 

the wilderness contains neither large subsurface 

deposits of iron and pyrrhotite, comparable to the Iron 

Mountain deposit located about 5 mi northwest of the 

wilderness, nor masses of magnetite-rich serpentinite 

like those that contain gold and silver west of the 

wilderness in the Sierra Nevada foothills. Most geochemical anomalies (as revealed by analyses of the 

stream sediments) appear to result from either known 

mineralization, geologic environments favorable for 

types of mineralization known to occur in the region 

(mineralization is il}ferred), or unmineralized but goochemically anomalous bedrock. 

SUGGESTIONS FOR FURTHER STUDY 

A geochemical survey of areas within the wilderness 

that have exposed calcareous metasedimentary rocks 

using different sampling, sample processing, and 

analytical techniques might reveal significant tungsten 

mineralization. In particular, collection of samples from 

pockets of heavy-mineral accumulations, concentration 
of samples by panning and heavy-liquid techniques, and 

analysis of samples by more sensitive methods than 

were employed in this study might prove useful. 

REFERENCES 

Dellinger, D. A., Diggles, M. F., and du Bray, E. A., 1982, Maps and 

interpretation of geochemical anomalies in the John Muir Wilder· 

ness, Fresno, Inyo, Madera. and Mono Counties, California: U.S. 

Geological Survey Miscellaneous Field Studies Map 

MF -1185-B, scale 1:125,000. 

du Bray, E. A., 1981, Generalized bedrock geologic map of the John 

Muir Wilderness, Fresno, Inyo, and Mono Counties, California: 

U.S. Geological Survey Miscellaneous Field Studies Map 

MF-1185-A, scale 1:125,000. 

du Bray, E. A., Dellinger, D. A., Oliver, H. W., Diggles, M. F., 

Johnson, F. L., Thurber, H. K. , Morris, R. W., Peters, T. J., and 

Lindsey, D. S., 1982, Mineral resource potential map of the John 

Muir Wilderness, Fresno, Inyo, Madera, and Mono Counties, 

California: U.S. Geological Survey Miscellaneous Field Studies 

Map MF-1185-C, scale 1:125,000. 

Lockwood, J. P., Bateman, P. C., and Sullivan, J. S., 1972, Mineral 

resource evaluation of the U.S. Forest Service Sierra Demonstra· 

tion Project area, Sierra ational Forest, California: U.S. Geological Survey Professional Paper 714, 59 p. 

269 
270 

37° 

15' 

119°15' 

Sa 

~ 

C.m !;, 

·~· / 

0 

• Geologic terrane with probable 

mineral-resource potential 

w Tungsten 

x Mineral occurrence 

119°10' 11 9°05' 

boundary 

~ ' 

( MAP LOCATION 

5 

M ILES 

EXPLANATION 

Volcanic rocks (Tertiary) 

Plutonic rocks (Cretaceous and Jurassic ) 

Metamorphic rocks (Triassic or Paleozoic) 

Contact 

Figure 78.-Kaiser Wilderness, California 
KAISER WILDERNESS, CALIFORNIA 

By DAVID A . D ELLI CER, 1 U.S. GEOLO I AL SUR EY and 

' 

ANDREW L ESZCYKOWSKI, U .S. BUREAU F MINE 

SUMMARY 

On the basis of a mineral survey of the Kaiser Wilderness by the USGS and 

USBM in 1969, a narrow band in the northern part of the wilderness is classified 

as having probable tungsten resource potential. Tungsten resources exist in this 

area and small undiscovered deposits may exist at depth. Resources of highpurity calcitic and dolomitic marbles also occur within the wilderness. The 

geologic terrane precludes the occurrence of fossil fuel resources. 

CHARACTER AND SETTING 

The Kaiser Wilderness is located on the gently sloping west flank of California's Sierra Nevada about 50 mi 

northeast of Fresno. Kaiser Ridge, which culminates at 

Kaiser Peak (10,320 ft), is the principal physiographic 

feature in the wilderness. Most of the wilderness lies on 

the south flank of Kaiser Ridge, north of Huntington 

Lake. The area is mostly forested but includes alpine 

terrain consisting of lakes, meadows, low shrubs, and 

stunted trees, typical of the Sierra Nevada crest. Access 

to the area is by State Highway 168 and several county 

and logging roads to the south. 

The Kaiser Wilderness was established in 1976 and 

the area was examined for mineral potential in 1969 as 

part of the USFS Sierra Demonstration Project (Lockwood and others, 1972). At that time, known deposits 

were visited and evaluated, stream-sediment and 

bedrock samples were collected and analyzed, and the 

resulting data were interpreted on the basis of existing 

geologic mapping. Pertinent information from their 

report, existing geologic mapping, and available aeromagnetic data were used to evaluate the mineralresource potential of the wilderness by du Bray and 

others (1983). The USBM evaluated resources at known 

deposits within the wilderness. 

Granitoid, metamorphic, and volcanic rocks and 

glacial and alluvial deposits are exposed in the Kaiser 

Wilderness. Most of the wilderness is underlain by two 

plutons: the Mount Givens Granodiorite and the granodiorite of Dinkey Creek. Metamorphic rocks account for 

about 1 percent of the rocks exposed in the wilderness. 

'Wit.h contributions from E. A. du Bray. USGS. 

Quartzite is the most abundant metamorphic rock type; 

it occurs principally as isolated blocks and masses 

within the granodiorite of Dinkey Creek. The other 

metamorphic rock types (marble, calc-hornfels, hornfels, 

and pelitic schist) are found chiefly in septa between the 

two principal plutons. The only volcanic rock exposed in 

the wilderness is trachyandesite, which crops out near 

the southern wilderness boundary on Black Point. 

Mining activity in the wilderness has been minor. 

Recorded production has occurred only at the Lucky 

Blue group of claims. Tungsten ore worth about $50,000 

was reportedly mined between 1951 and 1956 from the 

Lucky Blue deposits. Several claims have been filed 

since 1930 for a massive outcrop of highly pure calcitic 

and dolomitic marble southeast of the Lucky Blue 

claims, but no production has been reported and only 

discovery and exploration pits were found during the 

mineral survey. 

MINERAL RESOURCES 

Tungsten is the only metallic commodity known to be 

present in the Kaiser Wilderness. Tungsten ore material, known as tactite or skarn, is formed by the reaction 

of calcareous sedimentary or metasedimentary rocks 

with hot fluids released from intruding granitoid 

magmas. When the reacting fluids contain sufficient 

tungsten, the tungsten-bearing mineral scheelite 

(CaWO.) forms. Tactite deposits occur along many contacts between granitoid and calcareous metasedimentary rocks in the Sierra Nevada, though not all tactites 

contain scheelite. The largest tungsten reserves in the 

United States are in tactite deposits at Pine Creek, 

about 25 mi east of the wilderness. 

271 
The known tungsten deposits in the wilderness are included in the Lucky Blue claim group, located between 

Avalanche Lake and upper West Kaiser Creek. Tungsten occurs in scattered scheelite-bearing pods along the 

margins of a narrow band of metasedimentary rocks 

that in some places separates the Mount Givens Granodiorite from the granodiorite of Dinkey Creek, and in 

boulders moved by glaciers from their original positions 

along these contacts. As much as 200 tons of ore has 

reportedly been produced from the Lucky Blue claims, 

mostly from glacial erratics. The tactite pods in the 

bedrock are small and widely spaced; they occur over a 

lateral distance of about 7000 ft and a vertical distance 

of about 600ft. Most samples from these bodies contain 

less than 0.48 percent tungsten trioxide (W03), though 

one sample contained about one percent W03• 

The wide lateral and vertical extent of small tactite 

pods along the contact between metasedimentary rocks 

and the plutons on either side of them suggests that 

other tungsten-bearing tactite bodies exist at depth. On 

this basis, a narrow band along the boundary between 

the Mount Givens and Dinkey Creek plutons is considered to have probable mineral-resource potential. However, the tactite bodies exposed at the surface are small, 

widely spaced, and of variable, but generally low, grade. 

Subsurface exploration would be required to determine 

whether deposits exist in the subsurface and their size 

and grade. 

Calcitic and dolomitic marbles occur in the Potter 

Pass-Twin Lakes area in a massive lens-shaped outcrop 

about 3000 ft long and 500 ft wide. The Larry No. 1 

prospect is in this area, but no production has been recorded and only discovery and exploration pits were 

found. Assay results indicate the body is composed of 

high-purity calcitic and dolomitic marbles. The lenticular mass may contain as much as 60 million tons of highpurity material, based on the known surface dimensions 

and an estimated depth of 1500 feet. There is no indication that other similar bodies exist within the wilder272 

ness. The marble body is inaccessible, far from potential 

markets, and marble is readily available in areas closer 

to markets. 

Neither the geochemical nor the aeromagnetic 

surveys of the Kaiser Wilderness indicated potential for 

other mineral resources. Four samples in the southern 

part of the wilderness were anomalous in gold, but no 

other evidence of gold deposits has been found; gold 

resources probably do not exist in the wilderness. Copper and molybdenum anomalies also occur, but these 

are probably related to anomalous bedrock chemistry or 

minor mineralization in joints rather than the presence 

of undiscovered resources. The aeromagnetic map does 

not indicate the presence of concealed ore bodies; the 

single identified aeromagnetic anomaly is attributed to 

a body of mafic plutonic rock. 

SUGGESTIONS FOR FURTHER STUDIES 

Although undiscovered deposits of tungsten may exist in the Kaiser Wilderness, they will be small in size 

and in the subsurface, and further studies are probably 

not warranted. 

REFERENCES 

du Bray, E. A., and Dellinger, D. A., 1980, Geologic, aeromagnetic, 

and geochemical anomaly maps of the Kaiser Ridge Wilderness, 

central Sierra Nevada, California: U.S. Geological Survey Miscellaneous Field Studies Map MF - 1181, scale 1:62,500. 

du Bray, E. A., Dellinger, D. A., Leszcykowski, Andrew, Morlock, 

Clayton, and Willett, Spencer, 1983, Mineral resource potential 

map of the Kaiser Wilderness, Fresno County, California: U.S. 

Geological Survey Miscellaneous Field Studies Map MF-1515, 

scale 1:62,500. 

Lockwood, J. P .. Bateman, P. C., and Sullivan, J. S., 1972, Mineral 

resource evaluation of the U.S. Forest Service Sierra Demonstration Project area, Sierra National Forest, California: U.S. Geolog· 

ical Survey Profc:>sional Paper 714,59 p. 
KINGS RIVER, RANCHERIA, AGNEW, AND 

OAT MOUNTAIN ROADLESS AREAS , CALIFORNIA 

By WARREN j. O KLEBERG, 1 U.S. GEOLOGICAL R EY, and 

W ARRE D . L ONGWELL, .S. B RE OF MI NE 

SUMMARY 

On the basis of a mineral survey done in 1979-82, the Kings River, Rancheria, 

Agnew, and Oat Mountain Roadless Areas were found to have several areas 

with probable mineral-resource potential for tungsten in tactite, and one area 

with probable mineral-resource potential for lode gold in quartz veins. The extreme relief and inaccessibility in most of the roadless areas make exploration 

and mining very difficult. The geologic terrane precludes the occurrence of 

energy resources. 

CHARACTER AND SETTING 

The Kings River, Rancheria, Agnew, and Oat Mountain Roadless Areas occupy an area of about 145 sq mi 

in the Sierra and Sequoia National Forests in the central 

Sierra Nevada, adjacent to and west of the boundary of 

Kings Canyon National Park. The roadless areas are extremely rugged, and the canyons of the Kings River, 

which constitute part of the roadless areas, are among 

the deepest in the United States. The eastern boundary 

of the Kings River Roadless Area includes the deepest 

part of the Kings River Canyon, 7811 ft deep. Total 

relief in the roadless areas is about 9250 ft. No roads 

and few trails occur in the roadless areas, river crossings 

are hazardous, and there are many extremely steep and 

brushy areas. Many parts of the roadless areas can only 

be visited with difficulty on foot. Many of the steep, 

rugged, and brushy parts of the roadless areas had 

never been geologically mapped or sampled. California 

State Highways 168, and 180, Kings Canyon Highway, 

and Fresno County roads provide access to the roadless 

areas. The nearest population center is Sanger, California, about 20 mi west of the western margin of the Oat 

Mountain Roadless Area 

The roadless areas are in the central part of the Sierra 

Nevada, a faulted and westward-tilted range which is 

deeply incised by major river systems such as the Kings 

River. The roadless areas in this part of the range are 

mainly underlain by granitic rock, with lesser metamorphic rock, and sparse basalt and surfical deposits. The 

'With contributions from James G. Moore, USG . from Jwncs M. Spear. U BM . 

granitic rock occurs as many individual plutons which 

are generally elongate northwesterly, and which are 

generally of Early and middle Cretaceous age. The 

plutons have intruded and contact metamorphosed, 

highly deformed metasedimentary and metavolcanic 

rocks, principally of Triassic and Jurassic age. The 

metasedimentary rocks were originally quartzite, 

arkose, marl, mudstone, calcareous sandstone, and limestone. The metavolcanic rocks were originally rhyolite 

and dacite lava flows and tuff. The metasedimentary 

and metavolcanic rocks were regionally metamorphosed 

and intensely deformed before intrusion and contact 

metamorphism. 

The two largest bodies of metamorphic rock are the 

Boyden Cave roof pendant in the Agnew Roadless Area, 

and the Pine Ridge roof pendant in the Kings River 

Roadless Area A few ridges and small peaks are capped 

by Tertiary basaltic volcanic rocks. Sparse surficial 

deposits consist of talus, colluvium, and glacial till and 

moraine. 

Field investigations were conducted in 1979 and 1980 

by teams from the USBM (Nokleberg and others, 1983). 

Information was obtained on mining claims by searching the records of Fresno County and the U.S. Bureau of 

Land Management. Chip and grab lode samples were 

taken from mines, prospects, dumps, and mineralized 

areas and chemically analyzed; sand and gravel samples 

were taken from placer deposits for heavy-mineral 

determinations. Field investigations were conducted in 

1981 and 1982 by a team from the USGS (Nokleberg 

and others, 1983). All of the roadless areas were 

geologically mapped at a scale of 1:62,250. Thin sections 

273 
36° 

45' 

274 

D 

Au 

w 

~ 

X 

X' 

0 

MILES 

EXPLANATION 

Geologic terrane with probable 

mineral-resource potential 

Gold 

Tungsten 

Mine or deposit 

Mineral occurrence 

Mine 

10 

Granitic rocks 

Metavolcanic rocks 

Metasedimentary rocks 

Contact 

Fau lt 

Figure 79.-Kings River, Rancheria, Agnew, and Oat Mountain Roadless Areas, California 
of rock samples were examined, rock, stream-sediment, 

and heavy-mineral concentrate samples were collected 

and chemically analyzed. The geological work was augmented by analysis of an aeromagnetic survey by 

Andrew Griscom. 

Tungsten, and possible by-product molybdenum, and 

gold are the only commodities for which there are 

recorded production in the roadless areas. There are 

tungsten occurrences and deposits in the central part of 

the Kings River, southern part of the Rancheria, and 

southern part of the Agnew Roadless Areas. The Wet 

Spot prospect, in the north-central part of the Kings 

River Roadless Area, and the Lodge Pole prospect, in 

the southeast part of the Rancheria Roadless Area, contain small tonnages of low-grade tungsten mineral 

resource. About 20,000 tons of tungsten ore were produced from the Gamet Dike mine which is outside the 

Kings River Roadless Area within a narrow corridor 

that extends into the area About 8000 tons of 

moderate-grade tungsten mineral resources are 

estimated at the Obelisk prospect to the southeast of 

the Rancheria Roadless Area, and a small amount of ore 

was mined in the 1950's (Moore and Marks, 1972). 

Lode gold is known to occur in the southwestern part 

of the Kings River Roadless Area where part of one 

patented claim extends into the roadless area Gold and 

silver values are sporadic and generally low. About 337 

lode claims have been staked within and adjacent to the 

roadless areas for tungsten, gold, copper, molybdenum, 

chromium, and uranium, as have been about 80 gold 

placer claims and 9 millsite claims. Except for part of 

one gold claim that was patented in the Kings River 

Roadless Area in the 1950's, there are no other patented 

mining claims or millsites. 

MINERAL RESOURCES 

Tungsten, as scheelite (calcium tungstate), is the principal commodity produced from this region. It is in contact metasomatic deposits called tactite that generally 

replace carbonate beds near intrusive contacts with 

granitic rock. The tactite bodies are generally erratically 

distributed, small, irregular, and lenticular. Individual 

tactite bodies range from tiny pods and stringers to 

layers several hundred feet long. Lode gold, the other 

commodity found in this region, generally occurs in 

scattered gash quartz veins in granitic rock. Many veins 

narrow rapidly with depth and commonly contain accessory sulfide minerals, mostly pyrite. 

The mining history, results of recent mine and prospect examinations, and the geologic, geochemical, and 

geophysical data acquired during the study of the 

roadless areas indicate a few areas with probable 

mineral-resource potential for tungsten in the Kings 

River, Rancheria, Agnew, and Oat Mountain Roadless 

Areas. There is also one area with probable mineralresource potential for lode gold in the Kings River 

Roadless Area The extreme relief and inaccessibility of 

most of the roadless areas make exploration and mining 

difficult. Gold occurs in a few scattered placers in the 

Kings River Roadless Area; however these occurrences 

have very low concentrations of gold and no resource 

potential was identified. Criteria for classification of 

potential for specific mineral commodities are listed 

below by roadless area and mineral resource. 

An area with probable mineral-resource potential for 

tungsten is in the central part of the Kings River 

Roadless Area, as indicated by favorable geologic environment of marble, locally in schist, that is intruded 

by granitic rock; moderately abundant tungsten 

deposits and prospects; about 56,000 tons of demonstrated and inferred low-grade tungsten resources 

averaging 0.27 percent W03 in tactite at the Wet Spot 

prospect; several tungsten prospects and the Gamet 

Dike mine adjacent to the roadless area; and generally 

moderate anomalies of tungsten and molybdenum in 

some heavy-mineral concentrates. This area of probable 

tungsten resource potential is adjacent to the larger 

masses of marble where intruded by granitic rock; it extends into the steep, inaccessible south side of the Kings 

River Canyon, where although abundant marble is intruded by granitic rock, no tungsten occurrences are 

known. A small area of probable tungsten mineralresource potential is in the northwest part of the 

roadless area 

An area with probable mineral-resource potential for 

lode gold is in the southwestern part of the Kings River 

Roadless Area, as indicated by prospects; one patented 

lode gold claim which extends into the roadless area; 

sparse and generally narrow quartz veins in granitic 

rock; and low concentrations of gold and silver in quartz 

veins at prospects. 

An area with probable mineral-resource potential for 

tungsten occurs in the southern part of the Rancheria 

Roadless Area, as indicated by demonstrated low-grade 

tungsten mineral resources totaling about 12,000 tons, 

averaging 0.34 percent W03, at the Lodge Pole prospect; an estimated 8000 tons of moderate-grade tungsten mineral resources, averaging about 1 percent W03, 

at the Obelisk tungsten prospect near the roadless area; 

weakly anomalous concentrations of tungsten and some 

molybdenum in heavy-mineral concentrates; and locally 

favorable geologic environment of marble intruded by 

granitic rock. 

Two small areas with probable mineral-resource 

potential for tungsten are located in the Agnew Roadless Area, as indicated by favorable geologic environment of some marble in schist which is intruded by 

granitic rock; sparse tungsten occurrences; weakly 

275 
anomalous concentrations of tungsten and molybdenum in some heavy-mineral concentrates; sparse tactite with anomalous concentrations of tungsten and 

some molybdenum; and a magnetic anomaly indicating 

extension of a known tungsten deposit to moderate 

depth towards the southeast. 

An area with probable mineral-resource potential .for 

tungsten is in the central part of the Oat Mountain 

Roadless Area, as indicated by weakly to moderately 

anomalous concentrations of tungsten in heavy-mineral 

concentrates; and a minimally favorable geologic environment of sparse marble interbedded with biotite 

schist and intruded by granitic rock. Samples from 

prospects on quartz veins, in the central and western 

parts of the roadless area, show only traces of gold and 

silver; quartz veins in this area are extremely sparse. 

SUGGESTIONS FOR FURTHER STUDIES 

Tungsten deposits of the type found in the roadless 

276 

areas generally are near the contact of granitic rock and 

calcareous metasedimentary rock or marble. Prospecting for additional deposits could be done in these contact areas in all four roadless areas. However, the only 

parts of these areas where extensive prospecting has 

not already occurred are areas that are extremely steep, 

rugged, and brushy. Small additional deposits may exist in these areas, and the assessment of resource potential thus refined. 

REFERENCES 

Moore, J. G., and Marks. L. Y .. 1972, Mineral resources of the High 

Sierra Primitive Area, California: U.S. Geological Survey Bulletin 1371-A, 40 p. 

Nokleberg, W. J., Moore, J. G., Chaffee, M. A., Griscom, Andrew, 

Longwell, W. D., and Spear, J. M .. 1983, Mineral resource potential map of the Kings River, Rancheria, Agnew, and Oat Mountain Roadless Areas, Fresno County, California: U .. Geological 

Survey Miscellaneous Field Studies Map MF- 1564-A, scale 

1:62,500. 

278 

41 ° 

00' 

MAP LOCATION 

0 

M ILES 

122°45' 

The Cedar 

oldfiel ( 111pground 

/ (i. fRTY MINE 

Lake Eleanor 

Approximate roadless 

boundary 

/ 

f 

5 

EXPLANATION 

Surficial deposits (Quaternary ) 

*~~*§; Granitic rocks (Jurassic) 

Ultramafic rocks (Jurassic or older) 

Abrams mica schist (Devonian) 

Contact 

• • Thrust fault--Sawteeth on upper plate 

'X' Mine 

Figure 80.- Lake Eleanor Roadless Area, California 
LAKE ELEANOR ROADLESS AREA, CALIFORNIA 

By D ONALD F. H BER , 1 .S. GEOL GI L R\ 'EY, and 

ERIC E. CATHER , U . . B RE OF MI E 

SUMMARY 

On the basis of a mineral surveys in 1968-70 and in 1980-81, the Lake 

Eleanor Roadless Area has little promise for the occurrence of metallic, nonmetallic, or energy resources. 

CHARACTER AND SETTING 

The Lake Eleanor Roadless Area occupies an area of 

about 22.3 sq mi in the Trinity Alps of the Klamath 

Mountains, 14-28 mi north-northeast of Weaverville, 

California Altitude above sea level ranges from 3770 ft 

in the south along Swift Creek, to 7919 ft on Battle 

Mountain in the northwest part of the roadless area. 

The roadless area wraps around and shares the eastern 

and northeastern boundaries of the proposed SalmonTrinity Alps Wilderness. 

Almost the entire roadless area is underlain by ultramafic and granitic rocks; except for a small area of 

metamorphic rocks that underlies the northwest edge. 

The metamorphic rocks were probably thrust under the 

ultramafic rocks about 350 million years ago 

(Devonian). During the time from about 230 to 65 million years ago (Mesozoic), the granitic rocks intruded 

the ultramafic rocks. Also during this time the metamorphic and ultramafic rocks were accreted to the 

North American Continent by plate-tectonic processes. 

Mining began in the Trinity Alps about 1850 and has 

continued intermittently since then. There is no record 

of mining activity in the Lake Eleanor Roadless Area, 

but placer and lode mining occurred nearby. 

MINERAL RESOURCES 

Gravels along the Trinity River and Coffee Creek 

have yielded gold in the past. However, streams that 

drain the roadless area and empty into the Trinity River 

'With conLributions from OLL C. clson. USGS. and Joseph L. Riu:hey. U BM. 

and Coffee Creek contain no significant gold values, indicating that these streams do not drain the principal 

source areas for the placer gold. It is more likely that 

the gold washed downstream from other areas. 

At the Golden Jubilee and Liberty mines, both of 

which are less than 1 mi north of the roadless area, goldsilver fissure veins occur in the same granitic and 

ultramafic rocks that underlie the roadless area, but the 

veins are fractured and poorly exposed. Similar veins 

which might occur in the roadless area would probably 

be covered by glacial debris or soil on all but the 

steepest slopes. Because of the extensive exploration 

and mining activity that has occurred throughout the 

surrounding area there is little promise for the occurrence of lode gold deposits in the Lake Eleanor Roadless 

Area It is conceivable that subsurface quartz veins 

with gold are present in the roadless area, however, 

geochemical surveys in 1968- 70 and 1980-81 failed to 

reveal any anomalously high gold or other metal values 

in rock and stream-sediment samples from the roadless 

area Sand and gravel are common in most drainages, 

but are of small volume and far from present markets. 

No energy resources were identified in the roadless area. 

REFERENCES 

Hot.z. P. E .. Thurber, H. K., Marks, L. Y., and Evans. R. K., 1972, 

Mineral resources of the Salmon-Trinity Alps Primitive Area, 

California with a section on An aeromagnetic survey and interpretation by Andrew Griscom: U.S. Geological urvey Bulletin 

1371 - B, 267 p. 

Huber, D. F., and Nelson, S. C., Cather, E. C .. and Ritchey, J. L., 1983. 

Mineral Resource Potential of the Lake E leanor Roadless Area, 

Trinity County, California: U.S. Geological urvey Open-File 

Report 83-482, 19 p. 

279 
280 

37° 

30' 

D 

Cu 

Pb 

Ag 

w 

Zn 

X 

X' 

MAP LOCATION 

0 

Geologic terrane with 

Wheeler Ridge 

05040 

M '1!. 

Pine Creek Roof Pendant 

5 

MILES 

EXPLANATION 

probable 

mineral-resource potential 

Unconsolidated glacial and 

alluvial deposits 

Copper Plutonic rocks (Mesozoic) 

Lead 

Silver 

Metasedimentary rocks (Paleozoic) 

Tungsten 

Zinc Contact 

Mineral occurrence 

Mine 

Figure 81.- Laurel-McGee and Wheeler Ridge Roadless Areas, California 
LAUREL-MCGEE AND WHEELER RIDGE ROADLESS AREAS, CALIFORNIA 

By MIC HAEL A. COSCA, 1 U.S. GEOLOG ICAL SURV EY, a nd 

DO ALD 0. CAP TICK, U.S . B REA OF Ml E 

SUMMARY 

Geochemical sampling and mine and prospect surveys in 1980, identified 

small areas in the Laurel-McGee and Wheeler Ridge Roadless Areas in the eastem Sierra Nevada, California, that have probable potential for the occurrence of 

small deposits of tungsten and (or) base and precious metals. A number of mines 

and prospects in or near the roadless areas are in occurrences of one or more of 

the metals, tungsten, zinc, silver, copper, and lead. The geologic terrane 

precludes the occurrence of fossil fuel resources. 

CHARACTER AND SETTING 

The Laurel-McGee and Wheeler Ridge Roadless 

Areas occupy 15 and 25 sq mi, respectively, in the Inyo 

National Forest, Inyo and Mono Counties, California 

The areas are approximately 25 mi northwest of Bishop, 

California, and are accessible by several secondary roads. The Laurel-McGee Roadless Area may be 

reached by the McGee Creek Road from the southeast 

or the Convict Lake Road from the east both of which 

intersect California State Highway 395 near Crowley 

Lake. The Wheeler Ridge Roadless Area is accessible by 

the Rock Creek Road from the north, the Old Sherman 

Grade from the northeast, and the Pine Creek Road 

from the southeast, all of which intersect State Highway 395. The roadless areas lie between 13,748 ft and 

4880 ft in altitude, are semiarid, and sparsely covered 

with sagebrush, juniper, pinon pine and at higher altitudes limber and yellow pine. 

The roadless areas contain a thick sequence of metamorphosed limestone, dolomite, shale, and sandstone of 

Paleozoic age intruded by granitic rocks of Mesozoic 

age, which form the backbone of the Sierra Nevada In 

some instances, the granitic rocks appear to nearly 

engulf the layered rocks leaving isolated bodies of 

strata, now exposed in 3-dimensions because of deep 

erosion, as roof pendants. These roof pendants, especially at their contact with the granitic rocks, have 

proven to be favorable localities for the occurrence of 

tungsten-bearing skams. One of the best examples of a 

1

Willl contributions from Maurice A. Chaffee. USGS and ~Tedrick L. Johnson. U BM. 

skarn deposit is at the nearby Pine Creek mine 

(Newberry, 1982). 

Extensive pleistocene glaciation in the areas is 

evidenced by well-defined glacial moraines at the 

mouths of major canyons, and small patches of till and 

erratics on some upland surfaces. Alluvial and colluvial 

deposits of Holocene age are present in the valley floors. 

Major structural features include tight folds related 

to a prebatholithic regional deformation, and more 

localized deformation and metamorphism related to the 

emplacement of the Sierra Nevada batholith. Large normal faults occur in and adjacent to the roadless areas, 

and are related to the uplift of the Sierra Nevada in late 

Cenozoic time. Active movement along some of these 

faults has been documented by the recent earthquakes 

of 1980, 1981, 1982, and 1983. 

MINERAL RESOURCES 

The Bishop mining district, which includes the 

Laurel-McGee and Wheeler Ridge Roadless Areas, began producing tungsten about 1916, and has remained 

one of the world's largest producers of this commodity. 

Lesser amounts of molybdenum, copper, silver, and 

gold have also been mined primarily as a byproduct of 

tungsten production. In addition, the Bishop district 

has small nonmetallic deposits of pumice, perlite, barite, 

talc, building stone, ceramic materials, gravel, and limestone (Bateman, 1965). 

To determine the mineral-resource potential of the 

roadless areas, the USGS and the USBM analyzed 

samples of rock, stream sediment and heavy-mineral 

281 
concentrates collected from stream drainages, outcrops, 

and mines and prospects within or near the roadless 

areas (Cosca and others, 1983). Results of the geochemical analyses show several drainages, partially within 

the roadless areas, that contain concentrations of some 

elements (arsenic, barium, bismuth, copper, gold, lead, 

molybdenum, silver, and tungsten) above the normal 

background levels for the region. These elements are 

typical of the suite of elements common to tactite 

deposits and (or) base- and precious-metal deposits. 

The proximity of the Laurel-McGee and Wheeler 

Ridge Roadless Areas to known ore deposits with similar geologic settings, the pr~sence of small mines and 

prospects, and geochemical anomalies from parts of the 

roadless areas are factors that indicate a probable 

potential for the occurrence of undiscovered mineral 

resources. The contact zones between granitic rocks and 

metasedimentary rocks are the most likely sites for 

resources, especially tungsten in tactite deposits. 

However, extensive prospecting and exploration by 

private individuals has occurred within the roadless 

areas and has failed to detect any sizable deposits. 

SUGGESTIONS FOR FURTHER STUDIES 

Results of the studies of the Laurel-McGee and 

282 

Wheeler Ridge Roadless Areas have delineated small 

areas with probable potential for the occurrence of 

tungsten and (or) base- and precious metal resources. 

Detailed mapping and sampling of these areas should be 

undertaken in order to determine more precisely the 

location and size of the mineralized areas. 

REFERENCES 

Bateman, P. C., 1965, Geology and tungsten mineralization of the 

Bishop district, California: U. . Geological Survey Professional 

Paper 470, 208 p. 

Cosca, M.A., and Chaffee, M.A., 1983, Geochemical analy es of rock, 

stream-sediment, and panned-concentrate samples from the 

Laurel-McGee and Wheeler Ridge Roadless Areas, lnyo and 

Mono Counties, California: U.S. Geological Survey Open-File 

Report 83-3. 

Cosca, M. A., Chaffee, M. A., and Chap tick, D. 0., 1983, Mineral 

resource potential map of the Wheeler Ridge Roadless Area, Jnyo 

and Mono Counties, California: U.S. Geological Survey Miscellaneous Field Studies Map MF- 1411-B, scale 1:62,500. 

Cosca, M. A., Chaffee, M. A., and Johnson, Rick, 1983, Mineral 

resource potential map of the Laurel-McGee Roadless Area, 

Mono County, California: U.S. Geological Survey MisceUaneous 

Field Studies Map MF - 1411 -C, scale 1:62,500. 

Newberry, R. J., 1982, Tungsten-bearing skarns of the Sierra evada; 

The Pine Creek mine, California: Economic Geology, v. 77, p. 24. 
LOST CREEK ROADLESS AREA, CALIFORNIA 

By L. j. P ATRICK M UFFLER, U .S. GEOLOG J AL S R EY and 

' 

H ARRY W . CAMPBELL, . . BUREAU OF MI NE 

SUMMARY 

Geologic and mineral-resource investigations in 1981-82 by the USGS and 

USBM identified no mineral-resource potential in the Lost Creek Roadless Area 

Sand and gravel have been mined from alluvial flood-plain deposits less than 1 

mi outside the roadless area; these deposits are likely to extend into the roadless 

area beneath a Holocene basalt flow that may be as much as 40 ft thick. An oil 

and gas lease application which includes the eastern portion of the roadless area 

is pending. Abundant basalt in the area can be crushed and used as aggregate, 

but similar deposits of volcanic cinders or sand and gravel in more favorable 

locations are available outside the roadless area closer to major markets. No indication of coal or geothermal energy resources was identified. 

CHARACTER AND SETTING 

The Lost Creek Roadless Area encompasses 13 sq mi 

of Lassen National Forest in Shasta County, northcentral California, about 20 rni north of Lassen Peak. 

The nearest city is Redding, California, 50 rni to the 

southwest. Peripheral access is provided by State 

Highway 89 passing near the west boundary of the 

roadless area The Pacific Crest Trail passes along the 

west margin of Hat Creek Rim adjacent to the east 

boundary of the roadless area Most of the roadless area 

is a valley 3.5 mi wide, sloping from an altitude of 3800 

ft at the south boundary to 3220 ft on the north. The 

Hat Creek Rim, along the east boundary of the roadless 

area, is a series of precipitous cliffs that rise to altitudes 

of nearly 4500 ft. Hat Creek flows from south to north 

not far from the west boundary of the roadless area 

Lost Creek enters the valley from the southeast and 

disappears into the porous basalt and gravels near the 

Bidwell Ranch. 

The Lost Creek Roadless Area lies just east of the 

crest of the Cascade Range in a major north-southtrending valley containing Hat Creek, the principal 

northerly drainage of the volcanic highlands 20 mi 

south near Lassen Peak. The valley is bounded on the 

east by the conspicuous young fault scarps of the Hat 

Creek Rim. Faults on the west side of the valley are 

inconspicuous; the valley can be considered to be an 

asymetric fault block tilted to the east and partly filled 

by alluvial material and volcanic rocks derived primarily from the south. 

Rocks exposed in the hills to the west of the roadless 

area are a variety of locally derived andesite flows, 

faulted and partly eroded. No isotopic age determinations are available, but the degree of faulting and erosion is similar to andesite flows to the south, considered 

by Macdonald (1964) to be of Pliocene age. The andesite 

flows are stratigraphically beneath and significantly 

older than the dacite of Burney Mountain 10 rni to the 

west, dated at 240,000 years (G. B. Dalrymple, written 

commun.) by the potassium-argon method. 

Rocks exposed on the fault scarps on the east side of 

the Hat Creek fault block comprise a series of lowpotassium high-alumina olivine basalts correlative with 

those mapped by Macdonald (1964) as Burney Basalt 

south of the Lost Creek Roadless Area. Similar basalts 

are widespread over northeastern California east of the 

Cascade Range and probably range in age from Miocene 

to Quaternary. Although no isotopic ages are available 

for the Burney Basalt on the Hat Creek Rim and stratigraphic relationships are not clear, Macdonald's (1964) 

assignment of the Burney Basalt in the roadless area to 

the early Pleistocene is accepted. 

Geologic units exposed in the Hat Creek fault block 

are all very young. A few miles north of the Lost Creek 

Roadless Area is Cinder Butte, a small shield volcano of 

mafic andesite showing very rugged topography 

unmodified by erosion but cut by one branch of the 

young fault system along the Hat Creek Rim. The vent 

283 
284 

40° 

45' 

Hdt 

Cre 1 

H :1ger 

~tat on 

0 

\ 

~ ( 

121°30' 

FOREST SERVICE 

SAND AND 

GRAVEL PIT ~----.c 

~' 'l 

I "I 

( I' 

,.. ... -J 

-, 

I 

I 

.;"""""'-, __ I 

~ ~pproximate .;. ., 

'-7Q 

/ roadless --

"" boundary 

I 05089 

. ~---J Ran..:h 

WfL.COX .PIT · · . 

. . (Original sire/ 

121°25' 

MAP LOCAT ION 

Gr.Jssy 

La 

8'':<·:::-::::·<. WILCOX SAND AND GRAVEL PIT 

0 2 

MILES 

EXPLANATION 

Alluvium (Holocene) 

Basalt (Holocene) 

Basalt (Lower Pleistocene) 

Andesite (Pliocene) 

---Contact 

--,-- Fault--Bar and ball on downthrown side 

X Sand and gravel pit 

Figure 82.- Lost Creek Roadless Area, California. 
areas of this shield volcano lie 2 to 3 rni north of the 

northernmost part of the Lost Creek Roadless Area 

Coarse fluvial gravel and sand at least 30 ft thick are exposed in the Wilcox sand and gravel pit about 0.5 rni 

southeast of the Lost Creek Roadless Area 

The clasts in the gravel are well rounded and consist 

of a wide variety of volcanic rocks ranging in composition from basalt to dacite. These rocks are probably all 

derived from the highlands to the south in and adjacent 

to Lassen Volcanic National Park. At the deepest part 

of the gravel pit there are a few angular boulders of 

olivine basalt, interpreted as the top of a basalt flow 

underlying the gravel. This basalt has no natural exposures, and its extent and age are unknown. 

Overlying the fluvial gravel and sand is the Hat Creek 

lava flow, a low-potassium high-alumina olivine basalt 

which flowed north from vents near Old Station, 8 rni 

south of the southern boundary of the Lost Creek 

Roadless Area (Anderson, 1940; Macdonald, 1964). The 

distal extremity of the lava flow is 6 rni north of the 

Lost Creek Roadless area The Hat Creek lava flow has 

a rugged blocky surface with local relief of as much as 

20 ft. The thickness of the flow is uncertain, but is 

unlikely to exceed 40 ft except where the basalt was 

ponded locally. Conspicuous on the east side of the flow 

are lava slump scarps, where the cooled crust of the lava 

slumped westward over the fault scarps of the Hat 

Creek Rim as underlying still-liquid lava drained to the 

northwest (Finch, 1933; Anderson, 1940). 

The Hat Creek lava flow is almost certainly Holocene 

in age; preliminary analysis of paleomagnetic secular 

variation suggest an age of approximately 5000 years 

(Duane Champion, oral commun., 1982). 

Overlying the Hat Creek lava flow and the fluvial 

gravel and sand are patches of Holocene alluvium, in 

part interlayered with silicic ash derived from the 

pyroclastic eruptions that accompanied the extrusion of 

the Chaos Crags domes in Lassen Volcanic National 

Park 1050 years ago. The ash commonly has been reworked and winnowed by wind action. 

MINERAL RESOURCES 

No potential for metallic mineral occurrences was 

identified in or adjacent to the Lost Creek Roadless 

Area An oil and gas lease application is pending that includes the eastern part of the roadless area. No indication of coal or geothermal energy resources was found. 

The roadless area lies in an area of pronounced low heatflow caused by regional movement of cold ground water 

north from the volcanic highlands near Lassen Peak 

(Mase and others, 1982, fig. 7). Although the Hat Creek 

basalt flow is indeed very young, its vent area is 8 rni 

south of the Lost Creek Roadless Area; any thermal 

energy in the flow itself has long since dissipated. 

Significant sand and gravel deposits occur adjacent 

to the roadless area; the Wilcox sand and gravel pit 

about 0.5 rni to the southwest is an important source of 

construction aggregate for the region. This deposit is 

older than the Hat Creek lava flow and likely extends to 

the north for an unknown distance under the flow. Utilization of any gravels under the flow, however, would be 

subject to the necessity of removing the very resistant 

basalt cover. The basalt itself could be crushed and used 

as aggregate, but could not compete with volcanic 

cinders and sand and gravel that are readily available 

outside the roadless area Similar considerations would 

apply to the possible use of the basalt for dimension 

stone. 

SUGGESTIONS FOR FURTHER STUDIES 

No further mineral-resource studies are suggested. 

REFERENCES 

Anderson, C. A., 1940, Hat Creek Lava Flow: American Journal of 

Science, v. 238. no. 7, p. 477- 492. 

Campbell, H. W .. and Muffler, L. G. P., 1983. Mineral resource potential of Lost Creek Roadless Area. Shasta County, California: U.S. 

Geological Survey Open-File Report 83- 508. 

Finch, R. H., 1933, Slump scarps: Journal of Geology. v. 41, no. 6, 

p. 647-649. 

Macdonald, G. A., 1964, Geology of the Prospect Peak Quadrangle, 

California: U.S. Geological Survey Geological Map, GQ- 345. 

Mase, C. W .. Sass, J. H., Lachenbruch, A. H., and Munroe. R. J., 

1982, Preliminary heat-flow investigations of the California 

Cascades: U.S. Geological Survey Open-File Report 82-150, 

240 p. 

285 
286 

123°00' 

MAP LOC ATION 

Approximate boundary 

GEM LAKE 

" 

; / 

oV" / 7 ....- __/ 

~ r 

,J 

(/ 

../ •j' ~ 

~ 

-:. 

./'-. 

~ 

~ 

c. 

'~ 

0 10 

MI LES 

EXPLANATION 

- Geologic terrane with substantiated 

mineral-resource potential 

Geologic terrane with probable 

L.....---' mineral-resource potential 

Cr Chromium 

~ Mine or deposit 

Intrusive rocks (Jurassic) 

D Greenschist-facies metamorphic 

rocks (Jurassic and (or ) older) 

D Amphibolite -facies metamorphic 

rocks undivided (Paleozoic?) 

D Metamorphosed ultramafic rocks 

(Paleozoic?) D Marble (Paleozoic?) 

Contact 

• • + Thrust fault--Sawteeth on 

upper plate 

Figure 83.- Marble Mountain Wilderness. California 

L 
MARBLE MOUNTAIN WILDERNESS, CALIFORNIA 

By M ARY M. D O AT0, 1 U . . GEOLO !CA L RVEY, and 

WILLIAM . H ALE, .S. B REAU OF MI E 

SUMMARY 

Geologic, geochemical, geophysical, and mineral investigations done in 

1979-81 indicate that the Marble Mountain Wilderness has areas of probable 

and substantiated resource potential for placer gold, for chromite, and for marble. Specific areas with mineral potential are gold placer terrace deposits along 

the North Fork Salmon River, chromite deposits in the Shackleford Creek area, 

and marble deposits at Marble Mountain. The geologic terrane precludes the occurrence of fossil fuel resources. 

CHARACTER AND SETTING 

The Marble Mountain Wilderness is located in the 

north-central Klamath Mountains of northern California, about 40 mi west-southwest of the town of Yreka 

The wilderness encompasses about 335 sq mi of steep, 

rugged terrain between the Scott, Salmon, and Klamath 

Rivers, at altitudes ranging from 1450 to 8300 ft above 

sea level. The area is densely vegetated by Douglas-fir 

and mixed conifer forests at lower altitudes, and by true 

firs at altitudes above 5000 ft. Trailheads in the northern and western part of the wilderness are accessible via 

unpaved USFS roads leading south and east from 

California State Highway 96 (the Klamath River Highway) near the towns of Happy Camp and Somes Bar. 

The northeastern trailheads are reached by unpaved 

roads leading from the Scott River road via the town of 

Fort Jones and California State Highway 3. The 

southern trailheads are reached via paved and gravel 

roads leading from the towns of Etna and Sawyers Bar. 

The Marble Mountain Wilderness is underlain by 

metamorphic and plutonic rocks of the western Paleozoic and Triassic belt of the Klamath Mountains 

geologic province. The metamorphic rocks of the wilderness may be grouped into two units (Donato and others, 

1982). The first is a structurally lower amphibolitefacies unit interpreted as a metamorphosed tectonic 

melange. This unit, whose age is unknown but possibly 

Paleozoic, is exposed in the northern part of the 

wilderness, and contains a wide variety of lithologies, including chert, marble, amphibolite, ultramafic rocks, 

'With contributions by ROOert C. J ochens and David B. Smith. USGS. 

and schists of mainly sedimentary origin. Of these, only 

the ultramafic rocks and marble are significant in terms 

of mineral-resource potential. 

The second unit, which structurally overlies the first, 

is composed of greenschist-facies metasedimentary and 

meta volcaniclastic rocks of Jurassic and (or) older age. 

These rocks include a breccia which contains small (as 

much as a few hundred feet long) blocks of chert, limestone, and serpentinized peridotite in an argillite 

matrix. The serpentinite blocks are the possible source 

of geophysical anomalies, but they are insignificant in 

terms of mineral-resource potential owing to their small 

size. No chromite was observed in these serpentinite 

blocks. However, sampling by the USBM yielded placer 

gold in alluvial deposits in this terrane. 

The two metamorphic terranes are juxtaposed along a 

southward-dipping thrust fault which postdates the 

main metamorphic event. Both units are in turn crosscut by the Upper Jurassic Wooley Creek batholith, 

which underlies much of the western part of the wilderness. Unconsolidated deposits include landslide deposits, which often occur in areas underlain by ultramafic rock, and Pleistocene to Holocene alluvial 

deposits in stream beds and terraces. 

A geochemical survey of the wilderness was undertaken to aid in the resource evaluation. Streamsediment, panned-concentrate, and whole-rock grab 

samples were taken throughout the wilderness. The 

geochemical sampling delineated an area in the northeast quadrant of the wilderness which showed 

anomalous concentrations of chrome and nickel. The 

anomalous area is underlain primarily by metasedimentary, metavolcanic, and ultramafic rocks. The high 

287 
chrome and nickel values are the result of ultramafic 

rocks exposed in the drainage basins of individual sediment samples, as confirmed by several analyses of 

whole-rock samples of ultramafic rocks in the area 

Geophysical surveys were also employed in this investigation. The most useful of these was the aeromagnetic survey, since conspicuous aeromagnetic anomalies 

are associated with bodies of ultramafic rock, some of 

which contain small amounts of chromite. Four strong 

northeast-trending anomalies occur over the 

amphibolite-facies unit in the northern part of the wilderness and three of these are associated with large 

exposures of ultramafic rock. Only two magnetic 

anomalies are associated with exposures of ultramafic 

rock in the greenschist-facies terrane, neither of which 

contains chromite. illtramafic bodies in this terrane are 

typically composed of antigorite, and are not likely 

hosts for chromite. The generally featureless magnetic 

field over other parts of the greenschist-facies terrane 

within the wilderness indicates that no other large 

magnetic ultramafic bodies are concealed at shallow 

depth in this terrane. 

Placer gold was produced during the 1930's from 

Pleistocene terrace deposits on the North Fork of the 

Salmon River. Mining claims were located for marble 

(1920's) and gold (1930's) near Marble Mountain, and 

for chromite (1940's-1950's) and gold (1800's) in the 

Shackleford Creek region, but no mineral production 

came from within the wilderness. 

Fifty-six mining claims were identified from courthouse records. Five claims were for lode gold, six were 

gold placer claims, 20 claims were for chromite, and 25 

claims were for marble. No patented mining claims, 

mineral leases, or currently active mining claims are 

known in the wilderness. 

MINERAL RESOURCES 

Geologic, geochemical, and geophysical evidence indicates that the Marble Mountain Wilderness has resource potential for placer gold and chromite; marble 

resources are also present (Donato and others, 1983). 

Gold-bearing gravel deposits occur as discontinuous 

alluvial terraces and as river-level gravel bars at the 

mouths of tributaries in the southeastern part of the 

wilderness. Demonstrated placer gold resources occur 

at six localities along the North Fork of the Salmon 

River, two of which lie just outside the wilderness 

boundary. Approximately 0.05 sq mi of terrace and 

stream gravels were identified. Of these, approximately 

0.025 sq mi contain gold. Gold-bearing gravel in the wilderness is estimated to total about 149,000 cu yd averaging 0.002 oz gold./cu yd. Of this quantity, only 4000 cu 

yd would average over 0.01 oz gold./cu yd. 

288 

Chromite occurs as podiform bodies, disseminated 

stringers, schlieren, or discontinuous layers in metamorphosed ultramafic rock. Demonstrated and inferred resources are found in two localities in the northeastern 

part of the wilderness; near Gem Lake and near Calf 

Lake. The largest podiform chromite body, located at 

Gem Lake, is about 75 ft long by 6 ft wide. It constitutes an estimated 1400 tons of inferred chromite 

resource. Disseminated chromite veins and stringers 

also occur there. Demonstrated disseminated chromite 

resources total 4170 tons of rock averaging 2.4 percent 

Cr20 3• At Calf Lake, chromite occurs in veins and 

disseminated stringers. Demonstrated disseminated 

chromite resources total 145 tons of rock averaging 8.2 

percent CrzOs. 

Known chromite resources in the wilderness are small 

and low grade. However, because the wilderness contains several large ultramafic bodies, the potential for 

undiscovered chromite bodies in the subsurface probably exists. Such deposits would be difficult to detect 

with current exploration techniques. If and when better 

subsurface detection methods become available, presently unknown deposits may come to light. On this 

basis areas underlain by ultramafic rock, but containing 

no identified resources, are classified as having probable 

mineral resource potential. 

Marble Mountain itself is composed of interlayered 

calcite marble and siliceous and dolomitic schists. The 

marble is exposed in a massive outcrop 0.5 to 2 mi wide 

for about 2.5 mi along strike, and averages about 250 ft 

thick. A smaller outcrop about 0.25 mi wide and the 

same thickness crops out discontinuously for about 3 

mi. Grain size, mineral composition, and purity are 

highly variable. Because the marble occurs as a tectonic 

block in the metamorphosed melange rather than as a 

laterally continuous sedimentary layer, its extent in the 

subsurface is difficult to predict. The area of marble 

outcrop is classed as having a substantiated resource 

potential. 

SUGGESTIONS FOR FURTHER STUDIES 

It is unlikely that further studies utilizing current 

exploration techniques will uncover hidden mineral 

deposits in the wilderness. If new methods for subsurface exploration are developed in the future, hidden 

chromite deposits may be found in some of the larger 

ultramafic bodies. 

REFERENCES 

Donato, M. M., Barnes, C. G., Coleman, R. G., Ernst, W. G., and 

Kays, M. A .. 1982, Geologic map of the Marble Mountain Wilderness, Siskiyou County, California: U. S. Geological Survey Mis· 

cellaneous Field Studies Map MF- 1452- A. 
Donato, M. M., Hale, W. H., Jachens, R. C., and Smith, D. B., 1983, 

Mineral resource potential map of the Marble Mountain Wilderness, Siskiyou County, California: U. S. Geological Survey Miscellaneous Field Studies Map MF-1452- B. 

289 
290 

MAP LOCATION 

0 5 

MILES 

EXPLANATION D Geologic terrane with probable 

mineral-resource potential 

Cu Copper 

Fe Iron 

Pb Lead 

Mo Molybdenum 

Ag Silver 

Zn Zinc 

~ Mine or deposit 

~ Granitic rocks 

LJ Metamorphic rocks 

--- Contact 

2 Location discussed 

in text 

Figure 84.-Minarets Wilderness and adjacent areas, California 
MINARETS WILDERNESS AND ADJACENT AREAS, CALIFORNIA 

By . KI G H UBER, 1 U.S. GEOLOG ICAL R EY and 

H ORACE K. THURBER, U . . B REA OF MI E 

SUMMARY 

A mineral survey of the Minarets Wilderness and adjacent areas in the central 

Sierra Nevada, California was conducted during 1973-75. The results of the 

survey indicate that the study area has a substantiated resource potential for 

small deposits of copper, silver, zinc, lead, and iron, and a probable mineralresource potential for molybdenum. No energy-resource potential was identified 

in the study. 

CHARACTER AND SETTING 

The Minarets Wilderness is located in the east-central 

part of the Sierra Nevada along the southeast margin of 

Yosemite National Park. The area studied covers about 

237 sq mi, of which about 170 sq mi is within the officially designated Minarets Wilderness. The adjacent 

areas studied were designated as the San Joaquin and 

North Fork San Joaquin Roadless Areas at the time of 

the study. Because of subsequent boundary changes, the 

adjacent areas studied now cover only part of what is 

now designated as the San Joaquin Roadless Area 

The study area lies at the crest of the Sierra Nevada 

and is extremely rugged, with nearly 10,000 ft of total 

relief, ranging from an altitude of 3200 ft where the San 

Joaquin River leaves the area to 13,135 ft at Mount 

Ritter. More than 25 peaks higher than 12,000 ft in elevation lie within or on the boundary of the area. Much of 

the area at lower elevations is forested, but roughly 

50 percent of the study area is above timberline or supports only scattered growth because of precipitous 

slopes or other adverse conditions. The winter climate of 

the area is severe; it has one of the thickest annual snow 

packs in the Sierra 

The Sierra Nevada is a large block of the Earth's 

crust that has been uplifted on the east along an extensive system of high-angle faults and tilted westward. 

Most of the central Sierra is composed of Mesozoic 

granitic plutons that constitute the Sierra Nevada 

batholith. The batholith was intruded into Paleozoic 

'With conbibutions from Howard W. Oliver and Roy A. Bailey. USGS and Michael 

Miller, C. Thomas Hillman. David S. Lindsey. and Richard W. Monis. USBM. 

and Mesozoic sedimentary and volcanic strata, which 

are preserved in the walls of the batholith and as roof 

pendants, septa, and inclusions within the batholith. 

Such strata, now metamorphosed, underlie nearly half 

of the study area, mostly in a body of rock referred to as 

the Ritter Range pendant; many small bodies of metamorphic rock are scattered throughout the rest of the 

predominantly granitic terrane. With few exceptions, 

the known occurrences of mineralized rock are confined 

to the metamorphic rocks, and the exceptions appear to 

be confined to a few granitic rocks older than the bulk of 

the batholithic rocks in the study area 

MINERAL RESOURCES 

The study area is within a region where gold and other 

metals have been sought extensively, beginning at least 

as long ago as the mid-1800's; the prospecting accelerated around 1878 when gold was discovered in the 

Mammoth district, east of the study area Mines in the 

Mammoth mining district may have produced as much 

as $1 million worth of gold, silver, and other metals at 

then-current prices. The Strawberry mine, adjacent to 

the south boundary of the study area, produced more 

than 40,000 short-ton units of tungsten trioxide (W0 3). 

The host rocks in these two mineralized areas do not extend into the study area 

Many local mineralized areas are present within the 

study area and about 1200 mining claims have been 

filed for gold, copper, lead, zinc, silver, molybdenum, 

tungsten, and iron. About 25 claims were held during 

the time of investigation; nine have been patented. No 

291 
mineral production has been recorded from prospects 

within the study area 

Within the study area there are 3 localities with 

demonstrated resources that are surrounded by areas of 

probable mineral-resource potential: the Crown PointNidever prospect, Minarets magnetite prospect, and 

Mark prospect. A fourth area, Red Top Mountain, has a 

probable potential for silver and molybdenum. 

The Crown Point-Nidever prospect on Shadow Creek 

(no. 1 on map) has been explored by extensive trenching 

and several diamond-drill holes; it has an estimated 

9 million tons of demonstrated resources of copper, lead, 

zinc, and silver in tactite. In addition probable mineralresource potential occurs in areas extending southeasterly and northwesterly from the tactite, but no resource 

estimate could be made because the occurrences are too 

poorly exposed. 

An iron-bearing lens on the Minarets magnetite prospect (no. 2) west of Iron Mountain has been explored 

with two diamond-drill holes and contains an estimated 

8.5 million tons of demonstrated iron resources. An area 

with small, widely scattered magnetite masses that has 

probable mineral-resource potential surrounds the 

Minarets prospect. 

North-trending gash-fracture veins in metasedimentary rocks on the Mark prospect (no. 3) in the southern 

part of the area, contain at least 30,000 tons of demonstrated resources of silver and copper. At this locality, 

copper in the form of chalcocite and bornite occurs as 

very fine grains disseminated in equally fine grained 

metasedimentary rock. Locally the sulfide minerals 

have been deposited as thin stringers and irregular 

masses along fractures crosscutting the host rock; it 

was these local high-grade masses that were being explored by prospect pits at the time of the study. 

A geochemical survey indicated anomalous silver in 

a small drainage basin on the northwest side of Red 

Top Mountain and widespread anomalous molybdenum 

around the eastern side of the mountain (no. 4). Limited 

exposures preclude estimation of the size of the area 

of probable silver resource potential, but it is more 

than likely small. The area of molybdenum mineralization, seen in many prospects, is considered to have probable resource potential for possibly higher-grade mineralization at depth or of extensive disseminated 

mineralization. 

292 

The areas with mineral-resource potential mentioned 

above are in the established Minarets Wilderness except for the Minarets magnetite prospec_t and the Mark 

prospect, which were in the area designated ~ the 

North Fork San Joaquin Roadless Area at the tune of 

the study. 

SUGGESTIONS FOR FURTHER STUDIES 

Although mineralization of diverse types is widespread within the study area, it i~ mostly confined ~ 

favorable horizons or structures m the metamorphic 

rocks and areas of significant mineralization are few. 

The rocks in the area are generally well exposed and all 

stream-sediment geochemical anomalies recognized 

during the study were traceable to previously known 

mineralized areas; the probability of finding additional 

areas of unrecognized mineralization is considered low. 

However, of the four localities mentioned, only two have 

been explored sufficiently to make a reasonable estimate of their resource potential. The presence of molybdenum in the Red Top Mountain area, for example, has 

long been known, but the extent or grade of mineralization is wholly unknown. 

In 1975 the Mark prospect was the only one of the 

four localities discussed that was currently undergoing 

exploration. The amount and extent of the low-grade 

disseminated mineralization in this area, which may be 

quantitatively more important than the high-grade 

pockets, can only be determined by an extensive program of both surface and diamond-core-drill sampling. 

The estimated demonstrated and inferred mineral resources of 30,000 tons includes only the higher-grade 

material; the probability of adding to this resource base 

in the prospect area is considered high. 

REFERENCE 

U. S. Geological Survey and U. S. Bureau of Mines. 1982, Mineral 

resources of the Minarets Wilderness and adjacent areas, Madera 

and Mono Counties, California: U. S. Geological Survey Bulletin 

1516- A-D, 159 p. 
MIRANDA PINE, HORSESHOE SPRINGS, TEPUSQUET PEAK, 

LA BREA, SPOOR CANYON, FOX MOUNTAIN, AND 

LITTLE PINE ROADLESS AREAS, CALIFORNIA 

B y Y LRG!L A. FRIZZELL , jR. , 1 U.S. GEOLO 1 AL 

L CLA K lZO , .S . B UREA OF Ml E 

RVEY, and 

SUMMARY 

Mineral-resource surveys conducted in 1980-83 by the USGS and USBM indicate demonstrated resources of barite, copper, and zinc at two localities in the 

La Brea Roadless Area and demonstrated resources of phosphate at a mine in 

the Fox Mountain Roadless Area A building stone quarry is present on the 

southern border of the Horseshoe Spring Roadless Area and an area of substantiated resource potential extends into the area. The Miranda Pine, Tepusquet 

Peak, Spoor Canyon, and Little Pine Roadless Areas have little promise for the 

occurrence of mineral resources and there is little promise for the occurrence of 

energy resources in any of the roadless areas. 

CHARACTER AND SETTING 

The Miranda Pine, Horseshoe Springs, Tepusquet 

Peak, La Brea, Spoor Canyon, Fox Mountain and Little 

Pine Roadless Areas together occupy about 246 sq rni in 

the Los Padres National Forest, California For purposes of this report the individual areas will be referred 

to collectively as the study area 

The study area consists of most of the Sierra Madre 

Mountains and part of the San Rafael Mountains in the 

western part of the Transverse Range, and is situated 

between Santa Barbara and Santa Maria on the south 

and west and Cuyama Valley on the north. California 

State Highways 33, 154, and 166 provide access to 

paved and unpaved roads which in tum allow access to 

individual roadless areas. 

Much of the study area is characterized by steepwalled canyons and sharp ridges. Although summit 

ridges may locally support coniferous forests and 

riparian woodlands may line valley bottoms, impenetrable chaparral covers much of the mountain slopes 

and makes off-trail traverses difficult. 

Thick fault-bounded sequences of sandstone, siltstone, shale, and conglomerate underlie nearly all of the 

study area and are divided on the basis of age into a 

1

Wilh contributions by George E. Claypool. Andrew Griscom. and Dovid B. Smilh. USG . 

and Dale W. Avery. John R. Benhrun. Michael C. Hom. Terry R. Neumann. and Robin B. 

McCulloch. U BM . 

mostly pre-Miocene section and a mostly Neogene section (Frizzell and Vedder, in press). The pre-Miocene section contains nearly equal amounts of Mesozoic and 

Cenozoic rocks, which were mostly deposited in submarine fan environments near continental margins. 

Lesser amounts of Upper Cretaceous and Oligocene 

nonmarine rocks, which were deposited in alluvial fan, 

fluvial, or littoral environments, are also present. 

Organic-rich siltstone and shale, interbedded sandstone and lesser conglomerate predominate in the 

Neogene section. These rocks formed mostly from sediments deposited in relatively restricted marine basins 

where the organic remains of flora and fauna living in 

the water column constituted a relatively important 

source of sediment. Mapped with these rocks are lesser 

amounts of Neogene nonmarine rocks which occur along 

the southern edge of the Cuyama Valley. 

A sliver of igneous rock along the southwest margin 

of the study area includes Jurassic(?) gabbroic rocks and 

Tertiary volcanic rocks. 

In addition to the geologic mapping, multidisciplinary work in the study area included analysis of mines 

and prospects, geophysical investigations and organicand inorganic-geochemical studies. 

Placer gold mining by Spanish settlers began both 

northwest and east of the study area in the early 1800's, 

and gold and antimony were mined from bedrock lodes 

to the east of the study area at the end of the 1800's. 

293 
,_ 

r' '1 Tepusquet 

Peak 

05116 

isqu0 , 

Cu 

Zn 

Cu, Zn / 

WILDHORSE 

MOUNTAINS 

PROSPECTS S 

0 

MAP LOCATION 

1 'e\t. 

( UVcHl1a 

Approximate roadless 

boundary 

-_-_-_-_-_-_;--_-_---~-- -_-________ ..::-_-_-_-_-_-_-_-_-_:-_-_-_-_-_-_ ---------------- ----------------

10 

MILES 

EXPLANATION 

Geologic terrane with substantiated 

mineral-resource potential i Sedimentary rocks (Neogene) 

Copper 

Zinc 

Mine or deposit 

' 

-

Sedimentary rocks (Pre-Miocene) 

Volcanic , igneous, and metamorphic rocks 

undivided (Tertiary and Mesozoic) 

Contact 

Fault 

• • Thrust fault--Sawteeth on upper plate 

Figure 85.- Miranda Pine, Horseshoe Springs, Tepusquet Peak, La Brea, Spoor Canyon, Fox Mountain, and Little Pine Roadless Areas, 

California 

294 
Exploration for oil began in the study area just after the 

turn of the century and the Cuyama Valley oil fields 

immediately north of the study area began production 

in the late 1940's. Gypsum was discovered just east of 

the study area in 1892 and phosphate-bearing rocks 

were reported in the study area in the 1930's. 

Geophysical studies included the compilation and 

analysis of gravity and magnetic data (Griscom, in 

press). The northern edge of the Fox Mountain Roadless 

Area is on the southern margin of a negative gravity 

anomaly occupying Cuyama Valley. The gravity data 

do not support the presence of significant amounts of 

Neogene rocks there, below the South Cuyama thrust. 

Sediment samples taken from stream deposits, collected 

for a reconnaissance geochemical study, delineate areas 

with previously known mineralization (Smith and 

others, in press). Analyses of fine-grained sedimentary 

rocks collected for a reconnaissance study of organic 

matter mostly indicate low quantities of oil- and gasproducing materials. 

MINERAL RESOURCES 

While our studies, presented in Frizzell and others (in 

press), indicate that most rocks within the study area 

probably do not contain petroleum resources or favorable environments for the concentration of metallic 

minerals, four localities do have demonstrated 

resources; the Horseshoe Springs Roadless Area has 

demonstrated building stone resources at the Colson 

Quarry; the La Brea Roadless Area has two localities, 

one of demonstrated barite resources at the White Elephant mine and one of copper and zinc resources at the 

Wild Horse Mountain prospects; and the Fox Mountain 

Roadless Area has demonstrated phosphate resources 

at the Cuyama phosphate mine. 

The only active mining in the study area is for 

building stone in the Colson Quarry, one third of which 

is in the Horseshoe Spring Roadless Area The mine annually produces 2000 tons of sandstone for flagging and 

rubble (Hom, 1983). An area of substantiated resource 

potential for thin-bedded, fine-grained sandstone and 

interbedded siltstones of the Miocene and Pliocene 

Monterey Formation similar to that quarried at the 

mine extends 1 mi northwest and southeast of the site 

and includes demonstrated resources in excess of 

50,000,000 tons of raw material. 

Gabbroic rocks on Wildhorse Mountain in the La 

Brea Roadless Area contain vugs and fractures filled 

with malachite and azurite. Prospects in a high grade 

zone contain 1300 tons of demonstrated resources with 

1.87 percent copper and 3.13 percent zinc. An additional 

5850 tons of demonstrated and inferred resources containing 0.18 percent copper and 1.34 percent zinc are exposed adjacent to the high-grade material (Benham and 

McCulloch, 1981, p. 6). The patented White Elephant 

barite deposit (formerly called Eagle) was mined extensively in 1929 and 1930. The barite occurs as veins in 

Cretaceous sedimentary rocks and about 95,000 tons of 

73 percent barite are inferred to remain on the claims 

(Benham and McCulloch, 1981, p. 7). A high barium content in geochemical samples and high sulfate content in 

spring waters sampled indicate the possible presence of 

additional barite veins in the La Brea Roadless Area as 

well as in other localities, but no resource potential is 

identified. 

The Santa Margarita Formation, in the Fox Mountain Roadless Area, may contain more than 300 million 

tons of phosphatic pellet-bearing rocks (Fedewa and 

Hovland, 1981, p. 72), but most of these rocks are 

covered by thick overburden. The area does, however, 

contain more than 21 million tons of inferred phosphate 

resources at the Cuyama phosphate mine having 4.84 

percent P20 6 (McCulloch and Neumann, 1982, p. 4). 

Although there has been no mining from leases within 

the roadless area, similar material was mined north of 

the area between 1965 and 1970. 

Because the study area is predominantly underlain by 

sedimentary rock and located between the South 

Cuyama and Santa Maria oil and gas fields, oil and gas 

resource potential might be expected throughout the 

study area Reconnaissance oil and gas studies (Frizzell 

and Claypool, in press; Howell and Claypool, 1977), 

however, indicate little promise for the occurrence of 

petroleum within the pre-Miocene rocks in the study 

area Samples from pre-Miocene rocks contain organic 

matter in quantities and qualities below those necessary 

to produce significant amounts of hydrocarbons. 

Many of the Miocene marine rocks contain sufficient 

quantities and suitable types of organic matter necessary to generate hydrocarbons. The Miocene rocks exposed at the surface in the Tepusquet Peak, La Brea, 

and Little Pine Roadless Areas, though, are relatively 

thin (about 2000 to 4000 feet) and have generally been 

well breached by erosion. Likewise, the Miocene rocks 

at the surface in the Fox Mountain Roadless Area are 

relatively thin and have been well dissected, and, even 

though similar rocks are projected to occur below the 

South Cuyama thrust, gravity data do not support their 

presence in great thicknesses. 

SUGGESTIONS FOR FURTHER STUDIES 

Additional gravity data and development of gravity 

models may add to our understanding of Neogene rocks 

below the South Cuyama thrust and the potential for 

295 
occurrence of petroleum there. Detailed geological mapping and geochemical sampling may also add to our 

understanding of the barite occurrence in the La Brea 

Roadless Area 

REFERENCES 

Avery, D. W., 1981, Mineral resources of the Tepusquet Peak RARE 

II Area ( o. 5116), Santa Barbara County, California: U.S. 

Bureau of Mines Open File Report MLA 7-81, 6 p. 

Benham, J. R.. 1983, Mineral investigation of the Spoor Canyon 

RARE II Area ( o. 5118), Santa Barbara County, California: 

U.S. Bureau of Mines Open File Report, MLA 17-83,7 p. 

Benham, J. R., and McCulloch, R. B., 1981, Mineral resources of the 

La Brea RARE II Area ( o. 5117), Santa Barbara County, California: U.S. Bureau of Mines Open File Report MLA 9-82, 9 p. 

Capstick, D. 0., and Hyndman, P. C., 1982. Mineral resources of the 

Little Pine RARE II Area (No. 5278), Santa Barbara County, 

California: U.S. Bureau of Mines Open File Report MLA 53-82, 

7 p. 

Fedewa, W. T., and Hovland, R. D., 1981 , Phosphate resources of the 

upper Miocene phosphate deposits near ew Cuyama, Santa 

Barbara County, California, in Roberts, A. E., and Vercoutere, 

T. L., Geology and petrology of the upper Miocene phosphate 

deposits near New Cuyama, Santa Barbara County, California: 

U.S. Geological Survey Open-File Report 81-1037, p. 68- 245. 

Frizzell, V. A., Jr., and Claypool, G. E., in press, Petroleum potential 

map of Mesozoic and Cenozoic rocks in roadless areas and the 

Santa Lucia Wilderness in the Los Padres National Forest, 

southwestern California: U.S. Geological Survey Miscellaneous 

Field Studies Map MF- 1655- D. 

Frizzell. V. A. Jr., Smith, D. B .. Kuizon. Lucia, and Hale, W. ., in 

press, Mineral resource potential map of ·roadless areas and the 

Santa Lucia Wilderness in the Los Padres ational Forest, 

southwestern California: U.S. Geological Survey Miscellaneous 

Field Studies Map MF-1655-B. 

296 

Frizzell, V. A., Jr.. and Vedder, J. G., in press, Geologic map of 

roadless areas and the Santa Lucia Wilderness in the Los Padres 

National Forest, southwestern California: U . . Geological Survey 

Miscellaneous Field Studies Map MF- 1655- A. 

Griscom, Andrew, in press, Aeromagnetic map of part of the Los 

Padres National Forest in the southern Coast Range and western 

Transverse Range, California: U .. Geological Survey Miscellaneous Field Studies Map MF- 165 - A. 

Griscom, Andrew, in press. Bouguer gravity map of part of the Los 

Padres National Forest in the southern Coast Range and we tern 

Transverse Range, California: U .. Geological Survey Miscellaneous Field Studies Map MF- 1658- B. 

Horn, M. C., 1983, Mineral investigation of the mineral resources of 

the Horseshoe Spring RARE II Area (No. 511 5), Santa Barbara 

County, California: U.S. Bureau of Mines Open File Report MLA 

18-83, 9 p. 

Howell. D. G., and Claypool, G. E., 1977, Reconnaissance petroleum 

potential of Mesozoic and Cenozoic Rocks, Coast Ranges, California, in Howell, D. G., Vedder, J. G., and McDougall. K., eds., Cretaceous Geology of the California Coast Ranges, West of the San 

Andreas Fault: Pacific Section, Society of Economic Paleontologists and Mineralogist, Pacific Coast Paleogeography Field 

Guide 2, p. 85-90. 

Kuizon, Lucia, 1983, Mineral investigations of the Miranda Pine Rock 

RARE II Area ( o. 5114), Santa Barbara County, California: 

U.S. Bureau of Mines Open File Report M LA 19- 83, p. 

McCulloch, R. B., and eumann, T. R., 1982, Mineral investigation of 

the Fox Mountain RARE II Area ( o. 5120). Santa Barbara 

County, California: U.S. Bureau of Mines Open File Report MLA 

128-82, 9 p. 

Smith, D. B., Frizzell, V. A., Jr., Adrian, B. M., Vaughn, R. B., and 

McDougal, C. M., in press. Geochemical map of roadless areas 

and the Santa Lucia Wilderness in the Los Padres ational 

Forest, southwestern California: U.S. Geological urvey 

Miscellaneous Field Studies Map MF- 1655- E. 

U.S. Bureau of Mines, in press, Mines and prospects map of roadless 

areas and the Santa Lucia Wilderness in the Los Padres ational 

Forest, southwestern California: U.S. Geological urvey Miscellaneous Field Studies Map MF- 1655- C. 
MOKELUMNE WILDERNESS AND ADJACENT ROADLESS AREAS, 

CALIFORNIA 

By EDWI H. MCKEE,

1 U .S . GEOLOGICAL SURVEY and 

' 

FRA CIS E. FEDERSPIEL, U.S. BUREA OF Mr E 

SUMMARY 

On the basis of a mineral survey in 1979 most of the Mokelumne Wilderness 

and adjacent roadless areas including Caples Creek, Tragedy-Elephants Back 

(nos. 4-984 and 5-984), and Raymond Peak (no. 5-985) are considered to offer 

little promise for discovery of mineral resources. A small area in the northeast 

part of the Mokelumne Wilderness and parts of the Tragedy-Elephants Back 

and Raymond Peak Roadless Areas contains a previously known mining district 

(Summit City) in which small amounts of a number of metallic minerals occur 

and the area has a probable mineral potential for gold and silver resources. No 

energy resources were identified in this study. 

CHARACTER AND SETTING 

The Mokelumne Wilderness and adjacent roadless 

areas, most of which is directly west of the Sierra crest, 

comprise 197 sq mi south of Lake Tahoe. The area is 

dominated by the Mokelumne River canyon, a deep and 

rugged feature that runs from the Sierra crest westward 

to the Sacramento Valley. Important mountains in the 

area include Round Top (10,380 ft), Mokelumne Peak 

(9332 ft), and Mt. Reba (8758 ft). Two major highways, 

State Route 88 on the north and State Route 4 on the 

south side of Mokelumne Canyon provide access to the 

area Small roads and trails reach the drainage heads 

and the rim of the canyon at a number of places but access into and along the canyon is limited to a few trails. 

The nearest population center is South Shore Tahoe, 

about 20 mi to the northeast; the small town of Markleeville is about the same distance to the east. 

Geologic mapping, geochemical sampling, and mine 

and prospect evaluation for this study area was done by 

the USGS and USBM in 1979. A geologic map was published in 1981 (McKee and Howe, 1981); an aeromagnetic map in 1981 (Plouff and McKee, 1981); geochemical maps in 1981 and 1982 (Chaffee and others 1981, 

1982) and a mineral-resource potential map and report 

in 1982 (McKee and others, 1982). 

The rocks exposed in the study area are mostly 

Cretaceous plutons of the Sierra Nevada batholith. 

1

Witil cootributions by Maurice A. Chaffee. USGS. and Edward L. McHugh. Eric E. 

Catiler. Douglas F. Scot.L. and Clanton M. Rumsey. USBM. 

These granitic rocks have intruded and metamorphosed 

volcanic and sedimentary rocks of presumed Jurassic to 

Cretaceous age and several large, and numerous small, 

bodies of metamorphic rocks crop out as roof pendants 

within the granitic rock. Many of the ridges and peaks 

in the area are capped by Tertiary volcanic and sedimentary rocks, and a few prominent peaks are deeply eroded 

volcanic necks or complex dike swarms. The prevalent 

volcanic rock is andesite including lava flows and 

lahars. The sedimentary rocks contain a large amount of 

volcanic detritus and in places are almost entirely air 

fall ash deposits. The great variation in thickness, lenticular nature of units, and facies variations ranging 

from coarse fan-type deposits to thinly laminated, plant 

fossil-bearing siltstone indicate that there was considerable topographic relief in the Tertiary at the time these 

deposits accumulated. The Tertiary deposits and underlying rocks are now deeply eroded reflecting uplift of the 

Sierra Nevada and dissection by streams and glaciers. 

MINERAL RESOURCES 

The earliest reported mining activity in the study 

area centered around the Summit City mining district 

(northwest and west of Upper Blue Lake) where veins 

carrying silver minerals were prospected during the 

early 1860's and gravel along the head of Summit City 

Creek was worked for placer gold. The rush was short 

lived, however, and left no record of production. 

297 
298 

120°15' 

38° 

45' 

38° 

30' 

5-984 

Approximate 

boundary 

D 

Au 

Ag 

". 

0 5 

MILES 

EXPLANATION 

Geologic terrane with probable 

mineral-resource potential 

Gold 

Silver 

Mine 

0 

D 

D 

M rid' 

CABIN MINE 

CITY DISTRICT 

Volcanic rocks--Mostly Tertiary 

andesite 

Granitic rocks--Mostly Cretaceous 

granodiorite 

Metamorphic rocks--Mostly Jurassic 

or older gneiss and schist 

Contact 

x Mineral occurrence 

Figure 86.-Mokelumne Wilderness and adjacent roadless areas. California 

119°45' 
The only current mineral interest within the 

Mokelumne Wilderness is at the Monte Wolf property 

on the Mokelumne River above the mouth of Summit 

City Creek. It and several other scattered claims are 

undeveloped; they show little promise for the discovery 

of mineral resources. 

At least 20 mining claims were located in the Caples 

Creek Roadless Area (5-027), mainly for uranium, 

during the 1950's. Interest focused on pegmatite dikes 

that emitted radiation counts above background levels. 

None of these occurrences is of high grade and they are 

not considered as resources. A few claims have been 

staked on quartz veins and stringers for precious metals 

but these structures contain no significant amount of 

metals. 

No claims were identified within the TragedyElephants Back Roadless Area (4-984); although a 

small amount of silver and gold was identified in one 

silicified zone, the zone is small and the grade is low. 

At least 67 claims have been located within the 

Tragedy-Elephants Back Roadless Area (5-984) area 

since 1877. Two mines outside, but near the eastern 

border of the roadless area, have produced some gold, 

silver, copper, and lead. Neither mine is presently active 

and there is no evidence that their vein system extends 

into the roadless area Geochemical sampling within the 

roadless area has not revealed significant concentrations of metal. There seems to be little promise for the 

discovery of mineral resources. 

About 60 gold and silver claims and 28 uranium 

claims have been located in the Raymond Peak Roadless Area (5-985). Most gold-silver claims were at the 

head of Summit City Creek in the Summit City mining 

district and were located during the 1860's and early 

1900's. None are active today. The uranium claims were 

explored between 1971 and 1979 mostly by drilling. 

Some uranium was found and subsequent sampling by 

the USBM revealed as much as 0.009 equivalent-weight 

percent of U50 8 in an ancient stream channel. No 

resource potential was identified. 

Within the wilderness and adjacent lands only the 

area around Round Top seems to offer any potential for 

the occurrence of mineral resources and this area is of 

moderate interest at best. Geochemical sampling indicates a general enrichment in silver, gold, barium, 

bismuth, copper, iron, and lead in this vicinity. The area 

around Round Top is also the area in which most of the 

previous mining activity occurred and contains the 

Summit City mining district. The geologic setting, the 

anomalous metal values, and the particular suite of 

elements indicate that this is an area of hydrothermal 

alteration. The concentrations of metals are relatively 

low, however, in comparison with those detected in or 

near exposed mineral deposits. In general, average 

grades are low and metal distribution is erratic in the 

exposed mineralized quartz veins and shear zones that 

surround Round Top. 

The complex sulfide ores mined from altered Tertiary 

volcanic rocks from districts east of the roadless areas 

are not known to occur in similar rocks within the study 

area Tactite bodies in pre-Cretaceous rocks from districts east of the area contain scheelite and metallic sulfide minerals, but roof pendants within the Mokelumne 

Wilderness and adjacent roadless areas are less highly 

mineralized. 

Samples from mineralized zones from several abandoned mines within or near the study area suggest probable potential for local gold and silver resources in 

quartz-filled shear zones near these sites. The vein 

systems are not large and the grades are not high. 

SUGGESTIONS FOR FURTHER STUDIES 

Any further exploration in the Mokelumne Wilderness and adjacent roadless areas should focus on the 

area around Round Top. The Log Cabin mine outside 

the roadless area is presently inaccessible but its relatively rich vein system may extend into the roadless 

area, although no evidence for this was seen. Drilling 

based on careful geologic mapping is the only feasible 

method to explore this vein system further. 

REFERENCES 

Chaffee, M. A., McKee, E. H., Hill, R. H., Speckman, W. S., and 

Sutley, S. J.. 1981, Chemical analyses of samples of rock, 

m.inus-0.25-mm stream sediment and nonmagnetic heavy· 

mineral concentrate, Mokelumne Wilderness and adjacent 

RARE II Further Planning Areas, California: U.S. Geological 

Survey Open· File Report 81-670, 36 p. 

Chaffee, M. A., Hill, R. H., and Sutley, S. J., 1982, Geochemical map 

showing anomalous drainage basins, Mokelumne Wilderness 

Area and contiguous roadless areas central Sierra Nevada. 

California: U.S. Geological Survey Miscellaneous Field Studies 

Map MF-1201 -C, scale 1:62,500. 

McKee, E. H., and Howe, A. A., 1981, Geologic map of the 

Mokelumne Wilderness and RARE II Further Planning Areas, 

central Sierra Nevada. California: U.S. Geological Survey 

Miscellaneous Field Studies Map MF-1201-A, scale 1:62,500. 

McKee, E. H., Chaffee, M. A., Federspiel, F. E., McHugh, E. L., 

Cather, E. E., Scott, D. F., and Rumsey, C. M .. 1982, Mineral resource potential of the Mokelumne Wilderness and Caples Creek, 

Tragedy-Elephants Back, and Raymond Peak Roadless Areas, 

central Sierra Nevada, California: U.S. Geological Survey 

Miscellaneous Field Studies Map MF- 1201-D, scale 1:62,500. 

Plouff, Donald, and McKee, E. H., 1981, Aeromagnetic map of the 

Mokelumne Wilderness and contiguous RARE II Further Planning Areas, central Sierra Nevada. California: U.S. Geological 

Survey Miscellaneous Field Studies Map MF- 1201-B, scale 

1:62,500. 

299 
300 

36° 

15' 

Grouse 

p. 

~ ·~-:<>~ /vllio ~~ j; ~ 

I 

0 

118°45' 

J 

5 

MILES 

MAP LOCATION 

Cu . Pb, Zn , 

W, Ag 

J dan 

PCd 

EXPLANATION 

Geologic terrane with 

substantiated mineralresource potential D Geologic terrane with 

probable mineral-resource 

potential 

Cu Copper 

Pb Lead 

Ag Silver 

w Tungsten 

Zn Zinc 

Granitic rocks of the Sierra 

Nevada batholith 

(Cretaceous and Jurassic) 

Metasedimentary and 

Ld metavolcanic roof pendant 

(Middle Jurassic to Upper 

Triassic) 

--- Contact 

Figure 87.- Moses and Dennison Peak Roadless Areas, California 
MOSES AND DENNISON PEAK ROADLESS AREAS, CALIFORNIA 

By RIC HARD j. GOLDFARB, 1 .S. GEOLO l AL S R EY , and 

DAVID A. LIPTON , .S. B RE OF MI ES 

SUMMARY 

A mineral-resource survey was conducted by the USGS and USBM between 

1979 and 1982, in the Moses and Dennison Peak Roadless Areas, southeastern 

Sierra Nevada, California One area within the Moses Roadless Area is classified 

as having substantiated mineral-resource potential for small base-metal skarn 

deposits. Additionally, geochemical data indicate probable potential for small 

base-metal skarn deposits from one locality within Dennison Peak Roadless 

Area and for small tungsten skarn deposits from a region within Moses Roadless Area The geologic setting precludes the presence of energy resources. 

CHARACTER AND SETTING 

Moses Roadless Area includes 38 sq mi and Dennison 

Peak Roadless Area 10.5 sq mi in the southern Sierra 

Nevada of California, southeast of Sequoia National 

Park. Both roadless areas are contained totally within 

Sequoia National Forest. They are characterized by extreme relief and dense vegetation. The North Fork of 

the Tule River and the Dillonwood Sequoia Grove property separate Dennison Peak Roadless Area from the 

northern part of Moses Roadless Area Moses Roadless 

Area is bisected by the Mountain Home State Forest. 

Most of the exposed rocks within Moses and Dennison Peak Roadless Areas are Jurassic to Cretaceous 

plutons of the Sierra Nevada batholith. Granodiorite 

and alaskite are the most abundant intrusive rock 

types, but quartz diorite, diorite, and gabbro are also 

observed. Contacts between plutons are generally sharp 

but between some bodies agmatitic zones are present. 

Metasedimentary and metavolcanic rocks enclosed by 

plutons of granitic to gabbroic composition underlie 

about fifteen percent of the combined roadless areas and 

occur mostly as roof pendants along the North Fork of 

the Middle Fork of the Tule River and as small septa 

along the margins of plutons. Rock types in the pendant 

include thinly bedded quartzite and petite, pod.iform 

limestone, minor basaltic dikes, and, in the eastern 

portion, abundant porphyritic volcanic rocks that have 

been regionally metamorphosed to mid- to uppergreenschist facies. Subsequently, thermal metamor-

'WiLh contributions from David Leach. Michool Sawlan. and Suzanne maglik. USG . 

phism produced hornfels-grade assemblages adjacent to 

granitic and granodioritic plutons, and slightly higher 

grade assemblages near dioritic and gabbroic plutons. 

The metamorphic rocks are classified as a portion of the 

Tule River pendant within the Upper Triassic to Middle 

Jurassic (Saleeby and others, 1978). 

MINERAL RESOURCES 

Mineralized skarns in the Sierra Nevada province are 

common in regions characterized by roof pendants and 

septa of metasedimentary and metavolcanic rocks 

within the surrounding batholithic terrains. Contact 

metasomatic deposits of tungsten, lead-zinc-silver, and 

occasionally copper are found throughout the Sierra 

Nevada The Mineral King district, approximately 15 

mi northeast of Moses Mountain, contains complex sulfides of copper, lead, zinc, and silver within metasedimentary host rocks. The Pine Tree mine, 8 mi to the 

east of Moses Mountain and within the boundaries of 

the adjacent Golden Trout Wilderness, is presently producing minor amounts of scheelite from the Mineral 

King roof pendant. Additionally, minor scheelite was 

reportedly taken from the Royal Tungsten, Martin, and 

Good Hope mines, located within contact zones northwest of Dennison Peak Roadless Area 

One mine and 3 prospects, the Powell mine, the King 

Solomon prospect, and the Helen-Joyce prospects, are 

located within the eastern portion of the southern part 

of Moses Roadless Area (Lipton, 1983; Goldfarb and 

others, 1983). Very little production has been recorded 

301 
from these occurrences. Most of the mineralization is 

represented by silver, copper, and zinc minerals, and occurs in skarn-type deposits within the metasedimentary 

rocks in quartz veins or epidote-rich zones within calcareous layers adjacent to granocl.iorite. The chief 

gangue minerals are garnet, epidote, hornblende, actinolite, feldspar, calcite, and quartz. 

The mineralized area is characterized geochemically 

by anomalously high amounts of silver, zinc, boron, and 

bismuth in stream sediment and associated nonmagnetic, heavy-mineral concentrate samples. Although 

chalcopyrite is reported from some of the known mineral occurrences within the area, the sediment and concentrate samples showed relatively little copper enrichment. On the basis of the abundance of favorable host 

lithology, geochemical reconnaissance work, and the examination of known prospects, part of the southeastern 

Moses Roadless Area has substantiated resource potential for small zinc-silver-lead(?) skarn deposits, and to a 

lesser extent for small copper and iron skarn deposits. 

Two other localities within Moses and Dennison Peak 

Roadless Areas have probable mineral-resource potential. Both localities appear to be underlain by intrusive 

rocks, but small septa of metamorphic rocks could be 

present, hidden by the thick soil cover. The anomalous 

geochemical signatures of the sediment samples from 

these two localities are quite similar to those indicative 

of base-metal and tungsten-bearing skarns from elsewhere in the Sierra Nevada 

One of the two areas is found between Backbone and 

Pine Creeks within the northern part of Moses Roadless 

Area Nonmagnetic, heavy-mineral-concentrate samples 

are enriched in tungsten and bismuth. The concentrations of these elements at this locality are similar in 

magnitude to those surrounding the Pine Tree mine 

within the Little Kern River watershed, about 8 mi to 

the east (Leach and others, 1982). Minor scheelite along 

contacts between alaskite and small, unexposed metamorphic septa are likely in this part of the Moses Roadless Area 

A very strong geochemical anomaly is located around 

Kramer Creek, within the western part of Dennison 

Peak Roadless Area Stream-sediment and associated 

302 

heavy-mineral-concentrate samples are enriched in 

silver, arsenic, gold, lead, and boron. This area is 

underlain by a mafic granocl.iorite but lies within 2 mi of 

the Good Hope mine, characterized by metasomatic 

scheelite. Based on the geochemical evidence, this area 

has probable mineral-resource potential for small basemetal-bearing skarn deposits. 

SUGGESTIONS FOR FURTHER STUDIES 

Future studies of these roadless areas should emphasize detailed mapping of the metamorphic lithologies, to better define the calcareous host rocks favorable 

for mineralization related to contact metasomatism. 

The thick soil cover, however, may restrict such mapping in many places. Within the two areas of probable 

mineral-resource potential, detailed soil geochemistry 

surveys might aid in the location of the source of the 

stream-sediment anomalies. It must be noted that all 

production from the mines and prospects within and adjacent to Moses Roadless Area and Dennison Peak 

Roadless Area has been quite minor. Hence, future 

mineral discoveries within these wildernesses are expected to be similar. 

REFERENCES 

Goldfarb. R. J., Leach, D. L., Sawlan, M. G .. and Lipton, D. A .. 1983. 

Mineral resource potential map of the Moses and Dennison Peak 

Roadless Areas, California; U.S. Geological Survey Miscellaneous Field Studies Map MF- 1651- A. 

Leach, D. L .. Goldfarb, R. J .. and Domenico, J. A .. 1982, Geochemical 

map for anomalous nonmagnetic, heavy-mine1·al concentrates 

from the Golden Trout Wilderness, California: U.S. Geological 

Survey Miscellaneous Field Studies Map MF- 1231 - B, scale 

1:48,000. 

Lipton, D. A., 1983, Mineral resources of the Moses ( o. 5203) and 

Dennison Peak ( o. 5202) RARE II areas, Tulare County. California: U.S. Bureau of Mines Open-File Report. 

Saleeby, J. B., Goodwin. S. E., Sharp, W. D .. and Busby, C. J., 1978, 

Early Mesozoic paleotectonic reconstruction of the southern 

Sierra Nevada region; in Mesozoic Paleogeography of the Western United States: Society of Economic Paleontology and Mineralogy. Pacific Section, p. 311 - 336. 
MOUNT EDDY AND CASTLE CRAGS ROADLESS AREAS, CALIFORNIA 

By jOCELY A. PETERSO , 1 U.S. GEOLOGICAL S R EY, and 

DAVID K. DE TO , JR., U.S. B REA OF Mr E 

SUMMARY 

A mineral survey of the Mount Eddy and Castle Crags Roadless Areas, 

California, conducted in 1981 and 1982 shows probable mineral-resource potential for chromite and gold on the basis of local occurrences of these minerals and 

favorable geologic environment within the roadless areas. There is also 

geochemical evidence for mineralization, but surface evidence is scant. 

Although asbestos and copper minerals are present in the areas and the geologic 

environment is favorable for nickel and platinum-group metals, no resource 

potential for these was identified. No energy resources were identified in the 

study of the roadless areas. 

CHARACTER AND SETTING 

The Mount Eddy and Castle Crags Roadless Areas 

occupy 15 sq mi and 5 sq mi, respectively, in Shasta, 

Siskiyou, and Trinity Counties, California, approximately 8 mi west of the towns of Mount Shasta City 

and Dunsmiur. The areas are located in rugged terrane 

in the easternmost part of the Klamath Mountains 

where altitudes range from about 2500 ft in the southem Castle Crags Roadless Area to 9025 ft atop Mount 

Eddy. Interstate 5 passes east of the areas and secondary roads and trails provide access. 

The Mount Eddy Roadless Area and the southern 

Castle Crags Roadless Area are underlain by ultramafic 

rocks of the Trinity ultramafic sheet, the largest such 

mass in the United States. This ultramafic body is composed primarily of harzburgite, dunite, and plagioclase 

lherzolite. Dunite occurs as small pods and large tabular 

masses. The ultramafic mass has been intruded by large 

bodies of gabbro, one of which underlies most of the 

northern Castle Crags Roadless Area, and smaller 

stocks and plugs of hornblende diorite, prevalent in the 

northern portion of the Mount Eddy Roadless Area 

(Quick, 1981; Throckmorton, 1978). Between and extending east of the two parts of the Castle Crags Roadless Area is a large granitic pluton which has formed the 

striking topography of Castle Crags (Vennum, 1971). 

Plugs and dikes related to the Castle Crags pluton intrude the ultramafic rocks and gabbro in the northern 

'With contributions from Mary E. Caress. USG . and James M. Spear. USBM. 

part of the Castle Crags Roadless Area All of the units 

described are considered to be of Paleozoic age although 

exact times of formation are still unknown. The 

ultramafic rocks have undergone serpentinization which 

becomes more prevalent in the southern part of the 

mapped area Quartz veining is common in gabbro and 

hornblende diorite. Faulting within the area strikes 

west to northwest and is usually characterized by a 

serpentinized shear zone several feet wide. Asbestos 

fibers have developed in some of the shear zones. 

The Mount Eddy Roadless Area underwent glaciation 

during the Pleistocene Epoch and remnants of glacial 

material can be found at altitudes above about 4500 ft. 

Additionally, spectacular glacial topography was developed around Mount Eddy leaving razor sharp ridges, 

broad U-shaped valleys, and numerous cirque lakes or 

tams. Snow remains at the higher altitudes throughout 

most of the year. 

MINERAL RESOURCES 

Ultramafic rocks such as the ones found in the Mount 

Eddy and Castle Crags Roadless Areas may contain a 

variety of mineral commodities including chromium, 

nickel, cobalt, platinum-group elements, and asbestos. 

Sometimes gold is found in quartz veins coursing 

through ultramafic rocks. Many of these elements may 

also be found in lateritic soil overlying ultramafic rocks. 

Of these commodities chromium (in the mineral chromite) and asbestos have been found in sufficient 

303 
41 ° 

20' 

41 ° 

15' 

4 1° 

10 ' 

304 

122°30' 

C.nu a Mou•lta" Cr 

MAP LOCATION 

0 

122°25' 

PROSPECT 

MINE 

MILES 

122°20' 

Black Bu t 

Castle Crags 

Roadless Area 

Approximate 

roadless boundary 

= I ' 

10 

EXPLANATION 

122°15' 

M 1tH11 Sha " 

) 

/ 

'> n 

/ 

D Geologic terrane with pro bable 

mineral-resource potential 

Alluvium , talus, and glacial debris 

Cr Chromium 

Au Gold Horn blende diorite 

~ Mine or deposit Gabbro 

X Mineral occu rrence Ultramafic rocks 

Contact 

Figure 88.-Mount Eddy and Castle Crags Roadless Areas, California 
amounts to mine in localities within 5 mi of the roadless 

areas. 

One known chromite mine, the Johnson mine, occurs 

within the Mount Eddy Roadless Area, southeast of 

Mount Eddy. It produced an unrecorded amount of 

chromium during the 1940's from a dunite body in a 

shear zone of serpentinized peridotite. Potential exists 

for occurrence of chromite resources in the shear zone. A 

grab sample from the remaining stockpile assayed 39.8 

percent Cr20 3• The Ratero prospect, northeast of Mount 

Eddy, contains a chromite pod 16 in. wide exposed for 

40 ft in serpentinized peridotite. A sample assayed 38.1 

percent Cr20 3 and it is estimated that the pod contains 

260 tons of demonstrated chromite resources. The Bagley mine about 2 mi north of the Mount Eddy Roadless 

Area was estimated in 1943 to contain possibly 2500 

tons of ore. The deposits occur as banded chromite and 

dunite or disseminated ore. It is not likely that large 

surface deposits will be found because the area has been 

well prospected. Areas of chromite-bearing dunite occur 

in the Mount Eddy Roadless Area, particularly in the 

southern part; however, these areas are small and the 

occurrences low grade. The largest of these, that contain 

visible chromite, is south-southwest of Mount Eddy. All 

areas of dunite, however, are considered to have probable potential for chromium because no subsurface exploration has taken place. 

Surface exploration for asbestos has also been 

thorough. Like the chromite deposits, the known 

asbestos deposits are small. The usual asbestos mineral 

is chrysotile, a form of serpentine, but one property 

south of the Castle Crags Roadless Area contains the 

amphibole asbestos anthophyllite. The asbestos fibers 

range from brittle to flexible and fiber lengths are 1/16 

in. to 3/4 in. Some deposits contain slip-fiber asbestos 

while others contain cross-fiber asbestos. Within the 

Mount Eddy Roadless Area and the southern part of 

the Castle Crags Roadless Area asbestos minerals are 

frequently seen in talus debris and occasionally in shear 

zones as small cross-fiber veinlets as much as 1 in. wide 

and 2 ft long. No potential for asbestos resources was 

identified in areas having asbestos occurrences. 

Geochemical data indicate no anomalous occurrences 

of the commodities mentioned previously, except for 

gold (Peterson, 1983; D. K. Denton, Jr., unpub. data, 

1983). Stream-sediment data for barium, boron, and 

mercury indicate the imprint of hydrothermal activity 

on the gabbro and hornblende diorite units. This 

hydrothermal event may have also been responsible for 

forming quartz veins. A small amount of gold was found 

in two of the stream-sediment concentrate samples. 

This gold was probably derived from the numerous 

quartz veins cutting the gabbro, hornblende diorite, and 

to a lesser extent ultramafic rocks and an analysis of a 

sample from one of the veins showed 0.271 oz gold/ton. 

This sample was collected down slope from the Half 

Century No. 1 prospect, northwest of Dobkins Lake, 

where the quartz occurs as discontinuous, irregular, 

vuggy iron-stained lenses averaging 5 in. wide. The 

quartz contained small amounts of chalcopyrite, bornite, and malachite, and spectrographic analysis of a 

quartz sample indicated 700 parts per million copper. 

Another known gold prospect occurs in a quartz vein 2 

mi southwest of the northern part of the Castle Crags 

Roadless Area 

There may be low-grade nickel mineralization in the 

northern part of the Mount Eddy Roadless Area based 

on data from dunite samples. As the values are not particularly high (3000 parts per million), however, they 

may represent background variation. Lacking the presence of nickel-bearing sulfide minerals, a potential for 

nickel was not identified. Analyses by Quick (1981) of 

olivine samples show that nickel oxide is present in 

olivine structures; olivine is a common mineral in the 

dunite in the Mount Eddy Roadless Area Nickelbearing laterite occurrences bordering the Castle Crags 

Roadless Area are too low grade to constitute a 

resource. 

SUGGESTIONS FOR FURTHER STUDY 

The area around and including the roadless areas has 

been heavily prospected in the past and further exploration offers little promise of finding new surficial 

deposits. If geophysical methods to detect buried chromite deposits become available, further exploration for 

chrornite may be warranted. 

REFERENCES 

Peterson, J. A., Caress, M. E., and Quick, J. E., 1983, Geochemical 

analyses of rock and strearn·sediment samples from Castle Crags 

and Mount Eddy Roadless Areas. Shasta, Siskiyou, and Trinity 

Counties, California: U.S. Geological Survey Open·File Report 

83-13. 14 p. 

Peterson. J. A., Caress, M. E., Spear J. M., and Denton, D. K., Jr., 

19 3, Mineral resource potential map of the Mount Eddy and 

Castle Crags Roadless Areas, Shasta, Siskiyou, and Trinity 

Counties, California: U.S. Geological Survey Miscellaneous Field 

Studies Map MF- 1529-B, scale 1:62,500. 

Quick, J. E .. 1981, Part !- Petrology and petrogenesis of the Trinity 

Peridotite. northern California: Pasadena, California Institute of 

Tecnology, Ph. D. thesis, 288 p. 

Throckmorton, M. L., 1978, Petrology of the Castle Lake peridotitegabbro mass. eastern Klamath Mountains, California: Santa Barbara. University of California, M.A. thesis, 109 p. 

Vennum, W. R .. 1971. Petrology of the Castle Crags pluton, Shasta 

and Siskiyou Counties, California: Stanford, California. Stanford 

University, Ph. D. thesis, 140 p. 

305 
306 

D 

Fe 

w 

X 

YOSEMITE NATIONAL PARK 

Approximate 

roadless boundary~ ~ed fork _.,...,.- ,_..,., ___ _,~,- _.,"";A"" 

0 

,-

05242-l--

I 

MAP L::lCATION 

M ILES 

EXPLANATION 

Geologic terrane with probable 

mineral-resource potential 

Iron 

Tungsten 

Mineral occurrence 

5 

Granitic rocks (Mesozoic ) 

Metasedimentary rocks 

(Mesozoic and Paleozoic) 

Metavolcanic rocks 

(Mesozoic and Paleozoic) 

X' Mine 

Contact 

Figure 89.- Mount Raymond Roadless Area, California 
MOUNT RAYMOND ROADLESS AREA, CALIFORNIA 

By . KI G H BER , 1 U.S. GEOLOG ICAL S R EY, and 

DO ALD 0. CAPSTI K, U .. B REA OF MINES 

SUMMARY 

A mineral survey of the Mount Raymond Roadless Area in the central Sierra 

Nevada, California, was conducted by the USGS and USBM during 1980-82. 

Areas of probable resource potential for tungsten associated with iron-bearing 

rocks adjacent to the roadless area extend into the eastern and southwestern 

parts of the roadless area No energy resource potential was identified in the 

study. 

CHARACTER AND SETTING 

The Mount Raymond Roadless Area is in the central 

Sierra Nevada adjacent to the south boundary of Yosemite National Park. The area is small, but rugged; it 

encompasses about 10.5 sq mi and has a relief of 4400 ft, 

culminating at 9165 ft at Iron Mountain. Much of the 

area at lower altitudes is forested, but the higher parts 

support only scattered growth because of precipitous 

slopes or other adverse conditions. The area is accessible by a road from Fish Camp that roughly parallels 

the roadless area boundary on the south and east. Bedrock is well exposed on ridges and in glacial cirques, but 

most of the forested area is covered by talus and slopewash and locally by glacial moraine. 

The Sierra Nevada is a large block of the Earth's 

crust that has been uplifted and tilted westward by an 

extensive system of high-angle faults on its east side. 

Most of the central Sierra is composed of Mesozoic 

granitic plutons that constitute the Sierra Nevada 

batholith. The batholith intruded Paleozoic and 

Mesozoic strata, remnants of which are preserved as 

roof pendants, septa, and inclusions within the 

batholith. Granitic rocks underlie more than 80 percent 

of the Mount Raymond Roadless Area. Metamorphic 

rocks are largely confined to the southwest comer and 

the eastern margin of the area, including a southeastern 

prong. 

'With conLribuLions from Maurice A. Chaffee and Andrew Griscom. USGS. and t.ephen R. 

lv rson. U BM. 

MINERAL RESOURCES 

The Mount Raymond Roadless Area and vicinity 

have two types of metallic mineral occurrences. One 

consists of silver-lead-zinc minerals, and the other of 

various iron minerals. Some of the iron-rich mineral occurrences apparently also include tungsten minerals. 

Both types of occurrences have a history of prospecting 

dating back to at least the early 1880's. 

Silver, lead, and zinc occur as sulfide minerals in a 

small complex of alaskite dikes near Raymond Mountain. The known occurrences are discontinuous within 

the dikes, and are no more than 50 ft in maximum 

dimension. The only significant surface occurrence was 

developed as the Star mine in 1888-1889. After three 

unsuccessful attempts to operate profitably, the mine 

has remained idle since about 1908. Records of concentrates shipped or metal produced are not available, but 

production is not thought to have been significant. 

Although the presence of sulfide mineralization in the 

Star mine area suggests the area has a substantiated 

resource potential, this classification would be possible 

only if significant additional subsurface mineral zones 

were likely. Due to their character, the surface occurrences do not lend themselves to projection at depth. 

Occurrences of iron-rich minerals, particularly magnetite and hematite, are scattered southwest, south, and 

east of Raymond Mountain. These deposits were prospected during the same period as were the silver-leadzinc occurrences. Although several patents were 

granted on these claims during the early 1900's, little 

has been done to develop them; none of the patented 

claims are within the roadless area The iron-bearing 

307 
zones occur in highly altered metasedimentary rocks of 

both quartzose and calc-silicate (tactite) types. These 

occurrences are widespread, but are spotty, variable in 

size, and have indistinct boundaries. The altered rock is 

oxidized and disaggregated and it is difficult to determine from natural exposures what metallic minerals 

other than magnetite and hematite might be present. 

Panned concentrates of stream-sediment samples from 

streams draining these areas of altered metasedimentary rock commonly contain anomalous amounts of an 

element suite (boron, bismuth, molybdenum, tin, tungsten) considered to characterize tungsten mineralization. This suggests that at least some of the iron-rich 

rocks could contain possibly significant amounts of 

tungsten (Huber and Chaffee, 1983). All of the area 

underlain by metasedimentary rock is shown on the 

map as geologic terrane with probable resource potential for iron and tungsten because some of these rocks 

are known to contain iron-bearing zones; the ironbearing zones have not been specifically delineated and 

much of the metasedimentary terrane probably has no 

resource potential. 

SUGGESTIONS FOR FURTHER STUDY 

The geochemical survey was a limited reconnaissance. 

30 

Nevertheless, anomalous amounts of tungsten and 

tungsten-related elements in stream-sediment concentrates from streams draining areas of altered metasedimentary rock indicate the presence of tungsten 

mineralization, although no specific sources have been 

identified. A more detailed geochemical survey might 

help to better delineate possible source areas for the 

anomalous tungsten. 

REFERENCES 

Griscom, Andrew, and Huber, . K., 1983, Aeromagnetic map of the 

Mount Raymond Roadless Area. central Sierra evada. California: U.S. Geological Survey Miscellaneous Field tudies Map 

MF - 1417- D, scale 1:62,500. 

Huber, . K., 1982, Geologic map of the Mount Raymond Roadless 

Area. central Sierra Nevada, California: U .. Geological Survey 

Miscellaneous Field tudies Map MF-1417-A. scale 1:62,500. 

Huber, . K., and Chaffee, M. A., 1983, Geochemical maps of the 

Mount Raymond Roadless Area, central Sierra Nevada. California: U.S. Geological Survey Miscellaneous Field Studies Map 

MF- 1417-C. 

Huber, . K.. Chaffee. M. A., Griscom, Andrew, Capstick, D. 0., and 

I ver on. S. R., 1983. Mineral resource potential map of the 

Mount Raymond Roadless Area, central Sierra evada, California: U.S. Geological Survey Miscellaneous Field Studies Map 

MF - 1417- B, scale 1:62,500. 
MOUNT SHASTA WILDERNESS STUDY AREA, CALIFORNIA 

By R OBERT L. CHRISTIA E I 

' .S. GE L GI AL R EY and 

ER E T T. T UCH EK , .S. B REA F MI E 

SUMMARY 

The Mount Shasta Wilderness study area was surveyed in 1975. It lies wholly 

on the slopes and summit area of Mount Shasta and consists almost entirely of 

the products of geologically young volcanism. Small deposits of volcanic cinders 

and pumice are present. The volcanic system of Mount Shasta is judged to have 

probable resource potential for geothermal energy but that potential is least 

within the wilderness study area boundaries. Because any geothermal energy 

resource beneath the volcano would lie at considerable depths, exploration or 

development would be most likely at lower altitudes on the gentler slopes outside the study area 

CHARACTER AND SETTING 

Mount Shasta is the largest high conical volcano of 

the Cascade Range. The volcano rises to 14,162 ft, far 

above its 3000-ft base and the generally 5000-8000-ft 

mountains of the region, making it the dominant natural feature of northern California The communities of 

Weed, Mount Shasta, and McCloud lie at the base of the 

mountain, and Interstate Highway 5 and U.S. Highway 

97 flank it on the west and north. Other state highways 

and unpaved roads provide access to the wilderness 

study area from all sides. The study area occupies mainly the upper slopes of the mountain near and above 

timberline, which is generally at about 9500 ft; on the 

northwest, the study area extends to near the level of 

the Southern Pacific Railroad at about 5000 ft. 

The volcanic edifice of Mount Shasta grew by the successive eruptive emplacements of hundreds of lava 

flows and by associated mudflows and other fragmental 

deposits in at least four, and probably more, major conebuilding episodes. Growth of the volcano has been 

geologically recent, having occurred within about the 

past 500,000 years; most of the present edifice has 

grown since about 250,000 years ago. The two youngest 

major cone-building episodes occurred within the past 

10,000 years. During those last 10,000 years, significant 

eruptions have xcurred on the average of at least once 

every 800 years; during the past 4500 years they have 

1

With contributions from Frank J. Kleinhampl and Richard J . Blakely. USC . and Fredrick 

L. J ohnson and Mnrt.in D. Conyac. USBM. 

occurred about once every 600 yrs (Miller, 1980). The 

youngest known eruptions probably occurred during 

the latter half of the 18th century. Two areas of small 

sulfurous fumaroles (steam vents) occur near the summit of the volcano, and one of them includes a small acid 

hot spring. 

Throughout its evolution, during times between the 

major cone-building episodes, Mount Shasta has 

erupted dacites, lavas whose compositions are commonly thought to reflect the residence of magmatic 

liquids at relatively high levels in the Earth's crust for 

considerable periods of time. Intermittent volcanic 

eruptions during the generally erosional periods between major cone-building episodes also produced 

several small cinder cones and moderately extensive 

deposits of pumice. 

An aerial survey of the Earth's magnetic field in the 

area of Mount Shasta indicates a significant linear 

structural control for some eruptive vents of the 

volcano along a north-trending zone through the summit. Interpretation of the magnetic-field variations also 

indicates that a zone beneath the main summit area of 

the volcano induces a smaller field intensity than would 

be expected if the entire volcanic edifice were unifonnly 

magnetized (Blakely and Christiansen, 1978). 

MINERAL RESOURCES 

Metallic mineral resources are commonly found to be 

associated with the formerly deeply buried parts of old 

volcanic systems that may once have been similar to 

309 
310 

42° 

30' 

D 

0 

M ILES 

EXPLANATION 

Geologic terrane with probable 

geothermal potential 

LZZJ 

D 

D 

MAP LOC ATION 

20 

Lavas of Mount Shasta 

Cenozoic) 

(Upper 

Fragmental deposits of Mount 

Shasta (Upper Cenozoic) 

Other Cascades lavas (Upper 

Cenozoic) 

Older rocks (Pre-Tertiary) 

Contact 

Figure 90.- Mount Shasta Wilderness study area, California 
Mount Shasta Such metallic deposits, however, generally are accessible to development only after deep erosion has removed much or all of the surficial volcanic 

edifice, exposing rocks of types that would now lie many 

thousands of feet below the surface of Mount Shasta 

Young volcanoes of this type, even where they have 

been altered by hydrothermal activity (the hot waters 

and volcanic gases that can transport metallic constituents in solution), are typically barren of significant 

mineral deposits. Small areas of intense but localized 

hydrothermal alteration have been recognized near the 

original central vents of the four recognized cone 

segments of Mount Shasta but virtually nowhere else. 

Metallic trace elements are nowhere found to be significantly above background values (Christiansen and 

others, 1977). Parts of the wilderness study area have 

been prospected previously for mineral deposits, and 

three unworked prospects were located in the area No 

resources were found. 

Although there are several cinder cones on the lower 

flanks of the volcano, very few of them occur within the 

wilderness study area Minor deposits of cinders and 

moderately extensive pumice do occur, but they lie on 

steep slopes and are accessible only with difficulty while 

more extensive deposits are readily accessible nearby. 

A probable resource potential is judged to exist 

within the study area for geothermal energy. The 

geologic elements necessary for commercial development of geothermal resources are a source of heat within 

the Earth, water to provide a medium for the transferral 

of heat from its source to a point of extraction, and an 

aquifer or some suitable structure to control the appropriate subsurface movement of this hydrothermal 

fluid. Several factors suggest that a suitable geothermal 

heat source exists beneath Mount Shasta: volcanic activity has been intermittent for about 500,000 years, the 

most recent activity has been within about the past 200 

years, magma-filled chambers probably have formed 

repeatedly at high crustal levels beneath the volcano to 

produce its dacitic lavas, fumaroles remain active near 

the summit of the volcano, and the anomalously low 

magnetic intensity of the summit zone may reflect a 

high temperature at shallow depth beneath that part of 

the volcano (Blakely and Christiansen, 1978). 

Despite the likely presence of a heat source, several 

factors are unfavorable for the occurrence of geothermal 

energy at Mount Shasta. The volcanic edifice itself consists mainly of highly fractured or porous materials that 

generally retain ground water only poorly, and meltwater from the extensive winter snowfields of the mountain percolate readily downward. Consequently, few permanent streams drain the slopes of the volcano, and 

only parts of two of them, Mud Creek and Ash Creek on 

the south and east flanks, maintain substantial yearround flows. Thus, the shallow parts of the volcanic 

system are readily flushed by downward-percolating 

cold waters. There are no hot springs other than the 

small one near the summit, and no other significant 

manifestations of hot water at shallow depths are 

known in or immediately around the volcano. Thus, if a 

hidden geothermal system exists, it would not likely be 

high within the volcanic edifice itself but rather within 

the Earth's crust beneath it. It could be investigated 

only by deep drilling, and such drilling would be difficult or impractical from the high altitudes or the steep 

and unstable slopes typical of the parts of the mountain 

where most of the wilderness study area lies. 

SUGGESTIONS FOR FURTHER STUDIES 

Further studies within the Mount Shasta Wilderness 

study area are unlikely to reveal significant new information on its mineral-resource potential. The only important potential judged to exist- for geothermal 

energy-probably is least within the wilderness study 

area The potential for geothermal resources, both 

within the study area and in the larger area around the 

lower flanks of Mount Shasta, probably can best be 

evaluated by further work in the surrounding area 

Ultimately, only drilling can test the geothermal 

resource potential definitively, but careful chemical and 

isotopic studies of surface and subsurface waters 

around the base of the volcano might shed additional 

light on the possibility that hydrothermal waters circulate actively beneath and around the volcano. 

REFERENCES 

Blakely, R. J .. and Christiansen. R. L., 1978, The magnetization of 

Mount Shasta and implications for virtual geomagnetic dipoles 

determined from seamounts: Journal of Geophysical Research, 

v.83,p.5971 -5978. 

Christiansen, R. L., Kleinhampl, F. W .. Blakely, R. J., Tuchek, E. T., 

Johnson, F. L., and Conyac. M. D .. 1977, Resource appraisal of 

the Mount Shasta Wilderness study area Siskiyou County, 

California: U.S. Geological Survey Open-File Report 77- 250, 

53 p. 

Miller. C. D .. 1980, Potential hazards from future eruptions in the 

vicinity of Mount Shasta volcano, northern California: U.S. 

Geological Survey Bulletin 1503, 43 p. 

311 
312 

0 5 

MILES 

EXPLANATION 

-

Geologic terrane with substantiated 

mineral-resource potential 

D Geologic terrane with probable 

mineral-resource potential 

Cr Chromium 

Au Gold 

Ag Silver 

~ Mine or deposit 

'X' Mine 

Volcanic rocks (Tertiary) 

Granitic rocks 

(Cretaceous and Jurassic) 

Serpentinite (Mesozoic) 

Metamorphic rocks 

(Mesozoic and Paleozoic) 

--- Contact 

Fault 

Figure 91.- orth Fork of the American River Wilderness study area, California 
NORTH FORK OF THE 

AMERICAN RIVER WILDERNESS STUDY AREA, CALIFORNIA 

By D AVIDS. H ARWOOD, U . . GEOLOG I AL SURVEY and , 

FRANC IS E. FEDERSPIEL, .S . B REA OF M INE· 

SUMMARY 

Mineral-resource surveys of the North Fork of the American River Wilderness 

study area, conducted between 1975 and 1979, have identified a zone of substantiated resource potential for gold and silver within the western 6 mi of the area 

between the Rawhide and Pioneer mines. Zones of probable gold and silver 

potential occur in the eastern part of the area between the Wubbena and La 

Trinidad mines and locally around the Marrs mine. A zone with probable 

chromium potential occurs in the serpentinite belt along the western border of 

the area. o energy resources were identified in this study. 

CHARACTER AND SETTING 

The orth Fork of the American River Wilderness 

study area encompasses about 77 sq mi along one of the 

major drainages on the west slope of the Sierra Nevada 

located generally between Donner Pass (alt. 7088 ft) and 

Sacramento, California. From an altitude of 5200 ft at 

its eastern boundary, the study area extends westward 

24 mi down the river canyon to an altitude of 2000 ft 

just south of the settlements of Dutch Flat and Alta, 

early gold mining camps of the Mother Lode district. 

The western two thirds of the area is confined to the extremely steep, brush-covered river canyon, where local 

relief approaches 3000 ft. The eastern third of the area 

extends north of the canyon into less steep, relatively 

open glaciated terrane that provides spectacular vistas 

of sharp peaks along the Sierran crest, about 4 mi to the 

east. Interstate Highway 80 generally parallels the 

orth Fork of the American River and passes within a 

few miles of the northern boundary of the study area at 

several points between Alta and Soda Springs. 

Mineral-resource surveys were conducted in the area 

intermittently between 1975 and 1979, and a detailed 

evaluation of the mineral-resource potential has been 

published by Harwood and others (1982). 

The Sierra Nevada is a north-trending uplifted and 

westward-tilted range bounded on the east by an active 

fault system that has been the focus of several large 

earthquakes during historic time. However, this relatively young period of faulting and uplift is only the 

most recent phase of deformation in a complex geologic 

history that has shaped the range over the past several 

hundred million years. One of the most significant 

events in its geologic history, with respect to the 

mineral-resource potential of the Sierra Nevada, was the 

protracted intrusion of large masses of granitic rock 

into a variety of older sedimentary and volcanic rocks 

that form the framework of the range. The granite metamorphosed the country rocks and hydrothermal solutions locally deposited gold-bearing quartz veins. Following intrusion of the granitic masses, while the range 

underwent uplift and erosion, ancient rivers concentrated gold from widely distributed quartz veins into 

channelized placer deposits. Vast amounts of volcanic 

rocks, erupted from vents along the eastern range-front 

fault system, then blanketed the western slope of the 

Sierra Nevada and covered the ancient placer deposits. 

As uplift continued, modem rivers cut through the 

volcanic cover, exhumed the buried placer deposits, and 

further concentrated the gold from ancient placers into 

new channel gravels. 

After gold was discovered at Sutter's Mill on the 

South Fork of the American River in 1849, mining activity spread rapidly to all drainages on the west slope 

of the Sierra Nevada. Initial efforts of the forty-niners 

were concentrated on panning and sluicing the modem 

river gravels, but operations progressed rapidly to 

hydraulic mining of ancient placers, exposed high up on 

the canyon walls, and eventually to underground mining of lode deposits found primarily in gold-bearing 

quartz veins and the adjacent country rock. 

313 
MINERAL RESOURCES 

Because of its proximity to Sutter's Mill, it is not surprising that approximately 1100 lode and 900 placer 

claims and relocations have been filed in the North Fork 

of the American River Wilderness study area since 

1866. Most historic gold and silver lode production occurred in the western part of the area from the Rawhide, 

Black Hawk, and Southern Cross mines, which yielded 

31,000 troy oz of gold, 4000 troy oz of silver and 19,000 

lbs of copper. More than 85 percent of that production 

came from the Rawhide mine. In addition, the Pioneer 

mine, located just south of the proposed boundary of 

the study area, produced 50,000 troy oz of gold and 

9000 troy oz of silver between 1899 and 1922. 

These mines occur in a north-trending zone of altered 

rock pervasively cut by quartz veins. Based on past production and the geologic setting, these mines clearly 

define a zone of substantiated mineral-resource potential for gold and silver. It is estimated that 1.4 million 

tons of demonstrated lode resources averaging 0.04 to 

0.22 oz of gold per ton occur at and near the Rawhide, 

Black Hawk and Southern Cross mines and that an 

additional 6 million tons of gold resources may occur in 

a mineralized zone of substantiated gold and silver 

resource potential between the Rawhide and Pioneer 

mines. 

The Lost Emigrant, La Trinidad, and Wubbena mines 

in the eastern part of the study area have produced 

about 5000 troy oz of gold, 730 troy oz of silver, and 

480 lbs of copper since the 1850's. The Lost Emigrant 

mine has a demonstrated gold resource of 270,000 tons 

averaging about 0.27 troy oz of gold per ton and La 

Trinidad mine has a demonstrated gold resource of 

314 

150,000 tons averaging about 0.17 troy oz of gold per 

ton. Based on past production and geologic setting, the 

area between the Wubbena and La Trinidad mines is 

considered to have a probable gold resource potential. 

From bedrock and geochemical sampling, it is estimated that the area around the Marrs mine also has a 

probable gold resource potential. 

About 1000 short tons of chrome were produced from 

the serpentinite belt at the western end of the study 

area during World Wars I and II. Much of that production occurred at the surface of the serpentinite belt 

where the rock was deeply weathered and the chromebearing minerals had been naturally concentrated by 

the weathering process. From this we conclude that 

the serpentinite belt has a probable chrome resource 

potential. 

SUGGESTIONS FOR FURTHER STUDIES 

Clearly the hard work was done by the forty-niners 

and their followers who found and developed the 

deposits. Our studies have confirmed what they discovered, but more exploration work, especially at depth, is 

necessary to completely delineate gold deposits in the 

area. 

REFERENCES 

Harwood, D. S., Griscom, Andrew, Federspiel, F. E., Leszcykowsk:i, 

A. M .. and Spieker, F. A., 1982, Mineral resource potential map 

of the orth Fork of the American River Wilderness study area 

(RARE II no. 5-262). Placer County, California: U.S. Geological 

Survey Miscellaneous Field Studies Map M F - 1177 - C. scale 

1:62,500. 
NORTH FORK SMITH RIVER ROADLESS AREA 

CALIFORNIA AND OREGON ' 

By F L YD GRAY , .S. GEOLOGICAL RYEY, and 

MI HA EL H AMILTON, U.S. B REA OF MI E 

SUMMARY 

Geologic, geochemical, and geophysical investigations and a survey of mines 

and prospects were conducted in 1980-82 to evaluate the mineral-resource 

potential of the North Fork Smith River Roadless Area. The North Fork Smith 

River Roadless Area has probable and substantiated resource potential for 

nickel, chromium, copper, and mercury and approximately 2300 mining claims 

exist in or adjacent to the area The geologic terrane precludes the occurrence of 

fossil fuel resources. 

CHARACTER AND SETTING 

The North Fork Smith River Roadless Area in Del 

Norte County, California, and Josephine County, Oregon, is an oval-shaped area of approximately 63 sq mi 

within Six Rivers and Siskiyou National Forests. It extends from the ridge just west of the North Fork Smith 

River to Patrick Creek on the east and from the town of 

Gasquet, California, on the Middle Fork Smith River, 

north to the Wimer Road, an old stagecoach route running along the Oregon-California border that connected 

the coastal towns to inland areas. The roadless area can 

be easily accessed by the Gasquet Mountain road on the 

western side and by the Old Gasquet Toll Road-Patrick 

Creek road on the east. Both of the roads intersect with 

U.S. Highway 199 near Gasquet, California, the Redwood Highway. The roadless area includes rugged, 

highly dissected plateaus separated by the North Fork 

Smith River and its tributaries. Although annual rainfall in the area is greater than 150 in., vegetation (mainly Douglas fir, sugar pine, and manzanita) is sparse. 

The roadless area is underlain predominantly by 

ultramafic rock, part of an approximately 310 sq mi 

area of deep oceanic mantle rocks occurring in southwestern Oregon and northern California called the Josephine Peridotite. The minimum age of the Josephine 

Peridotite is 157 million years. 

All the components of an ophiolite sequence are present, however, faulting between units precludes any estimate of total thickness. The sequence of major components from lowermost to uppermost is peridotite, 

ultramafic cumulates, layered cumulate gabbro, and 

massive gabbro. Each component is briefly described to 

aid in the interpretation of the mineral-resource 

potential. 

The Josephine Peridotite, a harzburgite-dunite tectonite mass, is the lowermost unit exposed and forms 

the base of an essentially shallow dipping sheet of faulttransported material. Cumulus ultramafic and gabbroic 

rocks are present in a number of localities near the 

eastern edge of the roadless area. A massive serpentinite shear zone everywhere marks the contact between 

these cumulate rocks and the tectonite peridotite. 

Dunite, a predominantly olivine-rich rock containing 

podiform masses of chromite ranging in length from 

several inches to tens of feet, may be found in both the 

tectonite and cumulate ultramafic rock units. Most of 

the chromite mines in the North Fork Smith River 

Roadless Area are located in and adjacent to the contact 

zone between the peridotite tectonite and cumulate 

ultramafic rocks. illtramafic cumulates are overlain by 

layered cumulate gabbro which grades upward into a 

massive gabbro unit characterized by abrupt compositional and textural variations, intrusive breccias, and 

local diabase dikes. Minor volcanic rocks and associated 

diabase dikes crop out in the northeastern portion of the 

roadless area and are considered part of the Josephine 

Peridotite. Two separate intrusive events of possible 

Cretaceous to Tertiary age are indicated in the roadless 

area; the younger, a silicic event, is the most pervasive 

and is accompanied by widespread hydrothermal activity that penetrated the peridotite along shears and fractures. Weathering in tropical to subtropical conditions 

created soil horizons on exposed peridotite during a prcr 

tracted period in Eocene to Pliocene time. 

315 
316 

42° 

00' 

41 ° 

55' 

vHF CO 

LlFl H 

c: 

Q. 

MAP LOCATION 

124°00' 123°55' 

0 

MILES 

5 

123°50' 

~ ~05707 

'4( Approximate 

roadless 

boundary 

Cr 

n lf----- ~ f~frl k 

\\ ~ Cr K 

EXPLANATION 

- Geologic terrane with substantiated 

mineral-resource potential for indicated 

commodity and probable mineral-resource 

potential for mercury 

Geologic terrane with substantiated 

mineral-resource potential 

Geologic terrane with probable 

'-----' mineral-resource potential for mercury 

Cr Chromium Hg Mercury 

Cu Copper Ni Nickel 

~ Mine or deposit 

'X' Mine 

~ Young intrusive rocks (Tertiary 

to Cretaceous) 

Dothan Formation (Cretaceous 

and Jurassic) 

D Josephine Peridoite--ophiolitic rocks 

Uurassic or older) 

Contact 

Fault 

~ Thrust fault--Sawteeth on upper plate 

Figure 92.-North Fork Smith River Road.Jess Area. California and Oregon. 
The roadless area was studied for its mineral-resource 

potential in 1979-82 and the results were published by 

Gray and others (1983a, b), Page and others (1983), and 

Griscom (1983). Stream-sediment and whole-rock 

samples were collected and analyzed from the roadless 

area Mining claims and prospects were sampled and 

evaluated. An areomagnetic survey was flown and compiled in 1979 as part of a larger survey of the entire 

Josephine Peridotite in Northern California 

MINERAL RESOURCES 

The earliest prospecting and mining in the North 

Fork Smith River Roadless Area began in 1851. Chromite and copper were discovered at approximately the 

same period in 1853 (Maxson, 1933) and quicksilver 

deposits were discovered north of Diamond Creek in the 

1850's. Chromite was, by far, the most actively mined 

resource with domestic markets stimulated greatly by 

World Wars I and II. Currently nickel-laterite soils are 

being explored as a resource in and adjacent to the roadless area 

The most significant deposits in the roadless area are 

lateritic soils, developed on peridotite, that contain 

nickel, iron, chrome, and cobalt. Fresh or partly serpentinized peridotite contains approximately 1500-2000 

parts per million nickel, 110-200 parts per million 

cobalt, 1600-2400 parts per million chromium, and 

8- 12 percent iron. Weathering of the peridotite removes 

magnesium, silicon, and calcium and leaves behind a 

residual soil enriched in the above metals. These 

deposits are associated with uplifted Eocene to Pliocene 

erosional surfaces which form as ridge-top, landslideslump, and continuous-slope laterite surfaces. The 

thickness of lateritic soil formation ranges from 8 to 12 

ft, however soils on the eastern slope of Gasquet Mountain are 15 to 25 feet thick. The nickel content of the 

soils ranges from 3900 to 16,000 parts per million and 

the cobalt content ranges from 480 to 1300 parts per 

million as shown from analyzed samples. Chromium and 

iron are also present in these soils. Total demonstrated 

resources of nickel are approximately 16 million tons 

(minimum) from widely scattered areas of substantiated 

nickel resource potential. Another 29 million tons of ore 

exist in areas immediately adjacent to the roadless area. 

Chromite with byproduct platinum-group elements 

also is a resource in the roadless area Chromite occurs 

in dunite-rich rocks near the cumulate-tectonite interface. Podiform chromite deposits occur as lenticular 

bodies, usually complexly folded, and are composed of 

nearly pure chromite. Small disseminated deposits of 

chromite consist of grains and schlieren of chromite 

mixed with dunite. Byproduct platinum-group elements 

are present in analyzed chromitites from the roadless 

area and they may enhance the resource potential of 

these deposits. The largest deposit in the area, on High 

Plateau (Brown mine) contains approximately 26,000 

tons of demonstrated chromite resources. The remaining smaller scattered deposits in the area together only 

total another estimated 4000 to 5000 tons of demonstrated chromite resources. 

Mercury deposits and magnetite veins with copper 

and minor cobalt occur in silicic intrusive rocks in the 

roadless area The intrusive event was accompanied by 

hydrothermal fluids which may have acted as leaching 

agents to remove copper, iron, and minor amounts of 

cobalt from the peridotite body and redeposit them in 

veins. Mercury mineralization is related to the silicic 

magmas which ubiquitously intruded the peridotitetectonite and the mercury occurs as two depositional 

types. The largest mercury deposit is adjacent to the 

area at the Webb mine and occurs in highly sheared 

peridotite approximately 3000 ft west of a major fault 

contact between the ophiolite and metavolcanic rocks. 

Numerous small felsitic dikes and stringers intrude the 

shear zone. Alteration in the mineralized zone consists 

of thin carbonate veinlets, abundant kaolinization of 

silicic dike rock, and silicification of the serpentine into 

silica-carbonate rock as is characteristic of other mercury deposits throughout the Coast Range in California. 

Finely crystalline cinnabar, metacinnabar, and minor 

pyrite are found in the silica-carbonate rock as well as 

on fracture-vein surfaces in brecciated areas. These 

minerals as well as native mercury occur in clay gouge 

zones within the roadless area 

The second type of mercury deposit, displayed in the 

Big Boy group, occurs in hornblende diorite country 

rock that has been altered by later magmatic activity. 

The diorite has been thoroughly propylitized with constituent feldspar and hornblende minerals breaking 

down to kaolinite-sericite aggregates and limonite, 

respectively. Cinnabar is deposited on fine joint surfaces within the propylitized diorite. The roadless area 

has probable and substantiated resource potential for 

small deposits of mercury. 

Magnetite deposits with copper and minor cobalt occur as 2- to 15-ft thick replacement veins in serpentine 

shear zones and are closely associated spatially and 

temporally with rhyolitic dike rocks. Most of these 

deposits occur in two areas of substantiated copper 

resource potential along the west and northwest edge of 

the roadless area although scattered small deposits occur elsewhere. The veins are composed of dense magnetite grading outward into boxwork open-space-filling 

hematite that grades into hematite-coated serpentine. 

Either unaltered serpentine or partly serpentinized 

peridotite extend outward from this area The copper 

317 
minerals chrysocolla and azurite are common within the 

magnetite zones. Although substantiated, resources of 

iron, copper and cobalt from the vein deposits are 

thought to be small. 

Small seams of asbestos, primarily slip-fiber chysotile, crop out in partly serpentinized peridotite along the 

North Fork Smith River Canyon, however, no resource 

potential was identified within the area 

SUGGESTIONS FOR FURTHER STUDIES 

The North Fork Smith River Roadless Area contains 

a number of exposed mineral deposit types within and 

adjacent to its environment. However, mineral resource 

assessment, in a strict sense, requires three-dimensional 

knowledge of deposits yielding greater information as 

to shape, structures, as well as, extent, and grade consistency of ore at depth. The copper-cobalt-bearing 

magnetite veins, in particular, shed little light on their 

nature beyond small surface exposure. Rhyolitic dikes 

provided a heat source initiating hydrothermal fluids 

that deposited metals in shear zones at near-surface conditions. Other elements such as gold, silver, and arsenic 

may be finely disseminated in such a system and may 

be detectable only at or near the limits of determination. 

The veins may be interconnecting at depth and may 

have different chemical constituents down dip within 

shear structures reflecting thermal gradients in the 

hydrothermal system. A drilling and sampling program 

to intersect these veins at depth would identify grades 

318 

and structural dimension and characterize thermal conditions of this deposit type. 

REFERENCES 

Cater, F. W., and Wells, F. G., 1953, Geology and mineral resources of 

the Gasquet quadrangle. California-Oregon: U.S. Geological 

Survey Bulletin 995- C. 

Geological Society of America Penrose Conference. 1972. Ophiolites: 

Geotiines,v. 17, no. 12, p.24- 25. 

Gray, Floyd, Page, N. J, Cornwall, H. R. , and Huber, Donald, 1983a, 

Geology of the North Fork Smith River Roadless Area. Del Norte 

County, northern California. and J osephine County, Oregon: U .. 

Geological Survey Miscellaneous Field Studies Map MF- 1423·A, 

scale 1:62,500. 

Gray, Floyd, Page, N. J., and Hamilton, Michael. 1983b, Mineral 

resource potential map of the North Fork Smith River Roadless 

Area. Del Norte County, California: U.S. Geological Survey Mis· 

cellaneous Field Studies Map MF - 1423·B, scale 1:62.500. 

Gray, Floyd, Peterson, J. A., Carlson, R. R., Briggs, Peter, Haffty, 

J oseph, Cooley, E. F., and Page, N. J. 1982, Geochemical 

analyses of rock and stream-sediment samples from the North 

Fork Smith River Roadless Area. Del Norte County, California: 

U.S. Geological Survey Open·File Report 82- 976, 22 p. 

Griscom, Andrew, 1983, Aeromagnetic interpretation of the 

J osephine ultramafic body, California. in Geological and geophysical studies of chromite deposits in the J osephine peridotite, 

California and Oregon: U.S. Geological Survey Bulletin 1546. 

Maxson, J. H., 1933, Economic geology of portions of Del orte and 

Siskiyou Counties, northwestemrnost California: California Jour· 

nal of Mines and Geology. v. 29. p., 123- 160. 

Page, N. J , Carlson, C. A., Gray, Floyd, Carlson. R. A., Briggs, P .. 

Haffty, J oseph, and Cooley, E. F., 1983, Geochemical characteris· 

tics of the North Fork Smith River Roadless Area. Del orte 

County, California. and Josephine County, Oregon: U.S. 

Geological Survey Miscellaneous Field Studies, MF 1423·B. 
ORLEANS MOUNTAIN ROADLESS AREA (B5079), CALIFORNIA 

By MARY M. D ONAT0, 1 U .S . GEOLOGI AL SURVEY and 

j . M ITCHELL LI E . BUREAU OF ML E 

SUMMARY 

The Orleans Mountain Roadless Area (B5079) has substantiated mineralresource potential for placer and lode gold. This conclusion is based on a 

1979-80 investigation that included geologic mapping, study of known mines, 

prospects, and mineralized areas, gravity and aeromagnetic surveys, and 

geochemical sampling. Gravel deposits along the Salmon River contain placer 

gold. Resources of lode gold exist at mines in the northwest and southwest portions of the roadless area The geologic terrane precludes the occurrence of fossil 

fuel resources. 

CHARACTER AND SETTING 

The Orleans Mountain Roadless Area (B5079) is 

located in the Salmon Mountains of northern California, 

and comprises approximately 64.3 sq mi in the Klamath 

and Six Rivers National Forests. The roadless area is 

bounded on the northeast by the Salmon River, on the 

northwest by the Klamath River, and adjoins the 

Salmon-Trinity Alps Wilderness to the south. It is an 

area of great relief and rugged terrain, ranging in 

altitude from approximately 500 ft near Somes Bar to 

nearly 6200 ft above sea level at Orleans Mountain. 

Access is provided by California State Highway 96 

(Klamath River Highway), the Salmon River road, and 

by numerous logging roads which skirt the boundaries 

of the roadless area In addition, trails and fire breaks 

facilitate limited access by foot to many parts of the 

roadless area 

The Orleans Mountain Roadless Area is located in the 

Klamath Mountains geologic province of northern 

California A geologic map has been prepared by the 

USGS as part of this assessment (Donato, Barnes, and 

others, 1983). The roadless area is underlain primarily 

by metamorphic and plutonic rocks of the western 

Paleozoic and Triassic belt, but rocks belonging to the 

western Jurassic belt occur along the western margin. 

Two of the three subdivisions of the western Paleozoic 

and Triassic belt, the Rattlesnake Creek and Hayfork 

terranes, are also recognized in this region. 

1

W1th contributions from ROOert C. J achens and David B. mith. USGS. 

The structurally lowest unit in the roadless area, the 

Galice Formation, belongs to the western Jurassic belt. 

The Galice Formation in this region consists mainly of 

interlayered slate and metagraywacke, although greenstone is abundant locally. The Galice is separated from 

the overlying rocks by an eastward-dipping regional 

thrust fault called the Orleans fault, which forms the 

basal contact of the western Paleozoic and Triassic belt. 

The structurally lowest map unit of the western 

Paleozoic and Triassic belt in this region consists of a 

serpentinite-matrix melange containing blocks of greenstone, chert, gabbro, and minor limestone, and overlies 

the Galice Formation along the Orleans fault. These 

rocks of the Rattlesnake Creek terrane are believed to 

represent fragments of upper Paleozoic(?) and Triassic 

oceanic crust. An eastward-dipping sequence of 

greenschist-facies metasedimentary rocks belonging to 

the Hayfork terrane overlies the serpentinite-matrix 

melange along a shallowly dipping thrust fault. These 

rocks are predominantly volcanogenic sediments, including feldspathic sandstones, crystal tuffs, and 

volcanic conglomerates with interbedded siltstone, 

chert, and siliceous argillite, and are interpreted as an 

island-arc terrane. Eastward (upsection) the volcanogenic rocks decrease in abundance, giving way to argillite, chert, and chert-limestone-argillite breccia 

Intrusive rocks in the roadless area are mainly dioritic 

to granodioritic in composition, and include the Wooley 

Creek batholith, which crops out in the northeastern 

portion of the roadless area, as well as numerous small 

dikes and plutons. No evidence of mineralization 

associated with these intrusive rocks was observed. 

319 
Au 

320 

41 ° 

20' 

41 ° 

10' 

123°20' 

MAP LOCATION 

PLACER MINE 

Salmon Mountam 

0 

M ILES 

EXPLANATION 

Geological terrane with substantiated 

mineral-resource potential 

Gold 

Mine or deposit 

~ 

~ 

D 

D 

• • 

5 

Alluvium (Quaternary) 

Galice Formation (Jurassic) 

Serpentine-matrix melange (Triassic and 

Paleozoic) 

Metamorphosed volcanogenic sedimentary 

rocks (Triassic and Paleozoic) 

Intrusive rocks 

Contact 

Fault 

Thrust fault--Sawteeth on upper plate 

Figure 93.- 0rleans Mountain Roadless Area (85079), California 
The general structural aspect of the roadless area is 

one of eastward-dipping thrust plates. A major thrust 

fault, the Orleans fault, is present in the westernmost 

part of the roadless area, and is locally modified by later 

high-angle, north-south-trending faults. Thrust faults 

also form the boundary between the Rattlesnake Creek 

terrane and the overlying Hayfork terrane. Two of four 

lode gold mines are located near thrust faults. Although 

lode gold deposits are more characteristic of Hayfork 

than Rattlesnake Creek terrane, three lode claims occur 

in Rattlesnake Creek terrane in or near the roadless 

area; they are near the thrust fault separating Rattlesnake Creek from Hayfork terrane, which suggests 

that mineralization may be related to this fault. The majority of lode claims or prospects, however, occur within 

the metasedimentary units of the Hayfork terrane. 

A reconnaissance geochemical study of stream 

sediments and panned concentrates from the roadless 

area by the USGS yielded scattered anomalies of 

elements characteristic of lode and placer gold deposits 

in streams draining the eastern slope of the Salmon 

Mountains. This confirmed the previously known potential for lode and placer gold in the area Gravity and 

aeromagnetic surveys were also conducted over the 

roadless area and surrounding areas to supplement the 

geologic mapping and to aid in the assessment of the 

mineral-resource potential of the area The geophysical 

data have been used to infer the distribution of rock 

units and the attitudes of boundaries between them, but 

have generally not been useful in identifying or confirming areas of resource potential in this case. 

Three mining districts extend into the roadless area: 

the Salmon River, Orleans, and Red Cap mining districts. Gold was discovered on the Salmon River in 

1849. From 1932 to 1959 the district's production totaled 18,868 oz of gold and 15,981 oz of silver. According to USBM files, the Bloomer, Hom, and Pot Luck 

placer mines yielded over 12,000 oz of gold and 840 oz of 

silver before 1920. Small-scale placer mining continues. 

The Orleans mining district is in the vicinity of the 

town of Orleans and covers approximately 100 sq mi. 

The district's northeast comer overlaps the northwest 

part of the roadless area The Whitehorse, Chilton, and 

Whitmore Creek mines, all lode deposits, lie within the 

roadless area in the Orleans district. Production of 

100 oz of gold and 30 oz of silver came from the Chilton 

mine between 1927 and 1940, and is the only recorded 

mineral production from within the roadless area 

The Red Cap mining district is centered around Red 

Cap Creek and covers approximately 50 sq mi. The 

southern part of the district overlaps a small part of the 

roadless area in the vicinity of the Middle Fork of Red 

Cap Creek, where rocks of the Hayfork terrane are present. Placer mining in the Red Cap district began in the 

late 1870's along Red Cap Creek near its confluence 

with the Klamath River. Copper, chromium, gold, and 

silver lodes also occur in the district outside the roadless 

area Within the roadless area, gold and silver occur in 

quartz veins at the Red Cap Central mine, located in the 

Hayfork terrane. Underground exploration has been 

conducted at this mine, but no production is recorded. 

MINERAL RESOURCES 

The Orleans Mountain Roadless Area has demonstrated and inferred resources of placer gold, and both 

demonstrated resources and substantiated resource 

potential for lode gold (Donato, Linne, and others, 

1983). 

Placer gold occurs in bench placer deposits adjacent 

to the roadless area between Lewis Creek and Forks of 

Salmon, near the eastern boundary of the roadless area 

These deposits adjoin and extend into the roadless area, 

but no development has occurred within the roadless 

area Three bench placers from 50 to 400 ft above the 

present river channel are found at both the Bloomer and 

Hom mines, and one bench placer about 30 ft above the 

river channel is found at the Potluck mine. These bench 

placers are often overlain by thick layers of slide 

material. At several channel sample locations, gold 

values were found as much as 15 ft above bedrock, indicating that mineral deposition may have occurred as 

separate events without later reconcentration. Three 

placer mines occur adjacent to the east border of the 

roadless area and all have resources that extend into the 

roadless area At the Bloomer placer mine, 190,000 cu 

yd of inferred resources of gold-bearing gravel occur 

within the roadless area; at the Potluck placer mine, an 

estimated 700,000 cu yd of inferred resources of goldbearing gravel occur within the roadless area; and at the 

Hom placer mine, 40,000 cu yd of demonstrated 

resources and 20,000 cu yd of inferred resources of goldbearing gravel are within the roadless area At all three 

properties, there is little possibility for the occurrence of 

additional gold resources. 

Lode gold occurs in the roadless area in quartz veins 

as "free gold," associated with pyrite. These veins 

strike northeast or northwest and occur in metavolcanic 

and metasedimentary rocks of the Hayfork terrane. 

Veins at the Whitehorse and Whitmore Creek mines are 

probably associated with the Orleans fault. 

The Whitehorse, Chilton, and Whitmore Creek mines, 

all lode deposits, lie within the roadless area; the only 

mineral production was from the Chilton mine. At these 

three mines, there is a total of 49,000 tons of demonstrated and inferred resources with grades from 0.06 to 

0.62 oz gold/ton. Areas around these properties have 

substantiated potential for the occurrence of additional 

resources. 

321 
Underground exploration has been conducted at the 

Red Cap Central mine, located in the Hayfork terrane, 

but no production is recorded for this prospect. An inferred resource of 13,000 tons containing 0.26 oz 

gold/ton with some silver is estimated. The possibility 

for the occurrence of additional resources is high and an 

area of substantiated gold resource potential extends 

around the area of the mine. 

SUGGESTIONS FOR FURTHER STUDIES 

Because lode gold deposits are characteristic of the 

Hayfork terrane in the southern Klamath Mountains, 

and most of the Orleans Mountain Roadless Area is 

underlain by rocks belonging to that terrane, it is possible that additional lode gold deposits are present. The 

areas with known lode gold resources seem to be more 

322 

closely associated with faults in the western part of the 

roadless area than with Hayfork lithologies. Scattered 

geochemical anomalies found in panned concentrates 

taken from streams draining the eastern slope of the 

~alrnon Mountains suggest sparse mineralization in 

Hayfork rocks. Further exploration would be necessary 

to confirm or disprove the existence of deposits. 

REFERENCES 

Donato, M. M., Barnes, C. G., and Gray. G. G., 1983, Geologic map of 

the Orleans Mountain Roadless Area, Humboldt and Siskiyou 

Counties, California: U. S. Geological Survey Miscellaneous Field 

Studies Map MF- 1526- A. 

Donato, M. M., Linne, J. M., Jachens, R. C .. and Smith, D. B., 1983, 

Mineral resource potential map of the Orleans Mountain Road· 

less Area (B5079), Humboldt and Siskiyou Counties. California: 

U.S. Geological Survey Miscellaneous Field Studies Map 

MF- 1526- B. 
ORLEANS MOUNTAIN ROAD LESS AREA (C5079, B5079), CALIFORNIA 

By A. S. j AYK0, 1 U .S. G EO LOGICAL S RVEY, and 

L. Y. MARK , U.S . B REA OF Mr E 

SUMMARY 

The Orleans Mountain Roadless Area (C5079, B5079) located along the 

Siskiyou-Trinity County line in the Salmon Mountains of northern California 

was studied in 1969-70 by P. E. Hotz and others for mineral-resource potential, 

and reexamined in 1981-82. Several areas with probable gold resource potential 

were identified based on examination of mines and prospects, analytical values 

of selected elements, and historical records of gold and silver production. The 

geologic terrane precludes the occurrence of fossil fuel resources. 

CHARACTER AND SETTING 

The Orleans Mountain Roadless Area (C5079, B5079) 

occupies a rugged mountainous area of about 98 sq mi 

in the central Klamath Mountains 73 sq mi of which 

have been designated roadless by the USFS. The area is 

approximately 80 mi northeast of Eureka, California 

The area consists of Paleozoic and Mesozoic metamorphic and ultramafic rocks complexly folded and faulted 

together and intruded by Jurassic granitic rocks (Jayko 

and Blake, 1983). Mineral occurrences are commonly 

located in fault zones and along contacts where 

magmatic fluids migrated. 

Extensive geochemical studies and mine prospect examinations were performed by Hotz and others (1972), 

with additional sampling carried out in 1981. Rock, 

mine dump rock, stream-sediment, and pan concentrates from stream-sediment samples were analyzed. 

Mining activity began in the roadless area at the turn 

of the century with the first gold production recorded in 

1899 and continuing into 1951 (Hotz and others, 1972). 

Most of the gold and silver production in and immediately adjacent to the roadless area occurred between 

1929- 39 from nine lode mines and two placers. Of the 

30,500 oz of gold produced, 10,000 oz came from the 

Dorleska mine and 10,000 oz from the Nash placer mine 

located in Coffee Creek, just outside the roadless area. 

Forty-€ight hundred ounces of silver were produced, of 

which 2200 oz came from the Grand National mine l<r 

cated approximately 0.25 mi outside the eastern portion 

of the roadless area and 1400 oz came from the Nash 

'With contribution by M. C. Blake. Jr .. USG . 

placer. Silver and to a very minor extent lead and copper 

were recovered as byproducts of gold refining. Nineteen 

hundred pounds of copper were mined from the Grand 

National mine and 246 lbs of lead from the Geneva 

mine. There has been no production recorded from any 

of the mines during the last 40 years (Hotz and others, 

1972). 

MINERAL RESOURCES 

Gold, silver, and to a lesser extent lead and copper occur in vein systems that cut all the different lithologies 

in the roadless area These mineralized vein systems 

developed in association with late Mesozoic plutonic activity and are commonly located adjacent to, or along, 

fault zones or contacts between different lithologies. 

Three of the areas of probable mineral-resource potential include the Klatt mine, Grand National mine, and 

Mt. Shasta View prospect, which are closely related to 

brecciated intrusive contacts between granitic rock and 

ultramafic country rock. Four other areas of probable 

mineral-resource potential, located in the south-central 

portion of the roadless area, include the Dorleska mine, 

Geneva mine, Packer mine, and Hardscrabble mine 

which seem to be remotely associated with thrust faults 

that emplace metamorphic rock against metamorphic 

rock. One area of probable mineral-resource potential, 

the Carter prospect, is located entirely within granitic 

rock. An area with probable placer gold resource potential is along Coffee Creek, just outside the roadless area 

Six of the nine areas identified as having probable 

mineral-resource potential were previously mined and 

323 
41 ° 

00' 

324 

123°00' 

MAP LOCATION 

D 

Au 

Ag 

Geologic terrane with probable 

mineral-resource potential 

Gold 

Silver 

Mine 

0 

DORLESKA 

MINING 

DISTRICT 

MILES 

EXPLANATION 

8ZJ 

122°45' 

c ,, h l 

Approximate 

5 

Granitic rocks (Jurassic ) 

Ultramafic rocks (Mesozoic and Paleozoic) 

Metamorphic rocks (Mesozoic and Paleozoic ) 

Contact 

Fault 

Figure 94.-0rleans Mountain Roadless Area (C5079, 85079), California 
produced 63 to 10,000 oz of gold and as much as 2200 oz 

of silver, but none of the mines have been active within 

the last 40 years. Two areas of probable mineralresource potential, at the Carter and Mount Shasta 

View prospects, have no record of gold or silver production; the Mount Shasta View, has extensive workings. 

The mines that are located within the areas of probable 

mineral-resource potential are presently inactive. The 

immediate vicinity of the workings was identified as 

having probable mineral-resource potential based on 

results from mine and prospect sampling, geochemical 

sampling of nearby veins, and whole-rock samples 

which contained anomalous concentrations of selected 

elements. Additional mineralized vein systems may be 

present in the vicinity of the known deposits. 

The Orleans Mountain Roadless Area contains 56 

mines and prospects located entirely within or immediately adjacent (within 0.5 mi) to the roadless area 

Only three of these, the Grand National mine, Nash 

placer, and the Red Rock Mountain prospect (both 

located 0.25 mi outside the roadless area) are on 

patented land. 

Two small placer mines located within the roadless 

area produced a total of 680 oz of gold between 1912 and 

1937. These placers were on alluvial gravels. The 

streams that drain the roadless area have been extensively mined and little terrace gravel remains; therefore, 

the only placer gold resource potential identified is outside the roadless area, along Coffee Creek. 

The location of areas of probable mineral-resource 

potential was based mostly on past mining history and 

examination of mines and prospects; the results of 

geochemical surveys verified mine and prospect sample 

data If deposits are present they would probably be 

gold- and (or) silver-bearing quartz vein systems. 

Recreational placer mining is probably feasible along 

some of the larger streams. 

SUGGESTIONS FOR FURTHER STUDIES 

If further work were to be carried out within the 

roadless area the most promising region to study would 

be in the area around the Dorleska mining district. 

REFERENCES 

Hotz, P. E., Thurber, H. K., Marks, L. Y., Evans, R. K.. and Griscom, 

A., 1972, Mineral Resources of the Salmon-Trinity Alps Primitive 

Area, California, U.S. Geological Survey Bulletin 1371 - B, 267 p. 

Jayko, A. S. and Blake, M. C., Jr., 1983 Geologic map of part of the 

Orleans Mountain Roadless Area, Trinity and Siskiyou Counties, 

California: U.S. Geological Survey Miscellaneous Field Studies 

Map MF-1600- A. 

Jayko, A. S., and Blake, M. C., Jr .. in press, Geochemical map of part 

of the Orleans Mountain Roadless Area. Siskiyou and Trinity 

Counties, northern California: U.S. Geological Survey Miscellaneous Field Studies Map MF-1600-C. 

Jayko, A. S., Blake, M. C., Jr., Marks, L. Y., and Evans, R. K., in 

press, Mineral resource potential map of part of the Orleans 

Mountain Roadless Area, Siskiyou and Trinity Counties, northem California: U.S. Geological Survey Miscellaneous Field 

Studies Map MF-1600-B. 

325 
1 18°00' 

Pasadet>a 

D 

w 

X 

326 

D MAP LOCATION 

M .Jntatn 

M 0 N A N s 

To AzusJ 

0 5 

MILES 

EXPLANATION 

Geologic terrane with probable 

mineral-resource potential 

Tungsten 

Mineral occurrence 

Mine 

Quaternary deposits 

Tertiary rocks 

Tertiary or older Pelona Schist and 

mylonite rocks 

~'~1'~1' Cretaceous or Jurassic plutonic rocks (,'>~/'-:' 

Triassic or Permian plutonic rocks 

Precambrian gneiss 

Contact 

Fault 

Figure 95.-Pleasant View Roadless Area, California, 
PLEASANT VIEW ROADLESS AREA, CALIFORNIA 

By BRETT F. COX 1 U .S. GEOLOG I AL R EY, and 

D AVID A. LIPT , U.S. B U REA F MI ES 

SUMMARY 

The Pleasant View Roadless Area, located in eastern Los Angeles County approximately 17 mi northeast of Pasadena, California, was studied during 

1981-82. The study included a geochemical survey and geologic mapping by the 

USGS and an examination of mines and prospects by the USBM. There are no 

known mineral deposits and no evidence of past mineral production from the 

roadless area Nevertheless, the geochemistry and mineralogy of stream 

sediments indicate that occurrences of the tungsten mineral scheelite are present throughout an area of about 8.5 sq mi near the east end of the roadless area 

A probable mineral-resource potential for tungsten is assigned to this specific 

area No potential for other mineral or energy resources was identified. 

CHARACTER AND SETTING 

The Pleasant View Roadless Area includes approximately 42 sq mi of rugged terrain on the north slope of 

the San Gabriel Mountains directly south of the westem Mojave Desert region. The maximum altitude of 

8396 ft is located at Mount Lewis near the east end of 

the area Pleasant View Ridge, with several summit 

altitudes near 8000 ft, trends northwestward across the 

western part of the area Angeles Crest Highway (California State Highway 2) skirts the south boundary, pn:r 

vi ding access to neighboring ski resorts on Waterman 

Mountain and Kratka Ridge. Two trails cross the roadless area, connecting Angeles Crest Highway with 

campgrounds near Big Rock Creek. 

Several regionally significant faults are located within 

or immediately adjacent to the roadless area The inactive Punchbowl fault follows the foot of the range, nearly coinciding with the north boundary of the roadless 

area The recently active San Andreas fault, which lies 

outside the roadless area, is parallel to and approximately 2.5 mi north of the Punchbowl fault. A third 

steeply dipping structure, the Fenner fault, is located at 

the northeast comer of the roadless area between the 

Punchbowl and San Andreas faults. An ancient gently 

dipping fault, the Vincent thrust, lies approximately 1 

to 3 mi southeast of the roadless area. No mineral 

resources have been identified along the Punchbowl and 

'With contributions from Robert E. Powell. MargareL E. Hinkle. Curtis M. Obi. and Vicki A. 

Pulker.oon. uses. 

Fenner faults near the roadless area, but gold, silver, 

copper, and lead have been produced at the Big Hom 

mine, located near the Vincent thrust approximately 2 

mi southeast of the roadless area (Ridenour and others, 

1982). 

Movements on the Vincent, Fenner, and Punchbowl 

faults have juxtaposed four structural blocks that contain distinct assemblages of rocks. Most of the roadless 

area is located on the block west of and above the Vincent thrust and south of the Punchbowl fault. The rocks 

in this region include Precambrian gneiss (metamorphosed sedimentary and granitic rocks) and a diverse 

assemblage of mafic to silicic Mesozoic plutonic rocks. 

During or prior to earliest Tertiary time, these gneissic 

and plutonic rocks were faulted on top of metamorphosed sedimentary and volcanic rocks of the Pelona 

Schist that form the structural block east of and below 

the Vincent thrust. Rocks in the upper plate of the 

thrust were strongly deformed as a consequence of 

these fault movements. This episode of deformation is 

represented by a belt of mylonitic rocks located mostly 

east of the roadless area adjacent to the thrust, and by a 

broader zone of less intense, heterogeneous deformation, including localized fracturing and foliation, that 

extends into the roadless area as far west as the western 

drainage divide of the South Fork of Big Rock Creek. 

This broader zone of interspersed brittle and ductile 

deformation west of the Vincent thrust may have been 

partly responsible for localization of scheelite near the 

east end of the roadless area 

327 
Numerous faults of probable Cenozoic age cut the 

gneissic and plutonic rocks of the roadless area. One of 

these minor faults located north of Kratka Ridge is 

cross-cut by a large dike of Tertiary rhyolite. No 

evidence of mineralization was found associated with 

the minor faults or rhyolite rock. 

Two structural blocks north of the Punchbowl fault 

extend a short distance into the northeast part of the 

roadless area The block between the Fenner and Punchbowl faults consists primarily of metasedimentary and 

metavolcanic rocks of the Pelona Schist. A minor body 

of granite either intrudes or is faulted against the schist 

near the Punchbowl fault; this body is not shown on the 

map because of its small size. No mineral concentrations have been identified within either the schist or 

granite. The bedrock block north of the Fenner fault 

consists mostly of deformed Mesozoic plutonic rocks. 

Tertiary sandstone, shale, and conglomerate overlie the 

plutonic and metamorphic rocks both north and south 

of the Fenner fault, and extensive deposits of Quaternary sand and gravel are present along Big Rock Creek 

and on alluvial fans near Juniper Hills. The deformed 

plutonic rocks and overlying sedimentary units do not 

extend for significant distances into the roadless area, 

nor do they contain concentrations of metallic minerals. 

Rock materials suitable for general construction purposes are present in the roadless area Deposits of sand 

and gravel are found in a few places near the north 

boundary, particularly along tributaries of Big Rock 

Creek. Some of the gneissic and plutonic rocks within 

the roadless area could be used for crushed stone or 

riprap. However, sand and gravel and construction 

stone of equal or better quality are available rn 

neighboring areas outside the roadless area 

MINERAL RESOURCES 

No mineral production has come from within the 

Pleasant View Roadless Area and there are no patented 

mining claims or mineral leases. The Big Horn mine, located 2 mi southeast of the roadless area, has produced 

gold, silver, copper, and lead. It has the only nearby 

mineral production. The mine penetrates schist directly 

beneath the Vincent thrust. There is no evidence for 

similar deposits in the roadless area 

Three prospects are located within or directly adjacent to the roadless area (Cox and others, in press). The 

Sycamore prospect is located near a sheared intrusive 

contact between two Mesozoic plutons. A quartz vein at 

the prospect was analyzed and found to contain traces 

of silver and gold; the amount of mineralized rock is 

328 

small and no resources were identified. The Donaldson 

prospect is located in sheared, brecciated rock adjacent 

to a minor fault. The Fenner Canyon prospect is located 

in limonite-stained schist: No evidence of mineral resources was found at either prospect. 

Despite the absence of historic mineral production, 

there is a probable tungsten potential for small deposits 

in veins in the east part of the roadless area near Mount 

Lewis. This assessment is based on stream-sediment 

geochemistry and mineralogy, and comparison with 

vein occurrences in other parts of the San Gabriel 

Mountains. Anomalous amounts of tungsten were 

found (100-300 parts per million (ppm); background 

values less than the 100- ppm spectrographic detection 

limit)and grains of scheelite were identified in 11 of 12 

panned-concentrate samples collected from tributaries 

of Dorr Canyon and the South Fork of Big Rock Creek, 

and from one minor drainage on the north flank of 

Mount Lewis. Anomalous amounts of barium (7000-

10,000 ppm; background values 50-500 ppm) and 

grains of barite were also found in 11 of these same 12 

samples. The drainage area represented by the anomalous samples includes approximately 8.5 sq mi within 

the roadless area By contrast, only a few isolated 

geochemical or mineralogical anomalies for tungsten 

and barium occur in the 34 sq mi of the roadless area 

west of the South Fork of Big Rock Creek. 

Carbonate rocks, which commonly host metasomatic 

skarn deposits of scheelite, are not present in the 

roadless area, and the scheelite may occur instead 

within veins cutting the gneissic and plutonic rocks, 

although none were observed. The joint occurrence of 

barite and scheelite in the same cluster of streamsediment samples supports the idea of occurrence in 

veins, because barite is a common vein gangue mineral. 

Moreover, vein occurrences of tungsten have been 

reported in similar gneissic and plutonic rocks in 

neighboring areas of the San Gabriel Mountains 

(Ridenour and others, 1982; Zilka and Schmauch, 1982). 

These vein occurrences of tungsten are also located in 

upper-plate rocks near the Vincent thrust. 

The lack of panned-concentrate tungsten anomalies 

greater than 300 ppm and the inferred occurrence of the 

scheelite in veins rather than carbonate-hosted skarn 

bodies suggests that any tungsten concentrations that 

may exist near the east end of the roadless area probably are not large or particularly rich. Nevertheless, the 

clustering of tungsten anomalies and the similar 

geologic setting of vein occurrences in nearby areas indicates that the area surrounding Mount Lewis has 

probable potential for tungsten resources. No potential 

for other mineral or energy resources was identified in 

the area 
SUGGESTIONS FOR FURTHER STUDIES 

More detailed field and geochemical studies of veins 

and stream sediments are needed to fully evaluate the 

potential for tungsten in the east part of the Pleasant 

View Roadless Area Future studies might also test the 

hypothesis that tungsten concentrations may be related 

spatially, and possibly genetically, to deformation near 

the Vincent thrust. 

REFERENCES 

Cox, B. F., Powell, R. E., Hinkle, M. E., and Lipton, D. A., in press, 

Mineral resource potential map of the Pleasant View Roadless 

Area. Los Angeles County, California: U.S. Geological Survey 

Miscellaneous Field Studies Map, MF - 1649-A, scale 1:62,500. 

Ridenour, James, Schmauch, S. W., and Zilka. N. T., 19 2, Economic 

appraisal of mineral resources of the Sheep Mountain Wilderness 

study area. Los Angeles and San Bernardino Counties. Califor· 

nia. in Mineral resources of the Sheep Mountain Wilderne s 

study area and the Cucamonga Wilderness and additions, Los 

Angeles and San Bernardino Counties, California: U . . 

Geological Survey Bulletin 1506- D, p. 53-84. 

Zilka. N. T., and Schrnauch, S. W., 1982. Economic appraisal of 

mineral resources of the Cucamonga Wilderness and additions, 

Los Angeles and San Bernardino Counties, California. in Mineral 

resources of the Sheep Mountain Wilderness study area and the 

Cucamonga Wilderness and additions, Los Angeles and an Ber· 

nardino Counties. California: U.S. Geological Survey Bulletin 

1506- E, p. 85- 92. 

329 
330 

39° 

oo· 

38° 

50' 

MAP LOCATION 

0 

MILES 

EXPLANATION 

Sedimentary rocks (Quaternary) B Volcanic rocks (Tertiary) 

IYI-{>'f-{>1 Granitic rocks (Mesozoic) ''I''/' 

x Mineral occurrence 

LAI\t TAHOI 

5 

Metavolcanic rocks (Mesozoic) 

Metasedimentary rocks (Mesozoic) 

Contact 

Figure 96.-Pyramid Roadless Area, California 
PYRAMID ROADLESS AREA, CALIFORNIA 

By AUG T K. ARM TRONG , 1 •• GE LOGICAL U R EY, and 

DO GLA F. SCOTT, .S . BU REAU OF MI:\IE 

SUMMARY 

A geologic and mineral survey conducted in 1982 indicates that the Pyramid 

Roadless Area, California, has little promise for the occurrence of mineral or 

energy resources. 

CHARACTER AND SETTING 

The Pyramid Roadless Area is adjacent to and partly 

surrounds the Desolation Wilderness. The roadless area 

lies near the crest of the Sierra Nevada about 75 mi east 

of Sacramento, California The roadless area includes 

approximately 49 sq mi in El Dorado National Forest 

and the Lake Tahoe Basin Management Unit of El 

Dorado County. 

The roadless area is dominated by deep rugged canyons that run from the Sierra Nevada crest eastward to 

Tahoe Basin and westward from the crest to the Sacramento Valley. Altitudes range from about 5500 ft in the 

bottom of Big Silver Canyon to 8895 ft at Echo Peak 

along the southeast boundary of the roadless area U.S. 

Highway 50 on the south side and California Highway 

89 on the east side, provide access to the roadless area; 

secondary roads and trails reach the roadless area 

boundaries in a number of places, but access to many 

areas is limited to a few trails. The nearest population 

center is South Lake Tahoe, California, about 3 mi east 

from the eastern edge of the Pyramid Roadless Area 

Placerville is about 26 mi to the southwest of the 

western edge of the roadless area 

All the sedimentary and volcanic rocks intruded by 

the Sierra Nevada batholith in the Pyramid Roadless 

Area are thermally metamorphosed. These rocks are 

mostly biotite-hornblende gneiss and schists, porphyroblastic granitoid rock, and calc-silicate hornfels. 

Mineral assemblages suggest metamorphism to 

amphibolite facies or hornblende-hornfels contact facies 

(Dodge and Fillo, 1967; Loomis, 1964). The prebatholithic metamorphic rocks occur in a roof pendant in the 

east-central part of the roadless area Two groups of 

'With contributions from Maurice A. Chaffee. USGS. 

metamorphic rocks have been recognized, a metasedimentary sequence derived from argillaceous limestones 

and shales and a conformable overlying metavolcanic 

sequence. The metasedimentary rocks are fine-grained 

calc- and quartzo-feldspathic hornfels. Locally, lightcolored quartz-rich beds are interlayered with darker 

mafic hornfels, giving these rocks a banded appearance. 

The metavolcanic rocks in the roadless area south of 

Fallen Leaf Lake are dark quartzo-feldspathic hornfels, 

whose parent rocks probably were andesites or dacites. 

A broad area just east of the metavolcanicmetasedimentary contact is underlain by metavolcanic 

breccia Several masses of dioritic rocks are exposed in 

the northeastern and southwestern parts of the Pyramid Roadless Area In some places a complete transition from dark igneous or igneous-appearing rock to 

metamorphic rocks can be seen. The major rock type of 

the northeastern, southern, and western parts of the 

Pyramid Roadless Area is plutonic rock of granitic composition. Within the Desolation Wilderness, eight 

discrete granitic units were recognized by Dodge and 

Fillo (1967), but they made no distinctions between individual masses on their geologic map. Loomis (1960, pl. 

1) recognized seven distinct granitic plutons within the 

area of the Pyramid Roadless Area, granodiorite being 

the most prevalent rock type. The intrusive masses 

range from alaskite, quartz monzonite to quartz diorite. 

Quartz, plagioclase, and biotite are major constituents 

of the granitic rocks. A small mass of noritic rocks was 

described and mapped near the east side of the roadless 

area, southwest of Emerald Bay (Loomis, 1963, 1964; 

and Dodge and Fillo, 1967). 

Cenozoic andesite breccias and interbedded epiclastic 

stream conglomerates and sandstones crop out immediately to the south and southeast of the area, and porphyritic olivine basalt occurs on the northwest side 

of the roadless area The west-central part of the area 

331 
contains three peaks, Four Cornered Peak and two unnamed peaks, possibly volcanic necks, which are composed of olivine basalt. Dalrymple (1964) has documented volcanic activity of middle and late Miocene age 

for many localities in the central Sierra Nevada 

The Quaternary glacial deposits within the Pyramid 

Roadless Area are glacial moraines, outwash gravels, 

and lake and stream deposits. A record of the advances 

and retreats of the Quaternary glaciers is preserved in 

moraines. Four main advances are known and a fifth 

minor advance is represented by several rock glaciers 

that still may be active. Thick deposits of lateral and 

terminal moraines are found around Fallen Leaf Lake, 

Cascade Lake, and Emerald Bay and along General and 

Meeks Creeks in the northeast. Morainic material and 

outwash gravel are extensive south and east of Wrights 

Lake. 

USBM personnel conducted literature and courthouse 

record searches and fieldwork to determine the mineral 

resources of the roadless area Samples taken from 

mineralized areas in and adjacent to the roadless area 

were analyzed by atomic absorption, chemical, and fireassay methods. All samples were checked for radioactivity with a gamma-ray scintillometer and for fluorescence with an ultraviolet light. Most of the samples 

were analyzed by semiquantitative spectrographic 

methods to determine the presence of unsuspected 

elements. 

MINERAL RESOURCES 

The Pyramid Roadless Area contains mineral showings, but no mineral-resource potential was identified 

during our studies. Three granodiorite samples on the 

west side of the roadless area contained weakly anomalous concentrations of uranium. Two samples of roofpendant rocks, one metasedimentary rock and one 

metavolcanic rock, contain low concentrations of copper, and of copper and molybdenum, respectively. The 

anomalous concentrations in all of these samples probably only represent abnormally high background 

concentrations for the respective rock types. These 

analytical results corroborate those of Dodge and Fillo 

(1967) for the adjacent Desolation Wilderness. They 

found that, except for rock samples collected from 

previously known prospects, none of the rock samples 

contained anomalous concentrations of any elements 

that might be indicative of hydrothermal mineral 

deposits. 

The Cliff Ridge mining claims, north of Wrights Lake, 

were located for uranium in 1959 and 1979, respectively. 

Both claims are on a 4-ft-thick aplite dike that strikes 

N. 80 ° W., and dips 66 ° SW. in quartz monzonite. The 

332 

dike yields a slightly higher than background count 

using a gamma-ray scintillometer, but samples from 

these localities contained no uranium. 

Silicified and limonite-stained metasedimentary rocks 

near a granitic rock contact occur west of Fallen Leaf 

Lake. These rocks have locally as much as 2 percent 

disseminated sulfides, but no resource potential was 

identified. 

Three quartz stringers containing molybdenite 

rosettes and massive arsenopyrite occur in slightly 

limonite-stained quartz monzonite near Grass Lake. 

These stringers, 0.25 to 2 in. thick, trend northeastsouthwest, and contained from 0.28 to 1.06 percent 

MoS2 (molybdenum disulfide). These were not exposed 

in the roadless area 

SUGGESTIONS FOR FURTHER STUDIES 

Although none was identified, the geologic terrane is 

permissive for mineral occurrences and large-scale, 

detailed geologic mapping of the areas of metasedimentary and metavolcanic roof pendants in the Pyramid 

Roadless Area could define a mineral-resource potential 

for tungsten and precious metals. 

REFERENCES 

Armstrong, A. K., Chaffee, M. A., and Scott, D. F., in press, Mineral 

resource potential map of the Pyramid Roadless Area. central 

Sierra Nevada. California: U.S. Geological Survey Miscellaneous 

Field Studies Map MF-1616-A. 

Burnett. J. L., 1971, Geology of the Lake Tahoe Basin, California: 

California Divison of Mines and Geology, v. 27. no. 7, p. 119- 130. 

Dalrymple, G. B., 1964, Cenozoic chronology of the Sierra evada: 

University of California Publications in Geological Science, v. 47, 

41 p. 

Dodge, F.C.W., and Fillo, P. V., 1967, Mineral resources of the Desolation Valley Primitive area of the Sierra Nevada. California; U.S. 

Geological Survey Bulletin 1261- A, 27 p. 

Lindgred, Waldermar, 1896, Description of the Pyramid Peak 

quadrangle, California; U.S. Geological Survey Geologic Atlas, 

Pyramid Peak Folio 31. 

__ 1897, Description of the Truckee quadrangle, California; U.S. 

Geological Survey Geologic Atlas, Truckee Folio 39. 

Loomis, A. A., 1960, Petrology of the Fallen Leaf Lake area. California; Stanford, Calif., Stanford University, Ph.D. dissertation. 

__ 1963, Noritic anorthosite bodies in the Sierra Nevada 

batholith: Mineralogical Society of America Special Paper 1, 

p. 62-68. 

__ 1964, Geology of the Fallen Leaf Lake quadrangle: California 

Division of Mines and Geology Open-File Report, 17 4 p. 

__ 1966, Contact metamorphic reactions and processes in the 

Mount Tallac roof remnant, Sierra Nevada. California: Journal of 

Petrology. v. 7. p. 221-245. 

Scott, D. F., 1982, Mineral investigation of the Pyramid RARE II 

Area (No. 5023), El Dorado County, California: U.S. Bureau of 

Mines Open-File Report MLA 69-82, 12 p. 
RAYWOOD FLAT ROADLESS AREAS, CALIFORNIA 

By j O A T H AN C. M ATTI , 1 .S. GEOLOC I AL R EY and 

TEPH EN R. l VERSO .S. B REA f M I E 

SUMMARY 

The Raywood Flat Roadless Areas, studied in 1979-82, are situated adjacent 

to the San Gorgonio Wilderness in the southeastern San Bernardino Mountains, 

southern California. Geologic, geochemical, and geophysical studies, together 

with an investigation of mines and prospects, indicate that there is little 

likelihood for the occurrence of metallic mineral or energy resources in the 

roadless areas. In the eastern part of the roadless areas, a geochemical survey 

shows slightly anomalous amounts of lead, copper, molybdenum, tin, and 

bismuth and suggests that there are small and scattered occurrences of these 

metals in the bedrock. The inferred mineral occurrences lack the characteristics 

associated with metal concentrations that would identify resources. Marble and 

other construction materials occur in the area but, similar commodities occur 

outside the area, closer to markets. 

CHARACTER AND SETTING 

The Raywood Flat Roadless Areas consist of a 

further-planning area and a wilderness-recommendation 

area that are located in the southeastern San Bernardino Mountains, about 35 mi east of San Bernardino 

and about 10 mi north of Banning, California. The 

wilderness-recommendation area (A5-187) constitutes 

about 35 sq mi; the further-planning area (B5- 187) constitutes about 29 sq mi. The roadless areas are situated 

adjacent to the existing San Gorgonio Wilderness, and 

consist of rugged mountainous terrain that includes 

Allen Peak (7747 ft), Little San Gorgonio Peak (9140 ft), 

Galena Peak (9330 ft), and Kitching Peak (6598 ft). The 

roadless areas are drained by major streams that include Mill Creek, several tributaries of Oak Glen Creek, 

San Gorgonio River, and the North and South Forks of 

Whitewater River. Access to the roadless areas is 

gained from several entry points. In Mill Creek canyon, 

a paved road that branches from California State Highway 38 affords access to much of area B5- 187; southern 

parts of the area can be entered via dirt roads that lead 

from Oak Glen Road, a paved road that follows Oak 

Glen Creek. Access to area A5- 187 can be gained via 

dirt roads leading up Millard Canyon and its major 

'Willl contributions from Brcu. F. Cox. USGS. 

tributaries, and by pennit via a private dirt road that 

leads up San Gorgonio River. 

The Raywood Flat Roadless Areas are underlain 

mainly by a variety of crystalline bedrock, including 

plutonic igneous rocks and metamorphic rocks. Valley 

areas locally are mantled by Quaternary deposits of 

gravel and sand, and landslides are developed on some 

hillslopes. Three strands of the San Andreas fault 

system occur in the vicinity of the Raywood Flat Roadless Areas-the Mission Creek fault, the Mill Creek 

fault, and the South Branch of the San Andreas fault. 

The South Branch presently is an active strand of the 

San Andreas system; the Mill Creek and Mission Creek 

faults both appear to be abandoned strands. Many 

miles of right-lateral displacement on the Mission Creek 

and Mill Creek faults have carried rocks in the Raywood 

Flat Roadless Areas northwestward to their present 

location from their original location in the Salton 

Trough area to the east. 

North of the Mission Creek fault, the rocks consist of 

gneiss and several varieties of granitoid rock. The oldest 

rocks consist of biotite-rich, compositionally layered 

Precambrian gneiss. A younger gneiss terrane includes 

a heterogeneous assemblage of granite and granitic 

gneiss formed during Mesozoic time as a result of intense thermal and tectonic activity. These events involved partial melting of pre-existing continental crust 

accompanied by intrusion of granitic plutons and by 

333 
34° 

00' 

334 

T 

Glen 

------ov 

e 

R1vers de 

SOUTH 

SAN ANDREAS 

FAULT "' 

0 

~ Mine or deposit 

~ Mine 

I ilkt> Village 

GORGON 0 

B 0 

MILES 

EXPLANATION 

/ .: ~. '> Surficial deposits ~> .. ····'. ~~~~I~l Granitoid rocks 

10 

Granitic gneiss and gneissic granite 

Gneiss and schist 

--- Contact 

MAP LOCATION 

To lndto 

To Palm 

---::;;::-- Fault--Arrows indicate direction of relative movement 

~ Thrust fault--Sawteeth on upper plate 

Figure 97.-Raywood Flat Roadless Areas, California 
ductile shearing. These processes probably occurred at 

intermediate or deep levels in the Earth's crust, and produced fabrics and structures that impart a metamorphic 

rather than plutonic appearance to the rocks. The 

Precambrian and Mesozoic gneiss terranes have been intruded by several lithologically distinct varieties of 

Mesozoic granitoid rock that form plutons of moderate 

size. Locally, pods of biotite-sillimanite-garnet schist, 

metaquartzite, and marble occur as metasedimentary 

inclusions within the foliated and gneissose plutonic 

rocks. 

South of the Mission Creek fault, the rocks consist of 

two distinct terranes separated by a steeply dipping 

thrust fault that is part of the region-wide VincentOrocopia thrust system. The lower plate of this thrust 

contains metavolcanic and metasedimentary rocks; the 

upper plate consists of a lithologically monotonous 

assemblage that includes foliated granitoid rocks, 

gneissic granitoid rocks, and pegmatite. Most of these 

rocks represent deformed granitoid plutons that probably are Mesozoic in age, although bodies of Precambrian gneiss may be present. The rocks of this crystalline terrane have been crushed and sheared during one 

or more episodes of regional deformation. 

Little mineral production has come from the Raywood 

Flat Roadless Areas and only a few abandoned mines 

and prospects exist in the areas. Three claim are 

located within area BS- 187. One of these claims produced small amounts of marble (loc. 1, on map), and a 

second produced small amounts of low-grade uraniumbearing ore (loc. 2). 

MINERAL RESOURCES 

Geologic, geochemical, and geophysical investigations, together with a review of prospecting and mining 

activities, indicate little promise for the occurrence of 

mineral or energy resources in the Raywood Flat Roadless Areas. A reconnaissance geochemical survey of 

stream sediment in the Raywood Flat Roadless Areas 

was conducted to identify variations in streamsediment chemistry that might reflect local concentrations of metals in areas drained by the streams. The patterns of metal distribution indicated by the geochemical 

survey do not indicate mineralized rock within most of 

the roadless areas. Most of the analyses fall within 

ranges that are reasonable for norunineralized crystalline rocks and derivative stream sediment; few 

elemental values are anomalous with respect to the 

average geochemical background for the roadless areas. 

A single group of stream-sediment samples in the east 

part of area AS- 187 shows low-level geochemical 

anomalies for lead, barium, bismuth, copper, molybdenum, and tin. These elements commonly are found in 

veins and replacement deposits of hydrothermal origin. 

Steep brush-covered topography prevented our examination of much of the bedrock in the areas drained 

by the streams. Consequently, we have no direct 

evidence as to the type or scale of mineralization that 

may have occurred in this vicinity, and the inference 

that mineral occurrences exist in the drainage basins is 

based only on results of the geochemical survey. The 

drainages that yielded anomalous metallic values are 

fairly small, and the analytical values are not very high. 

The inferred occurrences of the metals are therefore 

regarded as probably small and scattered. The 

anomalies most likely reflect isolated small-scale occurrences in veins or in minerals disseminated in a larger 

mass of rock. Aeromagnetic and aeroradioactivity 

surveys similarly fail to provide evidence favorable for 

the occurrence of metallic resources. 

Small amounts of low-grade uranium-bearing rock 

containing uranothorite were taken from a small abandoned open cut near Alger Creek (loc. 2) (Hewitt and 

Stone, 1957). The uranothorite is disseminated in three 

adjacent pegmatite lenses composed of coarse-grained 

potassium feldspar and quartz and is surrounded by 

granitic gneiss. The pegmatitic lenses are small, and 

they contain relatively small amounts of uranium; 

analyzed samples across a radioactive zone in the 

largest lens assayed 0.019 and 0.002 percent uranium 

oxide U30. No persuasive evidence of uranium concentrations was found by the aerial radioactivity survey 

(Pitkin and Duval, 1981) or the geochemical survey. The 

uranium-bearing pegmatites are small and low in 

uranium content and no potential for resources was 

identified. 

Marble and other construction materials do occur in 

these roadless areas. Five and a half million tons of 

demonstrated marble resources are estimated for the 

Mill Creek mine (Ioc. 1). Development of marble at this 

site and of other construction materials (granitic rocks, 

sand and gravel) in the roadless areas is regarded as 

unlikely because of relative inaccessibility and greater 

distance to markets than similar deposits elsewhere in 

southern California 

SUGGESTIONS FOR FURTHER STUDIES 

These studies identified geochemically anomalous 

drainages in the eastern part of the Raywood Flat Roadless Areas, but were not sufficiently detailed to identify 

the source of the anomalous metals. We recommend 

that the area of anomalous stream-sediment samples be 

studied in detail in order to confirm the extent and 

geologic setting of mineral occurrences that we infer to 

exist there. 

335 
REFERENCES 

Hewett, D. F., and Stone, Jerome, 1957. Uranothorite near Forest 

Home, San Bernardino County, California: American Mineralogist, V. 42, p. 104- 107. 

Matti, J. C., Cox, B. F., and Iverson, S. R., 1983, Mineral resource 

potential map of the Raywood Flat Roadless Areas, San Bernardino and Riverside Counties, California: U.S. Geological Survey 

Miscellaneous Field Studies Map MF- 1563-A, scale 1:62,500. 

336 

Pitkin, J . A., and Duval, J. S., 1981, Interpretation of an aerial 

radiometric survey of the San Gorgonio Wilderness Area and 

vicinity. San Bernardino County, California: U.S. Geological 

Survey Miscellaneous Field Studies Map MF- 1161 - B. scale 

1:62.500 

U.S. Geological Survey, 1979, Aeromagnetic map of the southern San 

Bernardino Mountains area; U.S. Geological Survey Open-file 

Report 79- 1448 

38° 

55' 

338 

120°35' 

7 " 

Approximate 

0 3 

MILES 

EXPLANATION 

~ Mine or deposit § Volcanic rocks 

Diorite 

Metamorphic rocks 

Figure 98.- Rubicon Roadless Area, California 

MAP LOCATION 
RUBICON ROADLESS AREA, CALIFORNIA 

By DAVIDS. HARWOOD , U.S. GEOLOGICAL S RVEY, and 

ERIC E. CATHER, U .. BUREAU OF MI ES 

SUMMARY 

Based on mineral-resource surveys conducted in 1981 and 1982, the Rubicon 

Roadless Area has little promise for the occurrence of metallic or energy 

resources. A very small demonstrated gold resource occurs at the Pigeon Roost 

mine. Glacial deposits, which occur in the eastern part of the area, are too 

bouldery and too small to be of value as construction materials. 

CHARACTER AND SETTING 

The Rubicon Roadless Area encompasses about 8 sq 

mi along the lower reaches of the Rubicon River, a major tributary of the Middle Fork of the American River 

that drains the west slope of the Sierra Nevada in 

eastern California Although the roadless area is small 

compared to many proposed and established Sierran 

wildernesses, its proximity to Placerville, 21 mi to the 

southwest, and to Sacramento, 37 mi to the west, make 

it a popular retreat for outdoor recreation. Access to the 

area is provided by a hard-surfaced road that extends 

eastward from Georgetown, toward Uncle Tom's Cabin. 

The hard-surfaced road crosses the Rubicon at the east 

boundary of the roadless area and traverses the north 

wall of the river canyon and the interfluve between the 

Rubicon and the Middle Fork of the American River to 

the north. The USFS maintains a campground at 

Stumpy Meadow Lake. 

The roadless area is generally confined to the steep, 

wooded canyon walls of the Rubicon River where local 

relief is as much as 1500 ft. The river has exposed a 

variety of metamorphic rocks that are intruded by 

small, isolated plutons of the Sierra Nevada batholith. 

The Ordovician(?) to Devonian(?) metamorphic rocks 

and Jurassic and Cretaceous igneous rocks are unconformably overlain by Tertiary volcanic rocks that cap 

the interfluves north and south of the river. Small 

deposits of bouldery gravel, which represent outwash 

from Pleistocene glaciers that capped the higher parts 

of the Sierra Nevada to the east, are plastered along the 

canyon walls in the eastern part of the area. Mineralresource surveys were conducted in the area in 1981 and 

1982 and a detailed geologic and geochemical report of 

the area has been published by Harwood (1983). A detailed evaluation of the mineral-resource potential has 

been published by Harwood and others (1983). 

MINERAL RESOURCES 

Gold and silver have been the principal interests of 

prospectors in the region since the discovery of gold in 

1849 at Sutters Mill, which is located only 14 mi west of 

the study area. Despite the proximity of the classic 

Mother Lode district to the west, no record of mineral 

production from the study area was found. Tertiary 

gravel at the abandoned Pigeon Roost mine contains 

gold values as high as $138 per cu yd (assuming $400/oz 

for gold) but the deposit is small and gold values are 

erratic. It has only a very small demonstrated gold 

resource. Holocene alluvium in Pigeon Roost Creek 

below the mine workings contains trace amounts of 

gold, but these areas are not classified as having a gold 

resource potential. 

SUGGESTIONS FOR FURTHER STUDIES 

Further investigations of the roadless area offer little 

promise for the occurrence of hidden potential mineral 

deposits. 

REFERENCES 

Harwood, D. S., 1983, Geologic and geochemical maps of the Rubicon 

Roadless Area. Placer and Eldorado Counties, California: U.S. 

Geological Survey Miscellaneous Field Studies Map 

MF- 1501 - A, scale 1:24,000. 

Harwood, D. S., Cather, E. E., and Scott. D. F., 1983, Mineral 

resource potential map of the Rubicon Roadless Area, Placer and 

Eldorado Counties, California: U.S. Geological Survey Miscellaneous Field Studies Map MF - 1501 - B, scale 1:24,000. 339 
41 ° 

oo· 

40° 

45' 

340 

• 

Au 

Hg 

Approximate 

boundary 

MAP LOCATION 

_::.. / 

0 

123°00' 122°45' 

~ 8 

~I/ 

l /' 

10 

MILES 

EXPLANATION 

Geologic terrane with substantiated 

mineral-resource potential 

Gold 

Mercury 

;.;l;~~~~:~: Granitic rocks (Jurassic) ~~I~~~~i'~, 

Serpentinite and gabbro (Jurassic or older) 

"'"' < ., o.l 

".> ;,':. Submarine volcanic and sedimentary 

'----=--"""' rocks (Triassic or Paleozoic) 

X' Mine 

Amphibolite and schist 

'-----' (Devonian or older) 

Contact Fault 

• • Thrust fault--Sawteeth on upper plate 

Figure 99.- Salmon-Trinity Alps Wilderness, California. 
SALMON-TRINITY ALPS WILDERNESS, CALIFORNIA 

By PRESTON E. HOTZ, U .S. G EOLOGI AL S RVEY, and 

H ORACE K. THURBER, U.S. BUREAU OF Mit E 

SUMMARY 

As a result of field studies in 1968-70 and 1972 it was determined that the 

Salmon-Trinity Alps Wilderness has an area with substantiated potential for 

gold resources in known lode deposits. Small amounts of quicksilver have been 

produced from one mine but there is little promise for the discovery of additional 

mercury resources. Geochemical sampling showed that anomalously high 

amounts of several other metals occur in a few places, but there is little promise 

for the discovery of energy or mineral resources other than mercury and gold. 

CHARACTER AND SETTING 

The Salmon-Trinity Alps Wilderness in the Klamath 

Mountains province occupies an area of about 648 sq mi 

in parts of Trinity, Siskiyou, and Humboldt Counties, 

northwestern California The central part of the area is 

about 45 mi northwest of Redding. The principal town 

in the region is Weaverville, which is about 15 mi south 

of the southern boundary of the wilderness, and is the 

county seat of Trinity County, The area is accessible by 

subsidiary roads and trails from State Highway 299 on 

the south and State Highway 3 on the east; the northern 

part can be reached by spur roads and trails from a 

county road that follows the South Fork of the Salmon 

River. The entire region is mountainous and heavily 

wooded. The relief is great, in many places is 2000-

3000 ft, with deep, steep-sided, narrow-bottomed canyons and sharp ridges. Maximum relief in the Trinity 

Alps is in the central part of the wilderness where the 

highest point, Thompson Peak, has an elevation of 

9002 ft. 

The rugged Trinity Alps in the central part of the 

wilderness are spectacular, where erosion by glaciers 

has resulted in many U-shaped valleys, lake-filled rock 

basins, sawtooth ridges, and other scenic alpine 

features. 

The Salmon-Trinity Alps Primitive Area was established prior to the Wilderness Act of 1964. A mineral 

survey of the primitive area and adjacent lands was 

made during the field seasons of 1968-70 (Hotz and 

others, 1972). At the request of the USFS the proposed 

additions to the primitive area were studied in 1973 

(Hotz and others, 1982). 

Fieldwork by the USGS included reconnaissance geologic mapping, which consisted of new mapping in the 

western one fourth of the area and checking and updating existing maps in the rest of the area Many prospects and abandoned mines were examined by the 

USBM and other geological features studied. The major 

effort was the collection of samples for a geochemical 

survey of the study area. Stream-sediment samples and 

panned concentrates were taken at regular intervals 

from the principal streams, and all the common rock 

types were sampled, including those with visible alteration and other evidence of possible mineralization. The 

USGS also made an aeromagnetic survey of the area 

(Griscom, in Hotz and others, 1972, p. 45; Hotz 1982, 

p.17). 

Three north-south-trending belts or packets of rocks 

occur in the area Slightly more than one-third of the 

western part is underlain by an assemblage of weakly 

metamorphosed sedimentary and submarine volcanic 

rocks. Meager fossil evidence indicates that these rocks 

range from middle or late Paleozoic to Jurassic in age. 

The central part of the area is occupied by older (Devonian), more strongly metamorphosed volcanic and sedimentary rocks which have been transformed to dark 

amphibolites and schists and impure marble. This belt 

of older rocks is a folded sheet that overlies rocks of the 

western belt along an eastward-dipping thrust fault 

whose surface trace is the belt's western boundary. 

Along the eastern part of the central belt, the underlying younger, less strongly metamorphosed volcanic and 

sedimentary rocks of the western belt are exposed in the 

eroded core of an upwarped (antiformal) fold in the overthrust sheet. 

341 
The eastern belt is part of a large body of dark igneous rocks (serpentinite and gabbro) which have been 

derived from the Earth's mantle and are thrust westward over the metamorphic rocks of the central belt. 

Several bodies of granitic rock intrude rocks of all three 

belts; they range from less than 1 mi to as much as 

10 mi in their greatest dimension, and only some of the 

largest are shown on the map. Long, narrow, tabular 

sheets of serpentinite and gabbro also occur along 

north-south-trending faults in the eastern part of the 

western belt, but are not shown on the map. 

MINERAL RESOURCES 

The area is in a region where gold has been sought extensively and mined from lodes and placer deposits. 

Discovery of gold on the Trinity River in July 1848 

stimulated prospecting in streams of the Trinity River 

drainage, including streams in the present wilderness. 

The first "quartz" or lode mines were located in the 

early 1880's. Total production of gold from lode 

deposits in and immediately adjacent to the wilderness 

exceeded $5 million. Placer deposits have a smaller total 

recorded production, on the order of $500,000, but not 

all the placer gold produced was recorded. 

Gold, the principal mineral resource of the area, is 

widely distributed, but more occurs in the western half 

of the area than in the eastern. Lode mines in five 

districts have produced significant amounts of gold and 

byproduct silver: the Globe-Bailey-Chloride mine 

group, the Mary Blaine Mountain-Old Denny district, 

the Dorleska and Yell ow Rose mines, the Alaska and 

McClaron mines, and the Grand National and Klatt 

mines. Although deposits in these districts are not exhausted, the resources of all except the area of the 

Globe-Bailey-Chloride group are small and low grade. 

Based on available data, the area of the Globe-BaileyChloride group has substantiated mineral-resource 

potential. 

Although placer gold was produced from most of the 

streams in the area, the most productive sections have 

been essentially worked out. The only placer mining 

342 

today is confined to small sporadic operations and recreational prospecting. 

A few flasks of quicksilver (mercury) were produced 

from the Cinnabar mine in the Mary Blaine MountainOld Denny mining district. This known deposit is small 

and inaccessible, and additional exploration would be required to determine its extent. 

Many gold veins contain a little copper, and a few 

minor concentrations of copper minerals have been 

prospected, but no copper resources have been 

identified. 

A few minor occurrences of chromium minerals are 

known in serpentinite in the eastern part of the area, but 

there is little promise for the discovery of chromium 

resources. 

The geochemical samples revealed traces of a wide 

variety of elements in the rocks and stream sediments. 

Anomalously high amounts of several metals, including 

copper, lead, zinc, silver, molybdenum, and mercury occur in a few places in the volcanic and sedimentary 

rocks in the western one third of the area. However, the 

geochemical sampling program failed to provide any 

evidence that the area has promise for discovery of 

energy or mineral resources. 

SUGGESTIONS FOR FURTHER STUDIES 

It is unlikely that further studies would identify any 

additional mineral resources in the wilderness area Additional work would define the mercury potential at the 

Cinnabar mine. 

REFERENCES 

Hotz, P. E., Thurber. H. K., Marks, L. Y., and Evans, R. K., 1972, 

Mineral resources of the Salmon-Trinity Alps Primitive Area, 

California, with a section on An aeromagnetic survey and inter· 

pretation by Andrew Griscom: U.S. Geological Survey Bulletin 

1371- B, 267 p. 

Hotz, P. E., Greene, R. C .. Close, T. J., and Evans, R. K., 1982, 

Mineral resources of proposed additions to the Salmon-Trinity 

Alps Primitive Area, California: U.S. Geological Survey Bulletin 

1514, 54 p. 
SAN GORGONIO WILDERNESS, CALIFORNIA 

By BRETT F. COX,' U.S. GEOLOGIC L RVEY , and 

ICHOLA T. ZILKA, U .. B REA OF Mit E 

SUMMARY 

The San Gorgonio Wilderness, located approximately 75 mi east of Los 

Angeles, California, was investigated by the USGS and USBM using field and 

laboratory studies during 1978. Several abandoned prospect pits, within and immediately adjacent to the wilderness, mark minor occurrences of metallic 

minerals, uranium, and marble, but little mineral production has come from the 

area Our studies suggest that any undiscovered mineral deposits that may be 

present in the wilderness probably are small and scattered. Accordingly, we feel 

that the San Gorgonio Wilderness has little promise for the occurrence of 

metallic mineral and energy resources. 

CHARACTER AND SETTING 

The San Gorgonio Wilderness comprises about 55 sq 

mi of rugged terrain in the southeastern San Bernardino 

Mountains, and lies within the San Bernardino National 

Forest. San Gorgonio Mountain, the highest peak in 

California south of the Sierra Nevada, rises to 11,500 ft 

near the center of the wilderness. California State 

Highway 38 skirts the west and north sides of the area, 

providing access to several vacation resorts near Big 

Bear Lake. 

The San Bernardino Mountains and San Gorgonio 

Wilderness are situated in the eastern part of the Transverse Ranges, a geologic province bounded by faults 

that trend east-west across the prevailing northwestsoutheast structural grain of California Even the San 

Andreas fault system is deflected from its usual 

northwest-southeast course to a nearly east-west trend 

where it passes through this region. A major inactive 

strand of the San Andreas system, the Mill Creek fault, 

borders the south side of the wilderness. During late 

Cenozoic time the area of the San Gorgonio Wilderness 

and other lands north of the Mill Creek fault were 

moved by faulting, probably tens of miles southeastward relative to land south of the fault. 

The geology of the wilderness has been mapped by 

Morton and others (1980). Southwestern and northern 

parts of the wilderness are characterized by dark-gray, 

'With contributions from Jonathan C. Matti and Howard W. Oliver. USGS. 

biotite-rich gneiss which is tentatively assigned a 

Precambrian age. Light-gray granitic gneiss that may 

include a mixture of Precambrian and Mesozoic rocks is 

exposed in the southern and eastern parts of the wilderness. Small bodies of metamorphosed sedimentary rock, 

including metaquartzite, marble, and skarn, are locally 

embedded within the granitic gneiss. Several large 

bodies of undeformed granitic rocks of Jurassic and (or) 

Cretaceous age, including granodiorite, monzogranite, 

and quartz monzodiorite, are exposed in the central and 

western parts of the wilderness. The gneissic and 

granitic bedrock of the wilderness is covered in a few 

places by sand and gravel deposited during the Quaternary Period. The largest masses of sand and gravel are 

contained in glacial moraines deposited along the 

margins of ancient glaciers that once flowed down the 

northwest and east flanks of San Gorgonio Mountain 

(Sharp and others, 1959; Herd, 1980). 

Geologic field studies of the wilderness, supplemented 

by geochemical and geophysical studies, and studies of 

mines and prospects confirm the existence of small scattered low-grade mineral occurrences. Aerial geophysical 

studies conducted by members of the USGS include 

surveys of gamma radiation (Pitkin and Duval, 1981) 

and geomagnetism (H. W. Oliver, unpub. data). The geophysical surveys do not reveal any abnormal patterns of 

radioactivity or rock magnetism, and thus provide no 

indication of mineral deposits. 

Investigation of historic mining, prospecting activity, 

and mineralized areas by the USBM indicates that little 

mineral production has come from the San Gorgonio 

343 
344 

34° 

00' 

117°00' 

Q'r Cd pa 

x Mineral occurrence 

~ Mine 

8 E R 

N 4 

Ana 

0 

Rr er 

MILES 

\ 

" 

EXPLANATION 

5 

·:··:··.: ='· Glacial gravel (Quaternary) 

M 0 MAP LOCATION 

U' N T 4 

- -dl N s 

boundary 

,~ .... ,~~~~,,!,., 

,'l,'_-;~:{t::"~'l.:, Granitic rocks (Cretaceous and (or) Jurassic ) " ,,,.~, ... ,, 

Granitic gneiss (Mesozoic?, Paleozoic?, and Precambrian) 

.__ __ _, Biotite-rich gneiss (Precambrian) 

Contact 

Fault 

B Location discussed in text 

Figure 100.- San Gorgonio Wilderness, Caliiornia. 
Wilderness and that only a few abandoned mines and 

prospects exist in the wilderness. USFS records, which 

cover only the last 35 years, show that only three claims 

are located within or immediately adjacent to the wilderness. Two of these claims produced small amounts of 

marble (A, on map) and low-grade uranium ore (B), 

whereas the third claim is apparently located in barren 

rock (C). Evidence of earlier mining and prospecting activity is limited to a collapsed mine shaft northeast of 

San Gorgonio Mountain (D). There are no conspicuous 

signs of mineralization at the ground surface near this 

shaft, and analyses of mine tailings indicate only trace 

amounts of gold, silver, and lead. 

MINERAL RESOURCES 

The San Gorgonio Wilderness holds little promise for 

the occurrence of metallic mineral or energy resources. 

Geologic and geochemical studies indicate that geologic 

terranes potentially favorable for mineral concentrations are small in size, scattered, and lack conclusive 

evidence that significant mineral enrichment has actually occurred. These geologic terranes include small 

bodies of metasedimentary rock, quartz veins, zones of 

iron-stained rock, and pegmatite bodies. 

Gold and tungsten occur in mining districts less than 

15 mi from the San Gorgonio Wilderness, primarily in 

large bodies of metasedimentary rock that are surrounded by granitic rock. By comparison, only a few 

small masses of metasedimentary rock, consisting 

mainly of marble and skarn, are present in the San 

Gorgonio Wilderness. These masses of marble and 

skarn are scattered on the rugged south and east flanks 

of San Gorgonio Mountain, where most of them are 

embedded in gneiss rather than in granitic rock. 

Geochemical data indicate that some molybdenum and 

tungsten enrichment of the skarn deposits has occurred. 

There was no visible evidence of metallic mineralization 

in the few masses of skarn that we examined, although 

it is possible that small amounts of molybdenum or 

tungsten minerals are associated with other bodies of 

skarn that were not examined. 

&attered quartz veins contain trace amounts of 

several metallic elements, most notably copper, gold, 

lead, molybdenum, silver, and tin. In addition, south of 

San Gorgonio Mountain, a zone of iron-stained gneiss 

along the East Fork of Whitewater River is slightly 

enriched in barium, chromium, copper, lead, and 

molybdenum. These geochemical patterns apparently 

reflect incipient mineralization related to deep-seated 

hydrothermal processes. However, no evidence was 

found to indicate that significant concentrations of 

metals are present in the quartz veins or iron-stained 

gneiss. 

An occurrence of an uranium-bearing mineral, uranothorite, was reported at a small abandoned open cut 

near Alger Creek (Hewett and Stone, 1957), a short 

distance south of the San Gorgonio Wilderness (B). The 

uranothorite is disseminated in three mutually adjacent 

pegmatite lenses composed of coarse-grained potassium 

feldspar and quartz and surrounded by granitic gneiss. 

This occurrence of uranium in pegmatite was investigated because similar pegmatite lenses are common in 

biotite-rich gneiss and granitic gneiss within the San 

Gorgonio Wilderness. The pegmatite lenses at the open 

cut are small, in cross section measuring no larger than 

4 ft wide by 50 ft long. They contain relatively small 

amounts of uranium; samples that we analyzed average 

only 0.02 percent uranium oxide. No persuasive 

evidence of significant uranium concentrations was 

found in the aerial radioactivity survey (Pitkin and 

Duval, 1981) or the geochemical survey. Therefore we 

suspect that any undiscovered uranium-bearing pegmatite bodies that may exist in the San Gorgonio Wilderness are small and have a uranium content similar to 

that of the pegmatite lenses near Alger Creek. 

Nonmetallic mineral resources in the San Gorgonio 

Wilderness include marble, sand and gravel, and granitic rock. Numerous small lenticular bodies of marble, 

most measuring no more than 50 ft across, are scattered 

as inclusions in granitic gneiss south and east of San 

Gorgonio Mountain. A small quantity of marble was 

quarried at the abandoned Mill Creek mine on the north 

wall of Mill Creek canyon (A). Glacial moraines on the 

north and east flanks of San Gorgonio Mountain contain a large volume of loose sand and gravel. Granitic 

rocks of suitable quality for general construction purposes are extensively exposed near the west end of the 

wilderness. However, all of these deposits are relatively 

inaccessible compared to deposits of equal or better size 

and quality that are widespread in southern California 

SUGGESTIONS FOR FURTHER STUDIES 

Current studies indicate that the San Gorgonio 

Wilderness has little likelihood for the occurrence of 

metallic mineral or energy resources. Accordingly, we 

do not believe that further study or investigation of the 

wilderness would result in identification of other 

mineral resources. However, in the event that future 

studies are planned, we recommend the following approaches: detailed mapping and geochemical studies of 

skarn bodies on the south and east flanks of San 

Gorgonio Mountain to investigate their potential for 

molybdenum and tungsten resources; detailed mapping 

and geochemical studies of iron-stained gneiss along the 

East Fork of Whitewater River to determine the potential for vein-related or disseminated concentrations of 

base or precious metals. 

345 
REFERENCES 

Cox, B. F., Matti, J. C., Oliver, H. W., and Zilka, N. T., 1983, Mineral 

resource potential map of the San Gorgonio Wilderness, San Bernardino County, California: U. S. Geological Survey Miscellaneous Field Studies Map MF-1161 - C, scale 1:62,500 (in press). 

Herd, D. G., 1980, Summary of investigations and results of studies 

in the San Gorgonio Mountain area, southern California, in 

Evernden, J. F., Summaries of technical reports, Volume 9-

National Earthquake Hazards Reduction Program: U.S. Geological Survey Open-File Report 80-6, p. 15-16. 

Hewett, D. F., and Stone, Jerome, 1957, Uranothorite near Forest 

Home, San Bernardino County, California: American Mineralogist, V. 42, p. 104-107. 

346 

Morton, D. M., Cox, B. F., and Matti, J. C., 1980, Geologic map of the 

San Gorgonio Wilderness, San Bernardino County, California: 

U.S. Geological Survey MisceUaneous Field Studies Map 

MF- 1161- A, scale 1:62,500. 

Pitkin, J. A., and Duval, J. S., 1981, Interpretation of an aerial 

radiometric survey of the San Gorgonio Wilderness Area and 

vicinity, San Bernardino County, California: U. . Geological 

Survey Miscellaneous Field Studies Map MF- 1161- B, scale 

1:62,500. 

Sharp, R. P., Allen, C. R., and Meier, M. F., 1959, Pleistocene glaciers 

on southern California mountains: American Journal of Science, 

v. 257, p. 81-94. 
SAN JACINTO WILDERNESS, CALIFORNIA 

By BREIT F. COX, 1 U.S. GEOLOGI AL S R EY and ' 

MART I D. CO AC , U.S. B REA OF Ml ES 

SUMMARY 

The San Jacinto Wilderness, located in the San Jacinto Mountains approximately 4 to 11 mi west of Palm Springs, California, was investigated by field 

and laboratory studies during 1978. The wilderness contains no known mineral 

deposits and no evidence of past mineral production. Geologic, geochemical, and 

geophysical studies indicate that the San Jacinto Wilderness has little promise 

for the occurrence of mineral or energy resources. 

CHARACTER AND SETTING 

The San Jacinto Wilderness lies within San Bernardino National Forest in Riverside County, and includes 

two separate parcels located north and south of Mt. San 

Jacinto State Park. The two parcels cover approximately 34 sq mi. The north parcel occupies the precipitous northern face of 10,800-ft San Jacinto Peak, and 

consequently is relatively inaccessible. Interstate Highway 10 and California State Highway 111 are located a 

few miles north and northeast of the north parcel. A 

high plateau and adjacent ridges in the southern parcel 

are accessible by trails that originate near California 

State Highway 243 at the mountain village of Idyllwild. 

This trail system also connects with an aerial tramway 

in Mt. San Jacinto State Park. 

The San Jacinto Wilderness lies near the northern end 

of the Peninsular Ranges of southern California, a 

geologic province that is dominated by plutonic igneous 

rocks of Mesozoic age (Morton and others, 1980). Crystalline bedrock is exposed in most parts of the two 

parcels except for a few areas that are underlain by 

small deposits of Quaternary gravel. Roughly 85 percent of the bedrock consists of plutonic igneous rocks of 

Mesozoic age; the remaining 15 percent consists of 

metasedimentary rocks of Paleozoic and (or) Mesozoic 

age. 

Compositionally uniform hornblende-biotite tonalite 

is the predominant rock type in the north parcel. Two 

narrow bodies of quartz diorite with abundant mafic inclusions are surrounded by the tonalite. A heterogeneous assemblage of plutonic rocks is exposed directly 

east of the tonalite body in the south parcel and at the 

'WiLh cont.ribut.ions from JonatJ>an C. MaW and Howard W. Oliver. USGS. 

east end of the north parcel. This assemblage consists 

mainly of leucocratic rocks including granodiorite, 

monzogranite, and quartz monzonite, but subordinate 

amounts of mafic quartz diorite and gabbro are present 

locally in the north parcel. 

Metasedimentary rocks are located mainly in the 

eastern half of the south parcel and directly east of the 

north parcel. In both areas, but especially in the latter 

area, the metasedimentary rocks have been complexly 

intruded by leucocratic granitic rocks of the hetero· 

geneous plutonic assemblage. The metasedimentary 

rocks include biotite-rich gneiss and schist, micaceous 

quartzite, and minor amounts of marble and calc-silicate 

hornfels. These rocks are isoclinally folded and contain 

scattered quartz veins and abundant dikes and lenticular segregations of pegmatitic granite. 

Geologic field studies were supplemented by geochemical and geophysical studies. A reconnaissance 

geochemical survey of bedrock and stream sediments 

was conducted to search for characteristic associations 

or anomalous abundances of elements that might be 

caused by concealed mineral deposits. Geophysical 

studies were conducted only in the southern parcel; 

these include an aeromagnetic survey (U.S. Geological 

Survey, 1979) and a north-south gravity profile (H. W. 

Oliver, unpub. data, 1982). The north parcel was excluded from these two surveys because of steep 

topography. 

The history of mineral exploration and the present 

status of claims and prospects in the San Jacinto Wilderness and vicinity were investigated by the USBM. 

No mineral production has come from the wilderness 

and only 6 small blocks of inactive, unpatented claims 

existed in the area at the time of this study. No workings were found on any of the claims, and samples collected on the claims lack evidence of metallic minerals. 

347 
34 

34° 

45' 

SAN GORGON 0 PASS 

North Parcel 

San Jacinto 

Wilderness 

0 

MILES 

EXPLANATION 

Sand and gravel (Quaternary) 

Tonalite (Cretaceous) 

5 

Inclusion-rich quartz diorite (Cretaceous) 

Heterogeneous plutonic rocks (Cretaceous) 

MAP LOCATION 

Metasedimentary and plutonic rocks, undifferentiated 

(Mesozoic and Paleozoic) 

Contact 

Figure 101.- San Jacinto Wilderness, Calilomia 
Mineral resources in nearby areas outside the wilderness are limited, consisting of limestone and marble, 

sand and gravel, and minor amounts of gold. 

MINERAL RESOURCES 

Our studies indicate that the San Jacinto Wilderness 

has little promise for the occurrence of mineral resources. Most parts of the wilderness lack geologic environments that are suitable for the occurrence of mineral 

deposits. The north parcel and western half of the south 

parcel are underlain by plutonic igneous rocks that lack 

mineralized veins or dikes, or any other features of 

potential interest. The plutonic rocks themselves might 

be utilized as construction materials, but this is unlikely 

because similar deposits outside the wilderness are of 

equal or better quality, more accessible, and closer to ex· 

isting markets. 

Geologic enviroiL"'lents potentially favorable for the 

occurrence of mineral deposits are limited to the belt of 

metasedimentary rocks in the eastern half of the south 

parcel, particularly those parts of this belt that lie near 

intrusive contacts with plutonic igneous rocks. Elsewhere in the Peninsular Ranges, deposits of metallic 

minerals are locally concentrated where similar metasedimentary rocks have been intruded by Mesozoic 

plutons. However, during the geologic field studies no 

evidence of significant mineralization in the belt of 

metasedimentary rocks was identified. 

Geochemical data indicate that the metasedimentary 

rocks and their derivative stream sediments in the 

eastern part of the southern parcel locally contain 

above-average amounts of several elements, including 

boron, barium, cerium, chromium, copper, lanthanum, 

molybdenum, nickel, tin, tungsten, and zinc; but the 

maximum concentrations of these elements are low in 

comparison to values that have been reported in 

geochemical surveys of districts with known mineral 

deposits. The slight mineral enrichment of metasedi· 

mentary rocks indicated by the geochemical survey 

probably reflects weak metasomatism of country rock 

during the intrusion of plutonic igneous rocks, and no 

potential for resources was identified. 

Geophysical surveys of the south parcel also provide 

no indication of concealed mineral deposits. The aeromagnetic map (U.S. Geological Survey, 1979) shows 

remarkably little variation in magnetic intensity and 

thus indicates there are no significant mafic igneous in· 

trusions or concentrations of iron-rich magnetic 

minerals in the south parcel. The north-south gravity 

profile extending through the western part of the south 

parcel between Idyllwild and San Jacinto Peak confirms 

the relatively homogeneous nature of the plutonic rocks 

in this area and indicates there are no buried rock bodies 

with abnormally high or low density near the line of the 

survey. 

SUGGESTIONS FOR FURTHER STUDIES 

On the basis of our studies further exploration of the 

wilderness is not warranted. However, if future studies 

of plutonism and related processes of mineralization are 

conducted in the San Jacinto Mountains and vicinity, 

the metasedimentary rocks and bordering intrusive contacts in the south parcel of the wilderness might merit 

further examination. In particular, such future studies 

might further evaluate the origin and significance of 

minor stream-sediment geochemical anomalies for tung· 

sten, cerium, and lanthanum detected in our pannedconcentrate samples collected near the heads of Murray 

and Andreas Canyons. 

REFERENCES 

Cox, B. F., Matti, J. C., Oliver, H. W., and Conyac, M. D., 1983, 

Mineral resource potential map of the San Jacinto Wilderness, 

Riverside County, California: U.S. Geological Survey Miscellaneous Field tudies Map MF- 1159-B, scale 1:62,500 (in press). 

Morton, D. M., Matti, J. C., and Cox, B. F., 1980, Geologic map of the 

San Jacinto Wilderness, Riverside County, California: U.S. 

Geological Survey Miscellaneous Field Studies Map 

MF- 1159- A, scale 1:62,500. 

U.S. Geological Survey, 1979, Aeromagnetic map of the San Jacinto 

area, California: U.S. Geological Survey Open-File Report 

79- 1447. 

349 
350 

0 fon11ly Lak,. 

Ca,:I.,D 

Lake 

MAP LOCATION 

'-'o ~., 

ro., 

Jol'l star 

[ k 

9368 

., 

\ Approximate -..... \ 

roadless "\) 

boundary 

F507 ~ 

~ 

I 

I 

I ~ / 

"'Q, / 

o"( 

I 

I 

I 

119°05' 

37° 

37' L---~----------------------------------~--------~~--~ 

D 

D 

0 

MILE 

EXPLANATION 

Granitic rocks (Cretaceous) 

Metamorphic rocks (Jurassic, Triassic, 

and Ordovician) 

Contact 

Figure 102.-San Joaquin Roadless Area, California 
SAN JOAQUIN ROADLESS AREA, CALIFORNIA 

By EDWI H. M CKEE, U.S. GEOLOGI AL SURVEY and 

' 

DONALD 0. CAPSTICK, U.S. B REA OF Mr E 

SUMMARY 

The results of geologic, geochemical, and mining-activity and production 

surveys in 1981 in the central part of the San Joaquin Roadless Area indicate little promise for the occurrence of metallic-mineral or energy resources in the area. 

Sand, gravel, and pumice exist in the area but occurrences are small and isolated 

and farther from major markets than similar deposits outside the roadless area. 

Rocks in the area are exhibited in exposures of unaltered and nonmineralized 

granitic and metavolcanic rock along the steep western wall of the glacially 

carved valley of the Middle Fork of the San Joaquin River. Drainage in the area 

consists of seeps along fractures in the cliff or small cascading streams, a 

hydraulic setting not favorable for the development of placer deposits. No mines 

or prospect workings were found in the roadless area Alteration zones within 

the granitic and metamorphic rock that crop out within the area are small, 

isolated, and consist only of limonitic staining and bleached quartzose rock. 

CHARACTER AND SETTING 

The San Joaquin Roadless Area is composed of three 

noncontiguous areas on the eastern side of the Sierra 

Nevada in Madera County, California The central part 

of area F504 7 was classified by the USFS as a further 

planning area and was studied by McKee and Capstick 

(1982). The area is located about 5 mi northwest of 

Mammoth Lakes, California, and is contiguous with the 

Devils Postpile ational Monument on the south and 

the Minarets Wilderness on the west. The roadless area 

comprises about 3 sq mi along the western of the Middle 

Fork of the San Joaquin River. Altitudes range between 

about 7560 ft above sea level along the river, to about 

9800 ft on the western crest of the area Access to 

within 1 mi of the eastern edge of the area is provided by 

the road from Mammoth Lakes to Devils Postpile National Monument. 

The geology of the roadless area is shown on the geologic map of the Devils Postpile 15-rninute quadrangle, 

mapped by Huber and Rinehart (1965). Most of the area 

is underlain by Mesozoic granitic rock that intrudes 

regionally metamorphosed older Mesozoic volcanic 

rocks. A small amount of Pleistocene andesite similar to 

that of the Devils Postpile crops out in the area 

The northern part of the roadless area contains a 

metavolcanic sequence comprised of crystal-lithic tuff, 

tuff breccia, tuffaceous sandstone, and lava flows. 

These dominantly pyroclastic rocks are mostly rhyolite 

to dacite in composition but some basalts and andesites 

are present. The age of these rocks is considered by 

Huber and Rinehart (1965) to be Triassic(?) or Jurassic 

on the basis of fossils found about midway in the stratigraphic sequence. The lower part of the sequence may 

be as old as Permian (Huber and Rinehart, 1965). 

The southern part of the roadless area is comprised of 

granitic rock. These rocks range in composition from 

granodiorite to alaskite but have an average composition of quartz monzonite. K-Ar age determinations on 

biotite from this unit yield a Cretaceous age of about 

85 million years. 

Andesite flows almost contiguous with the flows that 

form Devils Postpile crop out on the eastern edge of the 

roadless area The andesite is medium-gray, aphanitic, 

and locally contains plagioclase and olivine phenocrysts. Well-developed platy and columnar joints characterize the unit. 

MINERAL RESOURCES 

The area lies along the steep western face of the 

Middle Fork of the San Joaquin River Canyon and is 

underlain by unaltered and nonmineralized granitic and 

351 
metavolcanic rock. o mmmg claim monuments or 

definite signs of mining or prospecting activity were 

found within the roadless area Placer deposits in the 

unconsolidated alluvium of the Middle Fork valley are 

not known although the river has undoubtedly been 

prospected many times by pan techniques. Sand, 

gravel, and pumice were found in the area, but occurrences are small and distant from forseeable markets. 

The geologic setting precludes the presence of oil and 

gas resources. 

Geochemical sampling of stream sediment to define 

element anomalies in eroded material from erosion 

basins is of limited value in this roadless area The only 

drainage in the area that is actively eroding bedrock and 

transporting sediment is the Middle Fork of the San 

Joaquin River, along the eastern boundary of the area 

Almost all eroded material carried by the Middle Fork is 

from outside the roadless area, the amount of sediment 

added to the Middle Fork from the roadless area is 

352 

negligible. Samples of stream sediment, nonmagnetic 

heavy-mineral concentrates, and rocks were spectrographically analyzed for 31 elements and show no 

anomalous amounts of any metallic element. 

SUGGESTIONS FOR FURTHER STUDIES 

Further study of the roadless area offers little promise 

for the identification of hidden mineral deposits. 

REFERENCE 

Huber, . K., and Rinehart, C. D., 1965, Geologic map of the Devils 

Postpile quadrangle, Sierra evada, California: U.S. Geological 

Survey Quadrangle Map GQ-437, scale 1:62,500. 

McKee, E. H., and Capstick, D. 0., 1982, Mineral resource potential of 

part of the San Joaquin Roadless Area, Madera County, California: U.S. Geological Survey Open-File Report 82- 993, 13 p. 
SAN RAFAEL PRIMITIVE AREA, CALIFORNIA 

By H. D. GOWER,' U .. G EOL GI L SURVEY 

SUMMARY 

No mineral-resource potential was identified by the USGS and USBM in 1965 

during studies of the San Rafael Primitive Area, located at the southern end of 

the Coast Ranges of California No petroleum has been produced from the area 

and there is little promise for the occurrence of energy resources. Limestone 

occurs in the area but also is found in abundance outside the area 

CHARACTER AND SETTING 

The San Rafael Primitive Area includes about 

220 sq rni in the Los Padres National Forest in the San 

Rafael and Sierra Madre Mountains in the southern 

part of the Coast Ranges of California The mountainous and rugged area, about 13 mi north of Santa 

Barbara and 25 rni southeast of Santa Maria, is characterized by sharp ridges and steep-walled canyons. 

Layers of resistant rock crop out along the ridges and 

canyon walls and form cliffs from 100 to more than 

400 ft high. Most of the slopes and ridges are densely 

covered by brush that is nearly impenetrable. 

The San Rafael Primitive Area is underlain by Cretaceous and Tertiary sedimentary rocks that are about 

22,000 ft thick. These rocks are mainly sandstone, conglomerate, siltstone, and shale, but they include some 

siliceous shale and minor amounts of limestone. Most of 

the rocks are of marine origin. The only igneous rocks in 

the area are two small intrusions. The sedimentary 

rocks are moderately to intensely faulted and folded, 

because deformation occurred after each episode of sedimentation recorded by the Cretaceous, Eocene, and 

Miocene rocks. As a result, the older rocks are generally 

more steeply dipping and faulted than the younger 

ones, and unconformities separate the main sedimentary sequences. Most major faults and folds trend 

N. 60 °-80 ° W., following the general alinement of the 

southern Coast Range structures. In fact, some of the 

larger faults in the area are among the major structural 

elements of the Coast Range fault system. 

The San Rafael Primitive Area was studied in 1965 by 

means of ground traverses, helicopter overflights, and 

1 Abstracted !Tom n repOrt by Gower and others (19661 by Susan 'l'u!t.s, wit.h contributions 

from J. G. Vedder. USGS. 

aerial photographs. Additional studies included geochemical analyses of stream sediments and bedrock 

samples, as well as fossil identifications. After the initial studies in 1965, the boundaries of the San Rafael 

Primitive Area were modified to include additional 

lands to the north and southwest and to exclude one 

small part of the original area Further studies were conducted late in 1965 to include the new areas, and the 

results were published the following year (Gower and 

others, 1966). 

MINERAL RESOURCES 

No mineral-resource potential was identified in the 

San Rafael Primitive Area, although the southern Coast 

Ranges of California elsewhere contain important deposits of petroleum, mercury, diatomite, and other mineral commodities. These commodities are localized in 

specific geologic environments of limited extent, and 

their occurrence is dependent on certain geologic factors. In general, the San Rafael Primitive Area lacks the 

geologic conditions associated with known major mineral deposits. 

There is no record of exploratory drilling for petroleum and natural gas within the San Rafael Primitive 

Area, although the primitive area is flanked at distances 

of several miles on the north, west, and southeast by 

producing oil fields. Test holes in adjacent areas were 

not productive, although minor amounts of petroleum 

were present in Miocene and possibly older rocks. 

Despite the fact that marine sedimentary rocks of 

Miocene age, which have been prolific producers of 

petroleum in nearby oil fields, underlie about 25 percent 

of the primitive area, they are thin and lack potential 

trap structures, except on a relatively small scale on the 

north limb of the Hurricane Deck syncline. Even there 

353 
55' 

45' 

MAP LOCATION 

354 

proximate boundary 

0 5 

MILES 

EXPLANATION 

Sedimentary rocks (Miocene) 

Sedimentary rocks (Eocene ) 

Limestone (Eocene) 

Sedimentary rocks (Upper 

Cretaceous) 

Contact 

---.-- Fault--Bar and ball on downthrown 

side 

Figure 103.-San Rafael Primitive Area, California 
the existence of petroleum accumulations is doubtful, 

because most of the potential reservoir rocks lie above 

the drainage level of the Sisquoc River. The other 75 

percent of the primitive area is occupied by rocks of 

Late Cretaceous and Eocene age, which have produced 

little or no petroleum in nearby areas. The largest of the 

possible structural traps for petroleum in the primitive 

area is the Mission Pine anticline, a broad east-plunging 

fold that is cut by several north-trending faults and terminates against a branch of the Big Pine fault near 

McKinley Mountain, just outside the southwestern 

border of the primitive area Possible entrapment of 

petroleum could take place next to the fault near 

McKinley Mountain or along any of the faults that cut 

the crest of the fold. However, there is little promise for 

the occurrence of petroleum because this large structure 

involves only Cretaceous rocks, which have not been 

productive nearby. Elsewhere in the primitive area, Cretaceous, Eocene, and Miocene rocks have been folded 

into several small anticlines, but these folds generally 

lack apparent structural closure. 

Although the San Rafael Primitive Area is bordered 

on the southwest by the once-productive Cachuma 

quicksilver (mercury) district, the carbonate-altered 

host rock of Late Jurassic to Early Cretaceous age for 

these deposits and closely associated serpentine intrusions are not known in the primitive area Geochemical 

studies of stream sediments and bedrock samples indicate a weak mercury anomaly in Sulphur Spring Canyon near the southwestern border of the area, but the 

mercury content of the richest rocks samples is only 

about one-thousandth of that of most mercury ores. 

Because of the presence of favorable host rocks for 

uranium, a scintillometer survey was taken after publication of the initial report on the area (H. E. Clifton, 

written commun., 1966). Readings were taken at several 

locations across the contact of Miocene and Cretaceous 

rocks, but none of the readings were sufficiently above 

the background levels for these rocks to indicate any 

uranium resource potential. 

Limestone of possible commercial use occurs in the 

southeastern part of the primitive area, but other areas 

outside the primitive area contain resources of limestone that are easier to obtain and closer to markets. 

Five mineral claims, or groups of claims, are recorded 

from the San Rafael Primitive Area, but no discovery 

pits were recognized in the field, although one prospect 

not previously recorded was found along the Sisquoc 

River in the central part of the primitive area This prospect consists of an adit 15 ft long driven in Upper 

Cretaceous sandstone; no evidence of mineralization 

was seen. There is no record of any mineral production 

within the primitive area 

SUGGESTIONS FOR FURTHER STUDIES 

Inasmuch as sampling and analytical techniques have 

improved significantly since this study was completed 

(1965), a restudy of the area using new methodology is 

possibly warranted. 

REFERENCE 

Gower, H. D., Vedder, J. G., Clifton, H. E., and Post, E. V., 1966, 

Mineral resources of the San Rafael Primitive Area, California; 

U.S. Geological Survey Bulletin 1230-A, 28 p. 

355 
u 

( 

, 101 

0 

MILES 

120°15 

WIDOW PROSPECT 

MAP LOCATION 

SAYLOR 

10 

EXPLANATION 

D 

Hg 

u 

X 

Geologic terrane with probable 

mineral-resource potential 

Mercury 

Uranium 

Mine or deposit 

Mineral occurrence 

Neogene sedimentary rocks 

Pre-Miocene sedimentary rocks 

Mesozoic igneous and 

metamorphic rocks 

Contact 

Fault 

Figure 104.- Santa Lucia Wilderness, and Garcia Mountain, Black Mountain, La Panza, Machesna Mountain, Los Machos Hills, Big Rocks, 

and Stanley Mountain Roadless Areas, California. 

356 
SANTA LUCIA WILDERNESS, AND GARCIA MOUNTAIN 

BLACK MOUNTAIN, LA ' PANZA, MACHESNA MOUNTAIN 

LOS MACHOS HILLS, BIG ROCKS, AND ' 

STANLEY MOUNTAIN ROADLESS AREAS, CALIFORNIA 

By VIRGIL A. FRIZZELL, jR. , 1 U .. GEOLOG ICAL R EY, and 

L UClA K UIZON, .S. BUREA OF MI E 

SUMMARY 

On the basis of a mineral-resource evaluation conducted in 1980-83, a small 

area in the Black Mountain Roadless Area has a probable mineral-resource 

potential for uranium, and a small area in the Stanley Mountain Roadless Area 

has probable potential for low-grade mercury resources. Although petroleum 

resources occur nearby in rocks similar to those found in the study area, no 

potential for petroleum resources was identified in the wilderness or any of the 

roadless areas. No resource potential for other mineral resources was identified 

in any of the areas. 

CHARACTER AND SETTING 

The Santa Lucia Wilderness Area and Garcia Mountain, Black Mountain, La Panza, Machesna Mountain, 

Los Machos Hills, Big Rocks, and Stanley Mountain 

Roadless Areas together occupy an area of about 218 sq 

rni in the Los Padres National Forest, California For 

purposes of this report the individual areas will be referred to collectively as the study area 

The study area is in the southern part of the Coast 

Ranges and western part of the Transverse Range near 

San Luis Obispo and Santa Maria, California California 

State Highways 58, 101, and 166 connect to paved and 

unpaved roads that allow access to the study area 

The study area is characterized by steep-walled canyons and sharp ridges. Although summit ridges locally 

support coniferous forests and riparian woodlands line 

valley bottoms, impenetrable chaparral covers much of 

the mountain slopes and makes off-trail traverses 

difficult. 

Thick fault-bounded sequences of sandstone, siltstone, shale, and conglomerate and igneous and metamorphic rocks are present in the study area (Frizzell and 

Vedder, in press). Cretaceous biotite granite and preCretaceous metasedimentary rocks underlie part of the 

'With contributions by George E. Claypool, Andrew Griscom, and David B. Smith, USG , 

and David J . Barnes, David K. Dent.on, Jr .. Leon E. Esparza. Pew . Gabby, David A. 

Lipt.on, and Charles E. Sabine. USBM. 

La Panza Range, and Jurassic oceanic volcanics and 

related sedimentary rocks and serpentinized peridotite 

occur in the southern part of the study area Mesozoic 

through Cenozoic sedimentary rocks underlie the remainder of the study area and are divided on the basis 

of age into pre-Miocene sedimentary rocks and Neogene 

sedimentary rocks. 

Pre-Miocene sedimentary rocks consist chiefly of 

interbedded sandstone, siltstone, shale, and conglomerate. These rocks range in age from Late Jurassic to 

Oligocene, but most are Late Cretaceous. They were 

deposited mainly in deep marine environments but local 

nonmarine strata are included. Mapped with these rocks 

are small areas underlain by the Franciscan assemblage, 

a unit of highly sheared and chaotically mixed sedimentary and less abundant igneous rock. 

Organic-rich siltstone and shale, interbedded sandstone and lesser conglomerate predominate in the 

Neogene section. These rocks formed mostly from sediments deposited in relatively restricted marine basins 

where the organic remains of flora and fauna living in 

the water column constituted a relatively important 

source of sediment. Lesser amounts of Neogene nonmarine rocks are also present. 

In addition to geologic mapping, multidisciplinary 

work in the study area included evaluation of mines and 

prospects, geophysical investigations, and organic and 

inorganic geochemical studies. 

357 
Mercury deposits were discovered just north of the 

Santa Lucia Wilderness in 1872 and just north of 

Stanley Mountain in 1915. Uranium minerals and minor 

uranium production were reported in the study area in 

the 1950's. Producing oil and gas fields are situated 

nearby, but exploration has not been successful in the 

study area 

Geophysical studies include the compilation and analysis of aerial gravity and magnetic data (Griscom, in 

press). The gravity data indicate that the Miocene 

marine rocks in the southern two-thirds of the Santa 

Lucia Wilderness occupy a basin on trend with the 

Huasna basin to the southeast but those rocks are 

isolated from the Huasna basin by a ridge of preMiocene rocks. Analytical results from stream-sediment 

samples only delineate areas with previously known 

mineralization (Smith and others, in press). Analyses of 

fine-grained sedimentary rocks collected for a study of 

organic matter mostly indicate low quantities of oil and 

gas producing materials. 

MINERAL RESOURCES 

Our studies (Frizzell and others, in press) indicate 

that most rocks within the study area do not appear to 

have been favorable hosts for the concentration of 

metallic minerals or petroleum resources. However, the 

Black Mountain Roadless Area has an area of probable 

potential for low-grade uranium resources and the Stanley Mountain Roadless Area has an area of probable 

potential for low-grade mercury resources. 

Although there are no producing mines in the study 

area, nearly all the separate roadless areas have had 

placer and lode claims for gold or uranium located in 

them, and some of these claims are still current. Spanish 

settlers found gold in alluvial deposits, and placer gold 

has been produced in small quantity within the Black 

Mountain, La Panza, and Machesna Mountain Roadless 

Areas. While these and other units of the study area 

still contain numerous localities underlain by terrace 

and alluvial deposits, our studies show that gold contents are low (Frizzell and others, in press; Barnes, 1981; 

Kuizon, 1983b; Denton, 1982). This and the generally 

small volumes of these deposits preclude any significant 

placer-gold resource potential within the study area 

Approximately 69 lode claims for uranium are located 

in the Black Mountain Roadless Area Metasedimentary rocks (biotite schist, gneiss, and marble) which 

have been intruded by granitic rocks, locally give scintillometer readings four to five times background. The 

Black Widow prospect occurs in an area of probable 

uranium resource potential and has probably produced 

358 

400 lbs of Us0 8• This and nearby prospects contain 

demonstrated and inferred low-grade resources of about 

156,000 tons of uranium-bearing rock averaging 

0.02-0.18 percent UsOs (Gabby, 1981, p. 9). 

Samples collected from the Clyde's Saylor prospect in 

the Machesna Mountain Roadless Area contain very 

low quantities of Us0 8, as well as minor gold and silver 

(Kuizon, 1983b), but no resource potential was 

identified. 

Cinnabar, an ore mineral of mercury, is locally found 

near major faults. The Deer Trail mercury mine, just 

outside the Stanley Mountain Roadless Area, is located 

on a fault and contains cinnabar-filling fractures in brecciated calcite. The mine produced 200 flasks of mercury 

prior to 1951, and contains inferred resources of about 

32,000 tons having 1.71 lbs of mercury per ton (Kuizon, 

1983c). Areas adjacent to the mine but inside the 

roadless area have a probable potential for low-grade 

mercury resources. 

Because the study area is predominantly underlain by 

sedimentary rock, is located near the Arroyo Grande 

and Santa Maria oil and gas fields, and because petroleum lease applications have been filed on lands in the 

area, oil and gas resource potential might be expected. 

Reconnaissance oil and gas studies (Frizzell and Claypool, in press; Howell and Claypool, 1977), however, 

indicate that this is not the case. Samples from preMiocene rocks collected for the studies cited above contain organic matter in quantities below that necessary 

to produce significant amounts of hydrocarbons. Furthermore, the organic matter is terrestrial woody 

material, rather than the type that normally produces 

oil. 

Miocene marine rocks, which are about 5000 ft thick, 

underlie the southwestern two-thirds of the Santa Lucia 

Wilderness and are a northwestern continuation of 

rocks that underlie the minimally petroleum-producing 

Huasna basin. The rocks contain sufficient quantities 

and suitable types of organic matter necessary to 

generate hydrocarbons, but the section here is relatively 

thin and has been well breached by erosion. Thus, although these Miocene marine rocks are the most likely 

to contain petroleum, no resource potential for petroleum was identified in the study area 

SUGGESTIONS FOR FURTHER STUDIES 

Detailed geologic mapping and geochemical sampling 

in the vicinity of the Black Widow prospect and Deer 

Trail mine probably would increase knowledge about 

distribution and modes of occurrence of uranium and 

cinnabar in those areas, respectively. 
REFERENCES 

Barnes, D. J., 1981, Mineral resources of the La Panza RARE II Area 

(No. 5109), San Luis Obispo County, California: U.S. Bureau of 

Mines Open-File Report MLA 34-81, 10 p. 

Denton, D. K., Jr., 1982, Mineral resources of the Los Machos Hills 

RARE II Area (No. 5111), San Luis Obispo County, California: 

U.S. Bureau of Mines Open-File Report MLA 3- 82,8 p. 

Frizzell, V. A .. Jr., and Claypool, G. E., in press, Petroleum potential 

map of Mesozoic and Cenozoic rocks in roadless areas and the 

Santa Lucia Wilderness in the Los Padres National Forest, 

southwestern California: U.S. Geological Survey Miscellaneous 

Field Studies Map MF- 1655- D. 

Frizzell, V. A., Jr., Smith, D. B., Kuizon, Lucia, and Hale, W. N., in 

press. Mineral resource potential map of roadless areas and the 

Santa Lucia Wilderness in the Los Padres National Forest, 

southwestern California: U.S. Geological Survey Miscellaneous 

Field Studies Map MF-1655- B. 

Frizzell, V. A., Jr., and Vedder, J. G., in press. Geologic map of 

roadless areas and the Santa Lucia Wilderness in the Los Padres 

ational Forest, southwestern California: U.S. Geological Survey 

Miscellaneous Field Studies Map MF -1655- A. 

Gabby, P. N., 1981, Mineral resources of the Black Mountain RARE 

II Area (No. 5108), San Luis Obispo County, California: U.S. 

Bureau of Mines Open File Report MLA 21-82, 12 p. 

Griscom, Andrew, in press, Aeromagnetic map of part of the Los 

Padres ational Forest in the southern Coast Range and western 

Transverse Range, California: U.S. Geological Survey Miscellaneous Field Studies Map MF-1658-A. 

Griscom, Andrew, in press, Bouguer gravity map of part of the Los 

Padres ational Forest in the southern Coast Range and western 

Transverse Range, California: U.S. Geological Survey Miscellaneous Field Studies Map MF- 1658- B. 

Howell, D. G .. and Claypool, G. E., 1977, Reconnaissance petroleum 

potential of Mesozoic and Cenozoic Rocks, Coast Ranges, California, in Howell, D. G .. Vedder, J. G., and McDougall, K., eds., Cretaceous Geology of the California Coast Ranges, West of the San 

Andreas Fault: Pacific Section, Society of Economic Paleontologists and Mineralogist, Pacific Coast Paleogeography Field 

Guide 2, p. 85- 90. 

Kuizon, Lucia, 1983a, Mineral investigation of the Big Rocks RARE 

II Area (No. 5112), San Luis Obispo County, California: U.S. 

Bureau of Mines Open File Report MLA 12- 83, 8 p. 

__ 1983b, Mineral investigation of the Machesna Mountain 

RARE II Area (No. 5110), San Luis Obispo County, California: 

U.S. Bureau of Mines Open File Report MLA 13- 83, 11 p. 

__ 1983c, Mineral investigation of the Stanley Mountain RARE 

II Area (No. 5113), San Luis Obispo County, California: U.S. 

Bureau of Mines Open File Report MLA 57-83, 13 p. 

Lipton, D. A., 1981, Mineral resources of the Garcia Mountain RARE 

II Area (No. 5107), San Luis Obispo County, California: U.S. 

Bureau of Mines Open File Report MLA 8- 82, 9 p. 

Sabine, Charles, and Esparza, L. E., 1981, Mineral resources of the 

Santa Lucia Wilderness, San Luis Obispo County, California: 

U.S. Bureau of Mines Open File Report MLA 16- 82, 6 p. 

Smith, D. B .. Frizzell, V. A., Jr., Adrian, B. M., Vaughan, R. B .. and 

McDougal, C. M., in press, Geochemical map of the roadless 

areas and the Santa Lucia Wilderness in the Los Padres ational 

Forest, southwestern California: U.S. Geological Survey Miscellaneous Field Studies Map MF- 1655- E. 

U.S. Bureau of Mines, in press. Mines and prospects map of roadless 

areas and the Santa Lucia Wilderness in the Los Padres ational 

Forest, southwestern California: U.S. Geological Survey Miscellaneous Field Studies Map MF - 1655-C. 

359 
35° 

35' 

360 

~------

s ' 0 ,----·_.. 't;, 

c., 

I I)Y, 

01) 

I 

I 

I 

I 

I 

0 

0 

Pinynn Pea~ 

X 

VALENTINE ' • • 

PROSPECTx 

Approximate roadless--J 

boundary -.::: Quartz 

05212 I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

0 " 

GREAT d I 

WHITE X ( \ 

• 

~ 

Ca,, I - ---?- e 

WAY~ 

Quartz ' \ 

' ' I · ---.-\... on 

I ----, 

MAP LOCATION 

----~·- "' I '-. Sk,nner I 

..Pea I 

~---~ .... 

0 

-...... , 

., 

MILES 

' -...... 

5 

EXPLANATION 

~ Mine or deposit 

x Mineral occurrence 

...._ Quartz vein 

Igneous rocks (Cretaceous) 

Quartz diorite (Jurassic) 

Metamorphic rocks (Mesozoic 

and Paleozoic) 

--- Contact 

--- Fault 

Figure 105.-Scodies Roadless Area, California, 
SCODIES ROADLESS AREA, CALIFORNIA 

By j OCELYN A. PETER ON, 1 .S. GEOLO l AL S R EY, and 

DO ALD 0. CAPSTICK, U.S. B REA OF MI E 

SUMMARY 

Geologic and geochemical studies carried out during 1980 and 1982 by the 

USGS and USBM in the Scodies Roadless Area indicate little promise for the 

occurrence of metallic mineral resources within the area Tungsten has been 

mined from tactite in pre-Cretaceous roof pendants in the Weldon tungsten 

district a few miles to the west and in the Indian Wells Canyon district to the 

northeast. Small outcrops of similar roof pendants occur in the Scodies Roadless 

Area, but no tungsten resource potential was identified. Three quartz veins occurring within the roadless area may be utilized for decorative stone. One, the 

Great White Way, has demonstrated resources of quartz. Because of their small 

size and remoteness no quartz resource potential was identified in the other 

veins. 

CHARACTER AND SETTING 

The Scodies Roadless Area occupies about 75 sq mi in 

Sequioa National Forest about 60 mi east-northeast of 

Bakersfield in Kern County, California It lies in the 

Sierra Nevada at altitudes ranging from 3500 to 7155 ft. 

Unpaved roads from Onyx, Weldon, and from California 

State Highways 178 and 14 provide access into the 

roadless area 

Most of the roadless area is an elevated plateau that 

has been cut by a few streams to form steep-walled canyons. The plateau supports pine forests and sagebrush, 

whereas the south and east parts of the roadless area, 

which are not on the plateau, contain desert shrubs and 

Joshua trees. Field work for geochemical, geologic, and 

mineral-occurrence information pertinent to the mineral 

resources of the area was carried out during 1980 and 

1982 by the USGS and the USBM. 

The Scodies Roadless Area lies at the southern end of 

the Sierra Nevada where granitic plutons have intruded 

and metamorphosed sedimentary rocks. In this area 

most of the metasedimentary rocks have been removed 

by erosion; remnants occur as small roof pendants 

suspended in the granitic rocks. The metasediments 

consist of quartzite, mica schist, phyllite, and marble. 

Locally the marble has been converted to a tactite containing coarse-grained epidote, garnet, and wollastonite 

'WiLh contri butions !rom Joy L. Hamer and J wnes F'. Seitz. USC . 

(Harner and others, 1983). One of these tactites in the 

northeast part of the roadless area has been prospected 

for tungsten. 

Three major igneous units occur within the area The 

oldest of these is a diorite that crops out in small 

isolated areas predominantly in the southern part of the 

Scodies Roadless Area The other two igneous units, a 

granodiorite and an alaskite, are intimately mixed and 

may be separate facies of the same intrusion. The granodiorite is more abundant than the alaskite. 

Dikes that are younger than the major igneous units 

are abundant in the area and transect all major units. 

One set of dikes is aplitic, the other a coarse-grained 

pegmatite. Also within the area are three large quartz 

veins; one vein, near the southeast comer of the roadless 

area, has been prospected. 

Two northwest-striking faults cross the northeastern 

and southwestern comers of the area 

MINERAL RESOURCES 

The presence of tactite and quartz veins in the 

roadless area would seem to provide favorable conditions for the occurrence of mineral deposits, particularly 

because tungsten has been mined from tactites in the 

Weldon tungsten district a few miles to the west and in 

the Indian Wells Canyon district to the northeast. Gold 

has also been mined from quartz veins in the Indian 

361 
Wells Canyon district. Despite these seemingly favorable geologic environments for mineral deposits within 

the Scodies Roadless Area, the favorable areas are small 

and few and no areas of resource potential were found. 

Geochemical evaluation of rock and stream-sediment 

samples indicated weakly anomalous amounts of gold, 

silver, and lead in the northern part of the roadless area 

and anomalous lead in the southeastern part of the area 

Because the anomalies were weak and because the lead 

anomalies were not associated with other anomalies 

expected of hydrothermal lead deposits, they are considered to represent fluctuation in background levels 

rather than mineralization. 

A tactite in a roof pendant in the northeast part of the 

roadless area (Valentine claims) was prospected during 

the early 1940's for tungsten. No record of production 

was found and no tungsten resource potential was identified in this study. 

A large quartz vein occurs near the southern bound362 

ary of the roadless area and is the site of the Great 

White Way prospect, where quartz, without visible 

metallic mineralization, was prospected during the late 

1950's. The vein containsa demonstrated resource of an 

estimated 22,000 tons of white massive quartz which 

could be used for decorative stone. However, the quartz 

vein is small and remote and the prospect is not active 

at present. Two smaller quartz veins occur elsewhere in 

the area, but no decorative stone or other resources were 

identified. 

REFERENCES 

Capstick, D. 0 ., 1983, Mineral investigations of the Sccxlies RARE II 

area (no. 5212), Kern County, California: U.S. Bureau of Mines 

Open-File ReportMLA 47-83, 10 p. 

Hamer, J. L., Chaffee, M. A., Seitz, J. F., and Capstick, D. 0., 1983, 

Mineral resource potential map of the Sccxlies Roadless Area. 

Kern County, California: U.S. Geological Survey Open-File 

Report 83-510. 
SESPE-FRAZIER, DIABLO, MATILIJA, DRY LAKES, SAWMILL-BADLANDS, 

CUYAMA, ANTIMONY, AND QUATAL ROADLESS AREAS, CALIFORNIA 

By VIRGIL A. FRIZZELL, JR.,' U.S. GEOLOGICAL URVEY and 

' 

WILUAM . H ALE, U.S . B REA U F MI E 

SUMMARY 

Studies by the USGS and USBM conducted from 1980 to 1983 indicate that 

the Sespe-Frazier Roadless Area contains demonstrated resources of gold, gypsum, phosphate and bentonite; deposits in the Cuyama Roadless Area have 

demonstrated resources of gypsum; mines in the Antimony Roadless Area have 

demonstrated resources of antimony, gold, silver, and marble; and the Quatal 

Roadless Area has demonstrated resources of bentonite. The Sespe-Frazier 

Roadless Area has substantiated potential for geothermal resources suitable for 

direct-heat purposes, probable and substantiated potential for oil and gas 

resources, and probable potential for gold resources. Small areas of probable 

resource potential for antimony and gold were identified in the Antimony 

Roadless Area 

CHARACTER AND SETTING 

The study area, consisting of the Sespe-Frazier, 

Diablo, Matilija, Dry Lakes, Sawmill-Badlands, 

Cuyama, Antimony, and Quatal Roadless Areas, occupies about 872 sq mi in the Los Padres National 

Forest, California For purposes of this report the 

roadless areas will be referred to collectively as the 

study area The study area is in the western part of the 

Transverse Range of California between the Santa Barbara area, on the Pacific Ocean, and the San Joaquin 

Valley. Interstate Highway 5 and California State 

Highways 33 and 126 join paved and unpaved roads 

that allow access to the study area. 

Much of the study area is characterized by steepwalled canyons and sharp ridges. Although summit 

ridges may locally support coniferous forests and 

riparian woodlands may line valley bottoms, impenetrable chaparral covers much of the mountain slopes 

and makes off-trail traverses difficult. Pre-Tertiary igneous and metamorphic rocks underlie the northeastern 

third of the study area (Frizzell and Vedder, in press). 

They consist of Precambrian metasedimentary rocks 

and granitic gneisses, metasedimentary rocks of 

unknown age, and Mesozoic granitic rocks. 

'Wi!.h contributions by Goorge E. Claypool. Andrew Griscom. and David B. Smi!.h, USG . 

and D. E. Graham. Lucia Kuizon, Robert H. Lrunbe!.h, Warren D. LongweU, Terry R. 'eu· 

mann, William H. White, and R. A. Wint.c"'. USBM. 

Most of the rest of the study area is underlain by 

highly folded sedimentary rocks ranging in age from 

Late Jurassic to Oligocene. They comprise a thick, 

heterogenous, incomplete marine section of interbedded 

sandstone, siltstone, shale, and conglomerate, with local 

nonmarine interbeds. 

Neogene sedimentary rocks include organic-rich siltstone and shale, interbedded sandstone, and lesser conglomerate. These rocks formed mostly from sediments 

deposited in relatively restricted marine basins where 

the organic remains of flora and fauna living in the 

water column constituted a relatively important source 

of sediment. Neogene nonmarine rocks occur mostly in 

the Cuyama Badland, Lockwood Valley, and along the 

eastern boundary of the study area in the Ridge Basin. 

In addition to geologic mapping, work in the study 

area included evaluation of mines and prospects, ge<r 

physical investigations, and organic- and inorganicgeochemical studies. Geophysical studies (Griscom, in 

press) included the compilation and anlaysis of gravity, 

magnetic, and radiometric data Analytical data from 

stream-sediment samples, collected for a reconnaissance 

geochemical study (Smith and others, in press), 

delineate areas with previously known mineral-resource 

potential, but failed to identify additional areas. 

The study area has a long and varied history of mining and exploration. Placer gold was mined from Piru 

Creek in the Sespe-Frazier Roadless Area in the 1840's 

and lode gold was discovered therein in the late 1800's. 

363 
SANTA 

119°00' 

M I D G I 0 

0 10 

MILES 

EXPLANATION 

Geologic terrane with substantiated 

mineral-resource potential 

CJ Geologic terrane with probable 

mineral-resource potential 

Sb Antimony 

Au Gold 

Ag Silver 

~ Mine or deposit 

X Mineral occurrence 

'X' Mine 

i Sedimentary rocks (Neogene) 

Sedimentary rocks (Pre-Miocene) 

Igneous and metamorphic rocks, <--·-~ .::.w.: undivided (Pre-Tertiary) 

Contact 

Fault 

• • • Thrust fault--Sawteeth on 

upper plate 

I 

Figure 106.-Sespe-Frazier, Diablo, Matilija, Dry Lakes, Sawmill-Badlands, Cuyama, Antimony, and Quatal Roadless Areas, California 

364 
At about the same time, lode gold was found in the 

Antimony Roadless Area where antimony had been discovered earlier. Exploration for oil and gas began in the 

southern part of the Sespe-Frazier Roadless Area in 

1887. Uranium was reported in the Antimony and 

Sawmill-Badlands Roadless Areas in the early 1950's. 

Marble has been mined in the Cuddy Valley region 

south of the Antimony Roadless Area since the late 

1800's. Gypsum was discovered in the Cuyama Roadless Area in 1892, and subsequently in other localities in 

the study area The Pine Mountain phosphate prospect 

in the Sespe-Frazier Roadless Area was explored in the 

1960's. 

MINERAL RESOURCES 

Our studies (Frizzell and others, in press) indicate 

that the Sespe- Frazier Roadless Area has demonstrated resources of lode gold, gypsum, phosphate, and 

bentonitic clay and geothermal resources; that the 

Cuyama Roadless Area has demonstrated resources of 

gypsum; that the Antimony Roadless Area has mines 

containing demonstrated resources of antimony, gold, 

silver, and marble; and that the Quatal Roadless Area 

has demonstrated resources of bentonite. 

Spanish settlers produced gold from placer deposits 

in the Sespe-Frazier Roadless Area This and other 

roadless areas still contain numerous localities underlain by terrace and alluvial deposits that contain placer 

gold (Frizzell and others, in press; Hale and others, 

1983; White, 1982a,b; Longwill, 1982). Because these 

deposits generally contain small volumes and have low 

gold content, as determined from this study, no probable placer gold resources exist within the study area 

Over 400 mining claims have been filed in the SespeFrazier Roadless Area since 1885 and gold was produced in or near the area until 1941. Demonstrated 

resources of about 8000 tons of 0.38 oz/ton gold are 

present at the Castaic mine. Other prospects or mines in 

this part of the roadless area contain smaller amounts of 

inferred resources of gold. The area around these mines 

is considered to have a probable resource potential for 

gold. 

The Lockwood Clay mine has 7.2 million tons of 

demonstrated resources of bentonitic clay of which 

about 4.7 million tons occur within the Sespe-Frazier 

Roadless Area Bentonitic clay has been produced from 

this deposit since 1954. Demonstrated bentonite resources from the Neogene Lockwood Clay (QUL Prospect) also exist in the Quatal Roadless Area (White, 

1982b, p. 14). 

The Miocene Santa Margarita Formation contains 

gypsum- and phosphate-bearing beds inside and north 

of the Sespe-Frazier Roadless Area, south of Pine 

Mountain. About 51 million tons of phosphate-bearing 

rock averaging 10 percent P20 5, and 8 million tons of 

gypsum, averaging 76 percent CaSO., occur within the 

Sespe-Frazier Roadless Area 

Several deposits in nonmarine rocks in the Cuyama 

Roadless Area contain demonstrated gypsum resources 

(Kuizon, 1981); the Santa Barbara Canyon deposit has 

30,000 tons averaging 83 percent CaSO.; the Wagon 

Road Canyon deposit has 276,000 tons averaging 85 

percent CaSO.; and the Brush Fence Canyon deposit 

has 61,000 tons averaging 90 percent CaSO •. Two prospects in the Sawmill-Badlands Roadless Area, the 

Frenchmans Point and Burges Canyon prospects, also 

contain gypsum but no tonnages are available (Longwill, 1982). 

The strongest geochemical anomalies occur in sediment samples from streams draining areas around 

Antimony Peak. The patented Antimony Peak mine 

produced 600 tons of ore (5 tons at the Padre mine) and 

contains 470,000 tons of demonstrated and inferred 

resources averaging 1.0 to 2.7 percent antimony 

(Kuizon, 1982). Geochemical and geologic evidence indicate a probable gold and antimony resource potential 

for nearby areas. The Black Bob and Cedar mines produced 358 oz gold, 367 oz silver, and 673 lbs of lead. 

They contain 1600 tons of demonstrated resources 

averaging 0.13 oz gold/ton and 0.5 oz silver/ton and 

11,000 tons lesser grade material. Metasedimentary 

rocks occur as scattered roof pendants near Brush 

Mountain, and although samples of metasandstone at 

the Brush claims contain minor amounts of U30 8 and 

gold and anomalous concentrations of other metals, the 

data are insufficient to define the metallic resource 

potential for the area of these metasedimentary rocks. 

Marble and dolomitic marble occur as roof pendants 

in granitic rocks. The Lebec prospects contain about 51 

million tons of demonstrated and inferred marble resources averaging 32.2 percent CaO and 2.8 percent 

MgO. The White Rock mine has produced 300,000 tons 

and contains 34 million tons of demonstrated and inferred marble resources averaging 32.4 percent CaO and 

24.8 percent MgO (Kuizon, 1982). 

The study area contains several thermal springs 

along the southern parts of the Dry Lakes (White, 

1982a) and the Matilija (Lambeth, 1982) Roadless 

Areas, and, notably, at Sespe Hot Springs, an area of 

substantiated geothermal resource potential that is a 

Known Geothermal Resource Area 

Reconnaissance oil and gas studies (Frizzell and 

Claypool, in press; Howell and Claypool, 1977) indicate 

that undiscovered petroleum resources are not likely in 

the pre-Miocene sedimentary rocks. These rocks generally contain organic matter in quantities and qualities 

365 
below those necessary to produce significant amounts 

of hydrocarbons, and they also generally have poor 

reservoir characteristics. 

The Neogene marine rocks in the southern parts of 

the Sespe-Frazier Roadless Area, however, do contain 

sufficient quantities and suitable types of organic matter necessary to generate hydrocarbons. Furthermore, 

they, and the Eocene marine and Oligocene nonmarine 

rocks which underlie them there, probably contain undiscovered oil. An elongate east-west negative gravity 

anomaly confirms the presence of Neogene rocks below 

the San Cayetano thrust where oil may be present. Part 

of the Sespe oil field extends into the Sespe-Frazier 

Roadless Area near the San Cayetano thrust and has a 

substantiated oil and gas resource potential. Two areas 

of probable oil and gas resource potential occur in the 

southern part of the Sespe-Frazier Roadless Area east 

and west of the Sespe oil field. Another negative gravity 

anomaly north of the Pine Mountain phosphate prospect indicates that about 4500 ft of Neogene rocks are 

present below the Pine Mountain fault. An area of probable oil and gas resource potential exists around the 

anomaly. 

SUGGESTIONS FOR FURTHER STUDIES 

Additional gravity data and development of gravity 

models may further our understanding of the rocks and 

petroleum potential below the San Cayetano and Pine 

Mountain faults. Detailed geologic mapping and geochemical sampling is required to better assess the 

resource potential of the Antimony and Sespe-Frazier 

Roadless Areas. 

REFERENCES 

Capstick, D. 0., and Hyndman, P. C., 1982, Mineral resources of the 

Diablo RARE II Area (No. 5127), Santa Barbara County, Califor· 

nia: U.S. Bureau of Mines Open-File Report MLA 55-82, 7 p. 

Frizzell, V. A., Jr., and Claypool, G. E., in press, Petroleum potential 

map of Mesozoic and Cenozoic rocks in roadless areas and the 

Santa Lucia Wilderness in the Los Padres National Forest, 

southwestern California: U.S. Geological Survey Miscellaneous 

Field Studies Map MF-1655- D. 

366 

Frizzell, V. A. Jr., Smith, D. B., Kuizon, Lucia, and Hale, W. N., in 

press, Mineral resource potential map of roadless areas and the 

Santa Lucia Wilderness in the Los Padres National Forest, 

southwestern California: U.S. Geological Survey Miscellaneous 

Field Studies Map MF- 1655- B. 

Frizzell, V. A., Jr. and Vedder, J . G., in press, Geologic map of 

roadless areas and the Santa Lucia Wilderness in the Los Padres 

National Forest, southwestern California: U.S. Geological Survey 

Miscellaneous Field Studies Map MF- 1655- A. 

Griscom, Andrew, in press, Aeromagnetic map of part of the Los 

Padres National Forest in the southern Coast Range and western 

Transverse Range, California: U.S. Geological Survey Miscellaneous Field Studies Map MF-1658- A. 

Griscom, Andrew, in press, Bouguer gravity map of part of the Los 

Padres National Forest in the southern Coast Range and western 

Transverse Range, California: U.S. Geological Survey Miscellaneous Field Studies Map M F - 1658-B. 

Hale, W. N., Winters, R. A., Graham, D. E., and Neumann, T. R., 

1983, Mineral investigation of the Sespe-Frazier RARE II Area 

(No. 5002), Ventura County, California: U.S. Bureau of Mines 

Open-File Report MLA 78-83. 

Howell, D. G., and Claypool, G. E., 1977, Reconnaissance petroleum 

potential of Mesozoic and Cenozoic Rocks, Coast Ranges, California, in Howell, D. G., Vedder, J. G., and McDougall, K., eds., Cretaceous Geology of the California Coast Ranges, West of the San 

Andreas Fault: Pacific Section, Society of Economic Paleontologists and Mineralogists, Pacific Coast Paleogeography Field 

Guide 2, p. 85-90. 

Kuizon, Lucia, 1981, Mineral resources of the Cuyama RARE II Area 

(No. 5135), Santa Barbara and Ventura Counties, California: U.S. 

Bureau of Mines Open-File Report MLA 9-81, 11 p. 

__ 1982, Mineral investigation of the Antimony RARE II Area 

(No. 5136), Kern and Ventura Counties, California: U.S. Bureau 

ofMinesOpen-FileReportMLA 71-82,14p. 

Lambeth, R. H., 1982, Mineral resources of the Matilija RARE II 

Area (No. 5129), Ventura and Santa Barbara Counties, California: U.S. Bureau of Mines Open-File Report MLA 64-82, 13 p. 

Longwill, W. D., 1982, Mineral resources of the Sawmill-Badlands 

RARE II Area (No. 5134), Ventura and Kern Counties, California: U.S. Bureau of Mines Open-File Report MLA 51-82, 18 p. 

Smith, D. B., Frizzell, V. A., Jr., Adrian, B. M., Vaughn, R. B., and 

McDougal, C. M., in press, Geochemical map of roadless areas 

and the Santa Lucia Wilderness in the Los Padres ational 

Forest, southwestern California: U.S. Geological Survey Miscellaneous Field Studies Map MF -1655-E. 

U.S. Bureau of Mines, in press, Mines and prospects map of roadless 

areas and the Santa Lucia Wilderness in the Los Padres National 

Forest, southwestern California: U.S. Geological Survey Miscellaneous Field Studies Map MF-1655-C. 

White, W. W., Ill, 1982a, Mineral investigations of the Dry Lakes 

RARE II Area (No. 5131), Ventura County, California: U.S. 

Bureau of Mines Open-File Report MLA 84-82, 17 p. 

__ 1982b, Mineral investigation of the Quatal RARE II Area (No. 

5268), Ventura County, California: U.S. Bureau of Mines OpenFile Report MLA 68-82, 15 p. 
SHEEP MOUNTAIN WILDERNESS STUDY AREA AND 

CUCAMONGA WILDERNESS AND ADDITIONS, CALIFORNIA 

By jAMES G. EVA ,

1 U .S. GEOLOG ICAL SURVEY, and 

j AME RIDE 0 R, U .S . B REAU OF Mr E 

SUMMARY 

A mineral survey conducted in 1975-76 indicates areas of probable and 

substantiated tungsten and gold resource potential for parts of the Sheep Mountain Wilderness Study Area and an area of probable tungsten and gold resource 

potential in the Cucamonga Wilderness and additions. The rugged topography, 

withdrawal of lands from mineral entry to protect watershed, and restricted 

entry of lands during periods of high fire danger have contributed to the continuing decline in mineral exploration. The geologic setting precludes the presence 

of energy resources. 

CHARACTER AND SETTING 

The Sheep Mountain Wilderness Study Area and 

Cucamonga Wilderness and additions encompass approximately 104 sq mi of the eastern San Gabriel Mountains, Los Angeles and San Bernardino Counties, 

California The Sheep Mountain Wilderness Study Area 

is 27 mi northeast of the Los Angeles Civic Center. 

Uplift of the range has resulted in the carving of deep 

canyons into the crystalline rocks, with 8000 ft of relief 

in the Sheep Mountain Wilderness Study Area and 4000 

ft in the Cucamonga Wilderness and additions. Old 

Baldy summit, at 10,000 ft altitude, is the highest point 

in the range and is visible from the heavily populated 

lowlands. Spectacular views across the Los Angeles 

Basin to Catalina Island and across the Mojave Desert 

can be seen from the high ridges. Some of these vistas 

and parts of the study area and wilderness can be seen 

at close range from several paved roads that provide access to the eastern San Gabriel Mountains. These include State Highway 39, State Highway 2, which forms 

part of the north boundary of the Sheep Mountain area, 

Glendora Ridge Road, which forms part of the south 

boundary of the same area, and San Antonio Canyon 

Road, which lies between the two areas and ends at a ski 

lift that provides further access to the area between Old 

Baldy and Thunder Mountain. 

Mining activity in the region began in the 1840's and 

has continued intermittently. Most activity has in1

With contributions from Leroy Pankratz. USG . and t.cven W. Schmouch ond Nicholas T. 

Zilka. USBM. 

volved recovery of placer gold from recent streambed or 

old perched stream channel deposits. The richest placer 

deposits were in the East Fork San Gabriel River south 

of the Sheep Mountain Wilderness Study Area The 

search for sources of placer gold in the late 1800's led to 

discovery of several lode mines. 

Scheelite (CaWO,) was discovered in Cattle Canyon, 

in the Sheep Mountain Wilderness Study Area, in the 

1950's and has been worked intermittently since then, 

mostly by handpicking the high-grade pieces of rock 

from talus and alluvium. 

Geochemical studies of the areas in 1975-76 included 

stream-sediment sampling of fine silt and pan concentrates, and collection of rock samples from mineralized 

outcrops, mines, and prospects. These samples were 

analyzed for gold, tungsten, and several other elements 

by the USGS and USBM. The results of these analyses 

along with a discussion of the geology were published in 

Evans and others (1977, 1982). The mineral-resource 

evaluation of the areas is based on these analyses and 

on geologic models of the deposits. An aeromagnetic 

study of the areas was also performed. 

The hard crystalline rocks that underlie the study 

area and wilderness range widely in age from Proterozoic to Miocene. They show evidence of a complex 

history involving the processes of sedimentation, intrusion of granitic magma in several widely spaced pulses, 

thermal metamorphism due to the great depth of burial 

as well as contact with hot magma, and dynamic metamorphism under varying conditions of strain. The major structure of the area is the nearly flat lying Vincent 

thrust, which separates two distinct terranes: schist in 

367 
368 

0 

M ILES 

EXPLANATION 

-

D 

Cu 

Au 

Geologic terrane with substantiated 

mineral-resource potential 

Geologic terrane with probable 

mineral-resource potential 

Copper 

Gold 

w Tungsten 

~ Mine or deposit 

'X' Mine 

5 

Schist 

Gneiss, mylonite, and granitic rocks 

Fault 

Vincent Thrust Fault--Sawteeth on 

upper plate 

Figure 107.-Sheep Mountain Wilderness Study Area and Cucamonga Wilderness and Additions, California 
the lower plate and gneiss, mylonite, and granitic rocks 

in the upper plate. The mylonite comprises a zone adjacent to the thrust of intensely sheared, nearly homogenized rock derived from parts of the gneiss, granitic 

rocks, and schist. A final pulse of granitic magma was 

emplaced after development of the thrust and mylonite. 

Since then, and continuing to the present, the range has 

been extensively uplifted. In addition, steep faults in 

the area have had predominantly horizontal slip, most 

notably along the San Gabriel and Punchbowl fault 

zones, which are splays of the regional San Andreas 

fault zone, located 1 mi north of the Sheep Mountain 

Wilderness study area Recent erosion has created the 

very great relief of the range. 

MINERAL RESOURCES 

Placer samples taken from the East Fork San Gabriel 

River in this investigation contained very little or no 

gold. Mines located during the search for the lode 

sources of the gold are in the schist and in the mylonite 

above the schist. The Big Hom mine, in the northwest 

part of the Sheep Mountain Wilderness Study Area has 

the largest recorded production and estimated demonstrated resources. It lies along the Vincent thrust, a 

structure which must have localized mineralizing solutions. The other lode gold mines in the Sheep Mountain 

Wilderness Study Area lie in a band between Iron 

Mountain and West Baldy, in an area in which geochemical sampling indicates a probable potential for additional gold resources. Another area northeast of Old 

Baldy has probable potential for gold resources based 

on stream-sediment samples. 

Tungsten (scheelite) deposits in alluvium and talus in 

Cattle Canyon were derived from veins, pods, and disseminations in fractures in the gneiss and granitic rock 

of the canyon walls. The area has a substantiated tungsten resource potential. Abundant evidence for similar 

kinds of deposits was found in Devil Gulch and the area 

is assessed a probable tungsten resource potential. 

Tungsten mineralization accompanies gold mineralization in the area of probable resource potential between 

Iron Mountain and West Baldy. A probable resource 

potential for low-grade tungsten and gold in the 

cataclastic rocks above the Vincent thrust fault exists 

in the northern part of the Cucamonga Wilderness and 

additions. 

In general, the rocks of the study area and wilderness 

show few indications of extensive mineralization; where 

gold or tungsten was found, the occurrences are 

restricted to narrow veins or zones. Much of the gold in 

the placer deposits of the East Fork San Gabriel River 

may have been derived from very small lode deposits 

which remain undiscovered today. In addition, the 

aeromagnetic data do not indicate any mineral-resource 

potential in the area The geologic setting of the area 

precludes the presence of energy resources. 

SUGGESTIONS FOR FURTHER STUDIES 

Additional study of the study area and wilderness offers little promise for identification of hidden mineral 

resources. 

REFERENCES 

Evans, J. G., Pankratz, Leroy, Ridenour, James, Schmauch, S. W., 

and Zilka, . T .. 1977, Mineral resources of the Sheep Mountain 

Wilderness study area and the Cucamonga Wilderness and additions, Los Angeles and San Bernardino Counties, California: U.S. 

Geological Survey Open· File Report 77-251.99 p. 

Evans, J. G .. Pankratz, Leroy, Ridenour, James, Schrnauch, S. W., 

and Zilka, N. T .. 1982, Mineral resources of the Sheep Mountain 

Wilderness study area and the Cucamonga Wilderness and additions, Los Angeles and San Bernardino Counties, California: U.S. 

Geological Survey Bulletin 1506,92 p. 

369 
370 

33° 

15' 

33° 

00' 

32 

45' 

117°00' 

z DIEGO 

116 °45' 

~~ 

I 

~~ 

0 

116°30' 

.f l: _ / Approximate road less 

;,.:· "·~~ boundary 

'JJ~.. Gem stones 

.t~t .iJcaliente . 

{~·'· 0 5017 ~ 

&~~$ ~? ~$~ ~ 

"'o .!'$ 

l.ake 

Au , w\._ 

_J ~J~ Ni , .. .. \;10' 

:•.>_ \ 

Au ~-;\' L_ 

-..:~ ~ 

MILES 

J_~' Ni, Au , W t:i~ Sill Hill 

~~ 05304 

10 

MAP LOCATION 

EXPLANATION CJ Geologic terrane with probable :::::: Plutonic igneous rocks 

mineral-resource potential 

Au Gold 

Ni Nickel 

w Tungsten 

Figure 108.- Sill Hill, Hauser, and Caliente Roadless Areas, California 
SILL HILL, HAUSER, AND CALIENTE ROADLESS AREAS, CALIFORNIA 

By VICTORlA R . TODD,' U .. GEOLOGICAL S R EY, and 

THOMAS j . P ETERS, .S. B REA OF Ml E 

SUMMARY 

Probable resource potential for metallic minerals and gemstones was identifed 

during mineral-resource surveys in the Sill Hill, Hauser, and Caliente Roadless 

Areas, California, by the USGS and USBM in 1980 and 1981. Parts of the Sill 

Hill Roadless Area have a probable potential for gold, tungsten, and nickel and 

by-product copper. Part of the Caliente Roadless Area has a probable potential 

for tourmaline, beryl, quartz, and possibly other specimen minerals and 

gemstones. No mineral-resource potential was identified in the Hauser Roadless 

Area, although potash feldspar is abundant as a rock-forming constituent in two 

parts of the area The Caliente Roadless Area lies less than 1 rni from an area of 

hot springs activity which may be part of a low-grade geothermal resource area, 

but no geothermal resource potential was identified in this or any of the other 

areas. No resource potential for nuclear energy was identified in this study and 

the geologic terrane precludes the occurrence of hydrocarbon resources. 

CHARACTER AND SETTING 

The Sill Hill, Hauser, and Caliente Roadless Areas occupy about 8.0, 12.5, and 9.0 sq rni, respectively, of the 

Cleveland National Forest in San Diego County, California Products of the mineral-resource survey include a 

detailed geologic map of the areas (Todd, in press), and a 

detailed evaluation of the mineral-resource potential 

(Todd and others, 1983). 

The Cleveland National Forest is in the Peninsular 

Ranges, the mountainous spine that extends for hundreds of miles from southern California into Baja 

California, Mexico, and separates the Pacific coastal 

lowlands on the west from the Colorado Desert on the 

east. The Cleveland National Forest is characterized by 

a Mediterranean climate and rugged, chapparal-covered 

slopes below conifer-forested peaks more than 1 mi high. 

Total relief in the three roadless areas ranges from 

about 2200 to 3400 ft. 

The Sill Hill, Hauser, and Caliente Roadless Areas are 

underlain by Creta~eous plutonic igneous rocks of the 

Peninsular Ranges batholith, rocks which form much of 

the crystalline bedrock of the Peninsular Ranges. The 

batholith is composed of a variety of plutons that 

intruded metamorphosed Paleozoic to Cretaceous sed.i-

'With contributions from Robert E. Learned. USG . and Ronald T. Muycrle. USBM. 

mentary and volcanic rocks, remnants of which are exposed between the plutons. Patches of upper Cenozoic 

stream deposits unconformably overlie the uplifted and 

deeply eroded batholith in all three roadless areas. 

Faults of various ages have formed along and across the 

steep layering in the batholithic rocks. In the Caliente 

Roadless Area, some of these faults cut Quaternary 

stream deposits. 

MINERAL RESOURCES 

Mineral occurrences within and near the Sill Hill 

Roadless Area indicate that parts of the area have a 

probable resource potential for gold, tungsten, nickel, 

and copper. The northwest part of the roadless area lies 

within the Boulder Creek gold district and has a probable gold resource potential. Although the Boulder 

Creek deposits are low grade, gold deposits in the Julian 

mining district, 6 mi to the north-northeast, produced 

$5,000,000 worth of gold in the late 19th and early 20th 

centuries. Deposits contained entirely or partially 

within metasedimentary schist have been much more 

productive than deposits contained in fractured, 

sheared, or metamorphosed granitic rock. The scarcity 

of schist in the Boulder Creek district may be a factor 

contributing to the low grade of the deposits there. A 

371 
prospect in the east-central part of the Sill Hill Roadless 

Area contains scheelite (CaWO,) in a small contact-type 

deposit. The Friday Nickel prospect, 4.5 mi northeast of 

the roadless area, contains nickel, with accessory copper 

and cobalt, in sulfide minerals in a gabbro pluton. 

Similar occurrences can be extrapolated to the eastern 

and southern parts of the Sill Hill Roadless Area, which 

are underlain by the same gabbro pluton. 

Chemical analysis of stream-sediment samples from 

the Sill Hill Roadless Area show anomalous concentrations of chromium, nickel, and vanadium associated 

with gabbro plutons; gold anomalies associated with 

quartz veins in granitic plutons; and lead, tin, tungsten, 

and nickel anomalies associated with contact-type occurrences between small calc-silicate metasedimentary 

inclusions and intrusive rocks. 

Results of this mineral-resource investigation indicate 

that the Sill Hill Roadless Area has a probable resource 

potential for gold, tungsten, nickel and by-product copper. Occurrences of gold, nickel, and tungsten are 

known in and around the roadless area Areas underlain 

by metasedimentary rocks have resource potential for 

gold deposits similar to those in the Julian mining 

district and for small low-grade tungsten resources in 

sparse calc-silicate rocks. That part of the Boulder 

Creek mining district which lies within the Sill Hill 

Roadless Area has probable gold-resource potential. 

Areas underlain by gabbro have a probable resource 

potential for nickel and the gabbro could be an exploration target. 

In the Caliente Roadless Area the inactive Cryo-Genie 

mine in the southwest part of the area has produced 

small amounts of specimen and gemstone tourmaline 

and beryl from a pegmatite dike. The Crest Gem mine, 

0.5 mi northwest of the area, was the largest local producer of tourmaline in the early 1900's; the mine 

presently yields several thousand pounds of quartz 

crystals and a few beryl crystals annually. A prospect in 

the southwestern part of the roadless area has minor 

scheelite in a contact-type deposit. Several small, lowgrade contact-type scheelite deposits occur in this part 

of San Diego County. The nearest tungsten mine, and 

once the largest producer in the county, is the inactive 

Pawnee mine, 6.5 mi northwest of the Caliente Roadless 

Area, which has produced small amounts of tungsten 

trioxide (W03) on an intermittent basis since 1917. An 

unnamed prospect in the northwest comer of the roadless area is in an inclusion of slightly radioactive metasedimentary rocks contained in granitic intrusive rocks 

and has minor uranium oxide. 

372 

Analysis of stream-sediment samples from the Caliente Roadless Area show generally high concentrations 

of boron, fluorine, uranium, yttrium, lanthanum, scandium, thorium, and zirconium, probably reflecting the 

presence of abundant tourmaline-bearing granitic 

pegmatite dikes and leucogranite plutons in the area 

Generally high and locally anomalous concentrations of 

lead, and anomalous tungsten in one sample may reflect 

the presence of small contact-type occurrences in the 

area Molybdenum, silver, copper, zinc, and arsenic 

anomalies probably represent small mineralized areas in 

metasedimentary rocks cut by, and possibly hydrothermally altered by, granitic pegmatite and quartz dikes. 

The results of this mineral-resource investigation indicate a probable resource potential for mineral 

specimens and semiprecious gemstones of tourmaline, 

beryl, quartz, and possibly other minerals. Rare occurrences of tungsten, uranium, and placer gold in the roadless area and stream-sediment sample analyses showing 

anomalous values for some metals are not considered to 

indicate a mineral-resource potential for these elements. 

No evidence of mining activity exists within the 

Hauser Roadless Area The Pacific mine, a potash feldspar deposit located 0.2 mi east of the roadless area, was 

a principal source of feldspar in California and at least 

one pegmatite body that is structurally and mineralogically similar to the Pacific deposit was noted within the 

Hauser Roadless Area No resource potential for 

feldspar was identified; other more accessible sources 

are available outside the roadless area within the Peninsular Ranges. 

Several hot springs occur south of the Caliente 

Roadless Area, but no evidence of hot spring activity 

exists within the roadless areas. No potential for 

geothermal, hydrocarbon, or nuclear energy resources 

was identified in any of the three roadless areas. 

REFERENCES 

Todd, V. R., in press, Geologic map of the Sill Hill, Hauser, and 

Caliente Roadless Areas, San Diego County, California: U.S. Geological Survey Miscellaneous Field Studies Map MF- 1547- B, 

scale 1:62,500. 

Todd, V. R., Learned, R. E., Peters, T. J., and Mayerle, R. T., 1983, 

Mineral resource potential map of the Sill Hill, Hauser, and Caliente Roadless Areas, San Diego County. California: U.S. Geological Survey Miscellaneous Field Studies Map MF- 1547- A, scale 

1:62,500. 
SNOW MOUNTAIN WILDERNESS STUDY AREA, CALIFORNIA 

By R OBERT D. BROW , jR., 1 U.S. GEOLOGICAL S R EY and 

' 

FRA CIS E. FEDERSPIEL, U.S. B REAU OF MI E 

SUMMARY 

The Snow Mountain Wilderness study area, located about 120 mi north of San 

Francisco and on the divide between the Sacramento and Eel Rivers contains 

some of the highest terrain in the Coast Ranges. Its mineral-resource' potential 

was evalua~d in 1977 by interpreting data from geologic field studies, from an 

aerom~etlc survey, from geochemical sampling of stream sediments, rocks, 

and spnngs, and from the examination and sampling of prospects. These investigations indicated that there was little promise for the occurrence of mineral or energy resources within the wilderness. 

CHARACTER AND SETTING 

The Snow Mountain Wilderness study area occupies 

about 50 sq mi in northern California The outline of the 

study area, its elevation, and many of its landforms are 

closely related to its geology. Snow Mountain and St. 

John Mountain, the most prominent landmarks in the 

study area, stand more than 6500 ft above sea level; the 

total relief is about 5200 ft. Roads lead to the area from 

Willows and Maxwell in the Great Valley and from Upper Lake near Clear Lake. 

Bordered by steep slopes and dissected by deep 

narrow canyons, the area's rugged surface and elevation 

have kept it remote and roadless in comparison with 

other parts of the Coast Ranges. The proposed boundary of the wilderness follows a major low-angle thrust 

fault. Flat or gently dipping for much of its extent, this 

fault separates volcanic rock from the underlying 

weakly metamorphosed sedimentary rock. The thrust 

block of volcanic rock above the fault stands high 

because it resists erosion more effectively than do other 

rock types in the vicinity. 

The volcanic rocks are of Late Jurassic age and consist chiefly of flows of finely crystalline pillow basalt 

with beds of sandstone, mudstone, and radiolarian chert 

and a few thin sills of diabase. Most of these rocks accumulated in deep water during an episode of submarine 

volcanism; many subsequently have been chemically 

altered. 

These rocks are faulted over· physically deformed and 

weakly metamorphosed sedimentary rocks that under-

'With contributions from by David J. Grimes, !WinhardL Leinz, and Andrew Griscom, 

USGS, and Andrew M. Leszcykowsky, USBM . 

lie much of the northern Coast Ranges and that are commonly assigned to the Franciscan Complex. Originally 

mudstone, siltstone, and sandstone, these sedimentary 

rocks now exhibit an intensely sheared fabric. They contain a few thin flows of intensely altered pillow lava, 

evidence that they accumulated in a marine environment, probably during Late Jurassic and Cretaceous 

time. 

A belt of sheared and crushed rock as much as 820 ft 

thick separates the volcanic rock above the thrust fault 

from the physically deformed sedimentary rock below. 

The sheared and crushed debris is chiefly sedimentary 

rock, but it contains some resistant masses derived 

from the volcanic thrust block and a few exotic rock 

types derived from much deeper levels of the Earth's 

crust. Most of the prospects and claims in the study 

area are in this belt of rocks or another that is similar 

but structurally lower. 

Serpentinite, in tabular masses and in lenses, occurs 

both along thrust faults and along high-angle faults. 

The most extensive serpentinite body follows a 

northwest-trending fault along the Middle Fork of 

Stony Creek. 

Unconsolidated deposits cover a small amount of the 

study area They include glacial and glaciofluvial 

deposits, landslide debris, terrace deposits, and 

alluvium. 

To evaluate the mineral-resource potential, both existing and new data were collected and interpreted 

(Brown and others, 1981). New work, done in 1977 for 

the evaluation, included geologic field studies in the 

west half of the area; the interpretation of data from an 

earlier aeromagnetic survey; geochemical interpretation 

based on the analysis of samples of stream sediment, 

373 
39° 

25' 

374 

J 

/ 

Approximate 

0 

MILES 

EXPLANATION 

D Serpentinite (Tertiary) 

D Undifferentiated sedimentary rocks 

(Cretaceous and Jurassic) D Volcanic rocks (Upper Jurassic) 

• • • 

122"40' 

/ 

5 

Contact 

Fault 

Thrust fault--Sawteeth on upper plate 

Figure 109.-Snow Mountain Wilderness Study Area. California 
rocks, and springs; and the examination and sampling 

of prospects. 

MINERAL RESOURCES 

The geology, as well as records of past mineral exploration and production, gives clues regarding the 

mineral-resource potential. Chromium, copper, manganese, and mercury have been mined from similar 

rocks in other parts of the Coast Ranges. At the 

Geysers, a steam field in the northern Coast Ranges, 

geothermal power is produced in a somewhat similar 

geologic setting. The potential for these and other 

resources in the study area have been evaluated by 

analyzing and interpreting the geologic, geochemical, 

and aeromagnetic data; the results disclosed that there 

is little promise for the discovery of mineral or energy 

resources. Variations in geochemical properties and 

anomalies in the aeromagnetic data can be explained by 

normal chemical and physical properties of the rock 

units within the area; nowhere do the geochemical or 

magnetic data indicate unusual concentrations of 

mineral commodities. 

These findings are consistent with the history of exploratory activity; the little previous prospecting done 

in the Snow Mountain Wilderness study area has not 

revealed commercial mineral deposits. According to 

courthouse records, only 19 lode claims have been 

located in, or adjacent to, the study area Most of the 

claims were for manganese. Samples from manganesebearing chert beds east of the area contain as much as 

33.6 percent manganese. These deposits have been 

mined, mainly during World Wars I and II. Chert with 

manganese-oxide coatings on bedding and fracture 

surfaces occurs in the study area, but the size and 

grade of these deposits are not sufficient for them to be 

considered a resource. Serpentinized peridotite crops 

out on some claims in the area, but analyzed samples 

contained insufficient chrome and nickel to be considered as resources. In the eastern part of the study 

area, one claim has been located for onyx and another 

for nephrite jade. No semiprecious gemstones were 

found during this investigation. 

Mineral springs formerly exploited at a spa near 

Fouts Springs no longer appear to have much resource 

value. Volcanic rocks and diabase suitable for crushing 

and for use in construction cover much of the study 

area; they have not been commercially exploited. 

SUGGESTIONS FOR FURTHER STUDIES 

Current appraisals of the mineral-resource potential 

of the Snow Mountain Wilderness study area do not 

encourage further study. New discoveries of unforeseen resources in other parts of the California Coast 

Ranges or in similar geologic settings elsewhere could 

prompt renewed study of Snow Mountain, but the 

nature of such studies cannot be determined now. 

REFERENCE 

Brown, R. D., Jr., Grimes, D. J., Leinz, Reinhardt, Federspiel, F. E., 

and Leszcykowsk.i, A. M. 1981, Mineral resources of the Snow 

Mountain Wilderness study area, California: U.S. Geological 

Survey Bulletin 1495, 48 p. 

375 
376 

C r 

Approximate boundary 

MAP LOCATION 

f'atrersor1 

Lnkc 

0 

/ 

Squaw Peak 

TERTIARY 

SEDIMENTARY 

Warre Pt lk 

AND 

0'' 

VOLCANIC 

"S HOCKS 

0 

c. Ra,der "? 

-I 

l> 

z 

(jl 

\ ~ 

)( 

Eage P uk 

5 

MILES 

Figure 110.- South Warner Wilderness, California 

1\fi</Jf, 

'k , 

Lnkc 

< 

l> 

,-

.-

m 

-< 

>-

w 

..J 

..J 

<( 

~ > -;> 

\ 

"V.L. 

( 

~Fag (VII 
SOUTH WARNER WILDERNESS, CALIFORNIA 

By W E DELL A. D UFFIELD, U .. GEOLOGICAL S RVEY, and 

R O BERT E. W ELDI , U. S. B REAU F MI NE 

SUMMARY 

A mineral appraisal carried out in 1972 and 1973 utilized geologic, 

geochemical, and geophysical data and an examination of mining claims in the 

South Warner Wilderness, California Results of this study indicate that little 

promise for the occurrence of mineral resources exists within the area. Small 

veins of optical quality calcite occur on the east side of the area but, are not considered a resource. 

CHARACTER AND SETTING 

The South Warner Wilderness is in northeast California, about 6 mi west of Nevada and 40 mi south of 

Oregon. The wilderness is more or less rectangular and 

measures about 7 mi east-west and 16 mi north-south. 

The area encompasses about 109 sq rni centered along 

the crest of the Warner Mountains, a north-trending 

range that rises to a maximum elevation of 9900 ft at 

Eagle Peak in the south part of the wilderness. 

The Warner Mountains are at the west edge of the 

Basin and Range physiographic province and provide a 

classic example of Basin and Range fault-block mountain structure. Offset along the Surprise Valley fault 

zone at the east edge of the Warner Mountains has 

resulted in a minimum vertical uplift of the mountains 

relative to the adjacent valley of 12,000 ft in about the 

last 13 million years; some of this fault movement has 

occurred within the last 10,000 years. Fault offset on 

the west edge of the range has been considerably less, 

with the result that originally flat lying rock strata are 

tilted westward about 25 degrees. This tilted, faultblock structure produces a rather gentle, heavily 

forested western slope to the range and a steep, deeply 

incised eastern face that presents characteristics of 

badlands terrane. 

The wilderness is underlain primarily by a conformable sequence of Tertiary sedimentary and volcanic 

rocks whose ages range from somewhat greater than 

32 million years old to about 13 million years old. Approximately the lower half of this sequence consists of 

conglomerate and mudflows that represent deposits 

derived from the flanks of major andesite stratovolcanoes in adjacent but unidentified areas. The upper 

half of the sequence consists of lava flows, pyroclastic 

flows, and beds of volcanic ash deposited as air-fall 

debris. This younger half of the sequence includes rock 

types that cover the entire spectrum of chemical composition from basalt through andesite to rhyolite. 

During parts of Quaternary time (the last 1.8 million 

years ) glaciers were present in the highest parts of the 

range; these left small volumes of glacial deposits such 

as moraines, sand and gravel, and also carved out a 

glacial cirque within which Patterson Lake, the largest, 

highest and most beautiful of the lakes in the wilderness, is located. With the melting of glaciers, Surprise 

Valley filled with water to a depth of at least 500 ft. 

Several high-level, wave-cut beach lines and alluvial 

cones of stream gravel banked against the walls of the 

valley provide graphic evidence of the former deep lake. 

Essentially the entire sequence of Tertiary rocks has 

been subjected to mild alteration by circulating hydrothermal fluids. This has resulted in the deposition of 

some secondary minerals such as zeolites, calcite, silica, 

and celadonite, a clay-like mineral that imparts a palegreen tint to many of the rocks. During the mineralappraisal study all rock types were sampled, as were 

sediments from all principal streams; chemical analyses 

of the samples indicate unmineralized, ordinary crustal 

material. An aeromagnetic survey similarly indicates 

that ordinary unmineralized crustal rocks underlie the 

area. 

MINERAL RESOURCES 

The only commodity ever produced commercially 

from within the area of the wilderness was calcite of optical quality (Duffield and Weldin, 1976). Production 

377 
came from a few small veins that crop out locally in the 

east face of the range. Such deposits have not been 

mined for many years; they are too small, and synthetic 

materials now serve most uses once provided by optical 

calcite. 

The deposits of stream gravel that lie adjacent to the 

wilderness on the east are used locally for concrete 

aggregate and road construction. Parts of some gravel 

deposits are very near the wilderness boundary, but it is 

unlikely that their possible future exploitation would 

extend within the area. 

Sources of geothermal energy may exist in Surprise 

Valley near the east boundary of the wilderness. Surface 

indications of this resource are in the form of hot 

378 

springs localized along the Surprise Valley fault zone. 

However, if geothermal energy proves to be a viable 

commodity in Surprise Valley, development will almost 

certainly be along the fault zone, or further east, well 

outside the wilderness area, in the thick sequence of 

sedimentary debris that partly fills the valley. 

REFERENCES 

Duffield, W. A .. and Weldin, R. D., 1976, Mineral re ources of the 

South Warner Wilderness, Modoc County, California, with a 

section on Aeromagnetic data by W. E. Davis: U . . Geological 

Survey Bulletin 13 5- D, 31 p. 
SUGARLOAF ROADLESS AREA, CALIFORNIA 

By R OBERT E. P OWELL, 1 U.S. GE LOG ICAL S R EY and 

' 

H ARRY W. CAMPBELL, U .. B REA OF MI NES 

SUMMARY 

On the basis of geologic, geochemical, and geophysical investigations by the 

USGS in 1981-82 and a survey of mines, quarries, and prospects by the USBM 

in 1981, the Sugarloaf Roadless Area, California, has little promise for the occurrence of metallic mineral or energy resources. Units of carbonate rock and 

graphitic schist have demonstrated resources of magnesian marble and 

graphite. Sand, gravel, and construction stone other than carbonate rock are 

present in the roadless area, but similar or better quality materials are abundant 

and more accessible outside the area 

CHARACTER AND SETTING 

The Sugarloaf Roadless Area, California, located in 

the central San Bernardino Mountains of San Bernardino County, encompasses about 14 sq mi within the 

San Bernardino National Forest. Sugarloaf Mountain 

(9952 ft), at the center of the roadless area, lies about 6 

mi southeast of Big Bear City and 21 mi east-northeast 

of San Bernardino. Several investigators have previously mapped the geology in the roadless area 

(Vaughan, 1922; Dibblee, 1964; Cameron, 1982; Sadler, 

1982). This report summarizes results presented by 

Powell and others (1983). 

The oldest rocks in the Sugarloaf Roadless Area consist of Precambrian metasedimentary and metaplutonic 

gneiss that is unconformably overlain successively by 

uppermost Precambrian and Paleozoic quartzite, schist, 

and carbonate rock. The quartzite consists of a lower 

unit of laminated gray quartzite and an upper unit of 

light-colored quartzite in which bedding is commonly 

obscured. Aluminous phyllite and schist, graphitic 

schist, and micaceous siltite occur generally above 

quartzite and beneath carbonate rock, although the rock 

types are complexly interlayered in detail. Carbonate 

rock consists of generally light gray crystalline 

dolomite and limestone (marble). Mafic and felsic Mesozoic plutonic rocks intrude the Precambrian gneiss and 

overlying metasedimentary units. Intrusive units include hornblende-biotite gabbro and diorite, hornblendebiotite monzodiorite, granodiorite, and tonalite and 

'With contribu tions from Jonathan C. Matti. BreLL F. Cox. nnd Eduardo A. Rodriguez. 

usc . 

biotite monzogranite. Miocene arkosic sandstone and 

conglomerate, with intrusive and extrusive basalt units, 

occur south of the Santa Ana fault. 

Faults that developed along the unconformity between Precambrian gneiss and the overlying sedimentary units, and perhaps within the metasedimentary 

section, have been deformed successively by east-westtrending and northwest-plunging fold-sets. The 

Cenozoic Santa Ana fault trends roughly east-west 

across the southern part of the roadless area, dips 

60- 65 ° to the north, and exhibits both reverse and leftlateral separation. Extensive landsliding has occurred 

throughout the Sugarloaf Roadless Area 

In addition to the geologic investigation, a reconnaissance geochemical survey was conducted for 32 

elements to determine spatial variations in streamsediment chemistry that might reflect local concentrations of ore minerals. Aeromagnetic and gravimetric 

geophysical surveys also were conducted in the Sugarloaf Roadless Area and their results compared to those 

of the geologic and geochemical surveys for evaluation 

of the mineral-resource potential. 

MINERAL RESOURCES 

Mining and quarrying within the Sugarloaf Roadless 

Area began with the discovery of graphite deposits in 

Green Canyon and near the confluence of Cienaga Seca 

Creek and the Santa Ana River. Crushed magnesian 

marble from the Green Canyon Quarry on the north 

flank of Sugarloaf Mountain was marketed as roofing 

379 
380 

Bear City 

8 £: 4 R 

\r 

4 L L 

Bernardino £ y 

N 

Moon ridge 

0 

F L 

0 

MILES 

EXPLANATION 

2 

116°45' 

H ~r tiar 

P•ak 

ST FRANCIS UPPER PROSPECT 

T FRANCIS LOWER PROSPECT 

---

~ Mine or deposit .'.:.::·:=.:,·::/:{ Quaternary and Tertiary deposits 

X Mineral occurrence Mesozoic plutonic rocks 

;:~~,4 Paleozoic and Precambrian 

metasedimentary rocks D Precambrian gneiss 

Contact 

Fault 

Figure 111.- Sugarloaf Roadless Area, California 
granules in 1960 (Dibblee, 1964). Uranium deposits in 

the vicinity of the roadless area came under scrutiny in 

the 1950's; the Thumbum mine was located in 1953 

about 1 mi northeast of the roadless area; the Rocky 

Point (B and B) claim was located in 1954, about 0.5 mi 

west of the area; and the Thirsty King claim was located 

in 1955 in the southeastern comer of the area The first 

commercial shipment of uranium from California was 

produced in July 1954 from the Thumbum mine (Troxel 

and others, 1957). 

In the survey of mines, quarries, and prospects within 

the Sugarloaf Roadless Area, prospects in carbon-rich 

beds within the schist unit were determined to have lowgrade graphite resources. The St. Francis upper prospect contains an estimated 10,000 tons of demonstrated 

amorphous graphite resources averaging 12 percent 

fixed carbon and 30,000 tons of inferred graphite resources of similar grade. The St. Francis lower prospect 

contains an additional15,000 tons of demonstrated, and 

56,000 tons of inferred amorphous graphite resources 

averaging 11 percent fixed carbon. The Princes prospect, which straddles the boundary of the roadless area, 

contains about 130,000 tons of demonstrated, and 

100,000 tons of inferred amorphous graphite resources 

averaging 7 percent fixed carbon. Resources inside the 

roadless area at this prospect amount to 100,000 tons of 

demonstrated, and 63,000 tons of inferred graphite 

resources. Most uses of amorphous graphite require upgrading to 90 percent graphite, which involves a costly 

process of concentration. 

Magnesian marble is abundant at prospects in the 

carbonate unit that crops out on the north flank of 

Sugarloaf Mountain and above Cienaga Seca Creek. 

Magnesian marble resources at the Green Canyon 

Quarry and the Sugarloaf Mountain prospect are suitable for use as industrial aggregate and agricultural soil 

conditioners, but have too much magnesium, silica, and 

loss on ignition to be suitable for cement production. 

Most of these resources have been claimed at various 

times since the 1940's, but superior deposits closer to 

markets are already developed. 

Stone other than magnesian marble is abundant, but 

similar deposits are equally abundant and more accessible outside the area Sand and gravel, largely confined 

to relatively narrow active streambeds, are not a significant resource. 

Resources are not estimated for hydrothermal 

uranium deposits that may be associated with pegmatite at prospects within the Precambrian gneiss; surface 

exposures were not observed during this study, and, according to earlier descriptions, underground ore bodies 

are erratically distributed and irregular in size and 

shape (Rohtert, 1981; Warne and Reeves, 1957). At the 

Thumbum mine, outside the Sugarloaf Roadless Area, 

very low grade supergene deposits contain an estimated 

320,000 tons of demonstrated, and 620,000 tons of inferred resources averaging 0.01 percent U90 8• No 

uranium resources are identified at the B and B and 

Thirsty King prospects. 

Within the Sugarloaf Roadless Area, no appreciable 

mineral concentrations have been observed along faults 

or intrusive contacts, in pegmatites in the Precambrian 

gneiss, in stratigraphic zones within the metasedimentary units, or in skams. A show of gold (traces in three 

grab samples) and silver (0.16 oz/ton in one grab sample) 

occurs in the contact zone between carbonate rocks and 

monzodiorite at the Pashby-Strong prospect, but concentrations are so low that no resources could be estimated. Neither hydrothermal veins nor extensive areas 

of clay or limonitic alteration has been found, although 

retrograde metamorphic alteration is pervasive. 

None of the elemental concentrations in streamsediment samples of the roadless area indicates a 

mineral occurrence large enough to be a target for 

further exploration. Most of the analyses fall within 

ranges that are reasonable for sediment derived from 

nonmineralized igneous rock, carbonate rock, and sandstone. The few values that exceed geochemical background are probably related to greater-than-normal 

abundances of disseminated non-ore minerals or traces 

of ore minerals rather than to mineral deposits. The 

principal magnetic and gravity anomalies in the roadless area correspond, respectively, with lithologic units 

of high magnetic susceptibility and of inferred high density relative to surrounding units, rather than to 

mineral deposits. 

SUGGESTIONS FOR FURTHER STUDIES 

Further study holds little promise for identification of 

unknown hidden mineral deposits within the Sugarloaf 

Roadless Area However, because the roadless area lies 

within a crystalline province characterized by high 

background concentrations for several elements (including molybdenum and tin) that tend to be concentrated with volatile constituents in late-stage plutonic 

differentiates and potentially with ore-fluids related to 

the differentiates, investigations of the regional geochemical and petrologic setting may yield insight into 

the processes of mineralization that have operated and 

where deposits are likely to occur. 

REFERENCES 

Cameron. C. S., 1982, Stratigraphy and significance of the Upper 

Precambrian Big Bear Group. in Cooper, J.D .. compiler, Geology 

of selected areas in the San Bernardino Mountains, western 

Mojave Desert, and southern Great Basin. California: Geological 

Society of America, Guidebook for Field Trip umber 9. 78th 

Annual Meeting of the Cordilleran Section, p. 5-20. 

381 
Dibblee, T. W., Jr., 1964, Geologic map of the San Gorgonio Mountain 

quadrangle, San Bernardino and Riverside Counties, California: 

U. S. Geological Survey Miscellaneous Geological Investigations 

Series 1- 431. scale 1:62,500. 

Powell, R. E .. Matti, J. C .. Cox. B. F., Oliver, H. W .. Wagini. Alexander, and Campbell, H. W., 1983, Mineral resource potential 

map of the Sugarloaf Roadless Area, San Bernardino County, 

California: U.S. Geological Survey Miscellaneous Field Studies 

Map MF- 1606- A. 

Rohtert, W. R .. 1981, Paragenesis of the Thumbum uranium deposit, 

San Bernardino Mountains, California: University of Colorado, 

unpublished Ph.D. thesis, 149 p. 

382 

Sadler, P. M., 1982, Geologic map of the Moonridge Quadrangle, 

California Division of Mines and Geology Open-File Map (San 

Francisco), scale 1:24,000. 

Troxel, B. W., Stinson, M. C., and Chesterman, C. W., 1957, Uranium, 

in J enkins, 0 . P., director, Mineral Commodities of California: 

California Division of Mines Bulletin 176, p. 669-687. 

Vaughan, F. E .. 1922, Geology of an Bernardino Mountains, north 

of San Gorgonio Pass: University of California, Department of 

Geological Sciences Bulletin. v. 13, p. 319- 411. 

Warne, J. D., and Reeves, R. G., 1957, Report of examination of field 

team, claims San Bernardino County, California: Defense Minerals Administration Report 4563, 7 p. 
SWEETWATER ROADLESS AREA, CALIFORNIA AND NEVADA 

By GEORGE L. K E EDY, 1 U .S. G EO LO ICAL URVEY, and 

R OBERT H. LAMBETH , U.S. BUREAU OF MI ES 

SUMMARY 

Mineral surveys of the Sweetwater Roadless Area, located on the east side of 

the central Sierra Nevada in California and Nevada, were conducted in 1978-82. 

On the basis of these investigations, the roadless area has probable and substantiated resource potential for gold, silver, copper, iron, molybdenum, and 

tungsten. If undiscovered resources are present, they are likely to be of the 

epithermal-vein and disseminated precious-metal (silver, gold), disseminated 

molybdenum porphyry, or contact-metasomatic (iron, copper, molybdenum, 

tungsten, gold) types. The geologic terrane precludes the occurrence of fossil 

fuel resources. 

CHARACTER AND SETTING 

The Sweetwater Roadless Area comprises approximately 113 sq mi of Toiyabe National Forest in Mono 

County, California, and Lyon and Douglas Counties, 

Nevada The roadless area, encompassing most of the 

Sweetwater Mountains, lies on the east side of the 

Sierra Nevada 20 mi northwest of Mono Lake and 40 mi 

southeast of Lake Tahoe. The area is highlighted by a 

series of spectacular barren peaks, from East Sister in 

the north to Mount Jackson in the south, and is underlain by bleached or brightly colored Mesozoic basement 

rocks and Tertiary volcanics. Altitudes range from 

11,673 ft on Mt. Patterson to 6160 ft near Devils Gate 

on the East Walker River. Vegetation types vary from 

semiarid to alpine. Access to the area is from U.S. 

Highway 395 on the southwest and west, Risue Road on 

the north, Nevada Highway 22 on the northeast, and 

California Highway 182 on the southeast. Bridgeport, 

California, 3 mi southeast of the roadless area, is the 

nearest populated area 

The mineral-resource evaluation of the roadless area 

was based on geologic mapping, geochemical analyses 

of rock, stream-sediment, and nonmagnetic heavymineral-concentrate samples, aeromagentic and gravity 

surveys, and an examination of mines, prospects, and 

mineralized areas (Brem and others, 1983; Brem, 1983; 

Lambeth and others, 1983). 

'With contributions from G. F. Brem. M. A. Chaffee. and D. Plruff, USG . and H. W. 

CampbeU, D. F. ScotL. and J. 0 . pear, USBM. 

The Sweetwater Mountains are underlain by a Mesozoic basement complex of dominantly silicic granitic 

rocks and minor amounts of metamorphic rocks. An extensive cover of Tertiary volcanic rocks and Tertiary(?) 

and Quaternary surficial deposits make up the remainder of the area Mineralized areas are associated 

with hydrothermally altered Cretaceous granite and 

Tertiary rhyolite, and thermally metamorphosed and 

metasomatized roof-pendant rocks. 

Metamorphosed volcanic and marine tuffaceous sedimentary rocks of Mesozoic age occur in small roof pendants and septa scattered throughout the roadless area 

Granitic rocks related to the Sierra Nevada batholith 

are exposed over about one-fifth of the roadless area and 

represent a sequence of predominantly Upper Cretaceous intrusions. Multiple intrusive episodes of alteration 

and mineralization are associated with the most extensive plutons. 

Nearly half of the roadless area is covered by Miocene 

volcanic rocks of varying compositions and provenance. 

The most extensive units, from oldest to youngest, are 

as follows: andesite of the Relief Peak Formation; 

rhyolitic hypabyssal intrusive rocks, lava flows and tuff 

breccias from Sweetwater volcanic center; and latite 

flows and tuffs of the Stanislaus Group from Little 

Walker caldera Hydrothermal alteration and mineralization associated with rhyolitic volcanism has affected 

rhyolitic and all underlying rocks. 

The remainder of the roadless area is covered by Tertiary(?) and Quaternary surficial deposits of varied 

origins. Fluvial gravels of uncertain age at the north 

383 
384 

38° 

35' 

119°25' 

Approximate 

road less 

boundary 

1 ' 

LITTLE WALKER \ 

CALDERA i 

....l-y 

7 

1 

i 

.Y 

119°15' 

NEVADA 

MAP LOCATION 

0 5 

MILES 

EXPLANATION 

- Geologic terrane with substantiated resource 

potential for gold and silver and probable 

resource potential for molybdenum 

D Geologic terrane with probable 

mineral-resource potential 

Cu Copper Mo Molybdenum 

Au Gold Ag Silver 

Fe Iron 

Mine 

w Tungsten 

Surficial deposits (Quaternary and Tertiary?) 

Volcanic rocks (predominantly Miocene ) 

, Plutonic rocks (predominantly Mesozoic) 

1--...;_----l 

Metamorphic rocks (predominantly Mesozoic) 

Contact 

B Area discussed in text 

Figure 112.- Sweetwater Roadless Area, California and Nevada 
and south ends of the mountain range may be related to 

Tertiary(?) uplift of the Sierra Nevada Younger fanglomerate and alluvium, associated with changes in 

drainage patterns, and normal faulting along the east 

side of the range indicate Quaternary uplift and westward rotation of the Sweetwater Mountains block. 

Prospecting in the Sweetwater Mountains probably 

began in the late 1850's or early 1860's. Following the 

discovery of silver, an area on the east side of the 

roadless area was organized into the Patterson mining 

district, eventually encompassing about 2000 staked 

claims. The district had three major periods of production, in the early 1880's, in the early 1900's, and again in 

the 1930's. Total production, mostly from the Silverado, 

Kentuck, and Frederick mines located just east of the 

roadless area, is estimated to be 3,400,000 oz silver, 

3000 oz gold, and 35,000 lbs copper. Only limited, mainly unrecorded, production has come from workings 

within the roadless area. No mines in the district are 

currently in production, but about 300 claims are kept 

active by mining companies; most are east of the roadless area between Sweetwater and Fryingpan Canyons. 

MINERAL RESOURCES 

On the basis of the mineral-resource investigations, 

parts of the Sweetwater Roadless Area have probable 

and substantiated resource potential for epithermalvein or disseminated silver and gold, probable resource 

potential for disseminated molybdenum, and probable 

resource potential for contact-metasomatic iron, copper, 

tungsten, and gold in metamorphic rocks. 

Two areas (A and B, on map) have a substantiated 

resource potential, and one area (C) has probable 

resource potential for epithermal-vein or disseminated 

silver and gold. Precious-metal deposits in all three 

areas occur in sheared, intensely silicified, argillized or 

sericitized rhyolitic rocks erupted from the Sweetwater 

volcanic center. 

Area A is the largest, contains most of the old silver 

mines in the Patterson mining district, and lies east of 

the mountain crest between Sweetwater and Fryingpan 

Canyons. The area extends eastward beyond the roadless area, where it is transected by Silverado Canyon. 

Precious-metal-bearing veins occur in north-trending 

shear zones in intensely altered rhyolite; disseminated 

precious-metal deposits are likely, particularly near vein 

deposits with previous mineral production. Vein minerals that may be found here include precious- and less 

abundant base-metal sulfides, native precious metals, or 

precious-metal tellurides in quartz-adularia gangue and 

rhyolite breccia. Fluorite and heubneritie have been 

found near the Kentuck mine, and several probable 

breccia pipes and dikes are also present. Extensive 

mineralization in vein and altered country rock is indicated by assays of numerous vein, dump, and rock 

samples. However, the podiform nature of vein 

deposits, extensive talus cover, and sporadic occurrence 

of disseminated precious-metal mineralization generally 

precludes calculation of resources. 

Area B, near Fryingpan Canyon, has substantiated 

resource potential for gold and silver, and is underlain 

by intensely silicified rhyolitic rock. Precious-metal vein 

deposits have been developed in a small mine with no 

known production, and disseminated deposits have 

been prospected for in the altered rhyolitic host rock. 

Gold distribution patterns are also indicative of a 

disseminated gold-silver deposit of hot-spring origin. 

Area C, west of Mt. Patterson, has probable resource 

potential for gold and silver. A small mine with no 

known production is developed here in a silicified shear 

zone in rhyolitic intrusive rock. Area D. near the eastern 

tip of the roadless area, is characterized by bleaching 

and weak gold and silver geochemical anomalies in 

leached andesite. No resource potential was identified. 

In Area E. north of Sweetwater Canyon, gold in association with magnetite occurs in small silicified shear 

zones in metavolcanic roof-pendant rocks that have 

been intruded by granitic rocks. Area E has probable 

resource potential for contact-metasomatic gold, as well 

as iron and tungsten. 

Molybdenum occurs in the roadless area in two geologic environments of different ages; disseminated in 

highly altered volcanic rock, and (or) as molybdenitebearing quartz veinlets in altered granitic rock. Molybdenum mineralization of highly altered rhyolitic rocks 

of the Sweetwater volcanic center is evident in three 

areas (A. B. C), all coincident with areas of preciousmetal mineralization of the same general age. Resource 

potential for areas A and B is probable. Although 

molybdenum occurs in area C, no resource potential was 

identified. Geochemical analyses indicate that selected 

vein and altered rock samples are anomalously high in 

molybdenum, and heavy-mineral-concentrate samples 

are moderately to strongly anomalous in the 

molybdenum-tungsten, base-metal, and hydrothermalalteration element suites. 

In Area A, the geochemical anomalies, the complex 

rhyolitic intrusive sequence, the breccia pipes and dikes, 

pervasive silicic and phyllic to argillic alteration, 

fluorite and heubnerite occurrences, and gravity and 

aeromagentic lows indicate that the Tertiary mineralization could have produced a disseminated molybdenum porphyry system at depth. Molybdenum in the 

system could have been derived from remobilization of 

molybdenum in Cretaceous granitic rocks, or less likely, 

from a Cretaceous episode yielding coarse molybdenite. 

385 
The combined geologic, geochemical, and geophysical 

characteristics suggest probable resource potential for a 

possible molybdenum porphyry system at depth. 

Coarse- to medium-grained molybdenite or its weathering products occur in quartz veinlets in altered 

granitic rocks at four places, three east of the roadless 

area between Silverado and Fryingpan Canyons, and a 

fourth (F) in the upper Swauger Creek drainage, only 

partly inside the roadless area Sericite associated with 

molybdenite in Silverado Canyon has yielded a Late 

Cretaceous age (Brem, 1983), indicating a Mesozoic 

molybdenum mineralization event. The widely spaced 

areas of mineralization and alteration, and the absence 

of appropriate host rock, suggest that the resource potential for a Mesozoic molybdenum system is probable. 

Iron-copper deposits in the form of metasomatic 

magnetite-serpentine rock with traces of copper-bearing 

sulfides or alteration products crop out near Sweetwater 

Canyon (G) and in a large metamorphic roof pendant 

just west of the roadless area Although a test batch of 

reportedly high grade ore was taken from Sweetwater 

Canyon, large near-surface deposits are unlikely 

because of the limited amounts of appropriate host 

rocks. Moderate amplitude magnetic and gravity anomalies suggest that the metamorphic bodies are of sufficient size to contain larger buried mineral deposits. 

Nevertheless, the mineral-resource potential for iron 

and copper-bearing bodies is only probable in area G, 

and west of the roadless area. A third, small body of 

metamorphic rock occurs in the upper Swauger Creek 

drainage, outside of the roadless area 

Tungsten mineralization may occur in contact metasomatic skarn mineral deposits developed in carbonate 

facies of the metamorphic rocks near Sweetwater Canyon (area G), and in two areas outside of the roadless 

386 

area, in the large roof pendant to the west and in the upper Swauger Creek drainage. These areas have probable 

resource potential for deposits of tungsten on the basis 

of weakly anomalous concentrations of elements related 

to tungsten mineralization, and the limited outcrop area 

of favorable host rocks. 

SUGGESTIONS FOR FURTHER STUDIES 

Identification of additional precious-metal resources 

in the roadless area will require intensive further investigation because vein deposits are generally high 

grade pods in otherwise barren veins, and disseminated 

deposits are sporadic in occurrence. In addition, the extent of a possible buried molybdenum porphyry system 

in the roadless area can only be determined by extensive 

additional investigations. 

REFERENCES 

Brem, G. F., 1983, Geologic map of the Sweetwater Roadless Area. 

Mono County, California. and Lyon and Douglas Counties, 

Nevada: U.S. Geological Survey Miscellaneous Field Studies 

Map MF-1535-B, scale 1:62,500 (in press). 

Brem, G. F .. Chaffee, M. A., Plouff, D., and Lambeth, R. H., 1983, 

Mineral resource potential map of the Sweetwater Roadless 

Area. Mono County, California. and Lyon and Douglas Counties, 

Nevada: U.S. Geological Survey Miscellaneous Field tudies 

Map MF -1535-A, scale 1:62,500 (in press). 

Lambeth, R. H., Campbell, H. W., Scott, D. F., and Spear, J. 0 ., 1983, 

Mineral investigation of the Sweetwater RARE II area (No. 

4657), Mono County, California. and Lyon and Douglas Counties, 

Nevada: U.S. Bureau of Mines Open·File Report MLA 69-83, 34 p. 
THOUSAND LAKES WILDERNESS, CALIFORNIA 

By ALISO B. TILL, 1 U.S. GE LOGICAL SURV EY, and 

EDWARD L. M CH UG H, U.S. B REA OF MI ES 

SUMMARY 

A mineral survey conducted by the USGS and USBM in 1979 of the Thousand Lakes Wilderness in northern California indicated little promise for the occurrence of mineral resources. Volcanic stone and cinders occur, but similar 

materials are found in abundance outside the wilderness. The wilderness is in 

the Cascade Volcanic Province, a setting locally favorable for geothermal 

resource potential. No geothermal potential was identified in the wilderness; 

subsurface potential cannot be evaluated without regional studies and drilling. 

CHARACTER AND SETTING 

Thousand Lakes Wilderness, an area of about 25.5 sq 

mi, is located about 50 mi east of Redding and 12 mi 

south of Burney, in eastern Shasta County, California 

The wilderness is part of Lassen National Forest, and is 

roughly 5 mi from north to south and 6 mi from east to 

west. The wilderness is on the crest of the Cascade 

Mountains and is dominated by a deeply eroded composite volcano. This volcano is the major volcanic 

edifice between Lassen Peak and Mount Shasta. Crater 

Peak, Magee Peak, and Fredonyer Peak are all on the 

volcano which will be called Crater-Magee volcano in 

this report. North and east of Crater-Magee volcano is 

the Thousand Lakes valley, which is at the center of the 

wilderness. Many small lakes are scattered in the valley 

between altitudes of 5600 and 8677 ft. Small Pleistocene 

shield volcanoes and Holocene flows and cinder cones 

are on the north and east sides of the wilderness. The 

Thousand Lakes valley is forested; peaks above the 

valley floor are generally free of vegetation. 

Thousand Lakes Wilderness is in the southern part of 

the Cascade Volcanic Province (Macdonald, 1966), a belt 

of Tertiary to Quaternary volcanic centers that extends 

from southern British Columbia to northern California 

The wilderness is 60 mi southeast of Mount Shasta and 

18 mi northwest of Lassen Peak. 

The bedrock in the wilderness is composed of volcanic 

rocks of Tertiary and Quaternary age. The oldest rocks 

exposed are pyroxene andesite of late Pliocene age 

(Macdonald, 1963). The pyroxene andesite is composed 

1

Wit.h contribuLions from Clayi.On M. Rumsey, USBM . 

of a thick sequence of flows, is regionally extensive, and 

is considered the basement rock of the area Younger 

(Pleistocene) shield and composite volcanoes overlie 

these flows. In the Thousand Lakes Wilderness, 

andesitic lavas of Crater Peak, Magee Peak, Fredonyer 

Peak, Freaner Peak, and Logan Mountain rest on the 

pyroxene andesite. Several faults in a north-northwest 

trending system of vertical to steeply dipping faults 

subsequently cut the flows in the northern and eastern 

part of the wilderness. During Holocene time, basalt 

and andesite flows emanated from cinder cones spaced 

along the fault system. These young flows occupy 

valleys along the east side of the wilderness. The 

youngest flow, the Devil's Rock Garden, extends across 

the south boundary of the wilderness. 

MINERAL RESOURCES 

No metallic mineral deposits are known in the Thousand Lakes Wilderness; nonmetallic deposits, consisting mainly of stone and cinders occur in the 

wilderness. A geochemical study revealed no significant 

anomalous values of metallic elements. An aeromagnetic survey showed no anomalies that suggest the 

existence of mineral deposits. 

No mining claims or prospects exist within the 

wilderness. No nearby metallic mineral deposits occur 

in the type of rocks found within the wilderness. Gold 

and silver were produced before 1934 from altered 

Cenozoic rhyolitic tuff at Hayden Hill, 50 mi northeast 

of the wilderness. The more mafic Cenozoic rocks within 

387 
40 

45' 

40 

40' 

388 

J 

c r > ,... 

.) 

Volcamc 

To Lessen 

N.Jt'l Park. 

I 

0 5 

MILES 

EXPLANATION 

Young basalt flows 

Glacial deposits 

., " o: Andesite of Crater-Magee Volcano 

1--.,-''----l 

Older andesite flows 

Contact 

--- Fault 

Figure 113.-Thousand Lakes Wilderness, California 

0 

To 

Su.Bnvrlle 

r 

MAP LOCATION 
the wilderness contain no analogous alteration. Gold, 

silver, copper, lead, and zinc have been mined from 

Mesozoic metavolcanic and sedimentary rocks 15- 20 mi 

to the west, but similar mineralized rocks do not occur 

within the wilderness. Coal, diatomite, and sulfur were 

also produced in the region but are not found in the 

wilderness. 

The Thousand Lakes Wilderness is in a region recognized as having potential for geothermal resources (U.S. 

Geological Survey, 1978). Hot springs are known some 

10 mi north along the Pit River, and south of the wilderness. To the south, geothermal activity occurs at several places within Lassen Volcanic National Park. The 

Morgan Springs Known Geothermal Resource Area 

(KGRA) along the south side of the park is 17 mi south 

of the wilderness. No geothermal resource potential was 

identified in the wilderness and further study and drilling would be required to fully identify any geothermal 

potential. 

Mineral resources within the Thousand Lakes 

Wilderness are limited to volcanic stone and cinders. 

Large volumes of good quality basaltic cinders occur 

throughout the area and cinders from nearby sources 

have been used in road building, for railroad ballast, and 

as lightweight aggregate. The hard, dense, and partly 

vesicular dark-gray andesite at Freaner Peak, Logan 

Mountain, and Devil's Rock Garden could provide large 

volumes of stone for construction. Plentiful and more 

accessible deposits of both volcanic stone and cinders, 

however, are available at several developed sites within 

20 mi of the wilderness closer to markets (Lydon and 

O'Brien, 1974, p. 144-147). 

SUGGESTIONS FOR FURTHER STUDIES 

Further study of the wilderness is not likely to identify metallic mineral or fossil fuel resource potential; the 

regional geologic setting, however, is favorable for geothermal resources. No surface indications of geothermal 

resources exist in the wilderness, so regional studies and 

drilling would be necessary to identify the potential. 

REFERENCES 

Lydon, P. A., and O'Brien, J. C., 1974, Mines and mineral resources of 

Shasta County, California California Division of Mines and Geology. County Report 6, 154 p. 

Macdonald, G. A., 1963, Geology of the Manzanita Lake quadrangle, 

California U.S. Geological Survey GQ- 248. 

__ 1966, Geology of the Cascade Range and Modoc Plateau, in 

Bailey, E. H., ed., Geology of northern California California Division of Mines and Geology, Bulletin 190, p. 65-96. 

Till, A. B., McHugh, E.L., and Rumsey, C. M., 1983, Mineral resource 

potential of the Thousand Lakes Wilderness: U.S. Geologic.al 

Survey Open-File Report 83- 408. 

U.S. Geological Survey. 1978, Lands valuable for geothermal 

resources. northern California: Office of Area Geologist, Conser· 

vation Division, scale 1:500,000. 

389 
0 5 

MILES 

EXPLANATION 

al Alluvium (Quaternary) 

bd Basin sedimentary deposits (Quaternary) 

Basalt (Tertiary) 

Figure 114.-Timbered Crater Roadless Area, California 

390 

Crum 

Restruon 

MAP LOCATION 

Contact 

Fault 
TIMBERED CRATER ROADLESS AREA, CALIFORNIA 

By jOCELYN A. PETERSO , 1 U.S. GEOLOGICAL SURVEY, and 

LEO E. ESPARZA, U.S . BUREAU OF MINE 

SUMMARY 

A mineral survey of the Timbered Crater Roadless Area conducted in 1979 ind.icated that the area has little or no promise for the occurrence of energy and 

mineral resources. Lava flows in the southern two segments of the roadless area 

contain large quantities of rubble that could be used in local construction projects. Further exploration in the area is unlikely due to the unfavorable geologic 

setting. 

CHARACTER AND SETTING 

The Timbered Crater Roadless Area occupies three 

small segments of land totaling about 7 sq mi in 

Siskiyou and Shasta Counties, 75 rni northeast of Redding, California The area is about 20 rni south of the 

Med.icine Lake Highland, the source for some of the lava 

flows found in the area The towns of Fall River Mills 

and McArthur lie about 8 mi south of the roadless area 

along U.S. Highway 299. Altitudes in and near the area 

range from about 3300 ft to 3981 ft and the area is 

characterized by rough often barren lava flows. 

The Fall River valley in which the Timbered Crater 

Roadless Area is located is a structural graben about 

30 mi long and 15 rni wide in the vicinity of the study 

area (Peterson and Martin, 1980). The southern part of 

the graben is filled by lake sed.iments. Further north in 

the graben these sed.iments are covered by Quaternary 

basalt flows. Springs emanate from the southern toes of 

these basalts, 1- 2 rni south of the roadless area 

The Quaternary basalts are d.ivided into three groups 

based on age and source area, but they all have similar 

trace-element chemistry and petrography (Peterson, 

1980; Peterson and Martin, 1980); these basalts have 

been combined into one unit for this report but are 

briefly described. The oldest group consists of possible 

Pleistocene basalt flows erupted from Timbered Crater 

which now are covered by a deep red soil and heavy 

vegetation. The second group of flows had its origin in 

the Med.icine Lake Highland area sometime in the 

Holocene. The lava was apparently very fluid and able 

1

With contributions from Linda M. Martin. USGS. and Gory J. Cwick. USBM. 

to flow down the pre-existing graben. The youngest 

basalt group consists of a small Holocene shield complex that erupted from several vents in the vicinity of 

Brushy Butte between the three segments of the roadless area 

MINERAL RESOURCES 

Between the late 1940's and 1971, flat lava decorative 

stone was removed from the vicinity of the Timbered 

Crater Roadless Area but further removal was banned 

by the U.S. Bureau of Land Management and USFS to 

protect local archeological sites. Recorded production of 

flat lava in the vicinity was 1700 tons, but twice that 

amount may actually have been removed. Geochemical 

and geophysical data (Peterson, 1980; Griscom, 1981) 

do not ind.icate the presence of any metallic commod.ities. Warm springs northeast of the area may indicate 

some geothermal potential but recorded temperatures 

are inadequate for power production. 

Based on the above discussion, it is concluded that 

the Timbered Crater Roadless Area has little promise 

for the discovery of energy and mineral resources. Some 

basalt rubble is present that could be used in the construction industry. 

SUGGESTIONS FOR FURTHER STUDIES 

It is unlikely that further stud.ies in the area would 

d.iscover any add.itional mineral resources. 

391 
REFERENCES 

Griscom, Andrew, 1981, Map showing aeromagnetic interpretation of 

the Baker-Cypress BLM Instant Study Area and Timbered 

Crater Forest Service Further Planning Areas, Modoc, Shasta, 

and Siskiyou Counties, California: U.S. Geological Survey 

Miscellaneous Field Studies Map MF- 1214-C, scale 1:62,500 

Peterson, J. A., 1980, Geochemical analyses and geochemical rock 

sample location map for the Baker-Cypress Area, California: U.S. 

Geological Survey Open· File Report 80-197, 4 p., scale 1:62,500. 

392 

Peterson, J. A., and Martin, L. M., 1980, Geologic map of the BakerCypress BLM Roadless Area and Timbered Crater Rare II 

Areas, Modoc, Shasta, and Siskiyou Counties, northeastern California: U.S. Geological Survey Miscellaneous Field Studies Map 

MF - 1214- A, scale 1:62,500. 

Peterson, J. A., Martin, L. M., Esparza, L. E., and Cwick, G. J., 1981, 

Mineral resource potential of the Baker-Cypress Instant Study 

Area and Timbered Crater Forest Service Further Planning 

(RARE II} Areas, Modoc, Shasta, and Siskiyou Counties, California: U.S. Geological Survey Miscellaneous Field Studies Map 

MF- 1214-B, scale 1:62,500. 
TIOGA LAKE, HALL NATURAL AREA, LOG CABIN-SADDLEBAG, AND 

HORSE MEADOWS ROADLESS AREAS, CALIFORNIA 

By j . F. SEITZ U.S. GEOL C ICAL RVEY, and 

F. E. F EDERSPIEL, U .S. B REA OF Mr tE 

SUMMARY 

Studies in 1979 of the geology and mineral resources of the Tioga Lake, Hall 

Natural Area, Log Cabin-Saddlebag, and Horse Meadows Roadless Areas indicate that parts of the Log Cabin-Saddlebag and Hall Natural Roadless Areas 

have a substantiated resource potential for gold and (or) silver resources, and a 

probable potential for tungsten and molybdenum resources. Tioga Lake Roadless Area has little likelihood for the occurrence of mineral resources and the 

Horse Meadows Roadless Area has a probable potential for low-grade tungsten, 

gold, and (or) silver resources. In the Log Cabin-Saddlebag Roadless Area, the 

principal mineralized areas are on the east flank of Mt. Warren in the vicinity of 

the Log Cabin mine and on the ridge between Saddlebag Lake and Warren 

Creek. In the Hall Natural Roadless Area the principal mineralized zone is at the 

site of the long defunct Great Sierra mine west of Tioga Lake. The geologic terrane in the roadless areas precludes the occurrence of organic fuel resources. 

CHARACTER AND SETTING 

The roadless areas described in this report are adjacent to each other in the eastern part of the Sierra 

Nevada range, Mono County, California They lie immediately east of Yosemite National Park where they 

extend from the crest of the Sierra east to the vicinity of 

Mono Lake. Altitudes in the glaciated and rugged terrain range from 6815 to 12,588 ft above sea level. 

California State Highway 120 provides access to the 

areas, entering from the west at Tioga Pass and from 

the east in the canyon of Lee Vining Creek. Two of the 

areas lie south of the highway and the other two immediately north of it. 

The Tioga Lake Roadless Area covers 1.25 sq mi and 

lies adjacent to and northeast of Tioga Pass. The Hall 

Natural Area covers 9 sq mi and extends west from 

Tioga Lake to the crest of the range and northward to 

the upper basin of Saddlebag Lake. Its west margin is 

composed of a series of cirques culminating in the peaks 

of Mount Conness and North Peak. The Log CabinSaddlebag Roadless Area, largest of the group with 23 

sq mi includes the Saddlebag Lake area and Mount 

Warren and extends east from the Hall Natural Area to 

Mono Lake. It is bordered on the south by Lee Vining 

Creek and on the north by Lundy Lake and the Hoover 

Wilderness. The fourth roadless area, Horse Meadows, 

covers 9 sq mi south of Lee Vining Creek. It is covered 

mostly by glacial moraines and has a less rugged topography than the other roadless areas of this group. 

The geology of the areas is dominated by a series of 

plutons that enclose roof pendants of metavolcanic and 

metasedimentary rocks. The larger plutons are of Cretaceous age and form the west margin of the areas. They 

are bordered on the east by a belt of metamorphic rocks 

13,000 ft thick whose protolithic ages are Paleozoic, 

Permian, Triassic, and Jurassic. East of this in the area 

of Mount Warren and Mono Dome are six separate 

plutons of Triassic and Cretaceous ages. These are 

bordered on the east by a smaller roof pendant composed of Paleozoic metasedimentary rocks. Bedding and 

foliation in the metamorphic rocks follow a northwest 

trend throughout. The principal faults, mostly located 

in the Saddlebag Lake basin, follow this same trend 

with the exception of a northeast-trending fault or fault 

system located along the course of Mill Creek. 

Mining activity began in this region in the late 1850's. 

Gold- and silver-bearing quartz veins were mined outside the roadless areas at the Log Cabin and May Lundy 

mines. Both mines were being reopened at the time of 

393 
394 

37° 

55' 

I· P 

MAP LOCATION 

0 

MILES 

EXPLANATION 

- Geologic terrane with substantiated 

mineral-resource potential D Geologic terrane with probable 

mineral-resource potential 

Au Gold 

M o Molybdenum 

Ag Silver 

w Tungsten 

~ Mine or deposit 

~ Mine 

M no 

5 

Metamorphic rocks 

Granitic rocks 

Contact 

Figure 115.-Tioga Lake, Hall Natural Area. Log Cabin-Saddlebag, and Horse Meadows Roadless Areas, California 
this study. The Hess mine, also outside the areas, contains small amounts of tungsten and molybdenum in 

calc-silicate metasedimentary rocks. 

More than 100 claims in these roadless areas have 

been recorded since 1880. None are placer claims. The 

Australian claim, on the south boundary of the Log 

Cabin-Saddlebag Roadless Area, was patented in 1912. 

Mining records and previous reports indicate most 

mining activity was undertaken in the early 1900's and 

1930's. During the mineral-resource survey in 1979, 21 

adits (17 of which were caved), 15 shafts (12 of which 

were caved), and numerous trenches and pits were 

found. Present mining activity is limited to assessment 

work by local miners; no large-scale mining or prospecting was noted in the roadless areas. 

MINERAL RESOURCES 

All known mineral deposits and zones of mineralization within the roadless areas are located in the metamorphic rocks of the roof pendants or along the 

contacts between the roof pendants and the bodies of 

intrusive rock. In places where fracturing of the slates 

and quartzites in the metamorphic rocks has provided 

channels, sulfide-bearing quartz veins have penetrated 

the country rock. Some of these veins are massive and 

others comprise a fine network. 

Gold and silver minerals occur in hydrothermally 

altered and silicified shear zones in Paleozoic metasedimentary and metavolcanic rocks that contain limonitestained vuggy quartz and disseminated pyrite. Tungsten minerals occur locally in calc-silicate rocks along 

Paleozoic metasedimentary and Cretaceous intrusive 

rock contact zones. 

Rock, stream-sediment, and nonmagnetic heavymineral concentrate samples were prepared and analyzed for the geochemical study of the Tioga Lake, Hall 

Natural Area, Log Cabin-Saddlebag, and Horse 

Meadows Roadless Areas. 

An aeromagnetic survey was flown of the four roadless areas to determine if any significant magnetic ironore deposits exist and to delineate areas with chromium 

and nickel on the basis of associations with highly 

magnetic mafic intrusions. A significant magnetic 

anomaly in the shape of an elongate magnetic high was 

identified along the south flank of the ridge connecting 

Mono Dome and Lee Vining Peak in the Log CabinSaddlebag Roadless Area This magnetic high is primarily associated witl:l two igneous plutons, the granodiorite of Mono Dome and the quartz monzonite of 

Williams Butte. The high also extends northwestward 

into the Hoover Wilderness where it terminates over a 

small body of gabbro about 1 mi west of Lee Vining 

Peak. Additional work was done to evaluate whether or 

not the magnetic high was related to mineral resources. 

Ground magnetic intensity and rock susceptibility 

measurements were made along several profiles across 

the aeromagnetic high to look for the source of the 

anomaly. The results indicate that the high is not 

related to mineralization, but is only the expression of 

the granodiorite of Mono Dome, which is an unusually 

high magnetic rock. 

The rock samples were collected primarily to provide 

information on the normal, or background, chemical 

composition of the rock units present in the roadless 

areas; consequently, only the stream-sediment and concentrate analyses are discussed here. 

Geochemical anomalies were identified from samples 

of both stream sediment and heavy-mineral concentrates collected from several parts of the Log CabinSaddlebag Roadless Area and from samples collected 

from the southern part of the Hall Natural Area The 

most significant anomalies are in drainage basins that 

originate in the Hoover Wilderness and continue into 

the Log Cabin-Saddlebag Roadless Area. The geochemical anomalies consist of the elements copper, lead, zinc, 

silver, gold, and tungsten, which form a suite that is 

commonly associated with contact-metasomatic sulfide 

deposits that may contain base and precious metals and 

(or) tungsten. Some of the anomalies may be, at least in 

part, the result of contamination from mining activity 

upstream from various samples sites. The geochemical 

anomalies occur along streams draining areas of locally 

hydrothermally altered metamorphic rocks, including 

both metasedimentary and metavolcanic units, and suggest that undiscovered contact-metasomatic deposits of 

base and precious metals and (or) tungsten may exist 

within the Log Cabin-Saddlebag Roadless Area or the 

Hall Natural Area Major faults are known in some of 

the anomalous areas; these faults may serve as 

favorable sites for undiscovered mineral deposits. 

Demonstrated resources in the roadless areas are estimated at about 640,000 tons of gold- and silver-bearing 

material. Approximately 38,000 tons of the demonstrated resources, possibly averaging as much as 0.04 

oz goldlton and 0.2 oz silver/ton, are in two areas of substantiated resource potential in the Log Cabin-Saddlebag Roadless Area; one on the east side at the 9991, 

Centipede, Klondike, and North Log Cabin prospects, 

and one on the west side at the Saddlebag Lake prospect. 

Resources in and near these prospects are in northerly 

trending, steeply dipping shear zones that range from 1 

to 3 ft thick. Zones at the Centipede, North Log Cabin, 

and Saddlebag Lake prospects contain limonite-stained 

metasedimentary rocks and quartz veins with as much 

as 5 percent disseminated sulfides (mainly pyrite). 

Zones at the 9991 prospect contain limonite-stained 

395 
quartz diorite and quartz veins with as much as 3 percent disseminated pyrite. 

Two additional prospects, the Australian and Golden 

Fleece, are each in a small area that has a probable 

potential for gold and silver resources. Resource 

estimates could not be made for these prospects because 

the underground workings were caved and mineralized 

zones were covered with talus. 

About 600,000 tons of demonstrated resources possibly averaging 0.01 oz gold/ton and 1.2 oz silver/ton are 

in the Hall Natural Area at the Great Sierra mine in an 

area of substantiated mineral-resource potential. 

Mineralization occurs in shear zones in metasedimentary rocks that are 6 to 40 ft thick, strike N. 20-30° W., 

dip steeply northeast, and contain brecciated metasedimentary rocks and quartz veins with arsenopyrite, 

pyrite, chalcopyrite, and sphalerite. 

The north and south parts of the Hall Natural Area 

also have a probable resource potential for tungsten and 

molybdenum resources. Southern extensions of the 

Hess mine may underlie the north part of the area and 

in the south part of the area small tactite deposits occur 

on the September claims. 

396 

Records of mining or prospecting are not available for 

Horse Meadows Roadless Area, but the area containing 

the Tungsten Queen prospect southwest of Williams 

Butte has a probable potential for low-grade tungsten 

resources. A probable potential for low-grade gold and 

silver resources exists at the unnamed prospect to the 

west. 

No resources were identified in the Tioga Lake Roadless Area 

REFERENCES 

Seitz, J. F., 1983, Geologic map of the Tioga Lake, Hall atural Area, 

Log Cabin-Saddlebag, and Horse Meadows Roadless Areas, 

Mono County, California: U.S. Geological Survey Miscellaneous 

Field Studies Map MF- 1453-A. scale 1:62,500 

Seitz, J. F .. Chaffee, M. A., Oliver, H. W., Federspiel, F. E .. Scott, 

D. F., Cather, E. E., Zilka, . T., and Leszcykowski, A. M., in 

press. Mineral resource potential map of Tioga Lake, Hall 

Natural Area, Log Cabin-Saddle Bag. and Horse Meadows 

Roadless Areas, Mono County, California: U.S. Geological 

Survey Miscellaneous Field Studies Map MF- 1453-B. 
TUOLUMNE RIVER ROADLESS AREA, CALIFORNIA 

By j OY L. H AR1 ER, 1 U.S. GEOLOGICAL S RVEY and 

PA L C. HYNDMA , U.S. B U REA F Mr E 

SUMMARY 

On the basis of mineral-resource surveys in 1975 and 1982, the western part of 

the Tuolumne River Roadless Area has a substantiated potential for the occurrence of gold and silver resources and has numerous mines and prospects with 

demonstrated or inferred gold resources. The gold is localized in high-grade 

shoots within quartz veins in the Calaveras Complex of metasedimentary rocks 

and as placer gold in Tertiary and recent river beds. The Tuolumne River bed 

has a probable placer gold resource potential. Limestone and dolomite deposits 

occur within the roadless area, and similar deposits are found outside the area. 

There is little promise for the occurrence of energy resources in the roadless 

area 

CHARACTER AND SETTING 

The Tuolumne River Roadless Area is approximately 

13 mi long and 5 mi wide, encompassing about 28.5 sq 

mi in the western Sierra Nevada, and is located about 10 

mi west of the Yosemite National Park. Groveland is 

situated just south of the roadless area along California 

State Highway 120. Altitudes range from 800 to 3880 ft 

above sea level. The major river in the roadless area is 

the Tuolumne, which drains the Hetch Hetchy Reservoir 15 mi to the east. The Tuolumne River has been 

popular for river rafting between Lumsden Bridge on 

the eastern edge of the roadless area and Wards Ferry 

17 mi downstream to the west. The Clavey River, which 

joins the Tuolumne River from the north is the largest 

tributary. The roadless area consists of gently rolling 

uplands cut by deep (2000 ft) steep-walled river and 

stream canyons. Vegetation includes evergreens, deciduous oaks, manzanita and grasslands, with conifers and 

digger pines above 2000 ft. Access to the roadless area 

is provided by unpaved and unimproved roads from 

Highway 120 to the south and from Tuolumne City near 

Highway 108 on the north, trails, and the Tuolumne 

River which is navigable through the roadless area by 

raft and kayak. 

The Tuolumne River Roadless Area is located in the 

western Sierra Nevada, where a metamorphic belt 

flanks the west side of the Sierra Nevada batholith. The 

1

Wit.h contributions from Jnmes F". Seitz. USG . 

roadless area is crossed by the East Belt, a mineralized 

zone which parallels the famed Mother Lode Belt about 

10 mi to the west, and which extends from the Stanislaus River southeast across the Tuolumne River Valley 

to approximately the south boundary of the roadless 

area In width it extends from about the mouth of the 

South Fork of Tuolumne River west for about 10 mi. 

Rocks of the roadless area include predominantly the 

Calaveras Complex of metasedimentary rocks of Paleozoic age (Schweikert and others, 1977), diorite and 

granitic intrusive rocks of Mesozoic age, numerous 

dikes and veins of probable Mesozoic age, and volcanic 

rocks of Tertiary age. 

The term Calaveras was originally applied to the 

Calaveras Formation and included all metamorphic 

rocks of Paleozoic age in the western Sierra Nevada 

The Calaveras Complex is now restricted by Schweickert and others (1977) as a northwest-trending metamorphic belt bounded by a fault zone on the west, and by 

the Sierra Nevada batholith on the east, stretching from 

Placerville to the Merced River area with extensions of 

the belt south of the Merced River in roof pendants at 

least as far south as the Tule River. The Calaveras Complex is a steeply dipping northwest-trending complex of 

metasedimentary rocks that include mica schist, phyllite, metachert, quartzite, and limestone. It is divided in 

the roadless area into three major units: an argillitephyllite unit, a chert unit, and a quartzite unit. The 

limestone is primarily within the argillite unit, and occurs as southeastern extensions of much larger marble 

397 
398 

37° 

55' 

37° 

50' 

120°15' 120°10' 

A IS! l ~ NA flO t\L 1- >HI Sl 

MAP LOC ATION 

W r 

111 < laM 

0 5 

M ILES 

EXPLANATION 

-

Geologic terrane with substantiated 

mineral-resource potential 

D Geologic terrane with probable 

mineral-resource potential 

Au Gold 

Ag Silver 

~ Mine or deposit 

' Volcanics (Cenozoic) 

Diorite (Mesozoic ) 

Calaveras Complex (Paleozoic) 

--- Contact 

Figure 116.-Tuolumne River Roadless Area, California 
masses to the west and north; minor outcrops also occur 

within the chert unit. Each of the units of the Calaveras 

Complex is composed of chiefly the rock type for which 

it is named, with lesser amounts of interbedded rocks of 

the other two types. Contacts run northwest, and the 

limestone bodies trend slightly more east-west. 

The diorite, with compositional variations to granodiorite, occurs in the eastern end of the roadless area, 

and is the westernmost extension of the Mesozoic intrusives that make up the Sierra Nevada batholith. Textures are fine to medium grained, equigranular, and foliated near the contacts with the metamorphic rocks. 

Mixed rocks of the plutonics and the metasediments, including breccias with diorite enclosing quartzite blocks, 

also occur near the contacts. 

Dikes and veins of pegmatite, aplite, quartz, and 

basalt composition occur throughout the roadless area 

The dikes represent several ages of emplacement as 

they exhibit complex crosscutting relationships. 

The volcanics are remnants of Tertiary flows (20 to 30 

million years old) that once covered much of the area 

near the present Tuolumne River. The flows commonly 

cap gold-bearing Tertiary stream gravel. Volcanic rocks 

are located in two places near the roadless area boundary; on Corcoran Flat and on Jawbone Lava Flat. 

A geochemical survey of the area was completed by 

the USBM during their study in 1975 for the Wild and 

Scenic Rivers appraisal; sediments were sampled along 

the Tuolumne River and in each of its significant 

tributaries. 

Geophysical maps were compiled from gravity and 

aeromagnetic surveys to aid in geologic mapping and 

mineral appraisal (Don Plouff, unpub. mapping, 1982). 

MINERAL RESOURCES 

Gold is the principal mineral commodity in the 

Tuolumne River Roadless Area It occurs in the East 

Belt in quartz veins and in silicified portions of shear 

zones and in placers. In some of the vein deposits silver, 

lead, copper, and zinc are associated with the gold. 

Placer gold occurs in Tertiary river gravels on the rims 

of the Tuolumne River Canyon and in Holocene gravels 

and in the present river bed. 

Gold in the roadless area occurs in both lode and 

placer deposits. The lode deposits occur as ribbon 

quartz veins and stringers, with disseminated pyrite, 

within shear zones in pyritic phyllite or marble. The 

highest gold values occur in shoots, reportedly as wide 

as 50 ft, that are at an angle to the dip of the veins. Lead 

and zinc occurring in galena and sphalerite usually accompany the higher concentrations of gold. The goldbearing zones generally strike east-west but some strike 

north and northeasterly. 

The Tertiary placer deposits, situated mostly on the 

south rim of the Tuolumne River Canyon, were capped 

by lava flows and preserved during subsequent uplift 

and erosion during the Sierran orogeny. Gold in the 

placer deposits of the present river have as their sources 

the Tertiary placers as well as the gold-bearing veins of 

the East Belt. 

In the geochemical study, detectable amounts of gold 

and silver were found in all stream-sediment samples. 

However, only one location contained an anomalously 

high concentration of gold, and only four contained 

anomalously high concentrations of silver. 

The geophysical study showed narrow magnetic 

highs that extend nearly 2 mi southeast from the 

Kanaka mine. The magnetic highs probably reflect 

magnetite-bearing veins or dikes that follow the 

regional geologic trend. 

Since the 1870's when county records were established, more than 1500 lode and 300 placer claims have 

been recorded, mainly in the western half of the roadless 

area An unknown number, probably quite large, were 

located between 1850 and 1870. Within the roadless 

area, 12 lode claims, and placer claims covering 571 

acres, have been patented. A total of about 100 shafts, 

adits, and pits were examined in the roadless area, and 

another 50 workings were examined that are near the 

area An estimated 940,000 troy oz of gold has been produced in the East Belt, of which about 86,000 oz was 

from mines in and near the roadless area (J ulihan and 

Horton, 1940, p. 18). Complete mine production records 

are not available. 

Twenty lode properties within the roadless area have 

demonstrated and (or) inferred gold and, in some properties, silver resources. Nine lode properties adjacent to 

the roadless area also have demonstrated and (or) inferred resources of gold and, locally, silver. Four placers 

within the roadless area, and one placer adjacent to it 

have demonstrated gold resources; one placer within the 

area and three placers adjacent to the area, have inferred gold resources. Several other lode and placer 

properties within and adjacent to the roadless area may 

also have low-grade gold resources. The Tuolumne 

River bed is a possible area for suction dredging for the 

recovery of gold and has a probable placer gold resource 

potential. Localized fissures in bedrock may yield very 

coarse gold nuggets. Some large, high-calcium marble 

deposits extend into the roadless area from the west. 

These occurrences, however, are far from present or 

potential markets and similar material is found outside 

the area There is little possibility for the occurrence of 

fossil fuel and geothermal resources in the roadless area. 

SUGGESTIONS FOR FURTHER STUDIES 

Additional rock sampling in the area of substantiated 

399 
gold resource potential would help define the gold 

resources of the roadless area and possibly identify 

other occurrences. 

REFERENCES 

Bateman, P. C., and Wahrhaftig, C., 1966, Geology of the Sierra 

Nevada in Geology of Northern California: California Division of 

Mines and Geology Bulletin 190, p. 107-169. 

Harner, J. L., Seitz, J. F., Plouff, Donald, and Hyndman, P. C., in 

press, Mineral resource potential map for the Tuolumne River 

Roadless Area, Tuolumne County, California: U.S. Geological 

Survey Miscellaneous Field Studies Map MF- 1617- A, scale 

1:62,500. 

400 

Hyndman, P. C., 1983, Mineral investigation of the Tuolumne River 

RARE II Area (No. 5258), Tuolumne County, California: U.S. 

Bureau of Mines Open-File Report MLA 73- 83, 17 p. 

Julihan, C. E., and Horton, F. W., 1949, Mines of the southern Mother 

Lode region, Part II, Tuolumne and Mariposa Counties: U.S. 

Bureau of Mines Bulletin 424, p. 1- 93 

Schweickert, R. A., Saleeby, J. B., Tobisch, 0 . T., and Wright, W. H. 

III. 1977, Paleotectonic and paleogoograpltic significance of the 

Calaveras Complex, Western Sierra Nevada, California, in Paleozoic paleogeography of the Western United States: Los Angeles, 

Pacific Coast Paleogeography Symposium 1, p. 381 - 394. 
VENTANA WILDERNESS, CALIFORNIA 

B y R . C. PEARSO , 1 U.S. GEOLOG L AL S RVEY, and 

P. V. FILLO, U.S. B UREA OF Mr E 

SUMMARY 

A mineral survey of the Ventana Primitive Area (now the Ventana 

Wilderness) was made in 1966- 67. On the basis of known mineral occurrences 

and our geologic and geochemical studies, this part of the Coast Ranges of central California contains little evidence for the existence of mineral resources. 

Small bodies of good quality marble are scattered through parts of the 

wilderness. Because of their small size these marble occurrences are not considered as having resource potential. 

CHARACTER AND SETTING 

The Ventana Wilderness is in the Santa Lucia Range 

southeast of Monterey and Carmel, California Its central part is drained by the Big Sur River, and its 

western boundary is generally along the coast ridge, a 

few thousand feet above the rugged and scenic Pacific 

coast. The area is characterized by northwest-trending, 

steep-sided, sharp-crested ridges that are separated by 

youthful V-shaped valleys. Many of the streams flow in 

narrow canyons with steep to vertical walls, waterfalls, 

and deep plunge pools. 

The Santa Lucia Range is part of a northwesttrending fault-bounded block of crystalline rocks. 

Sedimentary and probably volcanic rocks have been 

metamorphosed and are now schists and gneisses that 

have been intruded by plutonic igneous rocks that range 

from gabbro to granite. Younger unmetamorphosed 

sedimentary rocks, chiefly sandstone, siltstone, and 

claystone, lie on the crystalline rocks and are preserved 

as slices and blocks along and between faults. The block 

of crystalline rocks, which is over 300 mi long, is 

bounded by major faults: the San Andreas on the northeast and the Sur-Nacimiento on the southwest. Both of 

these are outside the Ventana Wilderness, but the principal faults within the area also trend northwest and account for the northwest pattern of ridges and valleys 

that make up the area Generally lesser faults of other 

trends are also abundant. 

Because the area is heavily vegetated, the rocks in the 

wilderness are weathered and the soil is thick, and the 

1

Wit.h cont.ribuLions from P. T. Hayes. U S. 

country is difficult to traverse on foot, much reliance 

was placed on geochemical sampling to assess the mineral resources. So far as known, no mining has been 

done, although 2 lode claims and 18 placer claims were 

filed many years ago and some prospecting has been 

done according to reports. 

MINERAL RESOURCES 

The southern Coast Ranges of California have produced substantial quantities of petroleum, mercury, and 

dolomite, and lesser amounts of chromite, manganese, 

asbestos, diatomite, limestone, and copper. All these 

commodities, except dolomite, limestone, and copper 

were derived from geologic terranes different from the 

crystalline rocks that dominate the Ventana Wilderness 

and, hence, they are not likely to occur here. The 

sedimentary rocks are not preserved in sufficient 

thickness to provide traps for petroleum. Dolomite has 

been quarried extensively about 40 mi northeast of the 

wilderness. Elsewhere, limestone has been exploited on 

a small scale, and negligible amounts of copper have 

been mined. Uranium, molybdenum, and mercury prospects are within a few miles of the wilderness but no 

significant prospects are known in the area. 

The geochemical studies generally confirm the scarcity of mineralized rock in the area as determined by the 

absence of mining and minimal observable evidence of 

mineralized rocks. Although a few samples of pyritic 

and graphitic schist and gneiss were highly anomalous 

in vanadium and molybdenum, and small amounts of 

copper and zinc, no resource potential was identified. 

401 
402 

36° 

30' 

36° 

15' 

121 °45' 121 °30' 

Approximate boundary 

0 

r 

MAP LOCATION 

0 10 

MILES 

EXPLANATION 

Sedimentary rocks (Tertiary and Cretaceous) 

Metamorphic and intrusive rocks 

(Pre-Tertiary) 

--- Contact 

---Fault 

Figure 117.-Ventana Wilderness, California 
Thin layers and small pods of limestone have a composition suitable as a source of lime, but the marble 

bodies are small, in very rugged terrain, and are remote 

from transportation. 

SUGGESTIONS FOR FURTHER STUDIES 

Detailed mapping and sampling of the sulfide-bearing 

gneiss and schist will be needed to determine the grade 

and extent of these rocks and the possibility that they, 

in fact, could represent significant resources. 

When the mineral survey of the Ventana Wilderness 

was made in 1966-67, no consideration was given to the 

possiblity of geothermal energy. The numerous thermal 

springs in and near the area suggest a high geothermal 

gradient and that geothermal-energy resources should 

be investigated. 

REFERENCE 

Pearson, Robert C .. Hayes, Philip T., and Fillo, Paul V., 1967, Mineral 

resources of the Ventana Primitive Area, Monterey County, 

California: U.S. Geological Survey Bulletin 1261-B, 42 p. 

403 
404 

36° 

15' 

PACIFIC 

OCEAN 

121 °30' 

0 5 

M ILES 

EXPLANATION 

Monterey Formation (Miocene)--Mudstone 

Sedimentary rocks (Tertiary and Cretaceous) 

Granite and gneiss of the Salinian block 

(Cretaceous and older) 

CJFranciscan assemblage (Lower Cenozoic and 

upper Mesozoic)--Metagraywacke and greenstone 

- -- Contact 

Fault 

Figure 118.- Ventana Wilderness Additions and the Black Butte, Bear Mountain, and Bear Canyon Roadless Areas, California 
VENTANA WILDERNESS ADDITIONS, AND THE BLACK BUTTE, 

BEAR MOUNTAIN, AND BEAR CANYON ROADLESS AREAS, CALIFORNIA 

By VICTOR M . SEIDER 1 U.S. GEOLOGICAL S RVEY and 

LEO E. ESPARZA, U .S. BUREA OF M l E 

SUMMARY 

On the basis of a mineral survey conducted in 1980-82, the Ventana 

Wilderness additions and adjacent roadless areas offer little promise for the occurrence of mineral or energy resources. There has been virtually no history of 

mining in the area and very little mining has been done in geologically similar 

regions nearby. Oil and gas are produced from the Monterey Formation nearby, 

but the small areas of Monterey rocks in the area appear to lie beyond the limits 

of productive sandstone. 

CHARACTER AND SETTING 

The Ventana Wilderness additions and adjacent 

roadless areas, hereafter referred to as study area, occupy an area of about 181 sq mi in the Los Padres National Forest. The study area is in the Santa Lucia 

Range, a part of the Coast Ranges of California, and lies 

between the Salines Valley on the east and the Pacific 

Ocean on the west. Paved roads reach the area from 

U.S. Highway 101 on the east and a road just south of 

the area crosses the range and connects with the Coast 

Highway (California State Highway 1). The area has 

rugged relief and dense vegetation. Cone Peak, only 3.2 

mi from the ocean, has an altitude of 5155 ft. Junipero 

Serra Peak, with an altitude of 5862 ft, is the highest 

point in the Santa Lucia Range. Much of the study area 

is covered by brush, with stands of oak, madrone, and 

pine in more moist locations and at higher altitudes. 

Redwoods grow in valleys near the coast. The large 

Marble Cone fire of 1977 burned much of the study area 

north of The Indians, temporarily eliminating a great 

deal of nearly impenetrable brush. Annual precipitation 

ranges from more than 100 in. near the coast to about 

20 in. inland, falling mainly between December and 

April. 

A mineral survey of the Ventana Primitive Area was 

carried out by the USGS and the USBM and a report 

was published (Pearson and others, 1967). The Ventana 

Wilderness, as established in 1978, expanded the 

original primitive area. The adjacent Black Butte, Bear 

'With contributions from Charles Sabine. J. M. Spear. Scott tebbins. and J. R. Benham. 

U BM. 

Mountain, and Bear Canyon Roadless Areas were established and a mineral survey of the additions to the Ventana Wilderness and the adjacent roadless areas was 

conducted in 1980-82 (Seiders and others, 1983). 

Most of the rocks of the study area are part of a large 

fault-bounded terrane of central California known as the 

Salinian block. The basement of the Salinian block consists of high-grade metamorphic rocks of unknown age, 

chiefly gneiss, intruded by large masses of Cretaceous 

and older igneous rock, chiefly granite and granodiorite. 

The basement rocks are unconformably overlain by 

sedimentary rocks of Cretaceous and Tertiary age. The 

rocks are largely sandstone, mudstone (shale), and conglomerate. The youngest unit of the sedimentary sequence of the area is a mudstone rich in organic material 

known as the Monterey Formation. The west edge of 

the Salinian block is a complex fault system that just 

reaches the west edge of the study area West of the 

fault zone are low-grade metamorphic rocks of the upper 

Mesozoic and lower Cenozoic Franciscan assemblage. 

These rocks are chiefly metagraywacke and shale, with 

subordinant greenstone, and minor serpentinite. 

MINERAL RESOURCES 

The Coast Ranges of central California have been the 

site of a considerable and varied mineral production but 

there has been no significant activity within the study 

area Mercury has been obtained from mining districts 

located within 65 mi of the study area, and small quantities of chromium and gold have been produced nearby. 

405 
However, nearly all the metallic mineral deposits have 

been found in rocks of the Franciscan assemblage. 

Rocks of the Salinian block, which underlie nearly all of 

the study area, have produced no significant metallic 

mineral deposits. Although Monterey County records 

indicate 107 claims located in the study area, none are 

currently active and very little evidence remains of past 

activity. Geochemical study of stream-sediment 

samples (Seiders and others, 1983) showed anomalous 

values of certain elements in 9 samples, but most of 

these anomalies appear to correlate with rocks in the 

area containing relatively high values of these elements. 

Field examination and chemical analyses of rock 

samples revealed little evidence of metallic mineralization. One rock sample contained anomalous amounts of 

silver, arsenic, bismuth, copper, and lead but no anomaly was defined from sediment samples taken from 

streams draining the area The area of mineralization 

does not seem to be large, and no resources were identified. A unit of graphitic, pyritic gneiss in the northwestern part of the study area shows anomalous values 

of vanadium, molybdenum, copper, and silver. Flour 

gold was detected in some placer samples. However, no 

resource potential for metallic mineral deposits was 

identified. 

Deposits of crystalline limestone occur in the 

metamorphic rock sequence of the Salinian block but 

they are small in extent and inaccessible. Sand and 

gravel occur in alluvium and alluvial terraces but the 

deposits are small and remote from markets. Larger 

deposits occur just outside the study area In the past, 

diatomite has been mined from the Monterey Formation in nearby areas but there has been no production 

since 1942. No similar deposits are known to occur in 

the study area Phosphate rock has been reported to occur as thin beds in the Monterey Formation in the study 

area However, based on available data, no resource 

potential for phosphate or other nonmetallic mineral 

deposits was identified. 

Considerable oil and gas is obtained from the Salinas 

Valley east and southeast of the study area Most production is from sandstones in the Monterey Formation. 

406 

The oil fields are located along a northwest-trending 

zone where sandstone, which is the reservoir of the oil, 

interfingers with the petroliferous mudstone that is the 

source of the oil. This zone is entirely east of the study 

area Some sandstone also occurs in the Monterey Formation southeast of the study area near a small basement high, the Lockwood high, but so far there has been 

very little production. The Monterey Formation within 

the study area contains organic-rich mudstone but appears to lack the productive sandstones. Sedimentary 

rocks that underlie the Monterey have not been productive in nearby areas nor do they show any favorable indications of oil and gas in the study area Therefore no 

resource potential for oil and gas was identified. 

Hot springs of moderate discharge occur just outside 

the study area at Tassaj ara Hot Springs and on the 

coast 9 mi northwest of Lucia. The springs are utilized 

as hot baths. No hot springs are known in the study 

area and little promise can be held for geothermal 

energy. 

SUGGESTIONS FOR FURTHER STUDIES 

Quantitative data on the abundance of phosphate in 

the Monterey Formation would be useful in evaluating 

its potential for future use. Exploration for oil and gas 

in the Monterey Formation in adjacent areas could provide new data that could modify this current assessment of the oil and gas potential in the study area 

REFERENCES 

Pearson, R. C., Hayes, P. J., and Fillo, R. V., 1967, Mineral resources 

of the Ventana Primitive Area. Monterey County, California: 

U.S. Geological Survey Bulletin 1261-B, 42 p. 

Seiders, V. M., Esparza. L. E., Sabine, Charles, Spear, J. M., Stebbins, 

Scott, and Benham, J. R., 1983, Mineral resource potential map 

of part of the Ventana Wilderness and the Black Butte, Bear 

Mountain, and Bear Canyon Roadless Areas, Los Padres a· 

tiona! Forest, Monterey County, California: U.S. Geological 

Survey Miscellaneous Field Studies Map, MF- 1559- A, scale 

1:50,000 (in press). 
WEAVER BALLY ROAD LESS AREA, CALIFORNIA 

By M. C . BLAKE, JR. , U .S. GEOLOGICAL R EY, and 

T. j. P ETERS, U.S. BUREAU OF M I E 

SUMMARY 

A mineral survey in 1982 indicates that an area of less than 1 sq mi in the 

northern part of the Weaver Bally Roadless Area has a substantiated mineralresource potential for gold and silver; a much larger area has a probable mineralresource potential for the same elements. The geologic terrane precludes the 

occurrence of fossil fuel resources and there is little promise for the occurrence of 

additional metallic, energy, or nonmetallic resources in the roadless area 

CHARACTER AND SETTING 

The Weaver Bally Roadless Area includes approximately 22 sq mi in the Shasta-Trinity National Forest, 

Trinity County, California The area abuts the southern 

boundary of the Salmon-Trinity Alps Wilderness and is 

characterized by steep and rugged topography, largely 

covered by conifer forest with areas of chapparal. Access is by USFS roads and 4-wheel drive and foot trails. 

A northern segment of the area was examined during an 

evaluation of the mineral resources of the SalmonTrinity Alps Wilderness (Hotz and others, 1972). 

Most of the area is underlain by the Salmon Hornblende Schist (Davis and others, 1965), which ranges 

from a very fine grained metavolcanic rock to a coarsegrained metagabbro. The schist is host for most goldbearing quartz lodes in the roadless area The lodes occur along shear zones that strike northeast, dip steeply 

southeast, and are generally coplanar with foliation 

(Cox, 1967, p. 47). 

The hornblende schist is intruded by a granodiorite 

stock near Monument Peak, and also contains many, 

small unmapped dikes and sills of dacite porphyry and 

alaskite that may be offshoots of the larger Monument 

Peak pluton. The dikes and sills are locally altered and 

cut by iron-stained quartz veins. These altered intrusives appear to be the source of the geochemical 

anomalies reported by Hotz and others (1972). 

Both stream sediments and rocks were sampled for 

geochemical analysis. All of the anomalous values of 

gold, silver, and other metals were found in rock 

samples; no anomalous values were identified in stream 

sediments. A geologic map of the area has been published (Blake, in press). 

MINERAL RESOURCES 

A substantiated mineral-resource potential was identified in an area encompassing the Globe Consolidated 

Group (Globe-Bailey-Chloride mines) at the north end of 

the roadless area Production between 1891 and 1953 

from these mines totaled more than 100,000 oz of gold 

and about 26,000 oz of silver (Hotz and others, 1972, 

p. B114-119). There has been no significant production 

since 1916. Additional demonstrated resources of an 

estimated 11,627 tons remain at the Globe mine, 

averaging 0.56 oz goldlton. The Globe workings were 

largely inaccessible at the time of this study. If goldsilver ratios follow past production, resources will also 

contain by-product silver. The Bailey workings are 

inaccessible; accessible portions of the Chloride mine 

contain only minor amounts of gold-bearing quartz, but 

the grade is encouraging. 

Other gold-bearing quartz lodes in the roadless area 

and vicinity with demonstrated gold resources include 

the Mason-Thayer mine, the Meckel-Fields mine, and 

the Arbuckle mine. Assay results from 12 other lode 

prospects in the roadless area do not indicate demonstrated resources, but exposure at many prospects is 

limited. 

Free gold was found in pan concentrates from 10 of 11 

known placer prospects in the roadless area Placer mining is limited to recreational dredging in stream beds 

because of the lack of gravel bars. Suction dredges were 

operating at two prospects at the time of this study. 

Based on the gold resources at the Globe mine plus 

additional gold-bearing quartz veins at four other prospects, and a high gold geochemical anomaly in altered 

dacite porphyry along Weaver Bally Mountain, the 

407 
408 

0 3 

MILES 

EXPLANATION 

Geologic terrane with substantiated 

mineral-resource po'tential D Geologic terrane with probable 

mineral-resource potential 

~ Mine or deposit Au Gold 

X Mineral occurrence 

Mine 

Ag Silver 

Granitic rocks 

Low-grade metamorphic rocks 

Salmon Hornblende Schist 

---Fault 

Figure 119.-Weaver Bally Roadless Area. California. 
entire area underlain by the Salmon Hornblende Schist 

is considered to have a probable mineral-resource potential for lode gold and disseminated gold in dacite porphyry. Placer mining will be limited to recreational 

dredging because of the absence of significant goldbearing gravel bars. 

SUGGESTIONS FOR FURTHER STUDY 

Detailed studies, including further geochemical 

sampling and drilling could be done in the region of the 

Globe mines. In addition, the outcrops of dacite porphyry dikes and sills and associated hydrothermal alteration should be mapped in detail. 

REFERENCES 

Blake, M. C., Jr., in press, Geologic map and geochemical data for the 

Weaver Bally Roadless Area, Trinity County, California: U .. 

Geological Survey Miscellaneous Field Studies Map 

MF- 1657-B, scale 1:48,000. 

Blake, M. C., Jr., and Peters, T. J., in press, Mineral resource poten· 

tial map of the Weaver Bally Roadless Area, Trinity County, 

California: U.S. Geological Survey Miscellaneous Field Studies 

MapMF-1657-A. 

Cox, D. P., 1967, Reconnaissance geology of the Helena quadrangle, 

Trinity County, California, in Short contributions to California 

geology: California Division of Mines and Geology Special Report 

92, p. 43-55. 

Davis, G. A., Holdaway, M. J., Lipman, P. W., and Romey, W. D .. 

1965, Structure, metamorphism, and plutonism in the southcentral Klamath Mountains, California: Geological Society of 

America Bulletin, v. 76, no. 8, p. 933- 966. 

Hotz, P. E., Thurber, H. K., Marks, L. Y. , and Evans. R. K., 1972, 

Mineral resource of the Salmon-Trinity Alps Primitive Area, 

California: U.S. Geological Survey Bulletin 1371-B, 267 p. 

409 
410 

-

D 

Cu 

Au 

Pb 

Hg 

~ 

X 

r.' 

CANYON PROSPECT 

F Ag. Pb , Zn 

G 

Hg Approximate 

' • roadless ,=c.,_o.:r---'"' • boundary 

30' 

.., 

J> 

N 

0 

M ILES 

EXPLANATION 

Geologic terrane with substantiated 

mineral-resource potential 

Geologic terrane with probable 

mineral-resource potential 

Copper Ag Silver 

Gold w Tungsten 

Lead 

Mercury 

Mine or deposit 

Mineral occurrence 

Mine 

Zn Zinc 

B 

10 

Sedimentary deposits (Quaternary ) 

Volcanic rocks (Cenozoic) 

Plutonic rocks (Mesozoic) 

Metamorphosed sedimentary and 

volcanic rocks (Pre-Jurassic) 

Marble (Jurassic to Paleozoic) 

Sedimentary rocks (Paleozoic and 

Proterozoic) 

Contact 

Area discussed in text 

Figure 120.-White Mountains and Birch Creek Roadless Areas, California and Nevada. 
WHITE MOUNTAINS AND 

BIRCH CREEK ROAD LESS AREAS, CALIFORNIA AND NEVADA 

By Mr HAEL F. DI GLE , 1 U.S. GEOLOGICAL S RVEY, a nd 

STEVE W . S HMAUCH , .S. B REA OF MINE 

SUMMARY 

The mineral survey of the White Mountains and Birch Creek Roadless Areas, 

conducted in 1980 and 1981 indicates that there is probable and substantiated 

resource potential for gold, silver, lead, copper, zinc, tungsten, and mercury as 

well as barite and pyrophyllite. Pumice resources occur in several areas in the 

White Mountains Roadless Area There is little promise for the occurrence of 

energy resources in the areas. 

CHARACTER AND SETTING 

The White Mountains and Birch Creek Roadless 

Areas occupy 243 and 88 sq mi, respectively, in the 

rugged, steep White Mountains about 15 mi northwest 

and west of Bishop, California. They are bounded on the 

west by Owens and Chalfant Valleys and on the east by 

Fish Lake Valley. Access is provided by secondary 

roads off of U.S. Highways 395 and 6, California State 

Highway 168, Nevada State Highway 3A, and from the 

White Mountains road. The geology of the roadless 

areas was mapped by McKee and others (1982). Geochemical and geophysical studies by the USGS and 

evaluation of mines, prospects, and other known 

mineral deposits by the USBM were conducted in 1980, 

1981, and 1982. A summary of the results of these 

studies and an evaluation of the mineral-resource potential is presented in Diggles and others (1983). 

The two roadless areas are underlain mostly by 

granitic rocks of the lnyo batholith which is an eastern 

extension of the Sierra Nevada batholith. The plutons 

intrude country rocks consisting of Late Proterozoic 

through Cambrian carbonate, sandstone, and shale; Ordovician argillite, chert, and shale; and metavolcanic 

and metasedimentary rocks of probable late Paleozoic 

to early Mesozoic age. Late Tertiary rhyolitic tuffs, 

flows, and dome rocks and local olivine basalt occur 

mostly in the northern part of the area 

The structural history of the roadless areas is marked 

by four periods of deformation. Prior to emplacement of 

the batholithic rocks, a thrusting event placed younger 

1

Wit.h contributions from Richard L. Rains. U BM. 

Cambrian strata over older rocks. The Cambrian and 

older rocks are found elsewhere in conformable sequences. Late Paleozoic to early Mesozoic metamorphosed volcanic and sedimentary rocks were deformed 

elsewhere and moved to their present location, possibly 

as a thrust sheet or accreted crustal fragment prior to 

intrusion of the oldest Mesozoic plutons. Local deformation is related to the emplacement of the plutonic rocks, 

and Tertiary through Holocene Basin and Range faulting is responsible for the present steep topography. 

Mining activity in the two roadless areas dates back 

to the early 1860's. The principle commodities mined 

from the White Mountains Roadless Area have been 

silver, gold, lead, copper, and zinc as well as 

pyrophyllite, pumice, barite, and andalusite. Silver, 

lead, and zinc have been produced from the Birch Creek 

Roadless Area The USBM evaluated 133 properties in 

and near the White Mountains Roadless Area; within 

this area at least 20 mines have produced metallic or 

nonmetallic minerals. Thirty-nine properties in and near 

the Birch Creek Roadless Area were studied; three properties within the area have produced small amounts of 

metallic minerals. 

MINERAL RESOURCES 

Four areas within the White Mountains and Birch 

Creek Roadless Areas were identified as having substantiated metallic mineral-resource potential (areas E, 

H, I, and L, on map). One area has a substantiated 

nonmetallic mineral-resource potential (area P). 

Area E, along the west side of the White Mountains 

411 
Roadless Area, consists of two small areas between 

Sacremento Canyon and Piute Creek. The Sacremento 

mine, within the roadless area, and the Moulas mine, 

just outside the roadless area have both produced small 

amounts of gold and copper. Geochemical anomalies 

(Diggles, 1983) and the small production indicate this 

area has substantiated potential for copper and gold 

resources. 

On the east side of the White Mountains Roadless 

Area, east of Fish Lake valley, the Indian-Marble Creek 

area (H) has substantiated mineral-resource potential as 

attested to by a rich mining history. The Green Monster 

mine produced silver, copper, lead, and zinc from 1938 

to 1953. The Evergreen mine produced silver, lead, zinc, 

and tungsten from tactite in the contact zone between 

Mesozoic intrusives and Late Proterozoic carbonate and 

clastic rocks. Geochemical anomalies in this area (Diggles, 1983) provide additional evidence for the mineral 

potential of area H. Area I consists of two small areas, 

and is a contact zone between Mesozoic granitic plutons 

and calcareous country rock that contains two mines, 

the Eva Belle on the north, and the Golden Siren, on the 

south, both of which have produced lead, copper, zinc, 

and gold. Geochemical anomalies for lead, copper, and 

zinc (Diggles, 1983) provide additional evidence for an 

area of substantiated mineral-resource potential. Area 

P, the Gunter Creek area, includes two mines which 

have produced barite from veins, and stream-sediment 

samples from this area contained anomalous levels of 

barium. The area has a substantiated resource potential 

for barite. 

In the Birch Creek Roadless Area, the Wynne and 

Ward mine has demonstrated resources of silver, lead, 

and zinc and is surrounded by an area of substantiated 

silver, lead, and zinc resource potential (area L). Nine 

areas (A, B, C, D, F, G, J, K, and M) have probable 

resource potential for metallic mineral resources. Two 

additional areas (areas N and 0) have a probable potential for nonmetallic mineral resources. 

Within the White Mountains Roadless Area, in area 

A, the Montgomery City townsite area, numerous 

claims were located for silver in the White Mountain 

fault zone. Silver occurs in short veins made discontinuous by faults. Silver, lead, zinc, and copper 

geochemical anomalies were found. There is a probable 

resource potential for small deposits containing these 

metals. Similarly, about 9 mi south along the fault zone, 

in the Mountain View and Prince mine area (B), geochemical samples contained low but anomalous levels of 

silver, lead, zinc, copper, and tungsten. There is a probable resource potential for small deposits of these 

metals in quartz veins. 

Geochemical samples collected in area C, the Gunter41 2 

Coldwater Canyon area, were anomalous in copper, 

silver, and tungsten. Outside, but near the White Mountains Roadless Area, the Southern Belle mine yielded 

small amounts of gold. Copper staining can be seen in 

the area A probable resource potential for small 

deposits of these metals is indicated. Area D contains 

several gold and copper prospect$, as well as anomalous 

amounts of copper in geochemical samples and has a 

probable mineral-resource potential. 

At the north end of the White Mountains Roadless 

Area, adjacent to the mining area of Queen Canyon 

(area F) geochemical sampling showed silver, lead, and 

zinc anomalies. In the past, the Queen Canyon mine produced small amounts of silver and the area has probable 

mineral-resource potential. To the east, adjacent to 

areas of active cinnabar prospecting, area G has a probable resource potential for mercury in Tertiary silicic 

volcanic rocks. Tertiary stream gravels capped by ancient basalt flows yielded minor amounts of placer gold 

in area J. There is a probable resource potential for gold 

in small placer deposits extending north into the roadless area 

In the Birch Creek Roadless Area, the contact zone 

between Cretaceous quartz monzonite and Proterozoic 

calcareous rocks, contains two areas (K, M) of probable 

resource potential for metallic mineral resources. Area 

K contains the Hole-in-the-Wall prospect and has probable resource potential for small deposits of lead, silver, 

zinc, and gold. Area M contains the Mexican mine and 

has probable resource potential for silver, lead, and zinc 

deposits in replacement bodies in dolomite and limestone. Both areas have probable resource potential for 

tungsten in tactite. 

Pyrophyllite and andalusite have been produced and 

are present in several deposits in the White Mountains 

Roadless Area and area N has probable resource potential. North of this area there are rutile occurrences in 

Jeffrey Mine Canyon. Further studies by the USGS are 

being conducted to determine if these occurrences constitute a titanium resource. There currently is no identified titanium resource potential at this site. Pumice is 

present at the U.S. Gypsum, Hidecker, and White Gull 

prospects in area 0 in the White Mountains Roadless 

Area This area has probable potential for small pumice 

resources. 

SUGGESTIONS FOR FURTHER STUDIES 

Recent USBM and USGS studies indicate several 

areas in the White Mountains Roadless Area should be 

considered for further study. In area E, the Moulas and 
Sacremento mines, and in area C, the Southern Belle 

mine should be drilled to prove and extend limits of gold 

mineralization. Drilling is also needed to better define 

the silver-bearing mineralized zones at the Evergreen, 

Green Monster, and Mollini mines, all in area H. Geochemical sampling could better define areas of silverbearing rock occurring at the nearby Silver Consolidated nos. 1-10 property. 

Drilling programs could be initiated on the Wynne 

and Ward and the Mexican mine properties in the Birch 

Creek Roadless Area to establish limits of mineralization. Geochemical results in areas K and L were sufficiently anomalous to justify additional geochemical 

sampling using more sensitive analytical techniques. 

Metasedimentary rocks in Jeffrey Mine Canyon along 

the range front of the White Mountains Roadless Area 

contain known rutile occurrences at the site of the 

Champion mine. Geochemical studies and (or) a drilling 

program could help define the possibility of a titanium 

resource. 

REFERENCES 

Diggles, M. F., 1983, Maps and interpretation of geochemical 

anomalies in the White Mountains, Blanco Mountain, Birch 

Creek, and Black Canyon Roadless Areas, California and 

Nevada: U.S. Geological Survey MisceUaneous Field Studies 

Map MF - 1361- B, scale 1:62,500. 

Diggles, M. F., Dellinger, D. A .. Sutley, S. J., Fey, D. L., and Hill, 

R. H .. 1982, Chemical data for samples of rock, stream-sediment. 

and dense-mineral concentrate in the White Mounains, Blanco 

Mountain, Birch Creek, and Black Canyon Roadless Areas, 

White Mountains, California and Nevada: U.S. Geological 

Survey Open-File Report 82-984, 188 p. 

Diggles. M. F., Schmauch, S. W., Lipton, D. A., Gabby, P. N., Rains, 

R. L., Hom, M. C., Barnes, D. J., Kuizon, Lucia. Cather, E. E., 

Avery, D. W., White, W. W., CampbeU, H. W., and Capstick, 

D. 0 ., 1983, Mineral resource potential map of the White Mountains (A5058) and Birch Creek (5060) Roadless Areas, Inyo National Forest, White Mountains, California and evada: U.S. 

Geological Survey Miscellaneou s Field Stud ies Map 

MF- 1361 - D, scale 1:62,500 

McKee, E. H., Diggles, M. F., Donahoe, J. L., and Elliott, G. S., 1982, 

Geologic map of the White Mountains Wilderness and Roadless 

Areas, California and Nevada: U.S. Geological Survey MisceUaneous Field Studies Map MF -1361-A, scale 1:62,500. 

413 
yb 

D 

• 

414 

121°15' 

r·-·-· . __J yb 

Chaos Crags A 

• Lassen Peak 

ob 

0 5 

MILES 

EXPLANATION 

Geologic terrane with substantiated 

geothermal resource potential 

Geologic terrane with probable 

geothermal resource potential 

Hot Springs 

Quaternary volcanics undivided 0b Young basalt 

0 Older basalt 

Quaternary volcanics ,------, 

Dacite to rhyodacite domes and flows 

Andesite to dacite hybrid rocks 

· ~ ' Basaltic andesite to dacite composite 

cone of Brokeoff Volcano 

Maidu volcanic center 

Dittmar volcanic center 

- Contact 

.A Volcanic vent 

Figure 121.- Wild Cattle Mountain and Heart Lake Road.less Areas, California 
WILD CATTLE MOUNTAIN AND 

HEART LAKE ROADLESS AREAS, CALIFORNIA 

By L. j . PATRICK M UFFLER , 1 U .S. GEOLOGICAL R EY, and 

D AVID K. D E TO , JR., U.S. B UREA of M INE 

SUMMARY 

The results of geologic, geochemical, and geophysical surveys in Wild Cattle 

Mountain and Heart Lake Roadless Areas in 1982 indicate little promise for the 

occurrence of metallic, nonmetallic, or fossil fuel resources. However, Wild 

Cattle Mountain Roadless Area and part of Heart Lake Roadless Area lie in 

Lassen Known Geothermal Resources Area, and noncompetitive geothermal 

lease applications have been filed on much of the rest of Heart Lake Roadless 

Area outside the KGRA. Both areas are adjacent to Lassen Volcanic National 

Park. Geochemical and geologic data indicate that the thermal manifestations 

in the Park and at Growler and Morgan Hot Springs just southwest of Wild 

Cattle Mountain Roadless Area are part of the same large geothermal system. 

Consequently, the entire Wild Cattle Mountain Roadless Area and part of the 

Heart Lake Roadless Area have a substantiated geothermal resource potential; 

the rest of the Heart Lake Roadless Area has a probable geothermal resource 

potential. 

CHARACTER AND SETTING 

Wild Cattle Mountain and Heart Lake Roadless 

Areas are in the southernmost part of the Cascade 

Range of northern California; the areas are about 45 mi 

east of Redding, and are in Lassen National Forest. The 

roadless areas, which were studied by Muffler, Clynne, 

and Cook (1982), and Denton and Graham (1982) are 

contiguous to the north and east with Lassen Volcanic 

National Park (LVNP) and lie partly within the Lassen 

Known Geothermal Resources Area (Lassen KGRA). 

Wild Cattle Mountain Roadless Area comprises 8.5 sq 

rni at altitudes between 4960 and 7680 ft, and Heart 

Lake Roadless Area comprises 14 sq mi at altitudes between 5600 and 7555 ft. Access to the areas is along a 

network of USFS gravel roads from California Highways 36 and 89. 

Wild Cattle Mountain and Heart Lake Roadless 

Areas lie on the southeast and southwest flanks, respectively, of Brokeoff Volcano, an eroded andesitic composite volcano formed between 0.6 and 0.35 million 

years ago. Remnants of Brokeoff Volcano are overlain 

1

Wit.h oontributions from Michael A. Clynne and Amy L. Cook. USGS. 

on the northeast by an extensive field of upper Pleistocene and Holocene dacites and andesites; historic 

volcanic eruptions occurred in 1915-1917 at the summit 

of Lassen Peak and in 1851 at Cinder Cone. 

To the south, the Brokeoff Volcano overlaps older volcanic rocks of the Maidu Volcanic Center, formed 1.8 

million years to 0.8 million years ago, which in tum 

overlaps the Pliocene Tuscan Formation, a sequence of 

andesitic breccias and flows that crops out extensively 

on the northeastern side of the Sacramento Valley. The 

nature of the basement under the central and northeastern parts of the Maidu Volcanic Center is uncertain; 

Cretaceous marine sedimentary rocks (the Chico Formation) and Mesozoic granitic and metamorphic rocks are 

exposed sporadically in canyons to the south, and 

Mesozoic granitic and metamorphic rocks crop out extensively in the northernmost Sierra Nevada 19 mi to 

the southeast (Lydon and others, 1960). These granitic 

and metamorphic rocks probably underlie the volcanic 

rocks of the region around L VNP to appear again to the 

northwest in the Klamath Mountains. 

Regional geologic structure south and southeast of 

L VNP is dominated by northwest-trending high-angle 

faults, none of which are expressed in the young 

volcanic rocks of the Wild Cattle Mountain and Heart 

415 
Lake Road.less Areas. North of LVNP, faulting trends 

northerly; this direction is also expressed by a line of 

small basaltic cinder cones just east of the Wild Cattle 

Mountain Road.less Area 

All of Wild Cattle Mountain and Heart Lake Road.less 

Areas has been glaciated, and till of Tahoe and Tioga 

ages (Pleistocene) cover most of both road.less areas. 

MINERAL RESOURCES 

No metallic mineral or fossil fuel resources are known 

in either the Wild Cattle Mountain or Heart Lake 

Road.less Areas, and geochemical analyses of stream 

sediments revealed no anomalously high metal values. 

The region around Lassen Volcanic National Park 

(LVNP) has long been recognized for its geothermal 

potential (Renner and others, 1975; Brook and others, 

1979), and an area of 141 sq mi just south of LVNP is 

classified as a Known Geothermal Resources Area 

(KGRA) (Godwin and others, 1971). This classification 

was based on the extensive vapor-dominated thermal 

manifestations to the north in LVNP and on the boiling 

silica- and chloride-bearing thermal waters at Morgan 

and Growler Hot Springs. 

Geologic observations, thermodynamic considerations, and extensive geochemical data on thermal 

waters and gases suggest that the fumarole areas 

within LVNP amd the hot springs at Morgan and 

Growler Hot Springs are parts of a single large geothermal system whose focus and major thermal upflow is 

under Bumpass Hell in LVNP (Muffler, Nehring, and 

others, 1982). Cold meteoric water percolates into 

Brokeoff Volcano in LVNP, flows underground, and is 

heated by a cooling igneous intrusion related to the 

silicic volcanic activity of the past 0.25 million years. 

Geothermal liquid at approximately 235°C at depth 

boils to form an overlying vapor-dominated reservoir, 

steam from which leaks upward to feed the fumaroles in 

L VNP. Part of the geothermal water flows laterally to 

the south to feed the Morgan and Growler Hot Springs 

and to the southeast where it is encountered in the 

Walker "0" No. 1 well at Terminal Geyser. 

This model for the Lassen geothermal system is consonant with the data on mercury and other trace 

elements in the superficial deposits (soils, muds, and 

alteration halos) of LVNP and vicinity (V arekamp and 

Buseck, 1983). In particular, the mercury anomaly that 

extends southerly down Mill Creek appears to be due, at 

least in part, to the addition of mercury accompanying 

steam that boils off the hot thermal water moving to the 

south from the center of the geothermal system. 

Nine shallow heat-flow holes have been drilled in 

Lassen KGRA (Mase and others, 1980). High gradients 

at depth in several holes suggest that thermal water 

416 

may extend under much of the northern part of Lassen 

KGRA, which includes all of the Wild Cattle Mountain 

Road.less Area, and the southeastern one-third of the 

Heart Lake Road.less Area This suggestion is supported by the detection of a minor thermal component 

in chemical analyses of cold waters from Domingo 

Spring (Thompson, 1982). 

Several types of geophysical surveys have been 

conducted in Lassen KGRA (Christopherson, 1980; 

Christopherson and others, 1980; Christopherson and 

Pringle, 1981; Fraser, 1983). These surveys all display a 

complex pattern of resistivity reflecting primarily nearsurface variations in lithology, porosity, and temperature. The known thermal areas in and adjacent to L VNP 

all show up as resistivity lows. Other conspicuous 

resistivity lows, however, may merely indicate nearsurface porous aquifers in alluvium, glacial deposits, 

and young basalts. 

In summary, geologic, geochemical, and geophysical 

evidence indicates a single geothermal system centered 

on the Bumpass Hell area of LVNP. The system consists of a vapor-dominated reservoir within L VNP and 

hot-water outflow to the south along Mill Creek and to 

the southeast to Terminal Geyser. The high thermal 

gradients at depths greater than 300 ft in several heatflow holes suggest that this lateral flow of hot water 

may not be confined only to the valleys extending south 

and southeast from Brokeoff Volcano. Instead, the entire Wild Cattle Mountain Road.less Area could be 

underlain by thermal waters, and the area have a substantiated potential for geothermal resources. 

The evidence for possible geothermal resources under 

Heart Lake Road.less Area is scanty, particularly pertinent geophysical and drill-hole data The area is indeed 

adjacent to the southwest part of LVNP, and lateral 

flow of thermal water from the main upflow zone at 

Bumpass Hell is possible. Although there are no 

thermal manifestations in or immediately adjacent to 

the road.less area, a heat-flow hole just south of the area 

does show a high temperature gradient at depths 

greater than 518 ft. Accordingly, the southern part of 

Heart Lake Road.less Area has a substantiated potential for geothermal resources, and the rest of the roadless area has a probable geothermal resource potential. 

SUGGESTIONS FOR FURTHER STUDIES 

Hydrologic modeling, gas and water geochemistry, 

and repetitive gravity surveys are being performed by 

the USGS for the U.S. National Park Service in order to 

predict and evaluate possible effects on L VNP of geothermal development in the Lassen KGRA. Evaluation 

of geothermal resources probably will not be advanced 
by further surface surveys but will require deep exploratory drilling. 

REFERENCES 

Brook, C. A., Mariner, R. H., Mabey, D. R., Swanson, J. R., Guffanti, 

Marianne, and Muffler, L. J. P., 1979, Hydrothermal convection 

systems with reservoir temperatures 2:: 90°C, in Muffler, L.J .P., 

ed., Assessment of geothermal resources of the United 

States-1978: U.S. Geological Survey Circular 790, p. 18-85. 

Christopherson, K R., 1980, Geophysical studies of the Lassen 

KGRA, California: Geothermal Resources Council Transactions, 

v. 4, p. 25- 28. 

Christopherson, K. R. Hoover, D. B., Lewis, V., Radtke, B., and 

Senterfit, R. M., 1980, Lassen Known Geothermal Resource 

Area. California-Audio-magnetotelluric, telluric profiling, and 

self-potential studies: U.S. Geological Survey Open-File Report 

80-313, 28 p. 

Christopherson, K. R., and Pringle, Laurel, 1981, Additional audiomagnetotelluric soundings in the Lassen Known Geothermal 

Resource Area. Plumas and Tehama Counties, California: U.S. 

Geological Survey Open-File Report 81-959, 18 p. 

Denton, D. K, Jr., and Graham, D. E., 1983, Mineral investigation of 

the Heart Lake (5096) and Wild Cattle Mountain (5043) RARE II 

Areas, Plumas, Shasta, and Tehama Counties, California: U.S. 

Bureau of Mines Open File Report MLA 30- 83, 9 p. 

Fraser, D. C., 1983, Airborne electromagnetic surveys of the Cascade 

Range, western USA: U.S. Geological Survey Open-File Report 

83- 92,35 p. 

Godwin, L. H., Haigler, L. B., Rioux, R. R., White, D. E., Muffler, 

L.J.P., and Wayland, R. G., 1971, Classification of public lands 

valuable for geothermal steam and associated geothermal 

resources: U.S. Geological Survey Circular 647, 18 p. 

Lydon, P. A., Gay, T. E., Jr., and Jennings. C. W., 1960, Geologic map 

of California, Westwood sheet: California Division of Mines and 

Geology, scale 1:250,000. 

Mase, C. W., Sass, J. H., and Lachenbruch, A. H., 1980, Near-surface 

hydrothermal regime of the Lassen "Known Geothermal 

Resources Area," California: U.S. Geological Survey Open-File 

Report80-1230, 31 p. 

Muffler, L. J. P., Clynne, M. A., and Cook, A. L., 19 2, Mineral and 

geothermal resource potential of Wild Cattle Mountain and 

Heart Lake Roadless Areas, Plumas, Shasta, and Tehama Counties, California: U.S. Geological Survey Open-File Report 82-846, 

25 p. 

Muffler, L. J . P., Nehring, . L., Truesdell, A. H., Janik, C. J ., Clynne, 

M. A., and Thompson, J . M., 1982, The Lassen Geothermal 

System: Proceedings of Pacific Geothermal Conference, Auckland, New Zealand, November, 1982, p. 349-356 (also published 

as U.S. Geological Survey Open-File Report 82-926). 

Renner, J. L., White, D. E., and Williams, D. L., 1975, Hydrothermal 

convection systems, in White, D. E., and Williams, D. L., eds., 

Assessment of geothermal resources of the United States- 1975: 

U.S. Geological Survey Circular 726, p. 5-57. 

Thompson, J . M., 1982, Preliminary chemical studies from Lassen 

Volcanic National Park and vicinity: Geothermal Resources 

Council Transactions, v. 6, p. 115- 118. 

Varekamp, J. C., and Buseck, P. R., 1983, Hg anomalies in soil- a 

geochemical exploration method for geothermal areas: Geothermics,v. 12,no. 1,p.29- 47. 

417 
40° 

oo· 

123°1 5' 

Approximate boundary 

Approximate roadless boundary -J. --

( BLUE \ 

JAY 

MINE \ 

Mn >- ;..5145 

, __ .,..... 

GRUBSTAKE PROSPECT 

- Cr. Ni, Co 

Big Butte __ -Shinbone .... 

-- ' 

Castle Pea/J 

l -

\ 

\ 

I ~-~ 

0 

MILES 

123°00' 

~ Mn 

Yolla Bolly-Middle Eel lderness 

\ ,_, 

5 

EXPLANATION 

MAP LOCATION 

D Geologic terrane with probable Mesozoic metamorphic, metavolcanic, and 

Cr 

Co 

Mn 

Ni 

mineral-resource potential 

Chromiu m 

Cobalt 

Manganese 

Nickel 

Mine or deposit 

sedimentary rocks 

§

"'. Pickett Peak terrane 

. , Yolla Bolly terrane 

Central terrane 

Fault 

Figure 122.- Yolla Bolly-MiddJe Eel Wilderness and Big Butte-Shinbone, East Fork, Murphy Glade, and Wilderness Contiguous RoadJess Areas, California 

418 
YOLLA BOLLY-MIDDLE EEL WILDERNESS AND BIG BUTTE-SHINBONE 

' EAST FORK, MURPHY GLADE, AND 

WILDERNESS CONTIGUOUS ROADLESS AREAS, CALIFORNIA 

By M . C. BLAKE, jR. , 1 U.S. GEOLOGICAL S R EY 

A . M. L ESZ YKOWSKI, U.S . B REA OF MI NES 

SUMMARY 

A mineral survey by the USGS and USBM in 1979-81 of the Yolla BallyMiddle Eel Wilderness identified a mine with inferred resources of manganese 

and an occurrence with inferred resources of nickel. The adjacent Big ButteShinbone Roadless Area to the west has an area of probable potential for the occurrence of chromium-nickel-cobalt resources and mines with demonstrated and 

inferred resources of manganese and chrome-nickel-cobalt. The known deposits 

are small and low grade. The East Fork, Murphy Glade, and Wilderness Contiguous Roadless Areas are considered to have little promise for the occurrence 

of mineral resources. The geologic terrane precludes the occurrence of fossil fuel 

resources. 

CHARACTER AND SETTING 

The Yolla Bally-Middle Eel Wilderness and adjacent 

roadless areas lie along the crest of the northern Coast 

Ranges in Trinity, Tehama, and Mendocino Counties, 

northern California and together will be referred to as 

the study area The area encompasses about 260 sq mi 

and includes the highest peaks in the entire Coast 

Ranges, with nearly 6000 ft of relief between South 

Yolla Bolly Mountain and South Fork of Cottonwood 

Creek. 

All of the rocks in the wilderness and roadless areas 

are assigned to the Franciscan assemblage which in this 

area is of Mesozoic age. We have subdivided this 

assemblage into three tectonostratigraphic terranes 

based on lithology, age, structure, and metamorphic 

history. 

The Pickett Peak terrane consists of quartz-mica 

schist, metagraywacke, and minor metabasalt. The Central terrane is a tectonic melange characterized by large 

blocks of resistant basalt, chert, and sandstone in a 

highly sheared shaly matrix. Geologic mapping and geochemical sampling suggests that there is little promise 

for the occurrence of mineral resources in these terranes, 

within the study area 

'Wil.h conlribul.ions from A. S. Joyko. USGS. and W. D. Longwill and Michael Cobia. 

US8M. 

Geologic and geochemical studies suggest that the 

sedimentary rocks of the third terrane, the Y olla Bolly 

terrane, consisting of interbedded graywacke-type sandstone and radiolarian chert, were deposited on the 

ocean-floor in an area undergoing rifting, perhaps similar to the present.<fay Gulf of California. During rifting, 

small sills of diabase and gabbro intruded the overlying 

sedimentary rocks and produced local hydrothermal 

alteration. Subsequently these rocks were folded and 

thrust faulted and small bodies of serpentinite were tectonically emplaced within and along the faulted boundaries of the Y olla Bolly terrane. 

MINERAL RESOURCES 

The study area was prospected and claims staked in 

the region as early as 1899, but no mining occurred until 

World War I when a few tons of chromite-bearing rock 

were mined and stockpiled at the Grubstake prospect, 

in one of the serpentinite bodies along the western 

margin of the Y olla Bolly terrane. Mining activity was 

renewed during World War II with the discovery of the 

Blue Jay manganese deposit in radiolarian chert that 

had been intruded and hydrothermally altered by a 

diabase sill. Production from this mine and a few others 

outside the study area continued intermittently 

419 
through the Korean war. About 2400 tons of demonstrated and inferred resources averaging 9.5 percent 

manganese remain at the Blue Jay mine. Geologic studies and geochemical sampling indicates another locality 

with inferred manganese resources near Bearwallow. 

The geologic occurrence is identical to that of the Blue 

Jay mine and approximately 10,000 tons of inferred 

resources averaging about 21 percent manganese are 

estimated in the pods exposed on the surface. 

Two other deposits associated with serpentinite were 

also evaluated. One is near the previously mentioned 

Grubstake prospect, where a red laterite soil, formed 

from weathering of the serpentinite, contains demonstrated resources of about 9700 tons averaging 1.25 percent chromium oxide (Cr20 3), 0.45 percent nickel, and 

0.03 percent cobalt. Weathered serpentinite extends to 

the south and the area is considered to have probable 

resource potential for similar contents of chromium, 

nickel, and cobalt. Weathered serpentinite also occurs 

on Wright's Ridge, where the inferred resource is approximately 2,400,000 tons of laterite averaging about 

1.00 percent nickel. 

420 

SUGGESTIONS FOR FURTHER STUDIES 

The manganese occurrences in the central part of the 

Y olla Bolly terrane have been exceptionally well exposed by glacial erosion. The relationship between the 

radiolarian chert, the diabase intrusives, and the 

manganese are little understood. Further studies in 

these well-exposed areas could lead to a better 

understanding of the genesis of manganese deposits of 

this type. 

REFERENCES 

Blake, M. C., Jr., and Jayko, A. S., 1983. Preliminary geologic map 

and cross-section of the Yolla Holly-Middle Eel Wilderness area 

and contiguous Roadless Areas, northern California: U.S. 

Geological Survey Miscellaneous Field Studies Map 

MF - 1595-A, scale 1:62,500. 

Blake, M. C., Jr., and Jayko, A. S., Lescykowski, A. M., Longwell, 

W. D., and Gobla, Michael, 1983, Mineral resource potential map 

of the Yolla Holly-Middle Eel Wilderness and adjacent roadless 

areas, northern California: U.S. Geological urvey Miscellaneous 

Field Stuclies Map MF- 1595- B. 

U.S. Geological Survey, 1979, Aeromagnetic map of the Yolla HollyMiddle Eel Wilderness Area: U .. Geological Survey Open-File 

Report 79- 1176, scale 1:62,500. 

4QO 

380 

422 

c 0 L 

1000 

. 1 

0

Craig 

Grand 

Junction 

e 22 

. 23 

4 

• . 6 ~\\}~~ 

9 

• e 10 

11 e 

e13 . 14 

e 24 

e 26 J)urango e 27 

0 

0 R A D 0 

104° 

106° 

e 2 .ct-

. 3 Platte ~ 

. 5 DENVER . 7 . s 

"§ 

0' 

0

Colorado 

Springs 

e 21 

e 25 

100 

MILES 

Location of areas studied. 
COLORADO 

Map 

No. Name of A rea 

12 Buffalo Peaks Wilderness Study Area 

18 Cannibal Plateau Roadless Area and Powderhorn Wilderness study area 

27 Chama-Southern San Juan Mountains Wilderness study area 

3 Comanche-Big South, Neota-Flat Top, and Never Summer wilderness 

study areas 

7 Eagles Nest Wilderness 

6 Flat Tops Primitive Area 

14 Fossil Ridge Wilderness Study Area 

21 Greenhorn Mountain Wilderness Study Area 

10 Hunter-Fryingpan Wilderness and Porphyry Mountain Wilderness study 

area 

5 Indian Peaks Wilderness 

19 La Garita Wilderness 

9 Maroon Bells-Snowmass Wilderness and additions 

1 Mount Zirkel Wilderness and vicinity 

11 Oh-Be-J oyful Wilderness Study Area 

26 Piedra Wilderness Study Area 

2 Rawah Wilderness 

15 Sangre de Cristo Wilderness Study Area 

4 Service Creek Roadless Area 

25 Spanish Peaks Wilderness Study Area 

16 Uncompahgre Primitive Area 

17 Uncompahgre Primitive Area, contiguous study areas 

8 Vasquez Peak Wilderness study area, and St. Louis Peak and Williams 

Fork Roadless Areas 

24 Weminuche Wilderness 

13 West Elk Wilderness 

23 West Needle Wilderness Study Area 

20 Wheeler Wilderness Study Area 

22 Wilson Mountains Wilderness 

423 
424 

39° 

00' 

• 

Clr'w (_ •cek Uesr> • 1 

~ 

\"Approximate 

0 boundary 

COLORADO 

• 

MAP LOCATION 

0 

106°00' 

rpld 

~\ 

10 

MILES 

EXPLANATION 

D 

Ba 

Au 

Ag 

u 

Geologic terrane with probable 

mineral-resource potential 

Barium 

Gold 

Silver 

Uranium 

Mine or deposit 

D 

D 

Volcanic rocks (Tertiary) 

Sedimentary rocks (Paleozoic) 

Granitic rocks and 

migmatic (Precambrian) 

Contact 

Fault--Bar and ball 

on downthrown side 

B Location discussed in text 

Figure 123.- Buffalo Peaks Wilderness Study Area, Colorado. 
BUFFALO PEAKS WILDERNESS STUDY AREA, COLORADO 

By D. C. H EDLU D,

1 U .S. G EO LOG ICAL URVEY, and 

R . H. W OOD, U .. B REA OF M! E 

SUMMARY 

The USGS and the USBM conducted field investigations in 1981- 82 to 

evaluate the mineral-resource potential of the Buffalo Peaks Wilderness Study 

Area, Colorado. On the basis of this study there is a probable mineral-resource 

potential for silver vein and bedding replacement deposits along the Weston 

Pass fault zone, for hydrothermal vein-type uranium deposits in the vicinity of 

the Parkdale iron pit, and for gold vein deposits in the parts of the Granite and 

Four Mile districts that are within the wilderness study area A probable barite 

resource potential occurs at Rough and Tumbling Creek and near Spring Creek 

on the east side of the study area There is little promise for the occurrence of 

energy resources. 

CHARACTER AND SETTING 

The Buffalo Peaks Wilderness Study Area occupies 

about 89 sq mi within the Mosquito Range of central 

Colorado, about llO mi southwest of Denver and near 

Buena Vista The study area is along a moderately high 

major divide that separates the Arkansas River and its 

tributaries on the west from South Park and the tributaries of the South Platte on the east. Altitudes range 

from 12,892 ft on South Peak near Weston Pass (alt. 

11,921 ft) to 13,326 ft on the volcanic flows of West Buffalo Peak. The Arkansas River valley is along a major 

rift structure that separates the Sawatch Range on the 

west from the Mosquito Range to the east; altitudes 

along the valley range from 8200 to 8880 ft. 

The study area is reached on the north from the 

secondary USFS Road 425 from U.S. Highway 285 on 

the east, over Weston Pass, and into Big Union Creek to 

the west. To the south the study area is accessible from 

the Otero Aqueduct line and the Lenhardy cutoff road. 

U.S. Highway 24 along the Arkansas River provides access to the Buffalo Meadows trail head along Fourmile 

Creek. The Low Pass Gulch road just north of Granite 

leads to the gold mines of Yankee Blade Hill and other 

mines of the Granite district. 

The high glaciated Mosquito Range is structurally a 

part of the N. 30 W.-striking east flank of the large, 

faulted Sawatch anticline. This anticline probably ex1

Wit.h contributions from G. A. owlnn. USGS. 

isted by about 70 million years ago and grew laterally as 

well as vertically from Late Cretaceous through the 

early Tertiary. Precambrian igenous and metamorphic 

rocks comprise the core of the anticline, and remnant 

east-dipping Paleozoic strata along the east side of the 

Mosquito Range are parts of the eastern limb. 

Precambrian rocks underlie more than three quarters 

of the study area and include a gneissic sequence of 

predominantly migmatite that is intruded by porphyritic granodiorite and by a still younger biotite 

granite. The Paleozoic section, about 8500 ft thick, is 

locally capped by the mid-Tertiary volcanic rocks of 

Buffalo Peaks. 

All of these rocks are within an uplifted and tilted 

fault block that is bounded by the Weston and Buffalo 

Creek faults to the east and the faults of the Arkansas 

valley graben to the west. Displacement along these 

faults probably occurred repeatedly through a long 

period beginning in the late Precambrian, and recurring 

in the late Paleozoic, Laramide and Pliocene-Miocene. 

Mineral surveys of the Buffalo Peaks Wilderness 

Study Area were made in 1981- 82 by the USGS and 

USBM and the results published by Hedlund and 

others (in press). 

MINERAL RESOURCES 

There are no active mines within the study area, but 

there are four inactive mining districts that extend into 

425 
the study area There is a probable mineral-resource 

potential in areas associated with these districts and 

they are in order of decreasing potential: the Weston 

Pass district (Behre, 1932) with its silver-bearing basemetal vein and bedding replacement deposits; the Salt 

Creek subdistrict and its vuggy uraniferous jasperoid 

deposits; the peripheral parts of the Granite district and 

the quartz-pyrite-gold-tourmaline veins; and the Four 

Mile district with quartz-pyrite-gold veins along northnorthwest-striking faults. There is a probable mineralresource potential for barite near the rhyolite stock of 

Rough and Tumbling Creek and within faulted upper 

Paleozoic strata along the Buffalo Creek fault near 

Spring Creek. A geochemical sampling survey of G. A. 

Nowlan (written commun., 1982) has indicated anomalous barium (2000 to 10,000 parts per million) and lead 

(1500 ppm) in analyzed panned concentrates from 

stream sediments at these localities. 

The lower Paleozoic strata along the Weston fault and 

its various branch faults are highly broken and fractured. In places the faults are mineralized with zinc, 

lead, and silver, especially where the host rock is the 

Mississippian Leadville Limestone (A, on map). Many 

of the mineralized fractures are silicified and vuggy and 

locally grade outward into bedding replacement 

deposits. The Ruby-Cincinnati, Collin-Campbell, Gates, 

and other abandoned silver-producing mines in the 

vicinity of Weston Pass are just outside of the study 

area. but many of the vein systems can be projected to 

the southeast within the study area along zones of intense faulting. 

The uraniferous jasperoids of the Parkdale iron pit in 

the Salt Creek district (B) are just within the study area. 

but several other smaller deposits occur outside of the 

boundary. C. M. Armstrong (written commun., 1977, 

1978) estimated demonstrated resources of about 4000 

tons of uraniferous j asperoid per vertical foot within an 

area of 1200 by 40ft. However, the exposed thickness is 

only about 3 or 4 ft and the uranium content is low, 80 

ppm (parts per million) uranium by fissure-track methods (R. A. Zielinski, oral commun., 1983). Equivalent 

U30 8 values of 36, 135, 241, 243, 287, and 288 ppm are 

reported for some j asperiods. Other elements include 20 

percent iron; 5000 ppm manganese; 150 ppm vanadium; 

2000- 3000 ppm zinc; 30-50 ppm lead; 5-55 ppm copper; 

30- 50 ppm nickel; and 30- 50 ppm cobalt; 12 analyses 

for gold indicate less than 0.005 oz gold/ton and silver 

values ranging from less than 0.2 to 0.3 oz silver/ton. 

The jasperoid is interpreted as a hydrothermal vein 

deposit that was localized in the Cambrian Sawatch 

426 

Quartzite by hydrothermal fluids migrating upward 

along fractures in the underlying Precambrian granite. 

The area of quartz-pyrite-gold-tourmaline veins in the 

Granite district (C) has a probable mineral-resource 

potential, but most veins are outside of the study area 

The gold veins of the district commonly occur as a series 

of closely spaced veins (18-19 veins in a 2000 ft interval) 

that strike N. 55-70 E. on Yankee Blade Hill. Significant production of gold (24,000 oz) has come from the 

Belle of Granite mine (J. C. Hersey, written commun., 

1982) and the district has yielded an estimated 65,000 

to 97,000 oz of gold. The veins are characterized by intensive chloritic and silicic wall rock alteration, the 

presence of anomalous boron (200 ppm), a relatively low 

base-metal content, a gold-to-silver ratio of 2.4:1, and a 

spatial association with rhyolite dikes at some of the 

mines. The gold content of the veins ranges from about 

0.2 oz/ton to about 1.4 oz/ton, whereas the silver values 

range from about 0.09 oz/ton to about 0.8 oz/ton. The 

veins are probably Laramide in age and contemporaneous with 65.3 million year old rhyolite dike intrusives 

(R. F. Marvin, H. H . Mehnert, and E. L. Brandt, written 

commun., 1983). 

Most of the quartz-pyrite-gold veins of the Four Mile 

district (D) are outside of the study area and generally 

have low gold values, 0.04 to 0.08 oz/ton. 

SUGGESTIONS FOR FURTHER STUDIES 

Further study of the area offers some promise for the 

identification of concealed mineral deposits, especially 

along the Weston fault system. A geochemical gold 

anomaly in stream sediments in the Buffalo Meadows 

area and barium anomalies in the vicinity of the rhyolite 

stock east of Rough and Tumbling Creek and along 

Spring Creek warrant further geologic and geochemical 

studies. The mineral resources of the Granite district, 

outside of the study area. also deserve further study. 

REFERENCES 

Behre, C. H., Jr., 1932, The Weston Pass mining district, Lake and 

Park Counties, Colorado: Colorado Scientific Society Proceed· 

ings, v. 13, no. 3, p. 53- 75. 

Hedlund, D. C., Nowlan, G. A., and Woods, R. H., in press, Mineral 

resource potential map of the Buffalo Peaks Wilderness Study 

Area, Lake, Park, and Chaffee Counties, Colorado: U.S. Geological Survey Miscellaneous Field Studies Map MF- 1628- A. 
CANNIBAL PLATEAU ROADLESS AREA AND 

POWDERHORN WILDERNESS STUDY AREA, COLORADO 

By WILLlAM N. SHARP, U .S . GEOLOGICAL S R EY and 

M. E. LANE, U.S. B REAU OF Ml E 

SUMMARY 

The Cannibal Plateau Roadless Area and the adjoining Powderhorn 

Wilderness study area are on the Gunnison-Hinsdale County boundary, approximately 50 mi southwest of Gunnison and a few miles east of Lake City. Part of 

the area has been known as the Powderhorn Primitive Area The mineralresource potential, assessed by the USGS and the USBM in 1979- 81, involved a 

basic geologic study, a geophysical survey, and a geochemical survey. No mining districts exist within the two areas, but the Lake City mining district 

adjoins the Cannibal Plateau Roadless Area area at the southwest edge. The 

mineral-resource survey indicates that the southwest part of the Cannibal 

Plateau Roadless Area has probable mineral-resource potential, for gold, silver, 

and molybdenum. There is little promise for the occurrence of mineral and 

energy resources for the remainder of the areas. 

CHARACTER AND SETTING 

The Cannibal Plateau Roadless Area, about 46 sq rni, 

and the adjoining Powderhorn Wilderness study area of 

approximately 80 sq mi, lie on the northern flank of the 

San Juan volcanic field, an extensive region underlain 

by a thick accumulation of Tertiary volcanic rocks and 

together will here be referred to as the study area 

Stratovolcanoes, intermediate in composition, and 

35- 30 million years (m.y.) old, are overlain by a widespread ash-flow-tuff field that accumulated 30- 22 m.y. 

ago. The sources for the ash-flow-tuff sheets are marked 

by clusters of volcanic subsidence structures (calderas) 

outside the study area; the western San Juan caldera 

complex is southwest, and the central San Juan caldera 

complex is south and southeast. Flood-basalt lava flows 

deposited after the period of ash-flow eruptions and 

caldera subsidence cap the high ridges in and near the 

study area To the north, near Powderhorn, erosion has 

cut through the volcanic cover to expose Precambrian 

crystalline rocks, which are believed to underlie most of 

the study area at depth. In the study area the erosion 

surface between the Precambrian basement and the 

volcanic cover appears to dip a few degrees southwest, 

so that in combination with rising topography southward, the Tertiary volcanic pile increases in thickness 

from approximately 1500 ft in the northeast to 5000 ft 

in the southwest. 

The older stratovolcanoes in the vicinity of the study 

area consist of dark andesitic flows, flow breccias, and 

volcanic conglomerates that crop out along cliffs on the 

west side of the plateaus of the study area, and form the 

hills of the northwest terrane of the study area and 

beyond. The overlying younger more silicic ash-flow 

tuffs, derived from caldera sources to the southwest and 

southeast, form widespread sheets of moderately to 

densely welded rocks that are exposed along extensive 

cliffs flanking valley walls on the south and east sides of 

the study area and along the deep, linear valleys that 

drain northward. Dark flood-basalt lava flows conspicuously capping the high plateau and associated ridges 

are part of the Miocene and Pliocene Hinsdale Formation, which consists of a bimodal assemblage of basalt 

lava flows and rhyolite lava flows and pyroclastic rocks. 

Several small plugs, marking former volcanic vents, 

cut the older lava flows and breccias of intermediate 

composition around the periphery of the study area The 

Trout Creek plug, near the north edge of the study area, 

and the Larsen Creek plug, just west of the valley of the 

Lake Fork Gunnison River, are examples. Several rhyodacitic dikes cut the volcanic edifices around these 

plugs. Hydrothermal activity during or after intrusion 

427 
428 

Precambrian 

rocks 

C&nnibal 

I 

COLORADO 

• 

Creede MAP LOCATION 

0 5 

MILES 

EXPLANATION D Geologic terrane with probable 

mineral-resource potential 

Au Gold 

M o Molybdenum 

Ag Silver 

" ... ... ., 

__.. Older lavas and breccias 

Ash-flow sheets 

Flood-basalt lavas 

~1~Jfn~ Intrusive plugs and related alteration 

... \\ ~ 

" • • .. Hydrothermally altered rocks ~ ¥ 

--- Contact 

-'---'- Caldera wall 

--- Northern limit of volcanic subsidence 

and venting 

Figure 124.-Cannibal Plateau Road.less Area and Powderhorn Wilderness study area, Colorado. 
commonly altered rocks adjacent to the intrusive 

centers, as well as the related dikes. Several late faults 

cut the volcanic rocks; along some of these faults the 

rocks are locally altered and show minor enrichment in 

several metals. 

The southwest comer of the study area is essentially 

part of the older Uncompahgre and younger Lake City 

volcanic calderas as shown by the caldera wall lines. 

This part of the study area is the most geologically complex because it is near large subsidence structures and is 

the site of extensive rock alteration and vein-forming 

processes related to the episodes of volcanism. 

No mining has been done within the study area; minor 

prospecting has been done around the Trout Creek plug 

and at the southwest comer of the study area in the 

altered terrane associated with the Lake City caldera 

However, mines near Lake City are on fissure veins near 

the boundary of the study area. The Golden Wonder 

mine and others produced silver and gold sporadically 

until 1900, and the mines have been promoted, maintained, and reassessed for production since then until 

the present time. 

MINERAL RESOURCES 

The study area is underlain entirely by volcanic rocks 

of Tertiary age along the northern side of the San Juan 

volcanic field. Despite the proximity of the study area 

to known mineralized districts near Lake City on the 

southwest and Powderhorn on the north and northeast, 

no evidence was seen in the geologic, geochemical, or 

geophysical surveys to indicate that any significant 

mineral occurrences exist within the study area except 

at the southwest edge near Lake City (Sharp and others, 

1983). Surface geology does not indicate exposed 

centers of mineralization elsewhere within the area, and 

no geologic environments were interpreted that might 

indicate hidden centers of this kind. Virtually all 

geochemical sampling results (Sharp and Lane, 1983) 

can be explained by sources in different bedrock terranes; anomalous metal concentrations that might indicate proximity to mineral deposits were detected only 

in the southwest edge of the study area near Lake City. 

Results of aeromagnetic (Martin and Sharp, 1983) and 

gravity surveys generally can be explained by the 

known or reasonably inferred distribution of bedrock 

types, without invoking special circumstances that 

might specifically indicate mineral potential. 

Although several periods of mineralization can be 

documented in the volcanic rocks exposed in mining 

areas near Lake City to the southwest, these episodes 

have affected rocks only within the area of the caldera 

that is in the southwest comer of the Cannibal Plateau 

Roadless Area near Slumgullion Pass. None of these 

episodes has affected rocks within the Powderhorn Wilderness study area The altered and mineralized rocks 

related to these periods of mineralization, sampled during the present study, did show anomalous concentrations of several metals (Sharp and Lane, 1983; tables 5 

and 6); gold and silver have been mined in this terrane 

near the study area These altered and mineralized rocks 

do overlap the boundary of the study area; and, as part 

of the Lake City-Uncompahgre caldera complex, this 

part of the study area is considered to have probable 

mineral-resource potential. Also, there is a probable 

resource potential for other metals such as molybdenum, disseminated in subvolcanic porphyries commonly associated at depth with silicic volcanism. No 

evidence was seen, however, that the altered and mineralized rocks extend northward or farther into the study 

area than the caldera rim. 

Many small mines and prospects in the Precambrian 

rocks near Powderhorn, north of the study area, were 

established to explore for base and precious metals, 

thorium, niobium, titanium, and rare-earth elements. 

Similar mineral occurrences could well underlie the 

volcanic rocks exposed in the Powderhorn Wilderness 

study area. If so, however, they would be at depths of 

1500 to 5000 ft and would have no geologic, geochemical, or presently determinable geophysical expression. 

Under these circumstances, such deposits would be 

very unattractive targets for exploration and consequently are not shown on the map. 

REFERENCES 

Martin. R. A .. and Sharp. W. N., 1983, Aeromagnetic map of the 

Powderhorn Wilderness study area and Cannibal Plateau Roadless Area. Gunnison and Hinsdale Counties, Colorado: U.S. Geological Survey Miscellaneous Field Studies Map MF- 1483-8, 

scale l :50,000. 

Sharp. W. ., and Lane, M. E., 1983, Geochemical map of the 

Powderhorn Wilderness study area and Cannibal Plateau Roadless Area. Gunnison and Hinsdale Counties, Colorado: U.S. Geological Survey Miscellaneous Field Studies Map MF- 1483-C. 

scale 1:50.000. 

Sharp, W. N., Martin, R. A. , and Lane, M. E .. 1983, Mineral resource 

potential and geologic map of the Powderhorn Wilderness study 

area and Cannibal Plateau Roadless Area. Gunnison and 

Hinsdal e Cou nties, Colorado: U.S. Geological Surv ey 

Miscellaneous Field Studies Map MF - 1483-A, scale 1:50,000. 

429 
430 

37° 

00' MAP LOCATION 

M ILES 

EXPLANATION 

.. 

Geologic terrane with substantiated 

mineral-resource potential 

D 

Cu 

Pb 

Mo 

Ag 

Zn 

Geologic terrane with probable 

mineral-resource potential 

Copper 

Lead 

Molybdenum 

Silver 

Zinc 

10 

Intrusive (Tertiary) 

Volcanic rocks (Tertiary) 

Sedimentary rocks (Tertiary ) 

Sedimentary rock s (Tertiary 

and Cretaceous) 

Contact 

---.-- Fault--Bar and ball on 

downthrown side 

+-

+-

2 

Anticline 

Syncline 

Caldera wall 

Area discussed in text 

Figure 125.-Chama-Southem San Juan Mountains Wilderness study area, Colorado. 
CHAMA-SOUTHERN SAN JUAN MOUNTAINS 

WILDERNESS STUDY AREA, COLORADO 

By MAURICE R . BROCK, U.S . GEOLOGICAL S RVEY, and 

ALEC E. LINDQUIST, U.S. BUREA OF Mr ES 

SUMMARY 

A mineral survey of the Chama-southern San Juan Mountains Wilderness 

study area in 1975 revealed demonstrated coal resources in an area of substantiated coal resource potential and areas of probable resource potential for 

petroleum and metals including molybdenum, copper, zinc, lead, and silver. 

CHARACTER AND SETTING 

The Chama-southern San Juan Mountains Wilderness study area, a rugged mountainous tract of 

315 sq mi that lies astride the Continental Divide in 

south-central Colorado, was studied in 1975 and the 

results published in 1977 (U.S. Geological Survey and 

U.S. Bureau of Mines, 1977). The Chama part of the 

study area, which adjoined the southern San Juan 

Mountains study area in the original study area proposal, was deleted from the proposal prior to commencement of this study; therefore, this investigation covers 

only the southern San Juan Mountains area. The west 

boundary of the study area lies about 8 mi east of the 

city of Pagosa Springs and its southernmost limit is 

about 2 mi north of the New Mexico border. Summit 

Peak (altitude 13,300 ft) is the highest of the many 

peaks in the area which exceed 11,000 ft. 

The southern San Juan Mountains contain a thick sequence of volcanic rocks that are the southeastern part 

of a very large volcanic field covering several thousands 

of square miles of the San Juan Mountain region. The 

wilderness study area lies within the southeastern part 

of this volcanic field where the preserved thickness of 

the sequence exceeds 4000 ft. The rocks, which include 

volcaniclastic debris, lava, and ash-flow tuff, originated 

from several eruptive centers in the region beginning in 

Oligocene time. Some of the centers are located near the 

northeast boundary of the area. The gently dipping volcanic strata are well exposed in the precipitous cliffs 

of numerous peaks and in the many miles of arcuate 

escarpments that were carved by glaciers along the high 

flanks of the Continental Divide. The volcanic rocks 

have been intruded by small plutons and many dikes of 

granitic and dioritic composition all of which are only 

slightly younger than the eruptive rocks (Lipman, 

1975). 

The layered volcanic rocks rest unconformably upon 

sedimentary rocks of earlier Tertiary and Late Cretaceous age that are poorly exposed in the lower flanks of 

the mountains. The Cretaceous and underlying upper 

Paleozoic rocks have been folded and extensively 

faulted. These rocks rest upon a Precambrian basement 

complex of gneisses, schists, and metaquartzite as 

determined from the few deep drill holes which have 

bottomed in basement rocks and as extrapolated from 

outcrops beyond the boundaries of the area. The volcanic and sedimentary rocks are locally covered by 

glacial till of two distinct generations: an older ice-cap 

glaciation that blanketed much of the San Juan Mountains in late Pleistocene time, and a younger, more localized, valley glaciation. Most of the till has been removed 

by erosion or buried by landslides. 

MINERAL RESOURCES 

Field investigations consisted of geologic studies 

closely coordinated with geochemical and geophysical 

investigations by the USGS, as well as a thorough 

search of mine production records and on-site study of 

several small mines and prospects within the study area 

by the USBM. The metals investigations were concentrated in the northern half of the study area which contains many porphyritic intrusive rocks of the type commonly associated with sulfide-bearing ore deposits. 

Geochemical samples were collected throughout the 

area; however, most were obtained from in or near the 

431 
hydrothermally altered and mineralized ground in terrane that borders several mining districts that are 

centered only a few miles north and northeast of the 

wilderness study area The oil and gas studies focused 

on the sedimentary rock terrane located in the southeastern part of the study area. which is located near two 

small oil and gas fields. Airborne and surface geophysical surveys, including aeromagnetic and gravity 

surveys, assisted in evaluation of these terranes for 

their metalliferous and oil and gas potential. The coal 

deposit was evaluated on the basis of its geologic setting and on meager information contained in the available production records. 

The only recorded production of coal and metalliferous sulfide ores is from mines located beyond the boundaries of the study area Beds of low-sulfur bituminous 

coal in the basal 65 ft of the Fruitland Formation of 

Cretaceous age have been mined intermittently since 

the early part of this century along the west boundary 

of the area near its northwest comer (area 2 on map). 

Thickness of individual coal beds is as much as 10 ft. 

The interval containing the coal crops out several places 

within a 4-mi-long area that contains five mines. The 

coal beds dip between 10 ° and 15 ° eastward beneath the 

western boundary of the study area The deposit contains a demonstrated coal resource of 8 million tons in 

an area of substantiated coal resource potential, of 

which about 90 percent occurs within the wilderness 

study area Resource estimates are based on a single 

4.5-ft-thick bed dipping at 10° to a .depth of 1000 ft 

beneath the surface. The area of substantiated coal 

resource potential is several times that of the demonstrated resource tonnage. 

The northernmost part of the area has been explored 

for base and precious metals periodically since 1882. 

The area contains a large body of altered and ironstained rock that is a western extension of a 20-mi-long 

mineralized belt which includes numerous mining districts. Mineralization in these districts is related to the 

emplacement of numerous plutons in middle Tertiary 

time in and near the Platoro and Summitville calderas. 

Mining records indicate there has been no production 

from the few mines located within the wilderness study 

area. but mines in the nearby districts have yielded 

432 

several million dollars in precious and base metals. 

Geologic, geochemical, and geophysical studies of about 

10 sq mi of the most intensely altered ground within the 

study area (area 1), suggest a probable resource potential for a large porphyry deposit containing copper and 

molybdenum with zinc, lead, and silver. 

The wilderness study area is located about 50 mi 

northeast of the major oil and gas fields in the San Juan 

Basin in New Mexico and Colorado. Two small oil fields 

lie near the southern boundary of the area The larger of 

these, the Gramp's field, lies 3 mi south of the boundary; the other, the Chromo field, is about 7 mi south of 

the area Two parts of the study area (areas 3 and 4) contain structures and strata similar to that in the nearby 

oil fields, and there is a probable resource potential for 

one or more oil pools within those areas. 

SUGGESTIONS FOR FURTHER STUDIES 

The coal deposit that underlies the northwestern part 

of the study area at its westernmost extension requires 

further study for a more accurate determination of the 

coal resources that underlie the area A drilling program 

consisting of six to eight holes to depths of 500-600 ft, 

located along the north-south trend of area 2 should provide needed information on the continuity and thickness 

of the contained coal beds. Drilling also is required to 

determine depth, magnitude, and tenor of the postulated porphyry deposit containing copper and molybdenum in the northernmost part of the study area 

Geophysical surveys and detailed geologic mapping in 

advance of drilling are needed in the areas delineated as 

having potential for oil and gas resources. 

REFERENCES 

Lipman, P. W., 1975, Evolution of the Platoro Caldera complex and 

related volcanic rocks, southeastern San Juan Mountains, Coler 

rado: U.S. Geological Survey Professional Paper 852, 125 p. 

U.S. Geological Survey and U.S. Bureau of Mines, 1977, Mineral 

resources of the Chama-southern San Juan Mountains wilderness study area, Mineral, Rio Grande, Archuleta, and Conejos 

Counties, Colorado: U.S. Geological Survey Open-File Report 

77- 309, 210 p. 
COMANCHE-BIG SOUTH, NEOTA-FLAT TOP, AND 

NEVER SUMMER WILDERNESS STUDY AREAS, COLORADO 

By R . C. PEARSO 1 , U .S. GEOLOG ! AL RVEY, a nd 

L. L. PAITEN, U.S. B REA OF MI NE 

SUMMARY 

A mineral-resource assessment was made in 1975-77 of three wilderness 

study areas adjacent to the north and west sides of Rocky Mountain National 

Park in north-central Colorado. The three areas have since been incorporated 

into the wilderness system. Gold, silver, and uranium prospects in major faults 

near the Comanche-Big South wilderness study area suggest the possibility that 

these commodities may also occur along numerous similar faults within the 

study area, but the lack of evidence for mineralized rock at the surface suggests 

little chance for deposits along these structures. The Neota-Flat Top wilderness 

study area shows no evidence of being mineralized and little likelihood for the 

occurrence of mineral resources. The Never Summer wilderness study area has 

strong geologic, geochemical, and geophysical evidence indicating probable 

resource potential for molybdenum deposits. The nature of the geologic terrain 

precludes the occurrence of organic fuels. 

CHARACTER AND SETTING 

The Comanche-Big South, Neota-Flat Top, and Never 

Summer wilderness study areas are in north-central Colorado, adjacent to the north and west sides of Rocky 

Mountain National Park and 25- 50 mi west of Fort Collins. The three areas correspond to parts of National 

Forest areas that were recommended as suitable for 

wilderness classification in 1979; in 1980 they were incorporated into the wilderness system as the Comanche 

Peak, Neota, and Never Summer Wildernesses. 

The Comanche-Big South wilderness study area occupies about 68 sq mi of mountainous terrain in the 

north-central Front Range. Comanche Peak (12,702 ft) 

is the northernmost peak of the Mummy Range, a subsidiary group of mountains within the much larger 

Front Range. The area is drained to the west, north, and 

east by tributaries of the Cache la Poudre River that approximately marks the west and north boundaries of 

the study area Ab~ve timberline, around Comanche 

Peak, the country is dominated by rock, tundra, and 

several glacial cirques; the zone below timberline is 

heavily forested and covered by a thick mantle of soil; 

1

With contribu tions from W. A. Braddock and V. J. Flanigan. USGS. 

and the lower slopes, especially along the Cache La 

Poudre River, make up a steep-sided rocky canyon. In 

addition to the small glaciers that existed around Comanche Peak, a large glacier moved north out of the park 

and down the Cache la Poudre River to Home at the 

northern tip of the area It deposited bouldery moraines 

along the valley sides and scoured the canyon walls. 

The rocks of the Comanche-Big South wilderness 

study area are almost entirely gneisses and granites of 

Precambrian age. The gneisses represent old sedimentary and volcanic rocks that were metamorphosed and 

folded before being intruded by the granites. All the 

Precambrian rocks were broken by east- to northeasttrending faults, parts of a regional fault system that 

crosses the Front Range. A few small dikes of Tertiary 

age have been intruded along faults. 

The Neota-Flat Top wilderness study area, about 12 

sq mi, lies southwest of the Comanche-Big South wilderness study area and is separated from it by a corridor 

2- 3 mi wide that is traversed by the Long Draw road. 

The area consists of three short glaciated valleys separated by generally bare flat-topped ridges. Most of the 

study area is formed of nearly flat lying volcanic rocks 

about 28 million years old that were deposited on Precambrian gneisses continuous with those in the 

Comanche-Big South wilderness study area 

433 
434 

D 

M o 

u 

MILES 

EXPLANATION 

Geologic terrane with probable 

mineral-resource potential 

Molybdenum 

Uranium 

Mineral occurrence 

Volcanic rocks 

Intrusive igneous rocks 

Contact 

Thrust fault--Sawteeth on upper plate 

Figure 126.-Comanche-Big South, Neota-Flat Top, and Never Summer wilderness study areas, Colorado. 
The Never Summer wilderness study area of 17 sq mi 

occupies the west flank of the Never Summer Mountains; it is bounded on the north by Colorado State 

Forest and on the east by Rocky Mountain National 

Park. It consists chiefly of parts of two glaciated valleys 

that drain westward into the Michigan River. The east 

edge of the study area is extremely steep, and the sharp 

crest of the range can be traversed on foot only with 

great difficulty. Access is by logging roads up Jack 

Creek and by several trails. 

The Never Summer wilderness study area is geologically more diverse than the Neota and Comanche-Big 

South wilderness study areas. Most of it is underlain by 

a part of a huge slab of Precambrian gneisses that was 

thrust westward out over sedimentary rocks about 

50-60 million years ago. The sedimentary rocks and 

overlying gneisses were arched and intruded by granite 

and related rocks about 28 million years ago. Mineralization associated with this granite was widespread and 

recognized by early prospectors. 

The geology of the three study areas was mapped, 

stream-sediment and rock samples were collected and 

analyzed, and aeromagnetic and gravity maps were 

compiled and interpreted. Information on mining claims 

was compiled, and prospect pits, mine workings, and 

veins were mapped and sampled. 

Small amounts of gold and silver have been mined 

from small districts northeast of the Comanche-Big 

South wilderness study area and adjacent to the Never 

Summer wilderness study area The Teller district in the 

Jack Creek valley includes the southern part of the 

Never Summer wilderness study area The Teller district, which was probably discovered in the late 1870's, 

is reputed to have been a silver district, but no records 

of mineral production have been found. It was explored 

in the 1970's for molybdenum. 

MINERAL RESOURCES 

Little evidence of mineralization was found in the 

Comanche-Big South wilderness study area and there is 

little likelihood for the occurrence of mineral resources 

in the study area A uranium prospect near the north 

boundary south of Spencer Heights lies outside the 

study area but claims have been staked that extend into 

the study area This uranium prospect was discovered 

in 1954, explored in the late 1950's by means of a shaft, 

and explored further in the 1970's by drilling. Insufficient mineralized rock was found to constitute an ore 

body. The uranium is localized along a major fault zone 

similar to numerous other such zones that cross the 

study area; uranium could occur along any of them, 

however no resource potential was identified. Base and 

precious metals in veins north and northeast of the 

Comanche-Big South wilderness study area are likewise 

associated with the major fault zones or with young intrusive rock. While the possibility of such deposits cannot be dismissed entirely- because of the presence of 

the fault zones- no indications were found in our 

studies nor, apparently, by the early prospectors. 

Although the volcanic rocks in the Neota-Flat Top 

wilderness study area are geochemically anomalous in 

molybdenum, tin, and zinc, they were not concentrated 

to form mineral deposits. No records of mining claims or 

indications of prospecting were found, and there is little 

likelihood of the occurrence of mineral resources. 

The Never Summer wilderness study area contains 

several north-trending veins that have been prospected, 

and small amounts of ore may have been shipped from 

some of them, although no record of such shipments 

could be found. These veins are too small-rarely wider 

than a few inches- and the ore minerals of silver, lead, 

zinc, molybdenum, and copper, are too sporadic in the 

veins for them to be considered as containing resources. 

They do indicate, however, leakage from mineralization 

associated with an inferred buried granite body, that 

may have concentrated molybdenum at depth. In Jack 

Creek valley, about 1 mi south of the study area, a 

molybdenum prospect was drilled in the 1970's, and 

mining claims have been staked for molybdenum northward into the study area. Another block of claims has 

been staked for molybdenum in the eastern part of the 

Never Summer wilderness study area On the basis of 

highly anomalous geochemical samples, a negative 

gravity anomaly, and widespread visible evidence of 

weak mineralization, a part of this study area is considered to have probable resource potential for molybdenum. If molybdenum ore bodies are present, they will 

probably be at depths of more than a few hundred feet. 

SUGGESTIONS FOR FURTHER STUDY 

An area of general favorability for molybdenum ore 

bodies has been defined in the Never Summer wilderness study area More precise delineation of the areas of 

potential might result from more detailed geologic and 

geochemical studies and by use of ground geophysical 

techniques. 

REFERENCE 

Pearson, R. C., Braddock, W. A., Flanigan, V. J .. and Patten, L. L .. 

1981, Mineral resources of the Comanche-Big South, eota·Flat 

Top. and Never Summer wilderness study areas, north-<:entral 

Colorado: U.S Geological Survey Open· File Report 81-578, 73 p. 

435 
39"30' 

436 

., Red Cliff 

"f· 

• Kokomo 

COLORADO 

MAP LOCATION 

0 

MILES 

EXPLANATION 

D 

Pb 

Ag 

Geologic terrane w ith probable 

mineral-resource potential 

Lead 

Silver 

Zn Zinc 

10 

Figure 127.-Eagles Nest Wilderness, Colorado. 

Sedimentary rocks 

Granite and Gneiss 

Fault 
EAGLES NEST WILDERNESS, COLORADO 

By 0GDE TwET0 ,

1 U.S. G EOLOGICAL S RVEY and ' 

FRANK E. WILLIAMS, U.S. B REAU OF MI E 

SUMMARY 

On the basis of a geologic and mineral survey in 1969, a primitive area that 

constitutes the nucleus of the Eagles Nest Wilderness was appraised to offer little promise for the occurrence of mineral or energy resources. Among the additional areas later incorporated in the wilderness, only a strip near a major fault 

west and northwest of Frisco and Dillon is classed as having probable mineralresource potential. If mineral deposits exist, they probably are of the silver-leadzinc or fluorspar types. Because of land development for recreational housing 

near the border of the wilderness, exploration is unlikely in the foreseeable 

future. 

CHARACTER AND SETTING 

The Eagles Nest Wilderness occupies an area of about 

210 sq mi in the mountainous region of north-central 

Colorado, about 60 mi west of Denver. The wilderness is 

centered over a spectacularly rugged segment of the 

Gore Range, which towers to a crestline at altitudes of 

12,500 to 13,500 ft. Imposing views of the range are 

seen by the traveler as he approaches the town of Dillon 

from the east via Interstate 70, or as he follows Colorado Highway 9 along the Blue River northwest of 

Dillon. Interstate 70 crosses the Gore Range near the 

southern end of the wilderness at Vail Pass (alt. 

10,600 ft). In that vicinity, the wilderness impinges on 

the vaguely defined border zone of the Colorado mineral 

belt, a northeast-trending belt that embraces almost all 

the mineral mining districts of central Colorado. Several 

of the nearest towns in the region, such as Dillon, 

Frisco, Breckenridge, Kokomo, Climax, Gilman, and 

Red Cliff, were established long ago as mining centers in 

this belt. Vail and Copper Mountain are comparatively 

new settlements devoted to the skiing and recreational 

industries, as also, nowadays, is Breckenridge. 

The nucleus of the Eagles Nest Wilderness was an 

established primitive area when the Wilderness Act was 

passed in 1964. As provided in that act, a mineral 

survey of the area was made in the summer of 1969, and 

the results were published early in 1970 (Tweto and 

others, 1970). When the Eagles Nest Wilderness was 

1

WiLh contribut.ions from Bruce Bryant. USGS. 

established several years later, the boundaries were extended outward from the original primitive area, more 

than doubling the size of the area Most of the added territory had been included in the 1969 survey, but some of 

it was examined only in reconnaissance. Consequently, 

the appraisal of some of the added territory remains tentative, and further examination of it is to be desired. 

The high and rugged part of the Gore Range and wilderness consists of hard and resistant granite and 

gneiss of ancient (Precambrian) age. These rocks lie 

within a gigantic uplifted block that is bounded on its 

northeast and southwest sides by, respectively, the 

Blue River and the Gore faults. Movements that displaced the rocks bordering these faults occurred repeatedly through a very long period of time, the latest major 

movements being in geologically recent time only a few 

million years ago. At that time the block of granite and 

gneiss between the two faults was reelevated at least 

3000 ft above its surroundings, and the present rough 

topography was later sculptured in it by intense glacial 

erosion. In contrast to the uplifted block, the territory 

on each side consists of sedimentary rocks, which in 

most places are thickly mantled by bouldery glacial 

deposits. On the east side of the range, the sedimentary 

rocks are comparatively young and thin above the basement of granite and gneiss. On the west side, by contrast, the sedimentary rocks are older and much thicker, 

reaching more than 10,000 ft in thickness. Although the 

Colorado mineral belt is characterized by younger intrusive igneous rocks, such rocks are absent in the adjoining wilderness except some minor dikes near the 

north end. 

437 
MINERAL RESOURCES 

The wilderness, and particularly its southern part, 

would seem likely to contain mineral deposits by virtue 

of its location. Not only is it adjacent to the mineral 

belt, but it contains part of the network of master faults 

to which mineralization in the region seems related. The 

Mosquito fault, which enters the area from the south, 

evidently was a localizing factor for the Kokomo zinclead district, the great Climax molybdenum deposits, 

and farther south, the Leadville silver-lead-zinc district. 

The Mosquito fault ends against the Blue River fault, 

which to the southeast passes through the Breckenridge 

and upper Blue River mineralized area, and to the northwest contains the silver deposits of the Boss mine. The 

Gore fault, which diverges northwestward from the 

Mosquito fault, possibly was a factor in the zinc-silverlead mineralization at Gilman, the connection between 

the fault and the deposits near Gilman being a 

northeast-trending shear zone in the deep basement. 

Despite these features of the setting, little evidence 

of mineral deposits was found. Rocks between the Blue 

River and Gore faults are broken by many lesser faults 

and shear zones. Some of these fractures contain small 

veins of quartz or carbonate minerals but little evidence of metallic minerals. Nonetheless, a geochemical 

survey revealed numerous anomalous values for one or 

more of several different elements in these small veins. 

In the absence of visible metallic mineral matter, or of 

rock alteration other than chloritic, the anomalies do 

not offer promise. They are regarded as "smoke" that 

found its way into the fracture system from a great 

distance or great depth, unaccompanied by power to 

alter the rocks and insufficient in quantity to deposit 

ore minerals. 

Sedimentary rocks are poorly exposed on the two 

sides of the range and show little evidence of mineralization except near the Blue River fault in the area between Frisco and the Boss mine. A northwest-trending 

fault 3 mi northwest of Dillon contains thick quartz 

veins that are cavernous, probably from leaching by 

fluorine-bearing solutions. A landslide deposit 

downslope from one such occurrence locally contains 

fluorspar. At other places nearby, granitic rocks on the 

west side of the Blue River fault are strongly altered 

(chloritized and locally sericitized or argillized). 

Sedimentary rocks (shale, limestone, and sandstone) 

on the east side of the fault are covered by glacial and 

landslide deposits, but considering the rock alteration 

and the occurrence of geochemical anomalies for silver, 

lead, and zinc along the fault, the sedimentary rocks 

possibly may contain mineral deposits. 

The Eagles Nest Wilderness contains nearly 50 patented mining claims. Prospect diggings are present in 

many places, but aside from very small quantities of 

438 

hand-picked ore obtained in a few localities, the only 

significant production has come from the Boss mine. 

The Boss mine consisted of a maze of adit workings, 

now all inaccessible, on nine patented and several unpatented claims. These claims were outside the boundary of the primitive area at the time of the 1969 survey 

but are inside the wilderness as finally established. The 

mine is credited with a production of about $250,000 in 

silver and subordinate lead and copper, mainly before 

1897, though a small output was made at times until 

1963. The mine produced hand-sorted sulfide ore that 

occurred in veinlets and pockets in quartz veins along 

fractures within the Blue River fault zone. Although 

the grade was high, the tonnage produced was small. 

Several mining companies have examined the property 

and turned it down as an exploration venture. However, only a small part of the mile-wide Blue River fault 

zone has been explored beneath the surface, and 

almost no exploration has been done beneath the 

tunnels. 

On the basis of the aforementioned features, a strip 

along the Blue River fault between Frisco and the Boss 

mine is classed as having probable mineral-resource 

potential. No known deposits exist within the area except at the Boss mine, which has a record of modest 

production. Geologic and geochemical data provide 

some additional evidence of probable potential. Physical exploration would be required to prove either the 

existence or the nonexistence of deposits. If deposits 

do exist, they probably would be of silver-lead-zinc or 

of fluorspar types. Whether they were of a size and 

grade that could be worked would also hinge on exploration. However, exploration is unlikely in the 

foreseeable future. Ranch lands that extend almost to 

the wilderness boundary are being rapidly subdivided 

for recreational homesites, discouraging or preventing 

mineral investigation. 

SUGGESTIONS FOR FURTHER STUDIES 

Further study of the wilderness itself offers little 

promise for the identification of hidden mineral 

deposits, but studies of the regional controls and timing of mineralization in surrounding areas might well 

reveal areas of promise for minerals near the borders of 

the wilderness. 

REFERENCE 

Tweto, Ogden, Bryant, Bruce, and Williams, F. E., 1970, Mineral 

resources of the Gore Range-Eagles Nest Primitive Area and 

vicinity, Summit and Eagle Counties, Colorado: U.S. Geological 

Survey Bulletin 1319- C, 123 p. 
FLAT TOPS PRIMITIVE AREA, COLORADO 

By W . W. MALLORY, ' U.S. GEOLOGICAL SURVEY , and 

R. B. STOTELMEYER, U.S. BUREAU OF MINES 

SUMMARY 

An investigation of the Flat Tops Primitive Area in 1965 revealed little promise for the occurrence of mineral resources. This study also indicated there is 

little promise for the occurrence of oil and gas or coal resources. 

CHARACTER AND SETTING 

The Flat Tops Primitive Area is located in parts of 

Garfield, Eagle, and Rio Blanco Counties in northwestem Colorado. The area occupies about 230 sq mi and 

ranges in altitude from less than 8000 to 12,246 ft. 

Although roads approach the borders of the primitive 

area from all sides, no roads are found within the area 

In addition, downed timber is so prevalent that movement in the forests is difficult at best. 

The Flat Tops Primitive Area is in the northern part 

of the White River Plateau, a broad dome that forms the 

northeasternmost outpost of the Colorado Plateau's 

physiographic province. Rocks within the area range in 

age from Precambrian through Quaternary. Most of the 

area is covered by thick basalt lava flows of Tertiary 

age, but north of the 40th parallel, the bedrock is gray 

shale of Late Cretaceous age. Sedimentary rocks have 

an aggregate thickness of 14,900 ft, consisting of 

7700 ft of Paleozoic rocks and 7200 ft of Mesozoic rocks. 

The Tertiary basalt flows vary widely in thickness, but 

are as much as 1500 ft thick in places. 

The investigation undertaken in 1965 had several 

facets. Geologic maps including much of the area (Bass 

and Northrop, 1963; Kucera, 1962; and Sharps, 1962) 

were checked in the field and unmapped areas studied. 

Stream-sediment and soil samples were taken as a part 

of a geochemical survey. Data on past mineral production were compiled through search of Federal and 

County records and interviews with local residents, and 

two known prospects reported to be sites of former mining activities were examined. Results of this investigation were published in 1966 (Mallory and others, 1966). 

'Abstracted from a report by Mallory and ol.he"' 11966) by H. E. Hodgson. 

MINERAL RESOURCES 

No metallic minerals, coal, gypsum, or other materials 

have been produced within the boundaries of the Flat 

Tops Primitive Area, nor have any wells been drilled for 

oil or gas. The results of this study indicate that there is 

little promise for the occurrence of mineral or energy resources. The geologic environment of the primitive area 

is such that deposits of copper, lead, zinc, gold, and 

silver minerals conceivably could exist in rocks of Precambrian through Paleozoic age. Additionally, the Morrison Formation and Dakota Sandstone of Mesozoic age 

could contain uranium deposits. The Mancos Shale and 

the basalts of late Tertiary age are unlikely sources of 

metallic mineral deposits. 

To appraise the possibility of hidden mineral deposits 

in the area, stream-sediment, panned concentrates from 

stream-sediment, and soil samples were collected for 

geochemical analysis. Inasmuch as most of the primitive area has a thick cap of barren basalt, most of the 

geochemical sampling was done near the borders, where 

older rocks that might be mineralized are exposed. An 

evaluation of samples with anomalous metal content indicated that the potential for metallic mineral resources 

in the area are extremely limited. The metal values are 

generally low in comparison with values that one might 

reasonably expect for a significantly mineralized area 

The only known prospect is the abandoned lead-silver 

Dade prospect. Workings consist of a 45.5-ft adit and 

small stoped areas in the Paleozoic Leadville Limestone. 

There is no recorded production from this prospect and 

only a few hundred pounds of mineralized rock could be 

seen. Aside from this prospect, metallic minerals were 

seen in only one occurrence, in rocks of probable Precambrian age, and are not considred to have resource 

potential. No evidence was noted of alteration of the 

country rock such as commonly occurs near significant 

mineral deposits. 

439 
40° 

00' 

440 

107°30' 

• 

COLORADO 

MAP LOCATION 

107°20' 

Whll£' 

0 

MILES 

EXPLANATION 

• 

Basalt (Tertiary) 

Shale (Cretaceous) 

Paleozo1c and 

Precambrian rocks 

X 

5 

Contact 

Mineral occurrence 

Figure 128.- Flat Tops Primitive Area, Colorado. 

107°10' 
The northeastern part of the primitive area geologically offered the best promise for uranium resources but 

no evidence of uranium was discovered. Local residents 

stated that the area had been extensively prospected for 

uranium, but that no discoveries had been made. 

Oil and gas resources could conceivably be present in 

the sedimentary rocks that underlie the Flat Tops 

Primitive Area, but no vestiges of oil or gas seeps were 

seen, nor have any been reported. The geologic structures within the primitive area are not favorable for 

accumulation of oil and gas. A few leases have been 

acquired, but the only drilling has been outside the 

primitive area 

Coal is produced in the Yampa field of northwestern 

Colorado from the Iles and Williams Fork Formations 

of the Mesaverde Group and from the Lance and Fort 

Union Formations. These formations are not present in 

the primitive area and no prospects for coal exist. 

The Paleozoic Eagle Valley Evaporite contains gypsum and is present within the primitive area but lies 

beneath a thick cover of basalt. More easily accessible 

resources of gypsum occur only a few miles outside the 

primitive area, in the valleys of the Colorado and Eagle 

Rivers. 

SUGGESTIONS FOR FURTHER STUDIES 

Oil is produced from fractured zones in the Mancos 

Shale in several places in Colorado, but methods of 

systematic exploration for this type of resource have 

not been developed. If such methods were to be developed, reexamination of the Mancos Shale in the primitive area might be desirable. Additional studies to 

improve the assessment of the mineral potential for 

deposits beneath the volcanic cover also requires development of new techniques. 

REFERENCES 

Bass, N. W., and Northrop, S. A., 1963, Geology of Glenwood Springs 

quadrangle and vicinity, northwestern Colorado: U.S. Geological 

Survey Bulletin 1142-J , 74 p. 

Kucera. R. E., 1962, Geology of the Yampa district, northwest Colorado: Boulder, Colorado University, Ph.D. thesis, 844 p. 

Mallory, W. W., Post, E. V., Ruane, P. J., Lehmbeck, W. L., and 

Stotelmeyer, R. B., 1966, Mineral resources of the Flat Tops 

Prinlltive Area. Colorado: U.S. Geological Survey Bulletin 

1230-C, 30 p. 

Sharps, S. L., 1962, Geology of the Pagoda quadrangle, northwestern 

Colorado: Boulder, Colorado University, Ph.D. thesis, 364 p. 

441 
442 

/ 

Approximate 

/ boundary 

0 5 

M ILES 

COLORADO 

• 

EXPLANATION 

- Geologic terrane with substantiated 

mineral-resource potential and 

probable mineral-resource potential 

( * Indicates resources with 

substantiated potential ) 

Geologic terrane with substantiated 

mineral-resource potential CJ Geologic terrane with probable 

mineral-resource potential 

~ Mine or deposit 

x Mineral occurrence 

~ Mine 

Cu Copper Th Thorium 

Au Gold Sn Tin 

Pb Lead w Tungsten 

Mo Molybdenum u Uranium 

Ag Silver Zn Zinc 

.,.;.~,~'.r,i:':..;,, . ;{:;~,~~~~~:-;: Terttary igneous rocks 

Mesozoic sedimentary rocks 

Paleozoic sedimentary rocks 

Precambrian crystalline rocks 

--- Contact 

--- Fault 

B 

Tertiary igneous dike 

Area discussed in text 

Figure 129.-Fossil Ridge Wilderness Study Area, Colorado. 
FOSSIL RIDGE WILDERNESS STUDY AREA, COLORADO 

By Eo D EWITT, U.S. GEOLOGICAL S RVEY, and 

STEVE E. KLUE DER, U.S. BUREA Of Ml E 

SUMMARY 

The Fossil Ridge Wilderness Study Area, approximately 20 mi northeast of 

Gunnison in central Colorado, was studied and its mineral-resource potential 

assessed during 1982. Portions of the study area have substantiated resource 

potential for gold, silver, copper, lead, zinc, molybdenum, uranium, thorium, 

rare-earth elements, and high-<:alcium limestone. Much of the area has a probable resource potential for the preceeding commodities as well as for tin. Various 

other elements are found in anomalous concentrations within the study area, 

but there is little likelihood for their occurrence in amounts sufficient to constitute resources. Exploration, especially for molybdenum, gold, and uranium, 

has been active in the past and is expected to continue in the future. No potential for fossil fuel resources was identified in this study. 

CHARACTER AND SETTING 

The Fossil Ridge Wilderness Study Area occupies 

about 85.5 sq mi within the Gunnison National Forest 

in central Colorado. Access is provided by a paved road 

along the Taylor River and Quartz Creek, and by allweather roads along Willow Creek and Gold Creek. The 

Gold Brick and Quartz Creek mining districts border 

the study area on the southeast, and the Tincup district 

adjoins the area on the east. The Cross Mountain mining distict is contained within the north-<:entral part of 

the study area Altitudes vary from 9200 ft along the 

Taylor River and Gold Creek to over 13,200 ft on Fairview Peak and Henry Mountain. Steep-sided glacial 

valleys and cirques are typical in the central and eastern 

parts of the study area, but the topography, although 

mountainous, is more subdued in the western part. 

Thick conifer forests in the lower parts of the area give 

way to alpine tundra and meadows above 11,400 ft. 

The study area is underlain chiefly by granitic and 

metamorphic rocks of Precambrian age that are in tum 

partly mantled by a thin cover of Paleozoic strata The 

Precambrian and Paleozoic rocks are cut by numerous 

small Tertiary intrusive bodies. Glacial deposits locally 

obscure much of the bedrock. Faults of probable 

Laramide to mid-Tertiary age cut all but the youngest 

rock units and locally have vertical offsets of 2000 to 

3000 ft. 

The layered Precambrian rocks consist of an older 

bimodal metavolcanic assemblage and a younger pelitic 

metasedimentary assemblage. The metavolcanic rocks 

were subaqueous pillowed basalt flows and felsic tuffs. 

Subvolcanic sill-like bodies of diorite are associated with 

the mafic rocks. The metasedimentary rocks were 

shales, siltstones, and quartzites. The layered rocks are 

intruded by at least five major plutonic bodies that 

range in age from approximately 1700 million ye:vs to 

1400 million years, and in composition from biotite 

granodiorite to muscovite granite. 

The Paleozoic rocks consist of the Cambrian Sawatch 

Quartzite, Ordovician Manitou Dolomite, Ordovician 

Harding Sandstone, Ordovician Fremont Limestone, 

Devonian and Mississippian(?) Chaffee Group (dolomite, siltstone, and sandstone), Mississippian Leadville 

Limestone, and Pennsylvanian Belden Shale. Pennsylvanian rocks younger than the Belden Shale and 

Mesozoic strata are present in surrounding areas, but 

not within the study area Lithologies and thicknesses 

of Paleozoic strata in the area are typical of central Colorado, except that the Sawatch Quartzite is locally 

thicker near the Taylor River than in outlying regions. 

Two ages and types of Tertiary igneous rocks were 

identified; an older andesite porphyry that forms silllike to laccolithic bodies within the Paleozoic strata, and 

a younger porphyritic rhyolite that forms high-angle 

dikes and small plugs in the Precambrian and Paleozoic 

rocks. 

443 
MINERAL RESOURCES 

Portions of the Fossil Ridge Wilderness Study Area 

have probable or substantiated resource potential for 

gold, silver, copper, lead, zinc, tin, molybdenum, 

uranium, thorium, rare-earth elements, and highcalcium limestone. Selected areas contain anomalous 

amounts of manganese, antimony, bismuth, cadmium, 

arsenic, nickel, cobalt, chromium, tungsten, beryllium, 

lithium, arsenic, tantalum, barium, and vanadium, but 

there is little promise for their occurrence as resources. 

Evaluation of the resource potential is based on 

knowledge of the geology, stream-sediment and rock 

geochemistry (DeWitt and Kluender, in press) and production records and assays from mines that have 

operated in the past (Kluender and McColly, 1983). 

The two largest areas with probable and substantiated gold and silver resource potential are along Gold 

Creek in the southeast part of the area (area A, on map), 

and along a northwest-trending zone from near Cross 

Mountain to southeast of Cameron Mountain in the 

north-central part of the area (B). The north-northeasttrending vein and shear zone system on the east side of 

Gold Creek has recorded gold, silver, lead, and copper 

production from five major and numerous minor mines. 

Anomalous concentrations of arsenic and zinc are 

associated with the precious metals. Mineralization 

along Gold Creek is related to a middle to late 

Tertiary(?) vein and fault system. The northwesttrending zone near Cross Mountain also has recorded 

gold, silver, and minor copper production from two 

small mines. Anomalous concentrations of arsenic, 

antimony, manganese, zinc, cadmium, and bismuth accompany the gold and silver, especially in replacement 

deposits in Paleozoic limestone on Cross Mountain. 

Vein and replacement mineralization in this area is of 

probable mid- to late-Tertiary age. 

The Green Mountain area (C) has probable and substantiated resource potential for gold and silver as indicated by production data from 'two mines and by 

stream-sediment and rock geochemistry. This area also 

has a substantiated resource potential for molybdenum 

and tungsten. Disseminated and vein mineralization are 

related to a mid-Tertiary pluton and its associated 

hydrothermal system. 

Past production of gold from gravels in Union Park 

and detailed sampling of those gravels in the current 

studies indicate areas of probable and substantiated 

potential for gold in Union Park and the northwardflowing tributaries to Lottis Creek (D). A small area of 

probable potential extends into the study area 

Three large areas and two smaller areas have a probable and substantiated resource potential for copper, 

lead, zinc, and molybdenum; bismuth and cadmium are 

444 

present in anomalous amounts. Lead and molybdenum 

are much more abundant than zinc or copper. Probable 

and substantiated lead and zinc resource potential is indicated by production data from mines in the Gold 

Brick, Quartz Creek, and Tincup mining districts, and 

by stream-sediment geochemistry for the area along 

and east of Gold Creek (area A) along the Boulder fault 

(area E), south of Green Mountain (area F), and north of 

Green Mountain (area C). Vein mineralization along the 

Boulder fault is probably related to movement on the 

fault. Base-metal mineralization south of Green Mountain occurs as both veins and replacement bodies within 

Paleozoic limestone. 

Parts of the Lamphier Lake-Mill Lake area (G) have 

probable or substantiated resource potential for molybdenum. The molybdenum mineralization is in quartz 

veins associated with a Precambrian granite. Two 

drainages between Cross Creek and Cameron Creek 

(area H) have anomalous concentrations of molybdenum, as does the Henry Lake area (!). 

Much of the study area contains highly anomalous 

concentrations of uranium. One large area and three 

smaller areas have probable and substantiated resource 

potential for uranium. The high cirques on the west side 

of South Lottis Creek (area J) have areas of probable or 

substantiated resource potential for uranium. The westflowing tributaries to Crystal Creek (area K) also contain sediments with anomalous amounts of uranium. In 

both areas, north- and northwest-trending shear zones 

in Precambrian granite host the mineralization. The entire Crystal Creek drainage baSin is geochemically 

anomalous in uranium. The Mill Lake area (G) contains 

uranium anomalies and has a probable resource potential, but the source of mineralization is unknown. A 

probable resource potential for uranium is indicated 

along the Boulder fault (area E), and north of Bronco 

Mountain (area L). Mineralization north of Bronco 

Mountain is contained within a northwest-trending 

fault zone. 

Areas along and northeast of Summerville Creek and 

Gandy Gulch (area M) have probable or substantiated 

resource potential for thorium and rare-earth elements. 

Very high thorium, cerium, lanthanum, hafnium, and 

ytterbium values indicate that there is a rare-earth 

element-rich zone within the Precambrian granite. A 

similar, but smaller area lacking thorium is noted east 

of Henry Mountain (area N). 

Limestone consisting of greater than 95 percent 

CaC03 and less than 1 percent MgO is present within 

the Mississippian Leadville Limestone along the central 

part of Fossil Ridge (area 0). This part of the study area 

is has a substantiated resource potential for highcalcium limestone. 

Anomalous concentrations of beryllium and tin in 
streams between South Lottis Creek and Crystal Creek 

probably reflect beryl or lepidolite and accessory tinbearing(?) minerals derived from a Precambrian granite. 

A probable resource potential for tin is assigned to 

areas west of Gold Creek (P) and northwest of Green 

Mountian (Q). Anomalous concentrations· of boron and 

lithium occur throughout the Crystal Creek, upper 

South Lottis Creek, and Beaver Creek drainages, and 

reflect disseminated tourmaline mineralization in a 

Precambrian granite and its adjacent wallrock. Scattered lithium anomalies in the eastern part of the study 

area are probably related to pegmatites in Precambrian 

granite. 'I\mgsten anomalies appear to correlate with 

tin anomalies, but anomalous tungsten also appears to 

be associated with dioritic Precambrian rocks west of 

upper Crystal Creek and northwest of lower Gold Creek. 

'I\mgsten and tin anomalies north of Green Mountain 

are spatially associated with mid-Tertiary molybdenum 

mineralization. Anomalous concentrations of nickel, 

cobalt, and chromium in upper East Beaver Creek, upper Alder Creek, and Willow Creek may be related to 

pegmatite mineralization or accessory minerals in a 

Precambrian syenite stock. 

SUGGESTIONS FOR FURTHER STUDIES 

Further geologic study of uranium, thorium, and rareearth element mineralization between Crystal Creek and 

South Lottis Creek is warranted due to the extent and 

degree of mineralization. Similarly, the base- and 

precious-metal mineralization from Cross Mountain to 

Cameron Mountain and along Gold Creek needs additional study, especially regarding the age or ages of 

mineralization, in order to refine assessments of mineral 

potential for this area 

REFERENCES 

DeWitt, Ed, Kluender, S. E., and McColly, R. A., in press, Mineral resource potential map of the Fossil Ridge Wilderness Study Area, 

Gunnison County, Colorado: U.S. Geological Survey Miscellaneous Field Studies Map MF- 1629- A, scale 1:30,000. 

Kluender, S. E .. and McColly, R. A., 1983, Mineral investigation of 

the Fossil Ridge Wilderness Study Area. Gunnison County, Colorado: U.S. Bureau of Mines Open-File Report MLA 66-83. 

445 
446 

1os•oo· 

COLORADO 

• 

MAP LOCATION 

0 2 

M ILES 

EXPLANATION 

D Geologic terrane with probable 

mineral-resource potential 

Alluvium and talus (Quaternary ) 

w Tungsten 

Volcanic rocks (Tertiary) 

f-"'"""'-......:.::j 

Intrusive igneous rocks (Tertiary) 

Sedimentary rocks (Cretaceous to 

'---__j Permian -Pennsylvanian ) B Metamorphic and intrusive igneous 

rocks (Precambrian ) 

---- Contact 

---,--- Fault--Bar and ball on downthrown side 

Figure 130.-Greenhom Mountain Wilderness Study Area, Colorado. 
GREENHORN MOUNTAIN WILDERNESS STUDY AREA, COLORADO 

By MARGO I. T OTH, 1 U.S. GE LO !CAL S UR ·Y, and 

G. DAVID BASK! , U . . B REA OF Ml1 E 

SUMMARY 

Mineral-resource studies of the Greenhorn Mountain Wilderness Study Area, 

Colorado, were done in 1981 and 1982 and one area of probable tungsten 

resource potential was identified. Sediment samples from streams draining into 

South Apache Creek have anomalously high values of tungsten. Although 

mineralization was not located in the underlying rock, similar rocks elsewhere in 

Colorado have known tungsten resources. There is little likelihood for the occurrence of oil and gas resources because of the geologic setting of the area and 

little promise for other mineral or energy resources. 

CHARACTER AND SETTING 

The Greenhorn Mountain Wilderness Study Area in 

south-central Colorado covers about 35 sq mi in Huerfano and Pueblo Counties. It lies 20 mi southwest of 

Pueblo and 130 mi almost due south of Denver. Cities 

within 10 mi include Rye to the northwest, San Isabel to 

the north, and Gardner to the southwest. 

Located at the southernmost end of the Wet Mountains, the Greenhorn Mountain Wilderness Study Area 

is characterized by a steep eastern flank with V-shaped 

canyons and a gently sloping western side typified by 

flat-bottomed arroyos. Altitudes range from 12,34 7 ft at 

Greenhorn Mountain to 7600 ft at the southern end of 

the wilderness study area Badito Cone, a round symmetrical peak (8942 ft), rises prominently just south of 

the study area Access to the periphery of the study 

area is provided by dirt roads, one of which leads to the 

base of Greenhorn Mountain. Foot trails provide access 

into the interior of the wilderness study area and across 

the Wet Mountains. 

The core of the Greenhorn Mountain Wilderness 

Study Area consists of complexely related Precambrian 

igneous and metamorphic rocks. Flanking these rocks 

are Permian-Pennsylvanian to Cretaceous sedimentary 

rocks as much as 4150 ft thick. Tertiary igneous plutons 

were emplaced at shallow depths and intrude the Precambrian rocks in Maes Creek and at Santana Butte. 

On the top of Greenhorn Mountain, Tertiary volcanic 

flow rocks and ash deposits exist as erosional remnants. 

In the southern part of the study area, a southeast-

'Witll contributions from Daniel R. Birch. USGS. 

plunging anticline is defined by tilted sedimentary 

rocks that wrap around the southern end. Bounding and 

less commonly traversing the study area, are high-angle 

normal faults. As indicated by breaks in topographic 

slopes, movement along some of the faults has occurred 

at least as late as Tertiary time. 

A detailed geochemical survey of the study area involved sampling stream sediments and representative 

mineralized rocks for chemical analyses. All samples 

were analyzed for 30 elements by semiquantitative 

spectroscopy and some rock samples were additionally 

analyzed for gold and silver. The results of the 

geochemical survey indicate that the Greenhorn Mountain Wilderness Study Area is generally lacking in 

elements associated with mineralization. The streams 

draining into South Apache Creek have anomalous 

tungsten, yttrium, barium, and lanthanum, and a few 

isolated anomalies are present in some of the other 

streams, but a geologic source for the anomalies was not 

identified in the field. 

A reconnaissance scintillometer survey was made of 

the study area by recording radiation measurements at 

randomly distributed locations and along obvious shear 

zones. By taking a large number of measurements it 

was possible to establish background levels and therefore delineate samples that were anomalous. Most of the 

samples fell within background levels but one sample 

from a fault zone in granite gneiss on the west side of 

the study area has radiation twice that of the background. The source of radiation is unknown, but it could 

be due to the presence of disseminated thorite as has 

been noted in similar occurrences in the northern Wet 

Mountains. 

447 
No mining districts are present in or near the study 

area but there are several small prospects inside the 

study area Most of the workings are small, probably 

dug for gold and (or) silver, and there is no evidence of 

production at any of the sites. 

Several oil and gas leases and lease applications were 

on record in the wilderness study area and vicinity in 

September 1982; however, only about 0.15 sq mi of the 

wilderness study area were covered by lease applications and no test drilling has taken place on those 

properties. 

MINERAL RESOURCES 

Our studies indicate that one area within the 

wilderness study area has mineral-resource potential. A 

cluster of anomalies in barium, lanthanum, yttrium, and 

tungsten is present in the streams draining into South 

Apache Creek. Although element enrichment is indicated for this area, our mapping did not locate any mineralization or evidence of alteration in the underlying 

Precambrian rocks. However, similar Precambrian 

rocks elsewhere in Colorado have demonstrated tungsten resources. Detailed mapping would be necessary to 

establish the presence of mineralized rock in the area of 

the stream-sediment anomalies but because the tungsten anomalies are so high, it is likely that tungsten 

resources are present and the area is shown as having a 

probable tungsten resource potential. 

Favorable structural and stratigraphic conditions for 

oil and gas reserves are present immediately south of 

448 

the study area within the Greenhorn anticline (Creely 

and Saterdal, 1956). Most drill holes reported in this 

area as of 1956 had shows of oil and (or) gas but none of 

the holes had any production. Although part of the 

Greenhorn anticline extends into the wilderness study 

area, closed structures which act to trap oil and gas are 

absent. Furthermore, extensive erosion has removed the 

vast bulk of the sedimentary rocks considered favorable 

for oil and gas reserves therefore we consider the likelihood for the occurrence of oil and gas resources to be 

remote. 

There is no known geological evidence for coal, geothermal resources, or other energy-related commodities 

within the wilderness study area 

SUGGESTIONS FOR FURTHER STUDIES 

Detailed geologic mapping in and near the drainage 

basin of South Apache Creek should be done in an 

attempt to identify the source of the tungsten mineralization. 

REFERENCES 

Creely, R. S., and Saterdal, A. 0 .. 1956, Badit<rAlamo Area, Huerfano 

County, Colorado, in Guidebook to the geology of the Raton 

Basin, Colorado: Rocky Mountain Association of Geologists, p. 

71 - 74. 

Toth, M. I., Birch, D. R., and Baskin, G. D., 1983, Mineral resource 

potential of the Greenhorn Mountain Wilderness Study Area, 

Huerfano and Pueblo Counties, Colorado: U.S. Geological Survey 

Open-File Report 83- 467. 

450 

106°45' 

Approximate boun 

Porphyry Mountain Wilderness 

study area 

• COLORADO 

MAP LOCATION 

0 

- Geologic terrane with substantiated 

mineral-resource potential 

D Geologic terrane with probable 

mineral-resource potential 

Au Gold 

Ag Silver 

~ Mine or deposit 

106°30' 

Hunter-Fryingpan Wilderness 

Au , Ag 

Pass 

Grizzly Peak caldera 

5 

MILES 

G Paleozoic Sedimentary Rocks 

0 Precambrian Gneiss, Schist, and Granite 

--- Contact 

Figure 131.- Hunter-Fryingpan Wilderness and Porphyry Mountain Wilderness study area, Colorado. 
HUNTER-FRYINGPAN WILDERNESS AND PORPHYRY MOUNTAIN 

WILDERNESS STUDY AREA, COLORADO 

By STEVE LUDT GTO , U.S. GEOLOGICAL S RV EY, and 

CLAREt CE E. ELLI , U.S. B REAU OF Mr E 

SUMMARY 

A mineral survey of the Hunter-Fryingpan Wilderness and the Porphyry 

Mountain Wilderness study area was conducted by the USGS and the USBM in 

1978 and 1979. Substantiated gold and silver resource potential was identified 

in one area and a surrounding area is judged to have probable mineral-resource 

potential for gold and silver. No other mineral or energy resources were identified in the study. 

CHARACTER AND SETTING 

The Hunter-Fryingpan Wilderness, located in a high, 

rugged region of the Sawatch Range in west-central Colorado, immediately to the east of Aspen, covers about 

109 sq m.i of the White River National Forest. The Porphyry Mountain Wilderness study area (known also as 

the Spruce Creek Wilderness study area) covers about 

12 sq m.i on the northwest side of the Hunter-Fryingpan 

Wilderness. Access is from Colorado 82 on the south, 

several USFS gravel roads on the west, a paved county 

road on the north, and by foot on the east, where the 

boundary is the Continental Divide. 

The area is almost entirely underlain by Precambrian 

gneiss, schist, and granite. A thin veneer of lower 

Paleozoic sedimentary rock covers the northwest part. 

A few lower Tertiary silicic dikes cut the Precambrian 

rocks, and the mid-Tertiary Grizzly Peak caldera is adjacent to the southeast corner of the area 

The present mountains are the result of tectonic uplift 

in the late Tertiary, on faults parallel to the Rio Grande 

rift to the east, followed and accompanied by erosion by 

ice and running water. 

MINERAL RESOURCES 

The Aspen mining district, immediately west of the 

Hunter-Fryingpan Wilderness, has been a significant 

source of silver in the past, and probably contains a 

significant silver resource. Virtually all production in 

the Aspen district was from the Mississippian Leadville 

Limestone and the Pennsylvanian Belden Formation, 

which are from 350 to 600 ft stratigraphically above the 

base of the Ordovician Manitou Dolomite. There is little 

or no promise, because of the absence of permissive host 

rocks, that silver mineralization similar to that which is 

characteristic of the Aspen district will be found within 

the study area 

The area immediately adjacent to the Independence 

and Mt. Hope mines, in the southeast corner of the 

study area, has substantiated resource potential for 

gold and silver in quartz-sulfide vein deposits. About 

45,000 oz of gold was recovered from the two mines and 

the remaining inferred resources are about 3600 oz of 

gold and about 10,800 oz of silver. 

A surrounding area is judged to have probable potential for the discovery of similar gold and silver resources 

on the basis of numerous inactive mines and prospects 

which exhibit some evidence of mineralization similar to 

that at the Independence and Mt. Hope mines. 

SUGGESTIONS FOR FURTHER STUDIES 

Topical studies to clarify the relationship of the two 

vein deposits to the adjacent Grizzly Peak caldera 

would be useful in refining assessments of the potential 

for discovery of more deposits. 

REFERENCE 

Ludington, Steve, and Ellis, C. E., 1981, Mineral resource potential of 

the Hunter-Fryingpan Wilderness and the Porphyry Mountain 

Wilderness study area, Pitkin County, Colorado: U.S. Geological 

Survey Miscellaneous Field Studies Map MF- 1236- D, scale 

1:50,000. 

451 
452 

40° 

00' 

!U 

Creelc f! 

\'lo~'''(\ a 

Me Jdc ( reeh 

Rc-;en 

/ r I ,() 'f" w••> 

\B 

• 

COLO RADO 

M AP LOCATION 

4rh 

Approximate 

boundary 

0 5 

MI LES 

WARD 0 

MINING 

DISTRICT 

L ' 

BOULDER 

Stock COUNTY 

CARIBOU TUNGSTEN 

MINING DISTRICT 

DISTRICT 11 ;;} 

d lc ~J'f. 1 {,:"" ~.::r--~'"b~,., 

Boulder 

EXPLANATION 

CJ Geologic terrane with probable 

mineral-resource potential 

Cu Copper 

Au Gold 

Pb Lead 

Mo Molybdenum 

Ag Silver 

u Uranium 

Zn Zinc 

~ Mine or deposit 

X Mineral occurrence 

~ Mine 

;\{~~~~. Intrusive igneous rocks 

Granite, gneiss, and schist L__ _ _J 

--- Contact 

--- Fault 

--r--r---.- Approximate northern boundary 

of Colorado mineral belt 

2 Location discussed in text 

Figure 132.- Indian Peaks Wilderness, Colorado. 
INDIAN PEAKS WILDERNESS, COLORADO 

By R OBERT C. P EARSO ,

1 U.S. GEOLOGICAL SURVEY and 

' 

C HARLES . PELTZ, .S. B REA OF MI E 

SUMMARY 

The Indian Peaks Wilderness northwest of Denver is partly within the Col<r 

rado Mineral Belt, and the southeast part of it contains all the geologic 

characteristics associated with the several nearby mining districts. Two 

deposits have demonstrated mineral resources, one of copper and the other of 

uranium; both are surrounded by areas with probable potential. Two other areas 

have probable resource potential for copper, gold, and possibly molybdenum. 

CHARACTER AND SETTING 

Located about 30 mi northwest of Denver, the Indian 

Peaks Wilderness occupies the crest and flanks of the 

Front Range and extends from Rocky Mountain National Park south for about 20 mi. Spectacular views of 

the outstanding mountain scenery are afforded daily to 

thousands of airline passengers approaching or leaving 

Denver's Stapleton International Airport. Most of the 

crest is high above timberline and has a rugged serrate 

outline as a result of intense glacial erosion. The peaks, 

most of which are named for American Indian tribes, 

rise to altitudes of 12,800 to 13,500 ft. The area is accessible by way of numerous impinging logging and 

mining roads that branch from highways along the east 

and west sides at distances of several miles. The nearest 

towns on the east side are Ward and Nederland that 

began as mining camps but now are residential communities. On the southwest side, the towns of Fraser 

and Tabernash, and the Winter Park ski area are within 

a few miles of the wilderness. 

The Indian Peaks Wilderness is in a large region of 

crystalline rocks of Precambrian age that are exposed in 

the core of the Front Range. The crystalline rocks consist of schists and gneisses that were derived from old 

sedimentary and volcanic rocks by metamorphism and 

of large masses of granite that intruded the schists and 

gneisses after they were crumpled and folded. Precambrian granites of two ages are recognized: one group 

1700 million years old, and another 1450 million years 

old. Much younger intrusive igneous rocks were em-

'With cont.ribul.ions from J . C. Rntul and Gordon Johnson. USGS. 

placed about the same time that the Rocky Mountains 

were forming some 60- 70 million years ago. The Front 

Range developed at that time as a broad low arch, and 

igneous activity continued intermittently and locally 

for another 30 million years. Most of the ore deposits in 

the Front Range are associated in space and time with 

these young intrusive rocks. 

The mineral-resource study in 1972 and 1973 involved 

geologic mapping, a geochemical survey, and interpretation of an aeromagnetic survey. The geochemical survey 

involved collection and chemical analysis of samples, 

about 25 percent of which were stream sediments, 25 

percent were unmineralized rock, and the rest showed 

some evidence of having been altered or affected by a 

mineralizing process. The aeromagnetic survey was 

flown in 1967 along east-west flightlines about 1 mi 

apart. 

Most mining districts in the central Front Range of 

Colorado were organized in the decade following the initial discoveries in 1859. Ore was discovered in the 

Ward district in 1861, in the Jamestown district in 

1865, and in the Caribou district in 1869. Later discoveries were the Eldora and Lost Lake districts in 1896 

and the Boulder County tungsten district, in which pr<r 

duction began in 1900. All these districts are within 

10 mi of the southeast edge of the wilderness. In 1909, 

some ore was mined from the Lake Albion mining area, 

which was included in the Indian Peaks mineral survey. 

Small ore shipments have also been made from two 

mines within the wilderness. The entire wilderness has 

been prospected; every part of the wilderness that exhibits evidence of mineralization also exhibits evidence 

of prospecting. 

453 
MINERAL RESOURCES 

The Indian Peaks Wilderness lies. along the northwest 

side of the Colorado Mineral Belt, an area with indefinite boundaries that contains most of the mining districts of central Colorado. The mineral belt is a narrow 

zone that extends southwestward diagonally across the 

mountain ranges from near the east edge of the Front 

Range. The belt is characterized by intrusive igneous 

rocks about 25-70 million years old, and by ore deposits 

of various types associated with them. On the basis of 

the presence of these favorable igneous rocks and the 

numerous small mines and prospects associated with 

them, the southeastern part of the Indian Peaks Wilderness is considered to be within the Colorado Mineral 

Belt, and hence to be more favorable for occurrence of 

mineral deposits than the rest of the wilderness. 

A system of northwest-trending faults similar to 

those that controlled emplacement of ore deposits in 

nearby districts crosses the area These faults are 

weakly mineralized, generally containing veins either in 

the main shears or in subsidiary fractures. The Arapaho 

Pass fault is the most prominent and continuous of 

these faults, and it is mineralized at the Fourth of July 

mine and numerous other places; it extends into the 

Caribou district east of the wilderness. Mineralizing 

fluids evidently used the faults as passageways and 

may have travelled long distances from their source. 

Within the Indian Peaks Wilderness, a copper deposit 

and a uranium deposit are sufficiently well exposed and 

sampled to be classified as containing demonstrated 

resources, and are in areas 1 and 2 that are geochemically anomalous, weakly mineralized, and of sufficient size 

to be classified as having probable mineral-resource 

potential. A vein exposed in prospect workings and outcrop in the northwestern part of the wilderness in the 

headwaters of Roaring Fork contains disseminated 

copper-sulfide minerals (area 1). The vein averages 

about 10ft wide over a length of about 1000 ft. Numerous samples contain 0.2-0.5 percent copper, 0.1-0.4 oz 

silver/ton, and a trace of gold. The deposit is small and 

in an inaccessible location, but nevertheless represents a 

demonstrated mineral resource. The Wheeler Basin 

uranium occurrence consists of disseminated uraninite 

crystals in complexly mixed rocks at the border of a 

454 

large granite body (area 2). Several thousand tons of 

rock that contains 0.1 - 0.2 percent uranium is present 

within a few tens of feet of the surface. It constitutes a 

demonstrated mineral resource, although its remote 

location discourages development. 

Near Rainbow Lakes (area 3), geochemical samples indicate a source of copper at the head of the valley above 

the lakes. Narrow quartz veins in that area are rich in 

several metals (copper, molybdenum, lead, silver, and 

tungsten) but are not abundant enough to account for 

the high metal values in the stream-sediment samples. 

Close-spaced joints in the granite are coated with 

limonite that probably weathered from sulfide minerals. 

These abundant mineralized joint surfaces and the 

small veins may represent leakage from a much deeper 

mineralized system, and thus the area is considered to 

have probable mineral-resource potential. 

Disseminated sulfide minerals in the region between 

Blue and Mitchell Lakes (area 4) contain minor quantities of copper and gold. Disseminated sulfides in rocks 

found at the surface indicate that a large mineralizing 

system existed in the area, and some evidence suggests 

that only the uppermost part is exposed. Thus the area 

has a probable mineral-resource potential for large lowgrade deposits of copper and gold, and possibly also for 

molybdenum, which is present in analyzed samples. 

SUGGESTIONS FOR FURTHER STUDY 

Detailed gravity and magnetic studies in the 

southeast part of the Indian Peaks Wilderness might 

detect in the subsurface igneous bodies that may be 

mineralized. Physical exploration such as drilling would 

be necessary to determine more precisely the copper 

resources at the Roaring Fork locality and uranium 

resources at Wheeler Basin. 

REFERENCE 

Pearson, R. C., and U.S. Bureau of Mines, 1980, Mineral resources of 

the Indian Peaks study area, Boulder and Grand Counties, Colorado, with a section on Interpretation of aeromagnetic data, by 

Gordon Johnson: U.S. Geological Survey Bulletin 1463. 109 p. 
LA GARITA WILDERNESS, COLORADO 

By T HOMAS A. STEVE , U .S . G EO LOGICAL S R EY, and 

C. L. BIE IEWSKI , U . . B REAU OF MI E 

SUMMARY 

Geologic and mineral-resource appraisal studies by the USGS and USBM in 

1967-68 and 1971 in and near the La Garita Wilderness in the central San Juan 

Mountains of Colorado have shown that all significant known mineral resources 

are outside the wilderness. A few small and low-grade veins containing local concentrations of lead, zinc, and silver occur in and adjacent to the western part of 

the wilderness and the area is considered to have a probable mineral-resource 

potential. 

CHARACTER AND SETTING 

The La Garita Wilderness covers about 76 sq rni of 

rugged terrain in the central San Juan Mountains of 

southwestern Colorado. Altitudes range from less than 

10,000 ft to 14,014 ft at the top of San Luis Peak. The 

geology of the wilderness was mapped by the USGS at 

various times during the 1960's, as part of other 

geologic studies in the central San Juans. Specific 

studies of mineralized areas and stream-sediment 

sampling of the whole wilderness were conducted by 

USGS personnel in 1967- 68 and 1971. Investigations 

by the USBM were done largely in 1971, when claim 

records and locations were investigated, and all mine 

workings that could be found were examined and sampled. The results of these studies were published by 

Steven and Bieniewski (1977). 

The La Garita Wilderness is underlain entirely by 

volcanic rocks or related intrusives that formed during 

a brief interval of geologic time, less than 2 m.y. (million 

years), between 28 and 26 m.y. ago. These rocks record 

only a small part of the volcanic activity that took place 

during that 2- million year span; further, the geology of 

the wilderness can be understood only in the context of 

the geologic history of the whole central San Juan area. 

The central San Juan Mountains were a major source 

area for voluminous ash flows, which spread as avalanches of incandescent hot ash that congealed into 

widespread sheets of densely welded tuff after deposition. Major volcanic subsidence structures (calderas) 

formed at the sources of most of these ash flows; five 

calderas have been recognized near the La Garita 

Wilderness. In addition, two more calderas may have 

formed but, if so, they were obliterated by younger 

calderas or were covered by younger rocks. Subsidence 

generally took place concurrently with eruption of the 

ash flows, and the calderas commonly are filled with 

masses of densely welded tuff as much as 4000 ft thick. 

The entire La Garita Wilderness lies within two nonconsecutive calderas that are part of the central San 

Juan caldera complex. The eastern two-thirds of the 

wilderness is within the large La Garita caldera, the 

oldest subsidence structure in the vicinity of the 

wilderness, and the western third is within the San Luis 

caldera, the third youngest of the subsidence structures. 

MINERAL RESOURCES 

Hydrothermal activity affected rocks in or near the 

La Garita Wilderness at least four times during 

volcanic activity. The intrusive core of an old andesite 

central volcano is exposed on the east wall of the La 

Garita caldera east of the wilderness; this core and the 

adjacent rocks are irregularly altered and are cut locally 

by quartz-pyrite veins. Valuable minerals are sparse in 

the exposed parts of this center, and the mineralized 

area is entirely outside the La Garita Wilderness; thus, 

virtually no potential for mineral resources related to 

this center can be postulated for adjacent parts of the 

wilderness. 

The thick mass of densely welded Nelson Mountain 

Tuff in the core of the San Luis caldera was affected 

455 
456 

margin of San Luis caldera 

boundary 

of San Luis caldera 

lc 

0 5 

MILES 

EXPLANATION 

D Geologic terrane with probable 

mineral-resource potential 

Pb Lead 

Ag Silver 

Zn Zinc 

Figure 133.-La Garita Wilderness, Colorado. 

COLORADO 

MAP LOCATION 
by pervasive propylitic alteration during postemplacement intrusive and extrusive activity and resurgent doming. Many minor quartz-pyrite and quartzcalcite-pyrite veins were formed along minor fractures 

during this period of hydrothermal activity, and some of 

these veins near the northwest margin of the wilderness 

contain local concentrations of lead, zinc, and silver 

of economic interest. Most of the deposits containing 

valuable minerals are 0.5 to 1 rni outside the wilderness, 

but some deposits are adjacent to the boundary and 

some extend within the wilderness. All these veins are 

small, however, and the concentrations of valuable 

minerals are so erratically distributed that no mineral 

resource can be postulated. Larger veins, with more persistent valuable metal concentrations, would have to be 

found in order to support even a small mining industry 

in the area 

A series of intrusive plugs marking the roots of 

former volcanoes extends from the western edge of the 

La Garita Wilderness westward for about 9 mi. Many of 

the centers were intensely altered by hydrothermal 

activity during waning stages of volcanic activity, and 

local areas containing somewhat anomalous metal concentrations have been identified. A low-level zinc 

anomaly was detected in stream-sediment samples 

along upper Mineral Creek in and adjacent to the wilderness. Although no deposits containing concentrations 

even remotely approaching ore grade were seen, there 

are widespread indications of mineralization and the 

area is considered to have a probable mineral-resource 

potential for lead, zinc, and silver. 

The most important mineralized area in the central 

San Juan Mountains is in the Creede mining district 

3-8 rni south and southwest of the La Garita Wilderness. The ores here were deposited after development of 

the Creede caldera, and are localized along a series of 

faults that extend radially north to northwest out from 

the caldera None of the faults that host the ores extend 

into the La Garita Wilderness, and it is unlikely that 

any mineral resources related to the Creede center of 

mineralization exist within the wilderness. No evidence 

was seen for geothermal energy or fossil-fuel resources 

within the La Garita Wilderness. 

REFERENCE 

Steven, T. A., and Bieniewski, C. L., 1977, Mineral resources of the 

La Garita Wilderness, San Juan Mountains, southwestern Colorado: U.S. Geological Survey Bulletin 1420, 65 p. 

457 
15' 

oo· 

45 

GENTER 

MINE 

• 

Marb e 

..0 

COLO RA DO 

MAP LOCATION 

Approximate boundary 

0 10 

MILES 

EXPLANATION 

- Geologic terrane with substantiated 

mineral-resource potential D Geologic terrane with probable 

mineral-resource potential 

Cu Copper Ag Silver 

Pb Lead Zn Zinc 

M o Molybdenum 

~ Mine or deposit 

~ Mine 

D Granodiorite plutons 

D Sedimentary rocks 

--- Contact 

Figure 134.- Maroon Bells-Snowmass Wilderness and additions, Colorado. 
MAROON BELLS-SNOWMASS WILDERNESS AND ADDITIONS, COLORADO 

By VALL. FREEMA , 1 U.S. GEOLOGI L S RVEY a nd 

ROBERT C. W EIS ER, U.S. BUREAU F MI ES 

SUMMARY 

The Maroon Bells-Snowmass Wilderness and Additions, located in western 

Colorado, was examined for mineral potential during 1974-76. Evidence of 

mineralization is widespread and numerous areas have either probable or 

substantiated mineral-resource potential for one or more of the following metals: 

gold, silver, lead, zinc, copper, and molybdenum. In addition, part of the 

wilderness has substantiated coal resource potential. There is little promise for 

the occurrence of oil and gas or geothermal resources. 

CHARACTER AND SETTING 

The Maroon Bells-Snowmass Wilderness and Additions, an area of about 270 sq mi, is located in the Elk 

Mountains of western Colorado a few miles southwest 

of Aspen, Colorado. Access to the area is from Glenwood Springs to the north or from Gunnison to the 

south. Altitudes range from about 7500 ft to 14,265 ft. 

This great relief, combined with the carving by glaciation, has produced an area of spectacular mountain 

scenery. The area surveyed included the existing wilderness and adjacent study areas. In 1980 new boundaries were established that enclosed most of the area 

surveyed and some additional area that has not yet been 

carefully examined. 

The rocks exposed in the wilderness are sedimentaryof Pennsylvanian and younger ages-that have been intruded and locally metamorphosed by igneous rocks in 

the forms of concordant and irregular plutons, sills, and 

dikes. Prior to the main intrusive period the sedimentary rocks were folded into a large anticline extending 

northwestward from the Sawatch uplift. Normal and 

thrust faulting occurred with the folding. Large areas of 

the bedrock are concealed by deposits of rock debris laid 

down during glaciation or later. 

The southern third of the wilderness is considered to 

lie within the Colorado mineral belt, a northeasttrending zone that embraces almost all the mineral mining districts of central Colorado. Within the Colorado 

mineral belt large replacement metallic ore deposits are 

mostly confined to a few stratigraphic rock units of 

'With contributions from David L. Campbell and Horley D. King. USG . and C. l.. 

Bieniewski. USBM. 

favorable chemical composition. These favorable host 

rocks are not exposed in the wilderness but are certainly 

present beneath the surface sedimentary rocks except 

where locally removed by faulting or displaced by intrusive rocks. The coal-bearing sedimentary units of the 

region remain only in the southwest comer of the 

wilderness. Likewise, the sedimentary units from which 

natural gas is produced in nearby parts of western Colorado are preserved only in the southwest comer. 

The work done in 1974-76 to evaluate the resource 

potential of the wilderness and additions included 

geologic mapping of previously unmapped parts of the 

wilderness; geochemical sampling of rocks, altered 

rocks, and stream sediments for analyses; geophysical 

surveying of the area for magnetic and gravity appraisal; and a records search of claim locations, examination and mapping of mine and prospect workings, 

and sampling of veins, mine dumps, and altered rock. 

The search of old records augmented the very visible 

signs of past prospecting in the wilderness. About 6000 

mining claims located in or very near the wilderness 

were found in the files of the County seats. About 3200 

of these filed claims were well enough described that 

they could be plotted on maps. Considering the amount 

of prospecting, very little production of mineral wealth 

occurred within the present wilderness. Many prospectors, attracted by the mineral riches of the nearby 

Aspen mining district, thoroughly examined the 

wilderness and additions and found much mineralized 

rock but little ore. The most favorable host rocks of the 

Colorado Mineral Belt, such as those that contained the 

rich ores found at Aspen, pass under the wilderness 

below levels of erosion that would make them accessible 

459 
to the scrutiny of those prospectors. Claim staking and 

exploration continues, and incluaes consideration of the 

area for low-grade, large stockwork molybdenum 

deposits. 

MINERAL RESOURCES 

Evidence relating to the assessment of the resource 

potential of metallic mineral deposits in the Maroon 

Bells-Snowmass Wilderness and Additions includes the 

following: (1) its location along the Colorado Mineral 

Belt, (2) the presence of intrusive rocks that might provide a source of metallic elements and heat to mobilize 

them, (3) faulting and fracturing that provided avenues 

for solutions containing metallic elements, (4) abundant 

occurrences of low-grade altered and mineralized rock 

that show that solutions containing metallic elements 

did indeed move through the rocks, and (5) the presence 

at the surface of large areas of sedimentary rock types 

that chemically are not themselves favorable for 

replacement-type ore bodies, but that overlie favorable 

host rocks. 

No metallic mineral resources were found in the 

wilderness in this study, but several areas were identified as having probable or substantiated mineralresource potential for metallic mineral resources at considerable depth; these areas are within three zones. 

The Snowmass Creek fault zone extends southwestward into the wilderness from near Eagle Mountain. Occurrences of metallic elements found in the wilderness 

are all of small size and low grade; however, a prospect 

near Eagle Mountain, outside the wilderness produced 

and shipped some ore (Bryant, 1979, p. 115-120). Metallic elements that were found in anomalous amounts 

along this zone include copper, silver, lead, zinc, 

molybdenum, cobalt, and gold. The zone, especially the 

northeastern part, has a probable mineral-resource 

potential for copper, lead, and silver resources at depth 

in favorable host rocks or along fractures near the contact of the pluton. 

Along the south side of the Mt. Sopris pluton, mineralized rock was found close to the igneous-sedimentary 

contact in veins and fractures. Metallic elements found 

in anomalous amounts include lead, silver, zinc, copper, 

molybdenum, cobalt, and gold. The area has been 

thoroughly prospected and ore was produced from small 

pods. Although there is little likelihood for deposits at 

the surface, there is a probable mineral-resource potential for copper, lead, zinc, and silver resources at depth 

along the edge of the pluton in small fractures and at 

the level of favorable host rocks. 

The southern third of the wilderness, west of Ashcroft, belongs within the Colorado Mineral Belt and this 

area contains widespread occurrences of mineralized 

460 

rock. Geologic factors are consistent with the possibility, if not the probability, of ore deposits being present 

where favorable host rocks occur at depth or where 

other rock types are faulted or fractured. The parts of 

the wilderness shown as having probable mineralresource potential are those parts where surface indications of mineralization are concentrated. The study 

found examples of mineralization with two differing 

suites of metallic elements. One suite, with molybdenum and copper and locally tungsten, tin, lead, zinc, 

silver, gold, mercury, arsenic, bismuth, and antimony, is 

found in a few fracture-related sites and also in zoned 

stockwork-ore deposits with associated pyritization and 

alteration (Bryant, 1971, p. D13-D25). The other suite 

with lead, silver, and zinc and locally antimony, cadmium, bismuth, molybdenum, copper, cobalt, gold, 

arsenic, mercury, and fluorine, is found mostly in veins 

and fractures. 

Two occurrences of stockwork molybdenum mineralization are considered to identify areas of substantiated 

potential and these areas are surrounded by areas of 

probable mineral-resource potential. These two occurrences, the East Maroon Creek and ConundrumCataract Creeks areas, were examined on the surface, 

and have been studied by mining companies, but ore 

deposits have not yet been found. The areas are thought 

to have resource potential because geophysical and 

geochemical studies suggest large masses of altered 

rocks below the surface. A geologic interpretation suggests intrusion of small plutons within and later than 

the main mass of the White Rock pluton and that some 

of mineral zoning may be related to the later plutons. A 

third area of stockwork molybdenum mineralization 

may be present northeast of Gothic in the Copper Creek 

drainage within the boundary of the 1980 addition to 

the wilderness but outside the area studied in 1974- 76. 

Because of the recent boundary changes this area was 

not included in this study and is not shown on the map. 

Its resource potential cannot be assessed on the basis of 

available data 

The other areas delineated as having probable 

mineral-resource potential, with the lead-silver-zinc 

suite of elements, have been thoroughly prospected and 

it is unlikely that undiscovered ore deposits are present 

at the surface. Some ore-grade rock has been shipped 

but no sustained mining took place. Of special note is 

the area of the Cummings property where small quantities of ore-grade rock may remain; the possibility of a 

deep deposit is good and a demonstrated lead-silver-zinc 

resource exists at this mine. A once-productive mine, 

the Montezuma, lies just outside the wilderness, and it 

is possible that ore bodies continuous with this deposit 

might extend into the wilderness. A small area of substantiated lead-silver-zinc resource potential extends 

into the wilderness from this mine. 
In the southwest comer of the Maroon BellsSnowmass Wilderness and Additions a 900-ft-thick 

sequence of coal-bearing rocks underlies an area of 

about 6 sq mi. The beds dip southwestward as much as 

40° or as little as 8° and, as the land surface slopes in 

the same direction, they are mostly less than 1000 ft 

below the surface. Gaskill and Godwin (1966) concluded 

that seven or more beds of coal underlie that part of the 

wilderness, ranging from 0.1 to 4 ft thick. Their data 

consist of measurements on coal outcrops that could not 

be traced more than 0.1 mi. The abandoned Holgate coal 

mine, 0.2 mi west of the wilderness, produced coking 

coal from a bed reported to be 4 ft thick. The Galloway 

coal prospect is within the wilderness; Hanks (1962) 

reported the coal there to be a bed of semianthracite 0.9 

ft thick. The Genter mine, 0.75 mi south of the wilderness, produced semianthracite and anthracite from a 

bed 3.1-4.9 ft thick (Boreck and Murray, 1979). The 

work of Donnell (written commun., 1982), who measured and correlated coal beds in the area, indicates that 

the coal beds are so lenticular that it is impractical to 

assume continuity of a coal bed for more than 0.75 mi. 

Demonstrated resources calculated from points at the 

Holgate mine and Gaskill and Godwin's measured outcrop total 8.3 million short tons of bituminous or 

anthracite coal. If it is assumed that all the area of coalbearing rocks in the wilderness is underlain by one or 

more coal beds, that aggregate 4 ft in thickness, the inferred resource is an additional 25 million short tons. A 

substantiated resource potential is assigned to this coal 

area 

The geologic evaluation of oil and gas potential for the 

wilderness took into consideration possible source beds, 

reservoir beds, structures, and geothermal history of 

the area There are no nearby producing oil fields. 

Traces of petroleum residue were found in sandstones in 

the wilderness but these were in strata not now structurally able to serve as reservoir rocks. The only possible combination of favorable source and reservoir strata 

in a conceivably favorable structural setting are the 

Pennsylvanian Belden Formation and the Mississippian 

Leadville Limestone. Interpretation of geothermal information indicates that temperatures were too high for 

preservation of oil in these formations. It is possible 

that natural gas might have survived in these strata in 

the western part of the area The younger strata that act 

as reservoir rocks in the gas fields west of the wilderness are preserved only in the southwest comer of the 

area, and the structural setting is unfavorable. Natural 

gas, dominantly methane, is certainly present in the 

coal beds but the coal thicknesses and burial depths are 

not favorable for production. The occurrence of oil or 

gas resources is unlikely in the Maroon Bells-Snowmass 

Wilderness and Additions. 

Other possible mineral commodities are present in the 

wilderness; these include sodium, rock products, and 

geothermal waters. On the basis of available data, none 

are judged to show promise for the occurrence of 

resources. 

SUGGESTIONS FOR FURTHER STUDIES 

The area added to the wilderness in 1980 was not adequately studied to evaluate the mineral-resource potential for metals in the area northeast of Gothic. It is a 

mineralized area, and like the other mineralized areas 

within the area studied, resources are likely to be present at depth. 

REFERENCES 

Boreck, D. L., and Murray, D. K., 1979, Colorado coal reserves depletion data and coal mine summaries: Colorado Geological Survey 

Open-File Report 79- 1. 

Bryant, Bruce, 1971, Disseminated sulfide deposits in the Eastern 

Elk Mountains, Colorado: U.S. Geological Survey Professional 

Paper 750- D, p. Dl3·D25. 

__ 1979, Geology of the Aspen 15-mi.nute Quadrangle, Pitkin and 

Gunnison Counties, Colorado: U.S. Geological Survey Profes· 

sional Paper 1073. 

Freeman, V. L., Campbell, D. L., King, H. D., Weisner, R. C., and 

Bieniewski, C. L., in press, Mineral resource potential map of the 

Maroon Bells-Snowmass Wilderness and Additions, Gunnison 

and Pitkin Counties, Colorado: U.S. Geological Survey Miscella· 

neous Field Studies Map M F - 164 7-A. 

Gaskill, D. L., and Godwin, L. H., 1966, Geologic map of the Marble 

Quadrangle, Gunnison and Pitkin Counties, Colorado: U.S. 

Geological Survey Geologic Quadrangle Map GQ-512. 

Hanks, T. L., 1962, Geology and coal deposits, Ragged-<:hair Mountain area, Pitkin and Gunnison Counties, Colorado: Brigham 

Young University Geology Studies, v. 9, pt. 9, p. 137- 160. 

461 
462 

40° 

45' 

40° 

30' 

Cu , Pb , Zn, Ag , Au , U, Th 

Cu, Pb n, ~ 

• 

COLO RADO 

MAP LOCATION 

0 

D 

Cr 

Cu 

Au 

Pb 

Mo 

Mo 

10 

MILES 

EXPLANATION 

Geologic terrane with probable 

mineral-resource potential 

Chromium Pt Platinum 

Copper Ag Silver 

Gold Th Thorium 

Lead u Uranium 

Molybdenum Zn Zinc 

PEARL DISTRICT 

boundary 

Cu , Pb, Zn , 

Ag, Au 

Cu. Pb, Zn, Ag , Au 

fluorite 

uo e 

U, Th, Mo, fluorite 

Figure 135.- Mount Zirkel Wilderness and vicinity, Colorado. 
MOUNT ZIRKEL WILDERNESS AND VICINITY, COLORADO 

By GEORGE L. SNYDER ,

1 U.S. GEOLOG ICAL S R EY, and 

LOWELL L. PATTE , U.S. BUREA OF MINES 

SUMMARY 

Several areas of metallic and nonmetallic mineralization have been identified 

from surface occurrences within the Mount Zirkel Wilderness and vicinity, Colorado. Three areas of probable copper-lead-zinc-silver-gold resource potential, two 

areas of probable chrome-platinum resource potential, four areas of probable 

uranium-thorium resource potential, two areas of probable molybdenum 

resource potential, and one area of probable fluorspar potential were identified 

by studies in 1965-73 by the USGS and USBM. No potential for fossil fuel or 

geothermal resources was identified. 

CHARACTER AND SETTING 

A survey of the mineral-resource potential of 945 sq 

mi that includes the Mount Zirkel Wilderness and 

northern Park Range vicinity, Colorado, was made by 

the USGS and USBM during the summers of 1965- 73. 

This survey was supported by geologic and petrological 

studies, by detailed examination of mining claims, and 

by geochemical and geophysical surveys. Assembled 

data are contained in Snyder, Patten, and Daniels (in 

press) and Snyder and others (1981). 

Scenery in the glaciated Mount Zirkel Wilderness is 

spectacular, especially in the vicinity of Mount Zirkel in 

the north and Mount Ethel in the south. Total relief is 

nearly 5000 ft with timberline lying at an average 

altitude of 10,500 ft. Nearly all of the wilderness is 

underlain by Proterozoic crystalline rocks, mainly amphibolitic to felsic high-grade metavolcanic rocks with 

minor interlayered metashale and marble that have 

been extensively intruded by bodies of syntectonic gabbro, quartz monzonite, quartz diorite, and peridotite, 

and by post-tectonic quartz monzonite and granite. 

Later during Mesozoic time the Precambrian crystalline 

rocks were covered by as much as 10,000 ft of marine 

sediments, three tiny areas of which are still contained 

within the boundaries of the wilderness. PostCretaceous compressional faults and post-Miocene tensional faults offset the younger sediments; some of 

these follow old Precambrian zones of weakness and 

some are at a large angle to them. Quaternary glacial 

'With cont.ribuLions from Jeffery J. Daniels. USG . 

drift and alluvial and colluvial deposits, as well as 

modem soil, lakes, and forest litter, mask most of the 

older rocks and structures at the present land surface. 

Rocks of the northern Park Range have been mineralized by introduced ore elements probably four times in 

the geologic past, twice in the Precambrian, once(?) at 

the close of the Mesozoic and beginning of the Tertiary 

(Laramide orogeny), and at least once later in the Tertiary. The Precambrian events coincide with the two 

major episodes of igneous intrusion, 1.7 to 1.8 b.y. (billion years) ago (the syntectonic event) and 1.3 to 1.4 b.y. 

ago (the post-tectonic event). Here and elsewhere in the 

vicinity there is evidence that elements in minerals 

originally deposited in the Precambrian have been remobilized in the Laramide orogeny or in Tertiary time. 

Several large areas of low-grade mineralization are present at the ground surface, some discovered as a result of 

this survey. 

MINERAL RESOURCES 

Fluorite is the main mineral that possibly occurs as a 

resource in the wilderness and is found largely in the 

Crystal district which extends into the wilderness. 

Other possible mineral resources are less certain but 

could be much more valuable. 

Areas of mineral-resource potential, shown on the 

map, are based on observations of outcrops and prospect pits, on geochemical anomalies in surface rocks and 

stream sediments, and on a detailed knowledge of local 

463 
geology and distant but geologically similar producing 

mineral provinces. Most outcrops are small and scattered, mainly near the fringes of the wilderness or adjacent areas, but some, for example the Gilpin district, are 

in the center of the wilderness. The areas of potential 

shown on the map are untested but could be significant. 

Most base- and precious-metal sulfide anomalies are 

in five prospected districts: Elkhorn, Farwell, Gilpin 

(entirely within the wilderness), Greenville, and Pearl. 

Other unprospected anomalous areas occur within the 

adjacent area Three belts of probable copper-lead-zincsilver-gold potential are determined by the bedrock 

geochemical anomalies and prospects and the northeasterly grain of both the mapped geologic units and 

some geophysical lineaments (some stream-sediment 

geochemistry suggests that the southern two belts may 

merge). Copper-lead-zinc-silver-gold occurrences in the 

northern two of these three belts are all within 2 mi of 

the contact of a 1.8 b.y. old granite body, which might 

have served as the concentrating engine for these 

elements; in the southern belt calc-silicate or marble 

beds have been favorable horizons for replacement 

deposits of lead-copper-zinc-silver-gold. A probable 

potential for base- and precious-metal stratabound 

sulfide deposits is assigned these geochemically 

favorable rocks. Many such massive sulfide deposits 

occur throughout the world in marine metasediments 

and metavolcanics of this age (1.8 b.y.). 

Chromium, platinum, palladium, cobalt, and nickel 

are clearly associated with ultramafic rocks in the 

wilderness, but not in amounts exceptionally large for 

ultramafic rocks as a class. In rocks, the maximum 

chromium from analyses was 3000 parts per million in 

the Troutman Draw malachitic homblendite that also 

had the maximum platinum plus palladium (0.09 parts 

per million). Two areas of probable potential for minor 

platinum-chromium resources are indicated on the map. 

One area includes a large peridotite intrusive on the 

ridge north of Lone Pine Creek and extends north to include high cobalt and chromium stream sediment 

anomalies measured on streams issuing from beneath 

rock glaciers. The other area is in the northwest part of 

the adjacent area and includes the gabbro of Elkhorn 

Mountain. Funnel-shaped bodies of layered gabbro the 

size of the gabbro of Elkhorn Mountain are known 

throughout the world to have a potential for magmatically segregated platinum-chromium ores. 

Three areas of probable potential for uraniumthorium are indicated near the boundaries of the 

wilderness and adjacent areas, and another is included 

within the molybdenum-potential area near the Crystal 

district. All of these are based on the presence of a 

geochemical suite of uranium, thorium, beryllium, 

niobium, and lanthanum. Although the potential is only 

464 

probable, a large low-grade uranium deposit in pegmatities and pegmatite veins of the Rossing type may exist beneath the indicated areas. The geochemical suite 

mentioned above for uranium is present in and also can 

characterize molybdenum-bearing apophyses near the 

tops of Tertiary porphyry vertical cylindrical intrusives 

in the western United States. Although no Tertiary intrusives occur at the surface in this part of the Park 

Range, such rocks are present both southeast and 

northwest of this geochemical belt. 

A discontinuous linear belt of probable molybdenum 

potential is shown as two areas extending from the 

Gilpin district through the Crystal district on the east 

side of the wilderness and southward on the southeast 

side of the wilderness. The northern part of this belt includes two aeromagnetic anomalies, which have no 

ready explanation in the surface geology and could be 

revealing the tops of deeply buried Tertiary intrusive 

pipes. 

Fluorspar veins are present just east of the Mount 

Zirkel Wilderness and some of these veins are known to 

extend into the wilderness. There is a probable potential 

for low-grade fluorite deposits everywhere within the 

steep-sided 1.4 b.y. old Mount Ethel pluton where interstitial fluorite could have been easily concentrated 

along joint sets, fault planes or fault breccia zones that 

penetrated these rocks. 

Other nonmetallic commodities occur in the wilderness and include mica, feldspar, cement rock, aggregate, 

riprap, and ornamental stone. These commodities are 

small, inaccessible, and far from potential markets and 

no resource potential was identified. 

Hydrocarbon resources have never been searched for 

within the Mount Zirkel Wilderness and vicinity and 

they are certainly not present anywhere near the present land surface. There are oil fields in suitable trapping 

structures on both sides of the North Park Range so the 

geologic environment may be suitable. A thrust fault on 

the west side of the range could serve as a capping seal 

for any hydrocarbons trapped in underlying Mesozoic 

rocks. Oil and gas have not been found in anticlines 

nearest to this thrust nor hydrocarbons in seeps 

anywhere within or adjacent to the wilderness, and 

there has been no attempt to drill through such a hypothetical crystalline caprock. It is not impossible that 

some oil and gas could be trapped locally at great(?) 

depth below the western boundary of the adjacent area 

but data are insufficient to assess the oil and gas potential of the area No potential for coal was identified. 

There is no evidence of a geothermal resource potential anywhere within the bounds of the Mount Zirkel 

Wilderness or vicinity even though there is a wellknown geothermal resource just outside of this area in 

the vicinity of Steamboat Springs, Colorado. 
REFERENCES 

Snyder, G. L., Hopkins, R. T., Jr., Domenico, J. A., Frisken, J. G., and 

Mitchell, J., 1981, Analysis of samples of rock and stream sediment samples from the Mount Zirkel Wilderness and Northern 

Park Range vicinity, Jackson and Routt Counties, Colorado: U.S. 

Geological Survey Open-File Report 81-186. 

Snyder, G. L., Patten, L. L., and Daniels, J. J., in press, Mineral 

resources of the Mount Zirkel Wilderness and northern Park 

Range vicinity, Jackson and Routt Counties, Colorado: U.S. Geological Survey Bulletin 1554. 

465 
3 

466 

• COLO RADO 

MAP LOCATION 

0 

M ILES 

EXPLANATION 

- Geologic terrane with substantiated 

and probable mineral-resource potential 

(*Indicates commidity with substantiated 

potential) 

Geologic terrane with substantiated 

L-_ _.___. mineral-resource potential D Geologic terrane with probable 

mineral-resource potential 

Pb Lead Ag Silver 

M o Molybdenum Zn Zinc 

'5<:' Mine 

M o 

2 

B 

• • • 

Intrusive rocks 

(Tertiary) 

Sedimentary rocks 

(Cretaceous and 

Early Tertiary) 

Contact 

Location discussed 

in text 

Vein 

Figure 136.-0h-Be-Joyful Wilderness Study Area, Colorado. 
OR-BE-JOYFUL WILDERNESS STUDY AREA, COLORADO 

By STEVE L DI GTON, .. GEOLOGICAL S RVEY, and 

CLARE CE E. ELLIS, U.S. B REA OF Mr E 

SUMMARY 

The Oh-Be-Joyful Wilderness Study Area, near Crested Butte, Colorado, was 

studied by the USGS and the USBM in 1976, 1980, and 1982. Resources of 

molybdenum are present in two deposits immediately adjacent to the area and 

are inferred at one location that is partly within the study area These three 

overlapping areas have substantiated mineral-resource potential for 

molybdenum, and are surrounded by an area of probable mineral-resource potential for molybdenum. Another area of probable mineral-resource potential for 

molybdenum occurs in the northwestern part of the study area Three areas that 

are entirely or partly within the study area, two of which contain resources of 

silver, lead, and zinc, have substantiated mineral-resource potential for those 

commodities. In addition, the western part, and a small area in the southern 

part of the study area have probable mineral-resource potential for silver, lead, 

and zinc. More than half the study area contains inferred coal resources and has 

substantiated mineral-resource potential for coal. 

CHARACTER AND SETTING 

The Oh-Be-Joyful Wilderness Study Area (approximately 8.6 sq mi) occupies the watershed of Oh-BeJoyful Creek on the east flank of the Ruby Range, a subsidiary of the Elk Range in west-central Colorado. 

Access is primarily via a jeep road up Oh-Be-Joyful 

Creek that traverses most of the study area and connects with an improved county road a few miles north of 

Crested Butte. 

Most of the study area is covered with marine and 

continental shales, sandstones, and conglomerates that 

range in age from Cretaceous to early Tertiary. These 

rocks are intruded and metamorphosed by two distinct 

suites of intrusive rocks. The oldest suite is Oligocene in 

age and consists of a group of stocks and dikes of 

diorite, granodiorite, and quartz monzonite that form 

the core of the Ruby Range. A younger series of rocks, 

Miocene in age, is expressed at the surface only as a 

small plug of rhyolite porphyry in Redwell Basin. immediately east of the study area At depth, these rocks 

are granites and granite porphyries that are the source 

of the Redwell Basin and Mt. Emmons stockwork 

molybdenum deposits. 

The area is broken by numerous normal faults, generally of small displacement. Some of these contain epithermal silver-lead-zinc vein deposits and some contain 

dikes. 

MINERAL RESOURCES 

Mt. Emmons and Redwell Basin, two stockwork 

molybdenum deposits having demonstrated resources, 

occur immediately adjacent to the Oh-Be-Joyful 

Wilderness Study Area on the southeast. 

A third deposit (A) is likely to be present in the subsurface beneath the valley of Oh-Be-Joyful Creek near 

the eastern boundary of the study area Mineral zoning 

in associated base-metal veins and the distribution of 

hornfels, mineral veining, and hydrothermal alteration 

are similar to the nearby Mt. Emmons and Redwell 

Basin deposits. High-silica granites and molybdenite 

mineralization are known at depth, and this area 

has substantiated mineral-resource potential for 

molybdenum. 

Just upstream, a fourth deposit (B) could exist in the 

subsurface. Some hornfels and minor veining is present 

and a distinct structural dome in the overlying sedimentary rocks suggests the presence of a silicic intrusive at 

depth. Because there has been no physical exploration 

467 
of this area by drilling, it exhibits probable mineralresource potential for molybdenum. 

Near the northwest corner of the area, a radial pattern 

of faults and base-metal veins indicates another area (C) 

of probable mineral-resource potential for molybdenum. 

Widespread occurrence of alteration and mineralization 

related to the Oligocene intermediate-composition intrusive rocks makes it difficult to clearly discern 

younger events, possibly related to molybdenite 

mineralization. 

Demonstrated and inferred resources of silver, lead, 

and zinc are present in two veins in the study area, the 

Independence (D) in the southeastern part of the area, 

and the Ruby No. 1 (E) in the northwestern part. Area C 

also has substantiated mineral-resource potential for 

silver, lead, and zinc because several veins that have 

high silver contents appear to intersect there. 

On the basis of numerous old mines and other workings that yield vein material with moderate to high 

silver, lead, and zinc contents, a large region in the 

western part of the area, along with the extension of the 

Scarp vein (F) in the southern part, has probable 

mineral-resource potential for silver, lead, and zinc. 

468 

Throughout the upper part of the Upper Cretaceous 

Mesaverde Formation, numerous thin (0.5 to 3 ft) beds 

of coal occur. The coal ranks between high volatile B 

bituminous and anthracite, depending on the degree of 

metamorphism. The area where these coal beds are at, 

or within a few hundred feet of, the surface has substantiated mineral-resource potential for coal. 

SUGGESTIONS FOR FURTHER STUDIES 

If mineral zoning patterns and ages of the base-metal 

veins were better known, they would be a useful exploration guide to molybdenum deposits. A detailed mineralogic and geochronologic study of the vein deposits 

would be a large contribution to the understanding of 

mineral genesis, in this area and others. 

REFERENCE 

Ludington, Steve, and Ellis, C. E., 1983, Map showing geology and 

mineral resource potential of the Oh·Be-Joyful Wilderness Study 

Area, Gunnison County, Colorado: U.S. Geological Survey Mis· 

cellaneous Field Studies Map MF - 1582- A, scale 1:24,000. 
PIEDRA WILDERNESS STUDY AREA, COLORADO 

By STEVE M . Co DO ,

1 U.S. GEOLOGI AL S R · , and 

S. D ON BROWN, U.S. B REA OF Mf1 E 

SUMMARY 

The Piedra Wilderness Study Area, located approximately 30 mi northeast of 

Durango, Colorado, was evaluated in 1982 for its mineral-resource potential. 

Geochemical and geophysical studies by the USGS and USBM indicate little 

promise for the occurrence of mineral or energy resources in this area 

CHARACTER AND SETTING 

The Piedra Wilderness Study Area covers about 65 sq 

mi of heavily wooded foothills along the northern edge 

of the San Juan Basin. It is located midway between 

Durango and Pagosa Springs, Colorado, and is 10 mi 

east of Vallecito Reservoir. 

Access to the study area by vehicle is limited. The 

southern part of the area can be reached by turning 

north along the Piedra River where it is crossed by U.S. 

Highway 160. This gravel road is closed at Horse Creek, 

about 5 mi north of the highway, but future repairs may 

open it as far as the confluence of the Piedra and First 

Fork. The northern part of the area can be reached only 

by driving northwest from Pagosa Springs and corning 

in from the east across the Werninuche valley. The road 

then parallels the northern and northwestern boundary 

of the study area 

Access within the study area is limited to foot, horseback, or motorcycle. A system of USFS trails follows 

many of the streams and ridges, Mosca Creek and 

Sheep Creek being exceptions. Once off the trails, travel 

is extremely difficult owing to the dense vegetation. 

The study area is a part of the Colorado Plateau 

physiographic province, and reflects the canyon and 

mesa topography typical of the province. Here, most of 

the mesas have been reduced by erosion to narrow 

ridges. The area is transitional between low, dry 

sagebrush country to the south and rugged, alpine 

mountains to the north; altitudes range from about 

7000 to 10,500 ft. 

A relatively high amount of rainfall (50 in. annually) 

and snowmelt from the higher mountains combine to 

produce a system of perennial streams throughout the 

1

Willl contributions from ROO Vaughn. USGS. 

study area The Piedra River is the main stream; it 

flows through and adjacent to the study area from 

northeast to south. The tributary streams have substantially less flow than the Piedra and generally flow 

from the north and west. 

The rocks of the Piedra Wilderness Study Area range 

in age from Precambrian to Tertiary, from about 1460 

million years to about 50 million years old, and include 

both crystalline and sedimentary types. 

There are two kinds of Precambrian crystalline rocks: 

the Eolus Granite and the Uncompahgre Formation. 

The Uncompahgre is the older of the two and includes 

quartzite, phyllite, and slate. The Eolus Granite, dated 

at 1460 million years, was intruded into the 

Uncompahgre. 

A series of younger sedimentary rocks, about 4000 

feet thick, rests on the Precambrian basement. The 

Cambrian Ignacio Quartzite, Devonian Elbert and 

Ouray Formations, and Mississippian Leadville Limestone were deposited in and along the margins of ancient oceans. The Pennsylvanian Molas and Hermosa, 

Pennsylvanian and Permian Rico, and Permian Cutler 

Formations, were deposited in shallow seas and along 

the flanks of mountains. The only formation of Triassic 

age is the Dolores Formation, deposited on land in a 

system of streams and lakes. Jurassic rocks are the Entrada, Wanakah, and Morrison Formations, which also 

were deposited on land as sand dunes and by lakes and 

rivers. The Burro Canyon Formation and Dakota Sandstone, the only Cretaceous rocks within the study area, 

were deposited on land and on the margin of an ocean. 

The Piedra Wilderness Study Area has undergone 

several cycles of uplift and erosion that have affected 

the distribution of rock units. The Rico, Cutler, and 

Dolores Formations, present in the southern part of the 

study area, have been eroded and are not present in the 

469 
470 

37° 

30' 

0 

107°15' 

boundary 

Horse 

X Moun tarn 

Mule 

X Mountarn 

M ILES 

EXPLANATION 

5 

Ch11s 

XMountarn 

COLORADO 

• 

MAP LOCATION 

Outcrops of Cretaceous Dakota Sandstone 

Outcrops of Precambtian rocks 

Contact 

Figure 137.-Piedra Wilderness Study Area, Colorado. 

/ 
northern part. The present structure consists of a series 

of anticlines that trend northwest, with the oldest 

(Precambrian) rocks exposed in the cores of these folds 

where streams have cut across them. 

MINERAL RESOURCES 

Several of the rock units found in the Piedra 

Wilderness Study Area contain known mineral deposits 

elsewhere. These are the Hermosa Formation, an oil producer in southeastern Utah; the Cutler Formation, 

which produces uranium in eastern Utah; the Entrada 

Sandstone, a former uranium-vanadium producer in 

southwestern Colorado; and the Morrison Formation, 

which currently produces uranium in southwestern Colorado. Because of this known potential, we gave special 

attention to these formations in our evaluation of the 

study area Geochemical studies consisted of analyses 

of stream-sediment samples, water samples, and rock 

samples for mineral concentrations. Geophysical studies consisted of traverses with a scintillometer to detect 

possible concentrations of radioactive elements. Additionally, this and surrounding areas were previously 

studied under the recent National Uranium Resource 

Evaluation (NURE) program. 

Mining activity in the vicinity of the study area has 

been minimal. The East and West Medicine mines are 

located just outside the western boundary and consist 

of several small prospect pits cut into the Wanakah Formation. A small amount of gypsum was mined for use in 

patent medicine. Two other surface cuts are present 

southeast of the study area, but no mineralization was 

noted. No prospect pits or any other sign of mining activity were found within the study area 

This lack of mining activity is not surprising; our 

sampling did not reveal any significant anomalous 

mineral concentrations. The Hermosa Formation has a 

favorable composition and structural setting for accumulation of oil, but no exploration has been done in 

the area Any oil present may have been destroyed by 

the near-surface exposure of the Hermosa The Cutler, 

Entrada, and Morrison Formations did not show any 

anaomalous concentrations of uranium, vanadium, or 

other elements. Gypsum beds occur in the Wanakah 

Formation; however, because of the small size and the 

inaccessibility of the deposits, no resource potential was 

identified. 

The Dakota Sandstone was also checked for possible 

deposits of coal, although the limited area of outcrop 

and inaccessibility would limit the usefulness of such 

deposits. Here too, results were negative. 

SUGGESTIONS FOR FURTHER STUDIES 

Field observations, geochemical studies, and geophysical studies indicate there is little promise for the 

occurrence of energy or mineral resources in the Piedra 

Wilderness Study Area This conclusion is supported by 

the findings of the earlier NURE study and is suggested 

by the absence of significant mining activity in the area 

Further evaluation of the area is not recommended. 

REFERENCE 

Bush, A. L., Condon, S. M., Franczyk, K. J., and Brown, S. D., in 

press, Mineral resource potential map of the Piedra Wilderness 

Study Area, Archuleta and Hinsdale Counties, Colorado: U.S. 

Geological Survey Miscellaneous Field Studies Map 

MF- 1630- A. 

471 
472 

40° 

45' 

• 

COLORADO 

MAP LOCATION 

N 0 R T I 

P A R K 

0 5 

MILES 

EXPLANATION 

D Sedimentary rocks 

(Permian) ---- Contact 

D Granite --- Fault 

Figure 138.- Rawah Wilderness, Colorado. 

1 05°45' 
RAW AH WILDERNESS, COLORADO 

By R. C. PEARSON ,' U.S. GEOLOGICAL SURVEY , and 

L. L. PATTEN, U.S. BUREAU OF MINE 

SUMMARY 

The Rawah Wilderness, as enlarged in 1981, and some adjacent lands were 

studied by the USGS and USBM and their mineral-resource potential was 

assessed using geologic, geochemical, and geophysical data Traces of copper, 

silver, uranium, tungsten, and molybdenum were found in geochemical samples, 

but there is little promise for the occurrence of mineral resources in this relatively unmineralized area 

CHARACTER AND SETTING 

The Rawah Wilderness occupies about 119 sq mi on 

the east flank of the southern Medicine Bow Mountains 

in north-central Colorado. The crest of the range, which 

is approximately the west boundary of the wilderness, is 

sharp, between 11,800 and 12,800 ft high, and scalloped 

by a series of glacial cirques. The east boundary is along 

the Laramie River valley. Highway 14 connects Fort 

Collins, Colorado (60 mi to the east), with Walden, Col<r 

rado (40 mi to the west), and crosses the mountains 

south of the wilderness at Cameron Pass. A gravel road 

follows the Laramie River valley. Several trails provide 

access to the area from these roads. 

The 43-sq-mi Rawah Wilderness was expanded to 

119 sq mi when the contiguous East Rawah and East 

Rawah A Roadless Areas were added by passage of the 

Colorado Wilderness Bill in 1981. 

Most of the area is occupied by inhomogeneous granitic rocks about 1700 million years old. Schists and 

gneisses of various kinds that represent the pre-granite 

country rocks are included within the granite. The inclusions are mostly less than 0.25 mi wide and 1 mi long. 

Much younger sedimentary rocks that formerly covered 

the old granitic rocks have been eroded from the wilderness except for two slabs preserved from erosion 

because they were dropped down against the granite 

along faults. Faults of many ages have broken the 

rocks. Those that trend northwesterly, parallel to the 

mountain range, are the most continuous. The entire 

southern part of the range is interpreted to have piv1

Wilh conLributions from M. :. McCallum. M. L .. Griswold. and V. J. Flanigan. USGS. 

otted toward the east along a shallowly west dipping 

thrust fault. 

The mineral-resource appraisal was made by examining the rocks during geologic mapping for signs of 

mineralization, by geochemical sampling, and by interpretation of aeromagnetic data No mines and very few 

prospect diggings are in the wilderness. The nearest 

mining district of significance is the Northgate 

fluorspar district 10 mi northwest of the area 

MINERAL RESOURCES 

The Rawah Wilderness is situated in a part of Coler 

rado in which little mining has been done with the exception of coal and petroleum which have been produced 

in the nearby sedimentary basins. In addition, fluorspar 

mining occurs to the northwest, there are a few small 

precious-metal districts to the east and south, and an 

uranium prospect occurs a few miles to the east. The 

precious-metal districts are associated with bodies of intrusive igneous rock not present in the wilderness. 

Several prospect pits and a shaft in the northeast part 

of the wilderness were dug in granite to test a weakly 

mineralized fault zone. Traces of copper minerals are exposed in the shaft but they are spotty and no resources 

of copper are evident. A few mining claims have been 

staked east and south of the wilderness, but little exploration was done on these claims and apparently no 

discoveries were made. 

The geochemical survey disclosed a few weak anomalies of copper, silver, tungsten, uranium, thorium, and 

molybdenum. The copper and silver are in the prospect 

diggings mentioned above. Tungsten was detected in a 

473 
few stream-sediment and panned-concentrate samples 

in areas that suggest the possibility of weak tungsten 

mineralization along some of the major faults. Uranium 

was found in anomalous amounts in a few samples; the 

highest, greater than 120 parts per million in a vein a 

few inches wide. The anomalous thorium content of 

stream-sediment samples results from trace minerals in 

the granite. Molybdenum is present in low amounts in 

numerous stream-sediment samples and a few fractured 

and altered rocks along faults. The geochemical survey 

suggests the occurrence of tungsten and uranium along 

faults although no specific areas or targets are indicated. The copper, silver, thorium, and molybdenum 

anomalies probably do not indicate the existence of 

resources of these commodities. 

A body of quartz-rich gneiss, an inclusion in the 

granite, in the northeast part of the wilderness contains 

rutile and ilmenite, ore minerals of titanium. Their content, however, is too low for the area of the quartz 

gneiss to be considered as having a resource potential 

for titanium. 

474 

In summary, no mineral resources are known in the 

Rawah Wilderness and the results of this study indicate 

that there is little promise for the occurrence of undiscovered mineral resources. 

SUGGESTIONS FOR FURTHER STUDY 

If our interpretation is valid that the southern Medicine Bow Mountains moved eastward along a gently 

west dipping thrust fault, it suggests the possibility 

that potential petroleum reservoir rocks are beneath the 

granite in at least parts of the area. This possibility 

could be investigated by seismic surveys or drilling. 

REFERENCE 

Pearson, R. C., McCallum, M. E .. Griswold, M. L., and Patten, L. L., 

1982, Mineral resources of the Rawah Wilderness, Larimer County, Colorado: U.S. Geological Survey Open-File Report 82- 376, 

27 p. 
SANGRE DE CRISTO WILDERNESS STUDY AREA, COLORADO 

By BRUCE R. jOHNSO , 1 U.S. GEOLOGICAL RVEY, and 

CLARENCE E. ELLIS , U.S. BUREA OF MI E 

SUMMARY 

Mineral surveys were undertaken, largely in 1981 and 1982, of a wilderness 

study area which includes most of the Sangre de Cristo Range of south-central 

Colorado. Four areas of probable mineral-resource potential for gold, silver, and 

base metals lie along a northwest structural trend which follows the western 

margin of the range north of the Great Sand Dunes National Monument and 

crosses the range south of the monument. An area of probable mineral-resource 

potential for similar minerals plus tungsten has been identified east of Blanca 

Peak at the extreme southern end of the study area Another area of probable 

mineral-resource potential includes molybdenum mineralization associated with 

the Rito Alto stock. A small area of probable geothermal resource potential exists on the west side of the area around the Valley View Hot Springs. There is little promise for the occurrence of oil and gas resources. 

CHARACTER AND SETTING 

The Sangre de Cristo Wilderness Study Area includes 

most of the main Sangre de Cristo Range in southcentral Colorado from about 7 mi south of Salida to 

Blanca Peale The study area is approximately 70 mi 

long and averages 5 to 8 mi wide, and totals approximately 350 sq mi. The boundary generally follows the 

foot of the mountains except where private land or 

roads cause deviations. The portion of the study area 

west of the range crest lies in the Rio Grande National 

Forest; the portion east of the crest lies in the San 

Isabel National Forest. The town of Westcliffe is about 

7 mi east of the center of the study area; Alamosa is 

about 15 mi southwest of the southern end of the study 

area 

Access is generally excellent for foot travel, with most 

drainages containing good trails into the heart of the 

range. Four-wheel drive roads cross the range at 

Hayden Pass on the north and at Medano Pass to the 

south. Altitudes range from 14,363 ft at Blanca Peak to 

about 8000 ft along the southwestern portion of the 

boundary. Several 14,000- ft peaks and numerous 

13,000-ft peaks form the crest of the range for most of 

the length of the study area 

Most of the rocks exposed in the study area are either 

'With contributions from David A. Lindsey. USGS. 

Precambrian crystalline rocks or upper Paleozoic clastic 

sedimentary rocks. Several thin, fault-bounded slivers 

of lower Paleozoic sedimentary rocks occur within 

Precambrian rocks near the western boundary of the 

study area Thin units of lower Paleozoic sediments also 

occur locally between Precambrian rocks and upper 

Paleozoic sedimentary rocks. Small patches of Jurassic 

sedimentary rocks and Tertiary volcanic and sedimentary rocks crop out along the eastern and northeastern 

boundaries of the study area The study area also contains several small granitic stocks of Tertiary age and 

numerous dikes and sills of mostly Tertiary age. 

The Precambrian crystalline rocks are composed of 

several gneissic units and numerous Precambrian intrusive bodies of all sizes. A banded and layered 

heterogeneous package of mafic and felsic gneissic 

rocks occurs along the western side of the study area for 

most of its length. At the south end of the study area, 

the gneissic package is intruded by a large body of 

leucocratic, gneissic tonalite and by several bodies of 

hornblende metadiorite. Similar metadiorite bodies also 

intrude the gneisses at the north end of the study area 

All of the gneissic units are intruded by later, weakly 

foliated to nonfoliated granitic bodies. 

Sedimentary rocks of early Paleozoic age which crop 

out along the west side of the range are composed 

dominantly of limestone, dolomite, and sandstone. The 

calcareous composition of many of the lower Paleozoic 

475 
476 

D 

Cu 

Au 

Fe 

Pb 

M o 

Au 

w 

~ 

106°00' 

38° 

15' 

38° 

00' 

Ill() 

ve 

105°45' 105°30' 

boundary 

C• on) 

p 

·· <J> , ... ~ 

~ . (<' . 

Au , Ag, Fe , Cu , Pb_:.- "'· .-.·.·:,r.·:-< 

K A \ 

'A IO.'AL MO. 

37° 

45' \)Ho r 

COLORADO 

• 

MAP LOCATION 

Valley fill 

and alluvium ·· 

0 10 

MILES 

EXPLANATION 

Ag, 

Cu , 

Geologic terrane with probable Felsic plutonic rocks (Tertiary) 

Sedimentary rocks (Paleozoic) 

Metadiorite (Precambrian) 

mineral-resource potential 

Copper 

Gold 

Iron 

Lead 

Molybdenum 

Silver 

Tungsten 

Mine 

Felsic plutonic rocks (Precambrian) 

Gneisses (Precambrian) 

Contact 

Fault--Bar and ball on downthrown side 4 • • Thrust fault--Sawteeth on upper plate 

B Location discussed in text 

Figure 139.-Sangre de Cristo Wilderness Study Area, Colorado. 
rocks makes them an ideal host for base-metal replacement deposits. Thick formations of mostly sandstone, 

conglomerate, and shale of late Paleozoic age crop out 

over much of the central and northern part of the study 

area Upper Paleozoic rocks consist of as much as 6900 

ft of Pennsylvanian Minturn Formation and as much as 

6000 ft of Pennsylvanian and Permian Sangre de Cristo 

Formation. Most of the Sangre de Cristo Formation is 

red; the redbeds overlie an interval of calcareous beds in 

the lowermost part of the Sangre de Cristo Formation 

and the upper part of the Minturn that contains numerous small mineralized lenses having concentrations of 

copper and uranium. 

The Precambrian and Paleozoic rocks of the study area 

have been folded and thrust in Laramide (Late Cretaceous to Eocene) time. The thrusts are part of a large 

thrust zone that extends from New Mexico northward 

along the east side of the Laramide San LuisUncompahgre uplift. 

Much of the Sangre de Cristo Range in the study area 

is bounded by two large normal faults; the Sangre de 

Cristo fault extends along most of the west side of the 

range and the Alvarado fault extends along the northern half of the area on the east. The range-front faults 

formed in response to extensional rifting that uplifted 

the Sangre de Cristo Range and downdropped the adjacent San Luis and Wet Mountain valleys. Rifting and 

attendant uplift of the range probably began in late 

Oligocene time, proceeded rapidly at intervals beginning in early Miocene time, and continues today. 

MINERAL RESOURCES 

Mining activity within the study area in recent years 

has been limited to exploration for uranium, molybdenum, copper, and gold. Within the 20th century, gold 

has been produced from various properties along the 

west side of the study area, and uranium has been produced from a few workings scattered through the area 

The study area contains no mines of significant recorded production. The Orient mine, located outside the 

western boundary of the study area, produced iron ore 

from 1880 to 1931. Production from other properties is 

given in Ellis and others (1983). The following descriptions of mineral resources are abstracted from Johnson 

and others (in press). 

Areas of probable resource potential for metallic minerals which extend ir1to the Sangre de Cristo Wilderness 

Study Area can be divided into three types: areas which 

lie along a northwest-trending fault zone that extends 

along most of the west boundary of the study area (A-D, 

on map), an area of northwest-trending veins north of 

Blanca Peak (E), and the Rito Alto stock and vicinity 

(F). 

The northwest-trending mineralized zone follows 

most of the faulted west side of the Sangre de Cristo 

Range north of the Great Sand Dunes National Monument, where it may pass beneath the sand dunes, and 

extends southeast across the range. The concentrations 

of mineral occurrences and geochemical anomalies along 

the mineralized zone are interrupted by more barren 

areas, but the structural trend is interpreted to be more 

or less continuous. Anomalous concentrations of metals 

characterize several streams draining the mineralized 

zone. Gold occurs throughout the zone, but the relative 

abundance of other metals varies. Occurrences of gold, 

silver, iron, copper, and lead are localized within the 

zone by faults, shears, and calcareous strata The calcareous rocks, which are favorable hosts for replacement deposits, crop out in the mineralized zone from 

Steel Canyon to Crestone, and locally further south. The 

iron deposits of the Orient mine, located outside the 

study area, replace faulted calcareous rocks. The occurrence of hot springs in the fault zone indicates potential 

for disseminated gold and perhaps other mineral deposits of hot-spring origin. 

The Rito Alto stock is a composite granitic pluton of 

Oligocene age. Molybdenum, copper, tungsten, and gold 

mineralization are associated with the stock and nearby 

granitic dikes. The area of the stock has been prospected for molybdenum recently, but accurate assessment of the mineral potential of the area is limited by 

current lack of understanding of the level of erosion of 

the stock, and by inability to interpret the extent of the 

original mineralization system; it is an area of probable 

molybdenum resource potential. 

At the southern end of the study area, around Blanca 

Peak, an area of probable mineral-resource potential has 

been identified on the basis of gold, silver, and tungsten 

mineralization associated with quartz veins. One 

northwest-striking quartz vein in Precambrian rock just 

outside the study area is exposed for about 2 mi along 

strike. The vein enters the study area, but is hidden 

under talus and its extent is unknown. The vein and its 

main branches have over 3000 ft of development work. 

Gold and silver are present in nearly every sample, and 

average 0.1 oz gold/ton and 2 oz silver/ton across a 4 ft 

width (Ellis and others, 1983). Scheelite is visible under 

ultraviolet light in many places. Other quartz veins 

within the area contain the same minerals. 

Mineralized sedimentary rocks containing concentrations of copper and uranium occur in the lower part of 

the Sangre de Cristo Formation and the upper part of 

the Minturn Formation. Mineralization occurs as stratiform lenses in carbonaceous limestone, shale, and siltstone beds. Most of the mineralized lenses do not exceed 

3 ft in thickness and do not extend more than a few hundred feet along strike, but one mineralized bed near the 

top of the Minturn Formation has been traced more or 

477 
less continuously for 8 mi along strike. These occurrences have been known for many years, have been explored extensively, and no mineral resources have been 

identified. 

Although very small massive-sulfide lenses may have 

escaped detection owing to the reconnaissance nature of 

this study, little evidence was found of Precambrian 

mineralization in the gneissic rocks of the study area, 

and there is little promise for their occurrence. No 

mineralized areas have been found associated with the 

Precambrian plutonic rocks in the study area with the 

exception of minor, local, disseminated sulfide minerals 

in the metadiorite near Blanca Peak. There is little 

likelihood of mineral occurrences associated with the 

Precambrian plutonic rocks. 

A probable potential for geothermal resources exists 

in a small part of the study area southeast of Valley 

View Hot Springs, along the west side of the range. 

Valley View Hot Springs are outside the study area, but 

smaller hot springs occur nearby within the study area 

There is little promise for the occurrence of oil and gas; 

favorable host and source rocks for oil and gas are not 

exposed, and are judged not to be present beneath 

thrusts in the study area 

478 

SUGGESTIONS FOR FURTHER STUDIES 

Mineral-resource appraisal of the Sangre de Cristo 

Wilderness Study Area is hampered by the reconnaissance nature of many of the geologic and mineraldeposit studies to date. Detailed study of the Rito Alto 

stock and vicinity might provide the data to conclude 

whether or not an extensive porphyry molybdenum 

system ever existed and if so, at what level the system 

is currently exposed. Similarly, detailed study of the 

mineralization near Blanca Peak would provide better 

estimates of the area's tungsten potential. 

REFERENCES 

Ellis, C. E., Hannigan, B. J., and Thompson, J. R., 1983, Mineral in· 

vestigation of the Sangre de Cristo Wilderness Study Area, 

Alamosa, Custer, Fremont, Huerfano, and Saguache Counties, 

Colorado: U.S. Bureau of Mines Open·File Report MLA 65-83. 

Johnson, B. R., Lindsey, D. A., Ellis. C. E., Hannigan, B. J ., and 

Thompson, J. R., in press, Mineral resow·ce potential map of the 

Sangre de Cristo Wilderness Study Area, south-eentral Colorado: 

U.S. Geological Survey Miscellaneous Field Studies Map 

MF- 1635- A, scale 1:62,500. 
SERVICE CREEK ROADLESS AREA, COLORADO 

By PAUL W. SCHMlDT,

1 U.S. GEOLOGICAL RVEY , a nd 

S . A. KLUE DER, U.S. B REAU OF MINES 

SUMMARY 

The Service Creek Roadless Area, near Steamboat Springs, Colorado, was 

studied by the USBM in 1980 and by the USGS in 1975-76 and 1982. Geologic 

mapping and geochemical sampling did not identify any mineral-resource potential in the area No mining activity has been recorded for the area An east-west 

topographic linear feature just south of Silver Creek, which contains clusters of 

single and multi-element anomalies of certain rare-earth and metallic minerals 

deserves further study. 

CHARACTER AND SETTING 

The Service Creek Roadless Area occupies an area of 

about 62 sq mi in the scenic mountainous regions of the 

Gore Range in northern Colorado. The area lies just 

south-southwest of Rabbit Ears Pass, about 12 mi 

southeast of Steamboat Springs and about 17 mi northwest of Kremmling. Total relief of the roadless area is 

about 4000 ft. The crest of Gore Mountain, one of the 

highest and only named mountainous feature in the 

area, has an altitude of 10,687 ft. The mountainous terrain along the western border of the roadless area, for 

the most part, abruptly grades into lower farm and 

ranch lands; whereas to the east mountainous terrain 

prevails. The Gore Range continues north and south of 

the roadless area Secondary USFS roads give access to 

the east and west sides of the roadless area; U.S. 

Highway 40 crosses the northwestern part of the area 

Two trails lead into and through the roadless area; one 

along Service Creek, the other along Silver Creek. Most 

of the terrain is covered by a moderate to dense coniferous forest. Downfall, especially within drainage 

basins, locally makes off-trail travel difficult. Only 

stretches along major drainages and a few relatively 

small and scattered upland areas, which are covered 

with lush grasses in the summer months, are free from 

trees. 

The roadless area is dominated by a 1. 7 billion-yearold batholith of quartz monzonite. Throughout this unit 

are randomly scattered small intrusions of younger 

Precambrian amphibolitic dikes and inclusions of older 

1

With oonllibutions by Goorge L. Snyder and T. G. Lovering. USG . 

Precambrian metavolcanic, metasedimentary, and igneous rocks. The quartz monzonite continues both to 

the east and south of the roadless area, however, to the 

north and west it is either discontinuous or overlain by 

younger rocks. To the north-northwest, the quartz monzonite is intruded and overlain by Tertiary volcanic 

rocks that enter the roadless area at the headwaters of 

Harrison Creek. At the western boundary of the roadless area, sedimentary rocks of the Tertiary Browns 

Park Formation locally overlap onto quartz monzonite 

in the roadless area 

MINERAL RESOURCES 

Geologic mapping and geochemical sampling of the 

Service Creek Roadless Area in 1975-76, north of lat 

40°15' (Snyder, 1980), and reconnaissance sampling in 

1982, mainly south of lat 40 °15' (Schmidt and others, in 

press), show no favorable conditions for the occurrence 

of mineral resources. No mining activity has been 

recorded within the roadless area; only three prospect 

pits, having no identifiable mineralization, were located 

within the roadless area (Kluender, 1982). 

The roadless area lies well north of the Colorado 

mineral belt, and is dominated by an essentially barren 

homogeneous batholith that lacks major tectonic structures, such as large-scale faults, and lacks any dominant 

veins or zones of alteration that would be suggestive of 

mineralization. Although former mining activity is 

recorded both north and south of the roadless area, it 

occurred well beyond the roadless area boundary and in 

a different geologic environment. 

Geochemical sampling in the Service Creek Roadless 

479 
480 

• 

COLORADO 

MAP LOCATION 

§ , 

. 

0 

8 

,-

( 

\ 

'' .... , 

\ ~ J -~"· ------- - - ----

MILES 

EXPLANATION 

1 

I 

J 

/ ~pproximate '- roadless 

Gortl ~ boundary 

Mounta:n J 

-J-A2104 ...__ 

5 

Volcanic and related rock (Tertiary) 

Browns Park Formation (Tertiary) 

Quartz monzonite (Precambrian) 

(Surficial deposits not shown) 

Contact 

Lineament 

Figure 140.-Service Creek Roadless Area, Colorado. 
Area has identified scattered single- and multi-element 

anomalies. Some stream-sediment samples contain 

anomalous concentrations of silver, barium, cobalt, 

chromium, lanthanum, manganese, nickel, lead, tin, 

thorium, uranium, and yttrium; some stream panconcentrate samples contain anomalous concentrations 

of barium, lanthanum, molybdenum, niobium, lead, tin, 

thorium, vanadium, tungsten, and yttrium; and some 

rock samples contain anomalous concentrations of 

boron, barium, chromium, copper, nickel, scandium, tin, 

and zinc. Of these anomalies, only cobalt, chromium, 

lanthanum, lead, nickel, thorium, uranium, and yttrium 

are reported in any appreciable number of samples. The 

analyzed rock samples that have anomalous values were 

taken from small intrusive bodies or inclusions in the 

quartz monzonite. The small inclusions and intrusions 

of rock within the quartz monzonite are themselves randomly spaced and widely scattered throughout the 

roadless area and show neither pattern nor aerial distribution that would suggest the presence of substantial 

mineralization. 

The principal area, possibly deserving further study 

within the roadless area is along and south of a linear 

feature just south of Silver Creek. This feature is identified from topographic and drainage features. Geochemical anomalies of both rock and stream-sediment 

samples identify small and isolated areas where clustering of anomalous localities exist, but no mineralresource potential was identified. 

SUGGESTIONS FOR FURTHER STUDIES 

Further study of the Service Creek Roadless Area 

offers little, if any, promise for the identification 

discovery of mineral resources within the area. 

Although the southern part of the roadless area was 

mapped by reconnaissance methods, it is felt that no 

further examination of the area is warranted. 

REFERENCES 

Kluender, S. A., 1982, Mineral resource investigation of the Service 

Creek Roadless Area, Routt County, Colorado: U.S. Bureau of 

Mines Open· File Report MLA 123-82, scale 1:62,500. 

Schmidt, P. W., Lovering, T. G., and Kluender, in press, Geologic and 

mineral resource potential map of the Service Creek Roadless 

Area, Routt County, Colorado: U.S. Geological Survey 

Miscellaneous Field Studies Map M F - 1639, scale 1:48,000. 

Snyder, G. L., 1980, Geologic map of the northernmost Gore Range 

and southernmost Northern Park Range, Grand, Jackson, and 

Routt Counties, Colorado: U.S. Geological Survey Miscellaneous 

Investigations Series Map 1- 1114, scale 1:48,000. 

481 
482 

37° 

20' 

Cuchara 

pISS 

Whole Peak 

0 

Approximate 

boundary 

D Geologic terrane with substantiated 

mineral-resource potential 

Cu 

Au 

Pb 

Ag 

Copper 

Gold 

Lead 

Silver 

Zn Zinc 

105°00' 

MILES 

Trull Cr k 

COLORADO 

• 

MAP LOCATION 

5 

Syenodiorite (Tertiary) 

Granite, granodiorite (Tertiary) 

Undifferentiated sedimentary rocks 

(Tertiary and Cretaceous) 

B Metasedimentary rocks (Tertiary) 

Contact 

Figure 141.-Spanish Peaks Wilderness Study Area, Colorado. 
SPANISH PEAKS WILDERNESS STUDY AREA, COLORADO 

By KARIN E. BUDDING , U.S. GEOLOGICAL URV EY and 

' 

STEVEN E. KLUE DER, U.S. BUREA OF MI E 

SUMMARY 

A geologic and geochemical investigation and a survey of mines and prospects 

were conducted in 1982 to evaluate the mineral-resource potential of the Spanish 

Peaks Wilderness Study Area, Huerfano and Las Animas Counties, in southcentral Colorado. Anomalous gold, silver, copper, lead, and zinc concentrations 

in rocks and in stream sediments from drainage basins in the vicinity of the old 

mines and prospects on West Spanish Peak indicate a substantiated mineralresource potential for base and precious metals in the area surrounding this 

peak; however, the mineralized veins are sparse, small in size, and generally low 

in grade. There is a possibility that coal may underlie the study area, but it 

would be at great depth and it is unlikely that it would have survived the intense 

igenous activity in the area There is little likelihood for the occurrence of oil and 

gas because of the lack of structural traps and the igneous activity. 

CHARACTER AND SETTING 

The Spanish Peaks Wilderness Study Area covers approximately 30 sq mi of the San Isabel National Forest 

in south-central Colorado. The area lies in the westernmost part of the Great Plains, bordering the eastern 

foothills of the Sangre de Cristo Mountaina. Altitudes 

range from 13,626 ft on the summit of West Spanish 

Peak to about 8400 ft in the western portion near 

Cuchara. The eastern half of the study area is characterized by rugged terrain; the land and drainages slope 

radially away from East and West Spanish Peaks. The 

principal drainages are Wahatoya and Trujillo Creeks. 

The relief in the western half of the study area is less 

severe; the major drainages are the north-trending 

Chaparral and Echo Creeks. North, Middle, and South 

White Peaks (altitude 10,446 ft) are located near the 

western boundary of the study area. 

Colorado Highway 12 and the Cucharas River parallel 

the study area on the west. USFS Route 415 and the 

Apishapa River run along the southern margin. A few 

secondary roads reach the boundary of the study area 

Sedimentary rocks, Paleozoic to Tertiary in age, surround the Spanish Peaks. Between 20 and 25 million 

years ago (Smith, 1979) the sedimentary rocks were 

intruded by a series of igneous rocks. The sequence of 

intrusion is as follows: (1) granite porphyry of East 

Spanish Peak, (2) compositionally similar granite of 

North, Middle, and South White Peaks, (3) porphyritic 

granodiorite intruding the core of East Spanish Peak, 

and (4) syenodiorite of West Spanish Peak. An impressive dike swarm, primarily trachyandesite porphyries, 

radiates away from West Spanish Peak; the dikes were 

emplaced throughout the igneous sequence. An aureole 

of metamorphosed sedimentary rocks surrounds the intrusive core of this peak. 

To assist the assessment of the mineral-resource 

potential of the study area a geochemical survey was 

made, utilizing stream-sediment, panned concentrate, 

and rock samples. Each sample was analyzed semiquantitatively for 31 elements using an optical emission 

spectrograph. Additional analyses for gold, bismuth, 

antimony, arsenic, zinc, and cadmium by atomic absorption and for uranium by fluorimetry were made on the 

rocks and stream sediments. Results of the geochemical 

survey are discussed in Budding and Lawrence (1983). 

West Spanish Peak is the site of past mining activity. 

The total production prior to 1908 from the mines on 

the peak was 168 oz of gold, 1176 oz of silver, 92 lb of 

copper, and 1067 lb of lead. Placer gold was reported by 

Hills (1901) from streams tributary to Wahatoya Creek 

and the Apishapa River. In 1932 and 1934, a few ounces 

of placer gold were produced from the north side of the 

study area Four tons of lead-silver ore were shipped 

from the area in 1934 and 1935 (Colorado Mineral Resources Board, 194 7). 

483 
MINERAL RESOURCES 

The majority of the geochemical anomalies revealed 

by the survey were found in the vicinity of the old workings on West Spanish Peak. The anomalous metals include lead, zinc, silver, copper, and minor gold. All 

known workings in the study area are found in the zone 

of contact metamorphosed sedimentary rocks surrounding the intrusive of West Spanish Peak. Mineralized 

veinlets along a N. 65 o E. shear zone have been worked 

in the Bulls Eye mine on the north side of West Spanish 

Peak. Quartz veins bear argentiferous galena, tetrahedrite, chalcopyrite, and sphalerite, associated with 

siderite, calcite, and barite. Two mines on the eastern 

side and southeastern side of West Spanish Peak (mines 

1 and 2), along with workings on several ridge tops, indicate additional areas of past activity. Vein material 

here is similiar to that found at the Bulls Eye mine. 

The known mineralized veinlets are few in number 

and low in grade. A substantiated mineral-resource 

potential for lead, zinc, copper, silver, and gold is assigned to areas proximal to the old workings and to other 

mineralized or anomalous areas as indicated on the map. 

The majority of the study area lacked significant 

anomalies indicating metallic deposits. There is a 

possibility that coal may underlie the study area, but it 

would be at great depth and it is unlikely that it would 

have survived the intense igenous activity in the area 

There is little likelihood for the occurrence of oil and gas 

4 4 

because of the lack of structural traps and the igneous 

activity. 

SUGGESTIONS FOR FURTHER STUDIES 

It is unlikely that further investigation of the study 

area will reveal additional resource potential. The recent 

drilling for petroleum and (or) for carbon dioxide just 

south of the study area boundary in the Apishapa River 

drainage should be monitored, and if successful, the 

potential for these commodities should be reevaluated. 

REFERENCES 

Budding, K. E., and Lawrence, V. A., 1983, Geochemical maps of the 

Spanish Peaks Wilderness Study Area, Huerfano and Las 

Animas Counties, Colorado: U.S. Geological Survey 

Miscellaneous Field Studies Map MF- 1542- B, scale 1:50,000. 

Budding, K. E., Lawrence. V. A., and Kluender, S. E., 1983, Mineral 

resource potential map of the Spanish Peaks Wilderness Study 

Area, Huerfano and Las Animas Counties. Colorado: U.S. Ge<r 

logical Survey Miscellaneous Field Studies Report MF - 1542-C, 

scale 1:50,000. 

Colorado Mineral Resources Board, 1947, Mineral resources of Colorado, Part I, Metals, nonmetals, and fuels, prepared under the 

supervision of J. W. Vanderwilt: Colorado Mineral Resources 

Board, Denver, 290 p. 

Hills. R. C .. 1901, Spanish Peaks folio: U.S. Geological Survey 

Geologic Atlas Folio Series o. 71, 7 p. 

Smith, R. P., 1979, Early rift magmatism at Spanish Peaks, Colorado, 

in Riecker, R. E .. ed., Rio Grande Rift-Tectonics and magmatism: American Geophysical Union, p. 313-321. 
UNCOMPAHGRE PRIMITIVE AREA, COLORADO 

By R. G. LUEDKE, U.S. GEOLOGlCAL SURVEY and 

' 

M. j. HERIDA , U.S. B REA OF MTNE 

SUMMARY 

A mineral-resource study was made in 1966 and 1967 of that part of the Uncompahgre National Forest constituting the officially designated primitive area. 

Because the primitive area and its southern border zone contained operating 

mines producing gold, silver, copper, lead, zinc, and minor amounts of a few 

other metals, and had been a part of a highly productive mining region since the 

1870's, the area was concluded to have large segments of both probable and 

substantiated mineral-resource potential in 1968. No energy resources were 

identified in the study. 

CHARACTER AND SETTING 

The Uncompahgre Primitive Area is in the northwestem San Juan Mountains of southwestern Colorado, and 

covers about 130 sq mi, mostly in the southern part of 

Ouray County and adjacent parts of Hinsdale, San 

Juan, and San Miguel Counties. It is an irregularly 

shaped area and is divided into two parts by a narrow 

corridor of excluded land that extends along the Million 

Dollar Highway (U.S. Route 550) through Ouray. The 

spectacularly rugged alpine terrain of the area, ranging 

in altitude from about 9000 ft to more than 14,000 ft, is 

dominated by sharp peaks, broad basins, and deep, 

steep-walled canyons; it is generally accessible by trails 

and a few jeep roads. Accessibility and climate, particularly the long and often severe winters, have caused 

problems in developing the mineral potential of the 

area. However, Ouray, Silverton, and Telluride, which 

serve as local centers to the mining and other industries 

of the area, are readily accessible by all-weather roads 

from Montrose and Durango, principal business and 

supply points in southwestern Colorado. 

The impressive topography of the primitive area was 

carved by glacial and stream erosion of a thick blanket 

of volcanic rocks that lies on a basement of metamorphic, sedimentary, and igneous rocks ranging in age 

from Precambrian to Tertiary. The volcanic rocks surround a complex of subsided blocks (cauldrons) in vent 

areas partly within but mostly south of the primitive 

area The rocks record a long, complex, and fairly complete sequence of geologic events that have affected the 

entire region through much of geologic time. The geologic history of the region includes several periods of 

deformation, erosion, and igneous activity. 

The mineral deposits were formed during two distinct 

periods. The older deposits are related to Laramide 

deformation and intrusive igneous activity, and they 

occur mainly in the sedimentary rocks in the vicinity of 

Ouray and Telluride as veins, replacements, and disseminations. The younger deposits, related to the waning phases of widespread Tertiary volcanism, occur in 

the volcanic and underlying basement rocks in the 

southern half to two-thirds of the area, and are localized 

mainly in and along the radial and concentric fractures 

about the cauldrons as veins, chimneys, replacements, 

and disseminations. Fissure veins constitute the major 

source of the precious- and base-metal ores produced 

from the area Erosion since ore deposition exposed the 

many veins and ore bodies at the surface; thus many of 

the larger mines within the primitive area have been 

developed through adits or tunnels driven from the deep 

canyons outside the area 

Prospecting and claim location within the area began 

after a treaty between the Federal Government and the 

Ute Indians was negotiated in 1874. During the next 30 

years most of the richest deposits were discovered and 

mined. Through the years, reduction of the costs of ore 

production resulted from the building of smelters, improving methods of ore treatment, and constructing 

roads and railways. The mining industry of the area 

generally has kept pace with economic trends, and 

through recent consolidation of properties is carrying 

out deeper exploration and mining. 

485 
486 

38° 

00' 

107°45' 

To Montrose 

0 

MILES 

EXPLANATION 

Geologic terrane with substantiated 

mineral-resource potential D Geologic terrane with probable 

mineral-resource potential 

Cu Copper 

Au Gold 

Pb Lead 

Ag Silver 

Zn Zinc 

107°30' 

boundary 

COLORADO 

• 

MAP LOCATION 

10 

Volcanic rocks 

Pre-volcanic rocks 

Fault 

Figure 142.-Uncompahgre Primitive Area, Colorado. 
Since passage of the the Wilderness Act in 1964, a 

mineral survey was made of the approximate 108 sq mi 

within the Uncompahgre Primitive Area (established in 

1932) and an additional 22 sq mi added in 1966. Results 

of that geological and geochemical study, made in 1966 

and 1967, were published in 1968 (Fischer and others, 

1968). The results of geophysical studies were released 

in 1970 (Popenoe and Luedke, 1970). Additional geologic maps and reports on various parts of the area have 

been published since 1970. 

MINERAL RESOURCES 

Mineral production from the primitive area and a 1 1/2 

mi-wide border zone has far exceeded $330 million since 

the early 1870's. Most of the production is in gold, 

silver, copper, lead, and zinc, but includes small 

amounts of bismuth, tungsten, uranium ores, fluorspar, 

bog iron ore, and some sand and gravel. Probably some 

antimony, arsenic, and cadmium have been recovered as 

byproducts at the smelters treating ores mined in the 

area Occurrences of barite, gypsum, limestone, manganese, molybdenum, and various clay minerals also are 

known in the area 

Claim records for 1966 showed that about 4000 

patented claims and more than 700 unpatented claims 

existed in and near the primitive area Only a few 

groups of claims, however, accounted for the output of 

ores, which in the 1950's, 60's, and 70's came from two 

large mining operations and several small ones. In 1965, 

mines mostly in and near the primitive area, within 

Ouray and San Miguel Counties, yielded nearly $9.5 

million worth of precious and base metals, which was 32 

percent of the total Colorado production of these metals 

in that year. Base- and precious-metal ore reserves in 

1967 were estimated to aggregate several million tons, 

representing about a 10-year supply of ore at the current (1967) rate of mining; additional undiscovered 

resources may be at least a few times greater than the 

known resources. 

The primitive area, particularly the approximate 

southern two-thirds, is part of one of the most intensely 

mineralized regions in the United States. Ore deposits 

in that part of the primitive area at Ouray occur mainly 

in east-trending veins and in some tabular and irregularly shaped ore bodies within limestone and sandstone 

beds centered in part about an intensely altered granodioritic stock exposed near Ouray. Veins and clastic 

dikes farther north of Ouray suggest additional intrusive bodies to the northeast; if fractures and other structures favorable for localization of ore are present along 

that zone, significant resources might be buried northeastward beneath the volcanic rocks. 

The southwestern part of the primitive area, between 

Ouray and Telluride and west of U.S. Highway 550, contains many veins and mines, including the area's two 

major operating mines in 1968. It is a part of the area in 

which there has been almost continuous mining since it 

was first opened to prospecting. Veins, some 2 to 4 mi in 

length, dominantly trend northwestward, radially to the 

cauldrons, and contain silver-bearing sulfides of lead, 

zinc, and copper, and gold-bearing quartz. Most of the 

ore came from veins in the volcanic rocks, but in recent 

years ore has been mined also from replacement deposits in the sedimentary rocks beneath the volcanic 

rocks. Much favorable ground remains to be explored. 

The southernmost part east of the highway, called the 

Red Mountains area, was mined in the late 1800's for 

very high grade silver-bearing copper and lead ores, 

mainly in chimney and pipelike deposits located within 

the intensely altered and silicified rocks of the cauldron 

ring-fracture zones. Some mines were virtually exhausted at that time, but low-grade ore probably 

remained in a few mines, and, possibly, blind or undiscovered high-grade shoots may exist in others. Geologic 

evidence also strongly suggests the existence of undiscovered deposits; geochemical prospecting techniques 

(Burbank and others, 1972; Fisher and Leedy, 1973) appear promising for the discovery of such deposits. 

That part of the area southeast of Ouray also contains 

many veins, some of which are well defined and are 

fairly extensive; they trend mostly northward and 

northeastward. A few small high-grade ore bodies of 

base and precious metals have been mined, but because 

only a relatively small part of the known veins have 

been explored by mine workings, the resources of the 

area southeast of Ouray can be determined best by extensive subsurface exploration. 

The mineral potential of the remaining parts of the 

primitive area, principally the relatively unexplored 

northern one-third, is not well known and is difficult to 

evaluate. Geologic relationships may be favorable for 

the occurrence of mineral deposits at depth, but the area 

is concealed beneath a great thickness of barren volcanic rocks and no resource potential was identified. 

Little or no prospecting work by modern methods has 

been done. 

The general distribution of individual mineral 

commodities- including elements that have been commercially important, and those that might be significant as geologic guides in exploration and appraisalvary in abundance from place to place in the primitive 

area Most of the production has come from the southwestern part. Gold, which occurs free in quartz, has 

been found mostly in veins in the southwestern part but 

was significant in deposits near Ouray. Most of the 

silver, which occurs mainly in lead sulfides, has come 

487 
from veins in the southwestern part and from pipelike 

deposits in the Red Mountains part. Lead and zinc, as 

the sulfide minerals galena and sphalerite, respectively, 

are ubiquitous to the mineralized parts of the area Copper, as copper sulfides, is intimately associated locally 

with the lead and zinc sulfides; the bulk of it was obtained from the southwestern part of the primitive area 

A small tonnage of tungsten ore from mines south of 

Ouray was shipped, but the tungsten resource potential 

is mostly unknown. Fluorite, the ore mineral of fluorine, 

is an abundant gangue mineral in scattered vein 

deposits, but resources are probably small. Uraniumbearing occurrences in the easternmost part of the area 

have yielded small amounts of ore but others elsewhere 

in the area appear low in uranium content; the presence 

of a uranium resource is not considered likely. Antimony, arsenic, bismuth, and cadmium have been 

recovered from widely scattered deposits as byproducts 

by smelters; the occurrence of these elements in quantities sufficient to constitute a resource is not considered 

likely. Cobalt, nickel, molybdenum, and tin also are 

widely but rather erratically distributed in minor 

amounts in samples of vein and mineralized material. 

These elements may be useful as guides for geochemical 

exploration. Moderate-sized deposits of sand and gravel 

along the major drainages will continue to be exploited 

locally. 

Much of the southern two-thirds of the Uncompahgre 

Primitive Area has a probable or substantiated mineral488 

resource potential for the occurrence of resources like 

those mined in the past, and unsuspected mineral occurrences may exist in nearly all of the primitive area 

SUGGESTIONS FOR FURTHER STUDY 

Because of the extensive past and recent geologic 

literature covering the primitive and nearby areas, further study of the area offers little promise except in 

selected localities where detailed geologic mapping, use 

of geochemical and geophysical prospecting techniques, 

and drilling might be warranted. 

REFERENCES 

Burbank, W. S., Luedke, R. G., and Ward, F. N., 1972, Arsenic as an 

indicator element for mineralized volcanic pipes in the Red Mountains area, western San Juan Mountains, Colorado: U.S. 

Geological Survey Bulletin 1364, 31 p. 

Fischer, R. P., Luedke, R. G., Sheridan, M. J., and Raabe, R. G., 1968, 

Mineral resources of the Uncompahgre primitive area, Colorado: 

U.S. Geological Survey Bulletin 1261- C, 91 p. 

Fisher, F. S., and Leedy, W. P., 1973, Geochemical characteristics of 

mineralized breccia pipes in the Red Mountain district, San Juan 

Mountains, Colorado: U.S. Geological Survey Bulletin 1381, 43 p. 

Popenoe, Peter, and Luedke, R. G., 1970, Inte.rpretation of the 

aeromagnetic pattern of the Uncompahgre primitive area, San 

Juan Mountains, Colorado: U.S. Geological Survey Open-File 

Report, 26 p. 
STUDY AREAS CONTIGUOUS TO THE 

UNCOMPAHGRE PRIMITIVE AREA, COLORADO 

By T HOMA A . STEVEN, U .S. GEOLOGICAL S RVEY and 

' 

CARL L. BIENIEWSKI , U .S . B REAU OF MI E 

SUMMARY 

Important mineral deposits of several ages have been exploited at many 

places in the western San Juan Mountains, including the originally studied 

Uncompahgre Primitive Area Although the three contiguous areas- western, 

central, and eastern-considered here are largely outside the more productive 

mining areas, a mineral study completed in 1972 indicated that there are areas 

of probable resource potential for base and precious metals near the margins of 

the areas. Results of this study indicate that there is little promise for the occurrence of fossil fuels and geothermal energy. 

CHARACTER AND SETTING 

A mineral survey was made by the USGS and the 

USBM in 1972 of three areas contiguous to the Uncompahgre Primitive Area in southwestern Colorado that 

were proposed for inclusion in the National Wilderness 

Preservation System (Steven and others, 1977). The 

combined area covers about 215 sq mi of rugged terrain 

in the western San Juan Mountains. 

The western San Juan Mountains, including the three 

contiguous areas studied, consist of a deeply dissected 

volcanic plateau built in middle Tertiary time on a platform of slightly deformed Paleozoic, Mesozoic, and local 

lower Tertiary sedimentary rocks. Paleozoic sedimentary rocks are exposed along the lower slopes above the 

Uncompahgre River near Ouray, along the San Miguel 

River near Telluride, and in small areas northeast of 

Ouray. Mesozoic sedimentary rocks overlie the Paleozoic rocks in all these places and generally are more 

extensively exposed. Intrusive rocks emplaced during 

latest Cretaceous time cut both the Paleozoic and Mesozoic sedimentary rocks near Ouray and to the northeast. 

Conglomerate of early Eocene age unconformably overlies the sedimentary and intrusive rocks in places near 

Ouray, and much more widely between Ouray and Telluride. A thick pile of middle Tertiary volcanic rocks overlies the sedimentary and early intrusive rocks and, 

together with related intrusive rocks, constitutes the 

great bulk of the San Juan Mountains. 

Mineralization took place during both the Late Cretaceous and middle Tertiary periods of igneous activity. 

MINERAL RESOURCES 

The southeastern part of the western contiguous area 

is cut by numerous veins. Some of them are the northwestern ends of major veins that have produced significant base- and precious-metal ore in the major mining 

area a few miles southeast, and mine maps indicate 

some underground workings within the western contiguous area Other shorter veins extend into the western contiguous area from the Sneffels intrusive center, 

which lies just to the east; some of them may contain 

significant metallic resources at depth and the area has 

a probable mineral-resource potential. The several veins 

cutting the volcanic rocks near the Whipple Mountain 

center in the western part of this contiguous area indicate widespread hydrothermal activity, however low 

metal concentrations measured at the surface and the 

weak vein structures do not favor the occurrence of mineral resources. 

Surface indications of hydrothermal activity are weak 

within the central contiguous area, but a probable 

mineral-resource potential exists for base- and preciousmetal occurrences in the southern part. The middle 

Tertiary volcanic rocks at the surface unconformably 

overlie productive Upper Cretaceous deposits exposed 

along the Uncompahgre River valley near Ouray, where 

only the western part of a mineralized intrusive center 

has been uncovered by recent erosion. If the eastern side 

of the center is mineralized comparably to the western 

side, a potential exists under the volcanic cover between 

the Uncompahgre River and western half of the central 

489 
108°00' 

38° 

oo· 

490 

1 07°45' 107°30' 

COLORADO 

• Central Lower Cow· 

Creek center, > v 

MAP LOC ATION 

Contiguous 

Area 

{cu·. 

' ' , ( 

, Cimarron volcanic 

c 

D 

Cu 

Au 

Pb 

Ag 

u 

Zn 

1' -~ cent:r v 

0 10 

MILES 

EXPLANATION 

Geologic terrane with probable 

mineral-resource potential 

Copper 

Gold 

Lead 

Silver 

Uranium 

Zinc 

[2] 

D 

~ 

~ 

Pre-Tertiary rocks, locally includes 

Eocene conglomerate 

Cretaceous intrusive rocks 

Tertiary volcanic rocks 

- Tertiary intrusive rocks 

Contact 

Fault--Bar and ball on downthrown side 

Figure 143.-Study areas contiguous to the Uncompahgre Primitive Area, Colorado. 

107°15' 
area. Much of this area is in the original Uncompahgre 

Primitive Area and south of the central contiguous area, 

but productive veins are known along the southwest 

side of the central contiguous area, and similar veins 

almost certainly exist under the adjacent volcanic cover 

to the northeast. Other intrusive centers, possibly with 

related mineral deposits, may exist elsewhere beneath 

the volcanic cover in the central contiguous area Such 

deposits would be difficult and expensive to find. The 

probability that they exist is sufficiently good, however, 

to postulate a probable mineral-resource potential for 

base and precious metal occurrences. 

The Upper Cow Creek intrusive center cutting volcanic rocks on Bighorn Ridge along the northern margin 

of the Uncompahgre Primitive Area southeast of the 

central contiguous area is locally altered and some 

samples contain anomalous concentrations of copper. 

This center could contain a disseminated porphyry-type 

copper deposit. 

Several mineralized areas occur along the southern 

periphery of the eastern contiguous area These areas 

are in part marked by aeromagnetic lows that may be 

related to hydrothermally altered rock and may have 

resource significance. The Matterhorn volcanic center, 

Iron Beds altered area, and Capitol City mining area are 

all just outside the southwestern margin of the contiguous area; these altered and mineralized areas are 

associated with monzonitic intrusive bodies, and all of 

them may have potential for the occurrence of mineral 

deposits. Base- and precious-metal veins· are known in 

lower Henson Creek along the south side of the eastern 

contiguous area, and at least two of these approach and 

may extend into the contiguous area Several of these 

veins have produced significant metal in the past and 

probably contain significant additional resources. The 

best area for the occurrence of mineral deposits, however, is largely south of the eastern contiguous area 

The Cimarron volcanic center is along the western 

side and partly within the eastern contiguous area The 

intrusive core and adjacent wallrocks are irregularly 

altered, but evidence for mineral deposits is sparse. The 

potential for disseminated copper or molybdenum deposits within the intrusive core seems better than for 

significant vein deposits, but available evidence does 

not favor the occurrence of deposits of either type. 

Anomalously radioactive rhyolite intrusions, which 

extend eastward across the southern part of the eastern 

contiguous area, contain at least three areas with small 

concentrations of secondary uranophane in fracture 

zones, and a few tons of uranium ore have been mined 

from one of these areas. Other similar concentrations 

may exist, and some of them may be of sufficient size to 

be considered resources. Most rock appears somewhat 

depleted in uranium, however, and the area has only a 

probable uranium resource potential. 

The remainder of the eastern contiguous area, embracing most of the area north of the Henson Creek 

drainage and east of the East Fork Cimarron River, 

shows only local evidence of hydrothermal activity and 

little likelihood for the occurrence of mineral resources. 

REFERENCE 

Steven, T. A., Lipman, P. W., Fisher, F. S., Bieniewski, C. L., and 

Meeves, H. C., 1977, Mineral resources of study areas contiguous 

to the Uncompahgre Primitive Area, San Juan Mountains, 

sout hwestern Colorado: U.S. Geological Survey Bulletin 1391-C, 

126 p. 

491 
492 

39° 

45' 

106°00' 

Approximate 

Cu , Pb, 

0 

MILES 

EXPLANATION 

Geologic terrane with substantiated 

resource potential for lead, zinc, 

and silver and probable 

molybdenum resource potential 

D Geologic terrane with probable 

mineral-resource potential 

Cu Copper Ag Silver 

Pb Lead u Uranium 

Mo Molybdenum Zn Zinc 

Mine 

1 05°45' 

I 

) 

-1/--/ 

('1) Ber hov , Pass 

Cu,Pb, Zn , Mo ,__ 

") 

~I ~( Q 

) 

;f( 

1-

~l 

~\ :z 

81 

) 

• 

COLORADO 

MAP LOCATION 

10 

- Sedimentary rocks 

(Mesozoic) 

CJ Metamorphic rocks 

(Precambrian) 

---- Contact 

--- Fault 

• • • Thrust fault 

rv -v "-' Fau It zone 

Figure 144.-Vasquez Peak Wilderness study area, and St. Louis Peak and Williams Fork Roadless Areas, Colorado. 
VASQUEZ PEAK WILDERNESS STUDY AREA 

AND ST. LOUIS PEAK, AND ' 

WILLIAMS FORK ROADLESS AREAS, COLORADO 

By P. K. THEOBALD,

1 U .S . GEOLOGICAL SURVEY and 

' 

A . M . BIELSKJ , U .S . BUREAU OF MI1 ES 

SUMMARY 

A mineral-resource survey was conducted during the years 1979-82 in the 

Vasquez Peak Wilderness Study Area and in the St. Louis Peak and Williams 

Fork Roadless Areas, central Front Range, Colorado. These three areas lie in the 

Colorado Mineral Belt, a long narrow region that reaches from the plains near 

Boulder to the southwest side of the San Juan Mountains in southwest Colorado. Probable resource potential for the occurrence of copper, lead, zinc, and 

silver in massive sulfide deposits has been identified in calcareous metamorphic 

rocks in the northern part of the St. Louis Peak Roadless Area and in the 

southern part of the Williams Fork Roadless Area. A probable resource potential for vein-type uranium deposits is identified along the Berthoud Pass fault 

zone in the eastern part of the Vasquez Peak Wilderness Study Area A large 

area encompassing the eastern and southeastern part of each of the three areas 

has probable and substantiated potential for either high-grade lead-zinc-silver 

vein deposits, or larger, lower-grade clustered vein deposits. A probable resource 

potential for stockwork molybdenum deposits related to porphyry molybdenum 

type mineralizaton exists beneath the lead-zinc-silver-rich veins. The nature of 

the geologic terrane indicates little likelihood for the occurrence of organic fuels. 

CHARACTER AND SETTING 

The three areas studied, the Vasquez Peak Wilderness 

Study Area. the Williams Fork Roadless Area. and the 

St. Louis Peak Roadless Area. are on the west side of 

the Front Range to the north of Interstate Highway 70 

and to the southwest of U.S. Highway 40 about 45 mi 

west of Denver. The altitudes range from less than 

9000 ft in the main valley of the Williams Fork to more 

than 13,500 ft on the Continental Divide. 

fault and the basement rocks moved upward and westward over Mesozoic sedimentary rocks that had been 

deposited between these periods of uplift. 

The uplift of the Front Range segment of the Ances· 

tral Rockies began more than 200 million years ago. 

Subsequent erosion stripped all Paleozoic rocks from 

the basement in the area studied. Renewed uplift, as a 

broad arch, shaped the present range about 70 million 

years ago. During this uplift, the rocks along the west 

side of the range broke along the Williams Range thrust 

1

With contributions by R. G. Eppinger. R. R. Carlson. H. . Barton. C. K. Moss. and R. L. 

Turner. USGS. Wld T. J. Kreidler and J,. W. Hamm. USBM. 

Igneous activity accompanied and followed the sec· 

ond period of uplift and was abundant north, east, and 

south of the areas studied. Within the three areas, a 

single swarm of minor mafic dikes is the only reflection 

of this activity, and the abundant mineralization associated with less mafic igenous rocks to the east and 

south is not evident. Erosion following this second 

uplift stripped the overlying rocks from the basement 

rocks and produced the deeply weathered, topographi· 

cally subdued surface of the present upland. 

A third episode of uplift, about 30 million years ago, 

produced the present altitude of the range. Igneous activity accompanying the third uplift was much more 

silicic and was associated with the major episode of 

mineralization that produced the large molybdenum 

deposits of Colorado. Rhyolite dikes belonging to this 

igneous episode occur along the southern edge of the 

493 
Vasquez Peak Wilderness Study Area and the eastern 

part of the Williams Fork Roadless Area 

The basement rocks that underlie most of the areas 

studied are nearly 2000 million years old. They consist 

of a variety of igneous and metamorphic rocks. Other 

than serving as the host rocks for subsequent mineralization, only two groups of these rocks directly relate to 

the assessment of mineral-resource potential. Massive 

sulfides occur in these basement rocks in a group of 

highly calcareous gneisses, including small amounts of 

marble, which crop out to the north of an ancient fault 

zone in the central and northern part of the St. Louis 

Peak Roadless Area Pods of sulfides, now seen at the 

surface as iron oxides that have replaced original iron 

sulfides, are contained in the more calcareous rocks of 

this group in many places. Float blocks containing the 

oxidized sulfides were found in a few places on the 

upland surface and more abundantly in the glacial 

deposits of the valleys. All of the sulfides seen in place 

have been in pods too small to constitute a resource in 

themselves, but their presence indicates that the processes that have produced larger deposits in similar terrane elsewhere in the central Rocky Mountains were 

operative here. Geologic mapping in detail adequate to 

establish the distribution of this group of rocks is not 

available for the western and southern part of the 

Williams Fork Roadless Area, although the reconnaissance geology available for these areas indicates that 

they may be present at least in the south. 

The youngest of the Precambrian basement granites, 

the Silver Plume Granite, crops out throughout most of 

the Vasquez Peak Wilderness Study Area, the southeastern part of the St. Louis Peak Roadless Area, and 

the eastern part of the Williams Fork Roadless Area 

The granite itself is abnormally radioactive. Most of the 

radioactivity is from thorium but a significant part is 

from uranium. Concentrations of these elements in the 

granite are low, but along the Berthoud Pass fault zone 

later events appear to have redistributed and locally 

concentrated the uranium. 

Tertiary igneous rocks, closely related to the major 

metal deposits throughout Colorado, are only sparsely 

represented in the areas studied and the mineralization 

associated with the early Tertiary igneous rocks is not 

significant within the areas. The middle Tertiary rhyolites seen occasionally in small dikes thoughout the 

southeastern part of the areas studied are related to 

mineralization. In the Henderson mine area, just south 

and east of the areas studied, a middle Tertiary intrusive center hosts the world's second largest accumulation of molybdenum ore. Within the areas studied, 

alteration, veining, and mineralization are abundant in 

the vicinity of the outcrops of the rhyolite dikes. The 

distribution of these features suggests that intrusive 

494 

centers similar to the one at the Henderson mine may 

exist at depth in the eastern part of the Williams Fork 

Roadless Area and in the easternmost lobe of the St. 

Louis Peak Roadless Area 

The areas studied are structurally complex; the 

ground is favorable for the occurrence of mineral 

deposits. In the north, north- and east-trending faults 

predominate. On the west, the Williams Range thrust, 

and parallel faults to the east of it, trend northwesterly. 

On the east, the Berthoud Pass fault zone trends northeasterly, converging southwesterly with the Williams 

Range fault system. The triangle within these three domains is a confusion of faults, and contains the most 

evidence of mineralization. 

Tertiary and Quaternary sedimentary rocks are unconsolidated and mantle the upland, the valley walls, 

and the valley floors. Slumping deforms the upland surface and landslides deform the valley walls. In all, this 

cover limits the amount of visible bedrock to less than a 

third of the area 

Geochemical evidence for mineralization has been obtained from concentrates of heavy minerals from stream 

sediments and soils, from rocks and soils collected over 

shear zones, altered areas, and from prospect pits. 

Although slightly anomalous values for lead were found 

in zones along faults in the Mesozoic sedimentary rocks 

and along faults in Precambrian rocks that extend 

southeastward into the Williams Fork Roadless Area 

from the main Williams Fork valley, these zones lack 

significant concentrations and are not regarded as containing resources. Many samples with anomalous 

amounts of copper, lead, zinc, and silver were found in 

the portions of the area studied underlain by the calcareous metamorphic rocks; these samples commonly contain pyrite and occasionally the zinc-bearing oxide 

mineral, gahnite. 

Many samples from the southeastern side of the 

Williams Fork Roadless Area and the Vasquez Peak 

Wilderness Study Area contain anomalous amounts of 

lead, silver, zinc, molybdenum, and some contain 

anomalous quantities of copper, tin, and gold. Pyrite 

and fluorite are seen in many samples and some contain 

galena, sphalerite, molybdenite, and chalcopyrite. A 

near-surface source for these metals is likely. 

Regional gravity surveys have defined a large regional gravity low approximately coincident with the 

major areas of mineralization in central Colorado. Three 

large molybdenum deposits as well as many smaller 

deposits are located along the edge of this gravity 

feature. The three areas studied are at the north end of 

this regional gravity low. More detailed gravity surveys 

within and adjacent to the areas define a cluster of 

smaller-scale gravity lows in the areas where rhyolite 

dikes have been seen and hydrothermal alteration is 
most intense. The observed coincidence of a general 

magnetic low found by an aeromagnetic survey with the 

gravity low is compatable with this interpretation. 

Two organized mining districts, the La Plata to the 

west and the Daily (Atlantic) to the east, overlap the 

three areas studied along the Continental Divide in the 

vicinity of the Henderson mine. 

Two unorganized mining districts, the Byers Peak 

(St. Louis Lake) and the Iron Creek, are just to the east 

of the main part of the St. Louis Peak Roadless Area on 

the west side of St. Louis Creek. 

MINERAL RESOURCES 

The pods of sulfides in the calcareous metamorphic 

rocks contain significant quantities of lead, zinc, silver, 

and copper. Two occurrences in well-exposed terrane 

east of the St. Louis Peak Roadless Area are large 

enough to have justified underground exploration. Similar, larger deposits of massive sulfides may exist in the 

poorly exposed terrane in the northern part of the St. 

Louis Peak Roadless Area, and in the southern part of 

the Williams Fork Roadless Area These areas have 

probable mineral-resource potential. 

Active, and reportedly favorable, exploration for 

uranium along the Berthoud Pass fault zone, and the 

observed occurrence of secondary uranium minerals in a 

few localities on the fault zone, indicate a probable 

resource potential for vein-type uranium deposits in the 

eastern part of the Vasquez Peak Wilderness Study 

Area 

Geologic, geochemical, and geophysical evidence, and 

the abundance of prospects and small mines, some with 

known production, support an evaluation of probable 

resource potential for portions of the southern part of 

the Vasquez Peak Wilderness Study Area, the southeastern part of the St. Louis Peak Roadless Area, and 

the eastern part of the Williams Fork Roadless Area 

and a substantiated resource potential for the northeast 

part of the Wiliams Fork Roadless Area The most likely type of near-surface deposit to be found in this area 

would be silver-, zinc-, and lead-bearing veins similar to 

those already known. Because the combined available 

evidence supports the concept of several centers of mineralization related to middle Tertiary igneous intrusives, a probable resource potential exists in these 

areas for stockwork-type molybdenum mineralization at 

depth. 

SUGGESTIONS FOR FURTHER STUDIES 

Geologic mapping in the southern and western parts 

of the William Fork Roadless Area is presently not sufficiently detailed to identify many of the subtle geologic 

features that control the mineral occurrences. Detailed 

geologic studies in these areas would be required to improve assessment of the resource potential. 

Improvement of the sensitivity of geochemical and 

geophysical techniques might provide better estimates 

of the size, nature, and location of mineral resources. 

Experimental work in the detection of massive sulfide 

deposits would be particularly desirable in the northern 

part of the St. Louis Peak Roadless Area where Precambrian massive sulfide deposits would not be expected to 

have large-scale or pervasive halos of alteration and 

mineralization. 

REFERENCES 

Bielski, A. M., Kreidler, T. J., and Hamm, L. W., 1983. Mineral investigation of the Vasquez Peak Wilderness Study Area, and St. 

Louis Peak and Williams Fork Roadless Areas, Clear Creek, 

Grand, and Summit Counties. Colorado: U.S. Bureau of Mine 

Open-File Report MLA 67-83. 

Theobald, P. K., Bielski, A.M., Eppinger. R. G., Moss, C. K., Kreidler. 

T. J., and Barton, H. N .. 1983, Mineral resource potential map of 

the Vasquez Peak Wilderness study area, and the Williams Fork 

and St. Louis Peak Roadless Areas, Clear Creek, Grand, and 

Summit Counties. Colorado: U.S. Geological Survey Miscellaneous Field Studies Map MF-1588-A. 

495 
107°45' 

37°45' 

37°30' 

496 

107°30' 107°15' 1o1•oo· 

Cu. Pb, Zn. 

COLORADO 

• 

MAP LOCATION 

0 10 

M ILES 

EXPLANATION 

- Geologic terrane with substantiated 

mineral-resource potential 

G Tertiary intrusive rocks 

Cu 

Au 

Pb 

Mo 

Ag 

s 

u 

Zn 

Copper 

Gold 

Lead 

G Tertiary volcanic rocks 

I MzPzs I Mesozoic and Paleozoic 

sedimentary rocks 

Molybdenum 0 Precambrian rocks 

Silver 

Contact 

Sulphur 

NM Location discussed in text 

Uranium 

Zinc 

Figure 145.- Weminuche Wilderness. Colorado. 
WEMINUCHE WILDERNESS, COLORADO 

By THOMAS A. STEVE , U .S . GEOLOGICAL S RVEY, and 

F. E. WILLIAMS U .S. BUREAU OF MI E 

SUMMARY 

A mineral survey of the Weminuche Wilderness was conducted in 1965- 68. 

Although little mineral production has been recorded in the area, it borders 

several highly productive mining districts and mineral deposits probably exist 

within parts of the wilderness. Within and near the wilderness, evidence of 

substantiated mineral-resource potential was found in the following four areas: 

(1) the Needle Mountains mining district, in the southwestern part of the 

wilderness, (2) Whitehead Gulch, in the northwestern part of the wilderness, 

(3) the Beartown mining district, along the north margin of the wilderness, and 

(4) the Trout Creek-Middle Fork Piedra River area, in and adjacent to the northeastern part of the wilderness. Of the four areas, the Needle Mountains mining 

district has the most promise for significant mineral resources, particularly of 

molybdenum and uranium. A probable oil and gas resource potential exists in 

the eastern half of the area in traps in sedimentary rocks under volcanic cover. 

CHARACTER AND SETTING 

A mineral survey by the USGS and USBM of the adjoining San Juan and Upper Rio Grande Primitive areas 

was made during 1965- 68 (Steven and others, 1969). In 

somewhat modified form, this combined area has since 

been included in the National Wilderness Preservation 

System as the Weminuche Wilderness, which covers 

about 500 sq mi of rugged terrain in the San Juan 

Mountains of Colorado. Subsequently, several areas 

contiguous to the W eminuche Wilderness have been 

designated for study to determine their suitability for 

inclusion within the wilderness system; these studies 

have not been completed and the present summary is 

limited to the primitive areas originally surveyed. 

Geologically, the Weminuche Wilderness is divisible 

into two parts that contrast strongly in age, rock types, 

stuctures, and conditions of origin. The older, western 

part of the wilderness consists of the Precambrian terrane of the Needle Mountains; this terrane consists of 

two sequences of metamorphic rocks cut by a succession of plutonic intrusive rocks. Most of the remainder 

of the area is covered by a younger assemblage of 

volcanic rocks of middle Tertiary age, whose complex 

history of eruption and accumulation bears little relation to the Precambrian geology exposed in the Needle 

Mountains. Paleozoic and Mesozoic sedimentary rocks 

intervene between these widely differing assemblages of 

rocks in adjacent areas and extend under the edge of the 

volcanics beneath the eastern half of the wilderness. 

The oldest unit in the Precambrian terrane of the 

Needle Mountains is the Vallecito Conglomerate, which 

forms a thick mass of metaconglomerate and pebbly 

quartzite near Vallecito Creek and Los Pinos River in 

the southern part of the Weminuche Wilderness. The 

Precambrian Irving Formation stratigraphically overlies the Vallecito Conglomerate with little or no apparent discordance. The Irving Formation consists of a 

varied assemblage of metavolcanic rocks with minor 

local siliceous beds containing enough magnetite to be 

called " iron-formation." Plutonic intrusive masses of 

Twilight Gneiss, Tenmile Granite, and Bakers Bridge 

Granite were emplaced into the Irving Formation during subsequent folding and metamorphism. Erosion 

then cut deeply into the older Precambrian rocks and 

conglomerates, sandstones, and black pyritic shales of 

the Precambrian Uncompahgre Formation were deposited. These sedimentary rocks, in turn, were folded and 

metamorphosed. Late in the second period of Precambrian deformation and metamorphism, five silicic 

plutons, including two of Eolus Granite (1.46 billion 

years old), invaded the earlier rocks. 

Few sedimentary rocks crop out in the Weminuche 

Wilderness, and these are almost entirely of the older 

497 
Paleozoic formations that cover the southward-dipping 

flank of the Needle Mountains. The upper part of this 

sedimentary section projects beneath the Tertiary 

volcanic rocks in the eastern half of the wilderness. 

Volcanic rocks in the Weminuche Wilderness comprise a complexly intertonguing assemblage of lava and 

pyroclastic units derived from many different centers. 

Some of these local centers are marked by intrusive 

cores, but others are obscured by their own or younger 

accumulations, or by volcanotectonic subsidence structures (calderas) that formed time and again in response 

to different eruptive episodes. The volcanic activity 

took place largely in mid-Tertiary time, mostly between 

35 and 26 million years ago. 

The volcanic rocks in the Weminuche Wilderness 

came from three major source areas. The Conejos Formation, the oldest volcanic unit in the southern and 

eastern parts of the wilderness, consists largely of conglomeratic debris that formed an outwash apron, 

marginal to a series of composite volcanoes of andesitic 

to rhyodacitic composition in the eastern San Juan 

Mountains. The great sequence of ash-flow deposits and 

related quartz latitic to rhyolitic lava flows overlying 

the Conejos Formation was derived largely from a great 

caldera complex that extends from the eastern part of 

the wilderness northward across the central part of the 

San Juan Mountains. The volcanic rocks in the western 

part of the wilderness, on the other hand, were derived 

largely from another caldera complex in the western 

part of the San Juan Mountains. The earliest rocks from 

this source make up rhyodacitic volcanoes that extended northeastward across the western San Juan 

Mountains. Renewed eruptions deposited a sequence of 

ash flows that spread widely and resulted in concurrent 

collapse of calderas in the source areas. 

Local centers, generally of andesitic to rhyodacitic 

composition, occur here and there throughout the 

volcanic terrane, and the related lava flows and volcanic 

breccias form local accumulations at many different 

stratigraphic positions. 

MINERAL RESOURCES 

The section of sedimentary rocks underlying volcanic 

rocks in the eastern half of the W eminuche Wilderness 

may contain oil- and gas-bearing reservoir rocks, and an 

oil seep exists in volcanic rocks just east of the wilderness. Although it is difficult to identify specific targets 

498 

for exploration, a probable potential for petroleum resources under the eastern part of the wilderness clearly 

exists. 

Four areas with substantiated mineral-resource 

potential-the Needle Mountains mining district, the 

Beartown mining district, the Whitehead Gulch area, 

and the Trout Creek-Middle Fork Piedra River areaare around the periphery of the Weminuche Wilderness, 

just inside or extending just outside the boundary. The 

Needle Mountains mining district and surrounding area 

(NM on map), has disseminated molybdenite in some of 

the intrusive rock that forms its center, and the surrounding Precambrian granitic rocks are cut by 

numerous related veins, some of which contain uranium, 

copper, lead, zinc, silver, and gold in significant concentrations (Schmitt and Raymond, 1977). The Beartown 

mining district (BT on map) has many small veins containing local shoots of rich gold-telluride ore. Although 

the small size of the veins and the sporadic distributions 

of the shoots mitigate against a large resource, the 

district has substantiated gold resource potential. 

Whitehead Gulch area (WG on map) lies along the south 

margin of a highly mineralized area along the southern 

flank of the Silverton caldera that has produced more 

than $70 million worth of base and precious metals. 

Veins in the Whitehead Gulch area are numerous but 

generally short and narrow, and the metal values are irregularly distributed in them. Although there seems to 

be little chance for the discovery of a large mineral 

resource in this area, there is a substantiated base- and 

precious-metal resource potential for several small 

deposits. Native sulfur has been mined from the Trout 

Creek area (TC on map) adjacent to the northeast 

margin of the wilderness, and scattered occurrences farther south indicate an area at least 3 mi across in which 

similar deposits might occur. Dense timber, soil cover, 

glacial drift, and younger volcanic rocks obscure relationships in much of the area of interest. A substantiated sulfur resource potential exists in the area, but 

physical exploration is needed for it to be fully assessed. 

REFERENCES 

Schmitt, L. J., and Raymond, W. H., 1977, Geology and mineral 

deposits of the Needle Mountains district, southwestern Colorado: 

U.S. Geological Survey Bulletin 1434,40 p. 

Steven, T. A., Schmitt, L. J., Jr., Sheridan, M. J., and Williams, F. E., 

1969, Mineral resources of the San Juan Primitive Area, Colorado: 

U.S. Geological Survey Bulletin 1261- F, 187 p. 
WEST ELK WILDERNESS, COLORADO 

By D. L. GASKILL, U.S. GEOLOGICAL S RV EY , and 

H. C. MEEVES, U .S. B REA OF MI E 

SUMMARY 

Mineral surveys of the West Elk Wilderness and adjacent areas were conducted in 1971-74 and included geologic mapping, geochemical sampling, 

geophysical studies, and an investigation of mines and prospects. Areas with 

substantiated mineral-resource potential for bituminous coal with 75 million 

tons of demonstrated reserves and areas with probable mineral-resource potential for base and precious metals associated with igneous intrusions of Tertiary 

age were identified in this study. There is little promise for the discovery of oil 

and gas resources in the area 

CHARACTER AND SETTING 

The West Elk Wilderness occupies about 275 sq mi in 

the southern part of the West Elk Mountains of westcentral Colorado between the towns of Gunnison and 

Paonia 

The southern part of the wilderness is a rugged, deeply dissected terrain of coarsely stratified volcanic 

deposits, breccias, lava flows, and tuffs, representing 

many volcanic eruptions from local and distant sources. 

The volcanic deposits locally form spectacular erosional 

features, such as hoodoos, pinnacles, castelated ridges, 

fluted spurs, and colorful escarpments. In contrast, the 

northern part of the wilderness is eroded into older 

sedimentary rocks, mostly shales and sandstones, intruded by a melange of porphyritic igneous (granodic:r 

rite) sills and laccoliths. Glacially sculpted laccolithic 

mountains flanked by precipitous cliffs, forested mesas, 

and spacious well-watered valleys dominate the northern part of the wilderness. Streams radiating outward 

from the area have cut many scenic canyons, some more 

than 2000 ft deep, across both the volcanic and sedimentary rock terrain. Most of the area is forested and includes a rich flora and fauna Altitudes range from 

about 7000 ft to over 13,000 ft. Many peaks and ridges 

in both the southern and northern part of the area are 

above timberline. 

The wilderness lies over an uplifted fault block (the 

Gunnison uplift) composed of crystalline Precambrian 

basement rocks and overlying sedimentary rock strata 

of Mesozoic age. The block was tilted north and beveled 

by erosion prior to extrusion of the volcanic rocks in the 

area Thus the volcanic rocks overlie a major erosional 

surface developed on the older northward-dipping sedimentary rocks. The sedimentary rocks range from less 

than 1000 ft thick along the southern boundary of the 

wilderness area to more than 8000 ft thick in the northernmost part of the wilderness. 

Most of the volcanic material in the area was derived 

from a now largely denuded volcano (the West Elk volcanic center, locality 1 on map). The West Elk volcanic 

center forms a broad dome of intrusive and basal extrusive rocks cut by a swarm of dikes radiating from a 

common center. The central basal core rocks of the 

volcano are surrounded by layered breccias and lava 

flows that dip away from the volcanic center on all 

sides. Other satellitic vent areas, dike conduits, and a 

number of granodioritic and rhyolitic intrusive bodies 

are located within the volcanic pile west and southwest 

of the West Elk volcanic center. The wilderness is transected by the southwest-trending Ruby Range intrusive 

zone and the westerly trending Curecanti fault zone 

(locality 2). These fracture zones intersect at the West 

Elk volcanic center. 

MINERAL RESOURCES 

The wilderness is on the trend of the Colorado Mineral 

Belt which contains many of the major mining districts 

in Colorado. These districts are localized around prc:r 

phyry intrusive centers of Late Cretaceous and Tertiary 

age. Although no metal production has been reported 

from the West Elk Wilderness, the area contains at 

499 
500 

Approximate boundary 

COLORADO 

• 

MAP LOCATION 

0 

M ILES 

EXPLANATION 

Geologic terrane with substantiated 

mineral-resource potential 

D Geologic terrane with probable 

mineral-resource potential 

Cu Copper 

Au Gold 

Pb Lead 

M o Molybdenum 

Ag Silver 

Zn Zinc 

8 . 

, 

. 

. 

10 

Igneous (intrusive) rocks 

Volcanic (extrusive) rocks 

Sedimentary rocks 

Contact 

Fault 

Dikes of intrusive igneous 

rocks 

Figure 146.-West Elk Wilderness, Colorado. 
least one major volcanic center, and several weakly 

mineralized igneous bodies of interest. The northeast 

boundary of the wilderness is about 2 mi southwest of 

the Ruby-Irwin mining district. Mines in this district 

have produced considerable silver, lead and zinc, and 

some gold and copper. Recent discovery in this district 

of what is referred to as the third largest known deposit 

of molybdenum in the world is currently being developed at Mount Emmons (locality 3), about 4-1/2 mi 

northeast of the wilderness boundary. 

A mineral survey of the West Elk Wilderness (Gaskill 

and others, 1977) included geologic mapping, geochemical and geophysical surveys, and investigation of mining claims and prospects. There are no patented mining 

claims in the wilderness. Most of the unpatented claims 

are in the vicinity of Sheep Mountain (locality 4), and 

in the northeast comer of the wilderness. Streamsediment, panned concentrate, fresh, altered and mineralized bedrock, and soil samples were collected and 

analyzed or assayed for 30 or more elements. 

Thick beds of bituminous, low-sulfur coal are present 

in the northern and eastern parts of the wilderness. The 

areas shown as having substantiated coal potential are 

those known or inferred to contain one or more thick 

coal beds. The only coal production within the wilderness has come from two small workings long abandoned. Most of the coal resources are located along Coal 

Creek and its tributaries where as many as five coal 

beds, 3 to 8 ft thick, are reported. Coal resource potential within the wilderness is estimated to have demonstrated coal resources of 75,000,000 tons. More extensive areas are inferred to be underlain by thick coal beds 

(locally overlain by laccoliths), but, due to thickness of 

overburden and structural complexities associated with 

igneous intrusions, are not presently considered as 

resources. 

Favorable criteria for the presence of metalliferous 

deposits in the wilderness include anomalously high 

values of base and precious metals (molybdenum, copper, lead, zinc, gold, and silver) and other elements 

associated with altered and locally pyritized rocks. 

Most of the anomalous metal values are clustered 

around Sheep Mountain (locality 4) and in the area of 

the West Elk volcanic center (locality 1). These and 

other metal anomalies are shown on sample location 

maps in Gaskill and others (1977). Most of the samples 

from these two localities contain anomalous amounts of 

several metals, and most of them seemingly relate to intrusive rocks or postulated volcanic vents. The relationship of anomalous metal values to geologic and inferred 

geophysical structures in the area indicate a probable 

mineral-resource potential at Sheep Mountain, in the 

area of the West Elk volcanic center. 

A central intrusive body at Sheep Mountain consists 

of an inner core, or plug of vertically flow banded porphyry surrounded by hydrothermally altered and pyritized granodiorite that has domed surrounding igneous 

sills and sedimentary strata The intrusive body is well 

exposed over a vertical distance of about 1800 ft. 

Samples from the intrusive contain anomalous amounts 

of base and precious metals. The geologic environment 

suggests the possibility of an ore deposit at depth under 

Sheep Mountain. 

The dike swarm at the hub of the West Elk volcanic 

center probably overlies a stock similar to those exposed in the Ruby Range (Ruby-Irwin mining district) 

northeast of the wilderness area The mineralized stocks 

of the Ruby Range appear to connect with the West Elk 

volcanic center by dikes and a broad zone of fractures. 

No drilling for oil or gas has been reported in the wilderness. The sedimentary formations in the area contain 

reservoirs of oil and gas elsewhere in the region; but 

within the West Elk Wilderness, these strata are intruded at many, or most, horizons by myriad thick sills 

and laccolithic bodies, suggesting that the discovery of 

oil and gas is unlikely. 

SUGGESTIONS FOR FURTHER STUDIES 

Further investigations by geophysical, geochemical, 

and geochronological methods are needed to locate 

buried intrusive structures, vent areas in the volcanic 

pile, and to establish timing of mineralization. Physical 

exploration, essentially deep drilling, will probably be 

necessary to prove the existence of buried mineral 

deposits. 

REFERENCES 

Gaskill, D. L., Rosenbaum, J. G .. King. H. D., Meeves, H. C .. and 

Bieniewski, K. L .. 1977, Mineral Resources of the West Elk 

Wilderness and vicinity, Delta and Gunnison Counties, Colorado: 

U.S. Geological Survey Open· File Report 77- 751, 111 p. 

Gaskill, D. L .. Mutschler, F. E .. and Bartleson, B. L .. 1981. West Elk 

volcanic field, Gwmison and Delta Counties. Colorado, in Epis, 

R. C., Western Slope Colorado: New Mexico Geological Society 

Field Conference Guidebook, p. 305-316. 

501 
502 

37° 

40' 

D 

u 

, ' 

Approximate 

boundary 

0 

d·..nentarY se 1 ... 

fy,qtit;IH 

X 

Peaks 

MINE 

MILES 

EXPLANATION 

Geologic terrane with probable 

Uran

mineral

ium 

-resource potential 

-

Mine 

5 

MAST A DON 

MINE 

COL ORADO 

• 

MAP LOCATION 

Uncompahgre Formation (Proterozoic) 

Twil ight Gneiss (Proterozoic) 

Tenmile Granite (Proterozoic) 

Eolus Granite (Proterozoic) 

Contact 

Fault--Bar and ball on 

downthrown side 

Figure 147.- West eedle Wilderness Study Area, Colorado. 
WEST NEEDLE WILDERNESS STUDY AREA, COLORADO 

By R IC HARD E. VA LOE E , U .S . GEOLOGICAL S RVEY and ) 

D AVID C. SCOTT, U .S. BUREAU OF Mr ES 

SUMMARY 

The West Needle Wilderness Study Area, southwestern Colorado, was 

evaluated for mineral-resource potential in 1982. An area extending westward 

into the wilderness near the Elk Park mine, has a probable mineral-resource 

potential for uranium. Uranium resources, and associated silver, nickel, cobalt, 

and copper, are located at the Elk Park mine, directly adjacent to the eastern 

study area boundary. No potential for other mineral or energy resources was 

identified in this study. 

CHARACTER AND SETTING 

The rugged West Needle Mountains lie within the San 

Juan National Forest, midway between Durango and 

Silverton and west of the Animas River in southern 

Colorado. The West Needle Wilderness Study Area occupies approximately 35 sq mi, or nearly all of the West 

Needle Mountains. The area consists of two parts; one is 

25 sq mi, in La Plata and San Juan Counties, and is 

managed by the USFS and the other is 10 sq mi, in San 

Juan County, and managed by the U.S. Bureau of Land 

Management (BLM). Both areas were studied simultaneously and are referred to only as the West Needle Wilderness Study Area 

The West Needle Wilderness Study Area was studied 

by the USGS and USBM in 1982 (Scott, 1983; Van 

Loenen and Scott, 1983). As the name implies, the West 

Needle Mountains are made up of very steep and rugged 

picturesque peaks resulting largely from glaciation. 

Altitudes range from 7800 ft along the Animas River to 

more than 13,000 ft on Twilight Peak. A spectacular 

natural boundary around most of the study area is provided by the Animas River canyon on the east and 

south and Lime and Cascade Creeks on the west. 

The area is accessible from U.S. Highway 550, the 

major road between Durango and Silverton, Colorado; 

the Lime Creek road (USFS road 591) which follows 

parts of the western boundary; and the DurangoSilverton Narrow Gauge Railroad, which follows the 

eastern boundary along the Animas River. The railroad 

and railroad right-of-way which separates the West 

Needle from the Weminuche Wilderness, provides access to several trails leading into both areas. This 

railroad, completed in 1882 for shipping ore from Silverton to Durango, is now a very popular tourist attraction 

and operates between these two towns during the summer months only. 

The West Needle Mountains are the western part of 

the Needle Mountain uplift, a deeply eroded domal arch 

exposing a large mass of metamorphic and igneous 

rocks of Proterozoic age. This uplift is flanked on the 

north and east by Tertiary volcanics and on the south 

and west by Paleozoic and younger sedimentary rocks. 

The metamorphic rocks are of two distinctive types; an 

older sequence derived from volcanic, intrusive, and 

sedimentary rocks called the Twilight Gneiss, and a 

younger succession of quartzites and slates called the 

Uncompahgre Formation. Both units were intruded by 

granites and highly deformed during metamorphism. 

The West Needle Wilderness Study Area includes 

parts of two mining districts and is near a third. Significant mineral production has come from these districts, 

the primary one being the Animas district which contains the Silverton cauldron complex, located approximately 8 mi north of the study area boundary. 

Prospecting in the West Needle Wilderness Study 

Area was intermittent from about 1881 to 1934. In 

1956, uranium was discovered at the Elk Park mine, on 

the eastern boundary of the West Needle Wilderness 

Study Area, but no mining activity was observed at the 

mine in June, 1982. 

No patented claims were on record in the study area 

as of September, 1982. However, 310 unpatented claims 

were on record in the West Needle Wilderness Study 

Area Most of the claims in the study area were staked 

by Exxon Minerals Company during their exploration 

503 
for uranium in 1980-1981, at the Elk Park mine, but 

dropped after 1981. 

During the time of the study, assessment work and 

prospecting were being done only at the Hidden Hole 

prospect, located inside the western boundary. 

MINERAL RESOURCES 

Although the study area is contiguous to several mining districts, only a small part of the area was found to 

have a potential for mineral resources. This area west of 

the Elk Park mine, in the northeastern part of the study 

area has probable resource potential for uranium. Structures that localized uranium in the mine extend westward into the study area 

Several small mines and prospects in and near the 

West Needle Wilderness Study Area are in the northwest part of the Needle Mountain mining district and 

were developed along quartz fissure veins. The Silver 

Star Extension mine and the Bitteroot mine are located 

on unpatented claims within the southern part of the 

West Needle Wilderness Study Area These veins occupy minor fault zones in the Twilight Gneiss. No 

records of production were found and analytical data 

from samples collected from these old workings do not 

indicate mineral-resource potential. Similar fractures in 

the younger overlying limestones to the north and west 

of the study area also contain traces of mineralization. 

Small isolated patches of limestone crop out within the 

study area, however no indication of mineralization was 

found. 

Based on analyzed samples, the limited nature of the 

controlling structures, and past records of production, 

no resource potential for fissure veins was identified in 

areas underlain by either the ancient Twilight Gneiss or 

the overlying younger limestones in the West Needle 

Wilderness Study Area 

The Uncompahgre Formation underlies the northern 

part of the West Needle Study Area and consists of 

nearly 8000 ft of east-west trending interlayered quartzite, phyllite, and slate and a thin discontinuous section 

of basal conglomerate. The phyllite and slate were intercalated pyritic black shale prior to metamorphism and 

are by far the most favorable host rocks for uranium 

occurrences in the study area They are commonly 

radioactive and have scintillation counts several times 

background. Anomalously high uranium values in 

samples reported by Bums and others (1980) ranged 

from 100 to 300 parts per million. Composite samples 

representing several hundred feet of rock averaged from 

5 to 25 parts per million uranium. Although the 

uranium concentrations are not unusual for this rock 

type (slate and phyllite from black shale), the anomalous 

504 

values may represent concentrations of uranium as the 

result of lateral secretion, that may have occurred during metamorphism. The basal conglomerate has been 

the subject of intensive studies by the USGS (Barker, 

1968) for its gold potential and more recently by Bums 

and others (1980) in a uranium evaluation for the U.S. 

Department of Energy. On the basis of numerous sample analyses, studies of environments of depositions, the 

age of the formation, and other factors, the conglomerate was determined to be unfavorable for the occurrence of deposits of uranium or gold of the Precambrian 

fossil placer type. 

Uranium was discovered near the west bank of the 

Animas River in Elk Park in 1956. Sporadic production 

since 1957 has yielded small amounts of uranium ore 

which averaged approximately 0.2 percent U30 8• The 

deposit is a fissure-vein occurring along faults cutting 

the Uncompahgre Formation. The quartzites and slates 

of this formation are isoclinally folded, along east-west 

trends, and in this area many of the folds have ruptured, 

allowing passage of the mineralizing fluids. The 

mineralized vein fillings range in size from tiny fractures to fault breccias several feet across. Uranium occurs in either simple veins associated with pyrite and 

hematite or in complex vein systems containing sulfides 

and arsenides (Scott, 1983). Small amounts of copper, 

cobalt, silver, zinc, and molybdenum were detected in 

uranium-bearing samples. Exxon Minerals Company 

conducted a drilling program during 1980 and 1981, 

which resulted in the delineation of a large low-grade 

resource. There was no activity at the Elk Park mine 

during the summer of 1982. The only access to the mine 

is that provided by the Durango-Silverton Narrow 

Gauge Railroad which now only operates during the 

summer months. 

Although the Elk Park deposit is located outside the 

West Needle Wilderness Study Area boundary, the 

east-west structures that localized the mineralization 

can be traced well inside the study area No surface indications of mineralization were found inside the study 

area; however, it is reasonable to assume that mineralization may occur at depth along these known structures. This area has a probable resource potential for 

uranium. 

If the original black shales did indeed provide the 

uranium and other metals for the Elk Park deposit, then 

it is conceivable other deposits might exist, given the 

same favorable conditions, elsewhere in the Uncompahgre Formation in the study area 

SUGGESTIONS FOR FURTHER STUDIES 

Further information on the origin of the uranium in 
the deposit at Elk Park would be useful in assessing the 

mineral potential of the Uncompahgre Formation. If the 

uranium was introduced from one of the younger Tertiary intrusive centers rather than it being derived from 

the original black shales, it would reduce the chances of 

other occurrences in similar host rocks to those at Elk 

Park. 

REFERENCES 

Barker. Fred, 1968, Gold investigations in Precambrian clastic and 

pelitic rocks, southwestern Colorado and northern ew Mexico: 

U.S. Geological Survey Bulletin 1272-F, 22 p. 

Burns, L. K., Ethridge, F. G. , Tyles, ., Gross, A. ., and Campo, 

A. M., 1980, Geology and uranium evaluation of the Precambrian 

quartz-pebble conglomerates of the eedle Mountains, southwest Colorado: U.S. Department of Energy Report GJBX118(80). 

Scott, D. C.. 1983, Mineral investigation of the West eedle 

Wilderness Study Area and the BLM West Needle Contiguous 

Wilderness Study Area. La Plata and San J uan Counties, Colorado: U.S. Bureau of Mines Open-File Report MLA 35- 83,47 p. 

Van Loenen, R. E .. and Scott, D. C., in press, Mineral resource potential map of the West eedle Wilderness Study Area, San Juan 

and La Plata Counties, Colorado: U.S. Geological urvey 

Miscellaneous Field Studies Map M F - 1632- A, scale 1 :50,000. 

505 
37° 

55 ' 

37° 

50' 

506 

106°50' 106°45' 

COLORADO 

• 

G -4 

R I .,. 4 MAP LOCATION 

111 0 1 "' .,. 4 

I tv S 

[ GEOLOGIC 

( 

WHEELER 

~ AREA 

~ 

SILVER 

P A R K 

Oligocene volcanic rocks 

Approximate boundary 

0 2 

MILES 

EXPLANATION 

---,..-- Fault--Bar and ball on downthrown side 

Figure 148.-Wheeler Wilderness Study Area, Colorado. 
WHEELER WILDERNESS STUDY AREA, COLORADO 

By WILLIAM H . RAYMO D,

1 U .S. GEOLOGICAL URVEY, and 

CARL L. BIE IEWSKI, U.S. BUREAU OF Mr ES 

SUMMARY 

No mineral-resource potential was identified in the Wheeler Wilderness Study 

Area as a result of field and laboratory investigations conducted by the USGS 

in 1982 and by the USGS and USBM in 1971 in the adjacent La Garita 

Wilderness. Analytical data and indications of previous mining or prospecting 

are negative with respect to indications of mineral deposits. If mineral deposits 

exist, they would likely be associated with one of two anomalies which may be 

related to an intrusive at a depth of 1000 ft or more, as indicated by aeromagnetic and gravity surveys. 

CHARACTER AND SETTING 

The Wheeler Wilderness Study Area occupies about 

21 sq mi in the La Garita Mountains in Mineral County, 

southwestern Colorado, about 6 mi east of Creede. The 

original focus of interest in the area was the Wheeler 

ational Monument, a 1/2 sq mi area containing outcrops of deeply dissected Rat Creek Tuff of Oligocene 

age, which was established as a national monument by 

Theodore Roosevelt in 1908. In 1950, Congress abolished the Wheeler National Monument and returned 

management responsibility to the USFS which, in 1962, 

delineated a 1-sq-rni tract including the original 

Wheeler National Monument, which was withdrawn 

from mineral prospecting, location, entry, or purchase; 

the 1-sq-rni tract was thereafter referred to as the 

Wheeler Geologic Area Subsequently, surrounding terrane was added resulting in the 21 sq mi Wheeler Wilderness Study Area covered in this report. 

The spectacular badlands in Rat Creek Tuff are 

perched on and amidst tuffs, flows, and breccias of the 

La Garita caldera The entire study area lies within this 

sequence of Oligocene volcanic rocks; no older rocks are 

exposed in or near the study area 

MINERAL RESOURCES 

Despite its proximity to the Creede mining district 

and the similarity of geologic framework, the Wheeler 

1

Wit.h contributions from James G. Crock . USGS. 

Wilderness Study Area appears to have little promise 

for mineral resources. Sulfide minerals were not identified within the study area, and there is no evidence of 

mining or prospecting activities. 

Anomalous zinc in stream-sediment samples and 

panned concentrates, occurs over a wide area in the 

drainage of West Bellows Creek, but analyses of magnetic concentrates from the same samples show that the 

zinc is in magnetite derived from the tuffs of the area It 

is therefore concluded that resources of zinc are not 

likely to occur in rocks exposed in the study area 

Anomalous uranium which occurs in widely scattered 

samples in the study area is attributed to a high 

background of uranium in volcanic glass, and it is 

unlikely that significant accumulations of uranium are 

present. 

One stream-sediment sample at the southern boundary of the area contains gold at the lower limit of detection, but there is no other evidence of occurrences of 

gold in the study area 

Two aeromagnetic anomalies were identified in this 

study. One of them is thought to be related to topography, the other may be related to topography but has 

been interpreted to be related to a buried pluton. Although the possibility of mineralization exists, no surface expression is known, and drilling would be required 

to verify this interpretation. 

The remote setting and very limited access, together 

with unfavorable geochemical data, would seem to preclude the occurrence of mineral resources in the study 

area. o energy resources were identified in this study. 

507 
REFERENCES 

Raymond, W. H., Crock, J. G., and Bieniewski, C. L., 1983, Maps 

showing geology and mineral resource potential of the Wheeler 

Wilderness Study Area, Mineral County, Colorado: U.S. Geological Survey Miscellaneous Field Studies Map MF-1571, scale 

1:50,000. 

508 

Steven, T. A., and Ratte, J. C., 1973, Geologic map of the Creede 

quadrangle, Mineral and Saguache Counties, Colorado: U.S. Geological Survey Geologic Quadrangle Map GQ- 1053, scale 

1:62,500. 

Steven, T. A., and Bieniewski, C. L., 1977, Mineral resources of the La 

Garita Wilderness, San Juan Mountains, southwestern Colorado, 

with a sectWn on Geophysical investigation by G. P. Eaton. U.S. 

Geological Survey Bulletin 1420, 65 p. 
WILSON MOUNTAINS WILDERNESS, COLORADO 

By CALVI S. BROMFIELD, U.S. GEOLOGICAL SURV EY and 

' 

FRA K E. WILLIAMS , U .S. BUREAU OF MIN E 

SUMMARY 

Based on a mineral survey completed in 1969, two areas in the Wilson Mountains Wilderness have a probable mineral-resource potential. One area is on the 

east margin of the area in the Trout Lake mining district, and the other is near 

the center of the area, the Mount Wilson mining district. Both areas have had a 

modest base and (or) precious metal production from narrow veins and have a 

probable potential for the occurrence of similar deposits. Of more significance is 

a probable mineral-resource potential for disseminated copper mineralization in 

the Mount Wilson mining district. 

CHARACTER AND SETTING 

The Wilson Mountains Wilderness consists of about 

68 sq mi in the San Miguel Mountains in southwestern 

Colorado. The San Miguel Mountains form a distinct 

west-trending group of rugged peaks on the west edge 

of the San Juan Mountain region. The area contains serrated ridges and towering peaks, three of which rise to 

over 14,000 ft (Mt. Wilson, 14,246 ft, El Diente, 14,159 

ft; and Wilson Peak, 14,017 ft). Magnificent panoramas 

of these imposing peaks can be had on State Highway 

145 which runs near the eastern and southeastern 

boundary of the area 

The high country in the San Miguel Mountains was 

already an established primitive area when the Wilderness Act was passed in 1964. As provided in that act a 

mineral survey was carried out by personnel of the 

USGS and USBM in the summer of 1966 and 1969, and 

the results were published (Bromfield and Williams, 

1972). 

Igneous intrusions of relatively young geologic age 

(middle Tertiary) have invaded nearly flat lying volcanic 

rocks of similar age and older sedimentary rocks along 

an east-west belt. The intrusive rocks, harder and more 

resistant to erosion, form the backbone of the San 

Miguel Mountains, and the sedimentary rocks, softer 

and more easily eroded, form the lower slopes, where 

they are widely concealed by glacial deposits and spruce 

forests. Though only about 5000 ft of sedimentary and 

volcanic rocks are exposed, total thickness of concealed 

rocks above the ancient (Precambrian) basement is on 

the order of 7000 to 8000 ft. 

MINERAL RESOURCES 

The Wilson Mountains Wilderness lies on the western 

fringe of the Telluride-Silverton-Ouray region, one of the 

great base- and precious-metal mining regions in Colorado. Most of the more than $500 million in total production has come from mines 8-10 mi northeast of the 

wilderness, chiefly from northwest-trending veins cutting volcanic rocks and radial to a large complex 

volcanic collapse or caldera West of the caldera is a 

similar system of westward-trending veins, closely 

associated with a belt of intrusive rock. This system, 

much weaker, and containing fewer veins than the 

northwest-trending system extends westward into the 

wilderness as far as the stock near Mt. Wilson. Within 

the wilderness veins of this system are found in an eastwest zone, or belt 1-2 mi wide and about 7 mi long extending from the east boundary westward into Silver 

Pick and Navajo Basin. The veins are generally narrow 

and ore shoots small, and are concentrated in two areas, 

the Trout Lake mining district on the east, and the 

Mount Wilson mining district in the center of the area 

Metal mining activity in the western San Juan Mountains began in the early 1870's and by 1877 claims had 

been located on the east margin of the area on the San 

Bernardo vein. The Silver Pick vein in Silver Pick Basin 

was discovered in 1883, and probably by 1900 all the 

known and now patented claims (about 50), had been 

located. Approximately $1.78 million in gold, silver, 

copper, lead, and zinc have been mined from the Wilson 

Mountains Wilderness, mostly in the years preceding 

1930. The bulk of the production has come from two 

509 
510 

38° 

oo· 

() 

I., 

s 

0 5 

MILES 

EXPLANATION 

D Geologic terrane with probable 

mineral-resource potential 

Cu Copper 

/ / ... , - ,_\:._•-,~~ 1 Intrusives ,, , , ,. 

Volcanic rocks 

• 

7 ., .., ... ... ,.. ~ 

(,. ,J .., < ,. > ... 

> < ... ..J " ~,.. r ,. 

.., .., or"., ... 

y ""! < ., l.o "' 

< ,.. zr- ,. ,_ ... ;\ y <( '- "' 

~:"~ ,.., : 

COLORADO 

MAP LOCATION 

Au Gold Sedimentary rocks 

Pb Lead Contact 

Ag Silver 

Zn Zinc 

X Mineral occurrence 

'X' Mine 

Figure 149.-Wilson Mountains Wilderness, Colorado. 
veins, the Silver Pick, mined chiefly for gold, and the 

San Bernardo, mined for silver, but with accompanying 

lead, zinc, and copper. 

Further evidence of mineralization is shown by widespread alteration in the area of the Wilson Mountain 

Wilderness. Disseminated fine-grained pyrite, which accompanies much of the alteration, has been oxidized and 

yields colorful and conspicuous areas of iron staining in 

the rocks. Alteration of this type commonly accompanies the mineralizing process in many metal mining 

districts and is considered presumptive evidence for the 

circulation of hot mineralizing fluids. Of more direct significance is an area of quartz monzonite in Navajo Basin 

that was found by our investigation to contain disseminated copper sulfide. This copper mineralization represents a possible copper resource, and the occurrence is 

similar to the porphyry copper deposits that have 

formed large low-grade deposits in the southwestern 

U.S. and elsewhere. 

A geochemical survey of stream sediments showed 

anomalous values of copper, lead, and zinc which 

generally reflected known areas of mineralization. 

Stream sediments from Navajo Basin consistently contained high copper values, and reflect the area that contains disseminated copper sulfides. 

Thin beds of low-rank bituminous coal occur in outcrop in the Cretaceous Dakota Sandstone just south 

and north of the area, and thus thin coal probably 

occurs in subsurface, but as this formation occurs at 

depths of more than 1000 ft, the area it underlies is not 

classified as having mineral-resource potential for coal. 

It is concluded from the historical, geologic, and 

geochemical evidence outlined above that two areas 

have probable mineral potential. One, the Trout Lake 

mining district on the east side of the wilderness; and, 

two, the Mount Wilson mining district in the center of 

the wilderness. The Trout Lake mining district can be 

expected to contain vein deposits of silver-lead-zinccopper type. The Mount Wilson mining district could be 

expected to contain vein deposits similar to the Trout 

Lake area, as well as gold-bearing quartz veins. Based 

on past experience veins in both areas would generally 

be narrow. Of considerably more significance is the 

potential for porphyry copper-type deposits in the 

Mount Wilson mining district. 

SUGGESTIONS FOR FURTHER STUDIES 

Exploration including extensive sampling and drilling 

would be needed to define the limits, grade, and volume 

of copper mineralization in Navajo Basin. However, a 

study utilizing the extensive growth of knowledge 

about alteration and mineralization zoning in porphyry 

copper systems would be valuable in assessing the 

mineral potential, and as a basis for planning a drilling 

project. 

REFERENCE 

Bromfield, C. S. and Williams, F. E., 1972, Mineral resources of the 

Wilson Mountains Primitive Area, Colorado: U.S. Geological 

Survey Bulletin 1353·A, 79 p. 

511 
F L 0 R I 

,~~~TALLAHASSE * 

Pensacola 3e 1 

0 100 

I I I I I I I I 

MILES 

Location of areas studied. 

512 

D A 

LAKE 

OKEECHOB() 
FLORIDA 

Map 

No. Name of Area 

3 Bradwell Bay Wilderness and Sopchoppy River Wilderness study area 

1 Clear Lake Roadless Area 

5 Faries Prairie and Buck Lake Roadless Areas 

2 Natural Area Roadless Area 

4 Savannah Roadless Area 

513 
514 

-

0 

M ILES 

EXPLANATION 

Geologic terrane with substantiated 

peat resource potential 

3 

Fibrous peat, 1-4 ft thick (Holocene) 

Humus peat, Y, -1 ft thick (Holocene) 

Muck and sand (Holocene) 

Beach and near shore sand (Holocene) 

Li mestone, St. Marks Formation 

(Miocene) 

Contact 

Figure 150.- Bradwell Bay Wilderness and the Sopchoppy River Wilderness study area, Florida. 
BRADWELL BAY WILDERNESS AND THE 

SOPCHOPPY RIVER WILDERNESS STUDY AREA, FLORIDA 

By CORNELIA C. CAMERON , 1 U.S. GEOLOGICAL S RVEY and 

' 

PETER C. MORY, U .S. B REA OF MI E 

SUMMARY 

A survey to determine the mineral-resource potential, especially for oil, 

phosphate, fuller's earth, sand, and peat, was conducted in 1974 in the Bradwell 

Bay Wilderness and the Sopchoppy River Wilderness Study Area. On the basis 

of this survey, the entire area was concluded to offer little promise for the occurrence of mineral resources except the commodity peat. Approximately 136,000 

tons of demonstrated peat resources, on a dry weight basis, are available in 

areas of substantiated peat resource potential from bay swamps in the area, but 

the deposits are shallow and widespread. Large quantities of quartz sand are 

available in ancient beach ridges and in deposits that were originally laid down 

in a shallow nearshore marine environment. Sieve tests show that the sand is 

generally too fine for mortar and masonry use; it is not suitable as moulding or 

glass sand because it lacks the required size grades and purity. 

CHARACTER AND SETTING 

The Bradwell Bay Wilderness and the Sopchoppy 

River Wilderness Study Area are within the Apalachicola National Forest, Wakulla County, Florida, approximately 20 mi southwest of Tallahassee. The Bradwell 

Bay Wilderness comprises 34 sq mi of swamp and pine 

woods bordered on the northeast by the Sopchoppy 

River Wilderness Study Area, a narrow strip of 2 sq mi 

along the river. The wilderness is one of many swamps 

in the Florida panhandle called "bays" because of the 

bay trees growing in them. 

The wilderness and wilderness study area are in the 

East Gulf Coastal Plain which in this region is divided 

into two subprovinces, the Tallahassee Hills on the 

north and the Apalachicola Coastal Lowlands on the 

south. The Cody scarp is the east-west dividing line between the subprovinces. The surface from the toe of this 

scarp drops southward across the Bradwell Bay Wilderness to the modem shore line. Slight differences in altitudes in the swamps on this surface mark ancient beach 

ridges and spits, and a few low scarps. 

The surface is covered by as much as 30 ft of sand and 

peat beneath a tangle of vegetation extending monoto1

WiLh conl.ributions from James B. CaLhcarL and Philip J . Gcrachi. USGS. 

nously in all directions. The Sopchoppy River flows 

southward from a flat-floored valley in the north 

through a narrow V -shaped valley cut in a sand-covered, 

deeply weathered limestone terrane along the eastern 

edge of the Bradwell Bay Wilderness. Bedrock exposures are limited to the banks and bed of the river. Here, 

weathering of limestone of the St. Marks Formation of 

early Miocene age forms karst topography, featuring 

honeycomb weathering and sinks. Older Oligocene and 

younger Miocene rocks are exposed in adjacent counties 

to the north and east and pre-Oligocene rocks are known 

only from drill holes in the surrounding areas. 

MINERAL RESOURCES 

The Hawthorn Formation, of middle Miocene age, 

from which phosphate and fuller's earth are chiefly produced in Florida, is not found in the Bradwell Bay Wilderness and the Sopchoppy River Wilderness Study 

Area; therefore, there is little promise for the occurrence 

of these resources. Some phosphate pellets, however, 

were found in auger holes in younger sands deposited in 

an estuary during Pliocene and early Pleistocene time. 

The sands were derived from older rocks presumably 

the Hawthorn Formation and do not constitute a resource for phosphate. 

515 
The Bradwell Bay Wilderness is about 175 mi eastsoutheast of the Jay oilfield in the western panhandle of 

Florida. Part of the production is from the Smackover 

Formation of Jurassic age, which is also the target formation for drilling in the vicinity of the wilderness. Four 

oil test holes have been drilled in the vicinity of the 

Bradwell Bay Wilderness but all proved to be unsuccessful. These four test holes, now abandoned, are alined 

along a northeast trend immediately northwest of the 

Bradwell Bay Wilderness. There is little promise for the 

occurrence of oil and gas in the Bradwell Bay Wilderness and Sopchoppy River Wilderness Study Area 

because although hydrocarbons may have been generated in the area, no evidence of an oil trap was found in 

the abandoned test wells to the northwest. 

According to ASTM Committee, the term "peat" 

may be used only with respect to organic matter of geological origin, and not for lignite or other coal. According to the ASTM, peat forms mainly from dead plant remains through the agency of water in the absence of air; 

it is found in a bog, swampland, or marsh and has an 

ash content not exceeding 25 percent on a dry-weight 

basis. The peat deposits of the United States are currently being studied for use in agriculture as a soil conditioner and in horticulture as a packing material and 

growing medium. They are also being studied for potential gaseous and solid fuel potential. 

The most favorable environment for peat accumulation in the Bradwell Bay Wilderness and Sopchoppy 

River Wilderness Study Area is the bay swamp which is 

characterized by the presence of sweetbay trees, which 

are protected from fire encroachment by surrounding 

swamps of cyrillaceous shrubs that act as buffers. 

Elsewhere, bay swamps are adjacent to fire-prone pinepalmetto flatwoods and are subject to burning before 

much peat can accumulate. Within this most favorable 

type of area are an estimated 136,000 tons of peat on a 

516 

dry weight basis having an ash content of not more than 

25 percent. However, the peat layer is discontinuous, 

only 1 to 4 ft thick, and drainage, clearing, and access 

problems are severe. Thicker peat in more accessible 

areas is available elsewhere in Florida 

Quartz sand from abandoned beaches can be found on 

terraces southeast of the wilderness and within Wakulla 

County. Quartz sand from a similar environment is also 

abundant in the wilderness, but fails to comply with 

acceptable ASTM standards for use in mortar and 

masonry. Nor is the sand recommended as a source of 

moulding and glass sands as defined by the American 

Foundrymen's Society. Beds of tidal-marsh deposits 

near the surface are contaminants. 

The Florida-Georgia fuller's earth district, the major 

area for producing fuller's earth in the United States, is 

24 mi north of the wilderness. The Hawthorn Formation, the principal host for fuller's earth deposits, has 

not been found in the Bradwell Bay Wilderness and 

Sopchoppy River Wilderness Study Area and there is 

little promise for the occurrence of fuller's earth 

resources. 

SUGGESTIONS FOR FURTHER STUDY 

Further study of the wilderness offers little promise 

for identifying mineral or energy deposits with resource 

potential. 

REFERENCE 

Cameron, C. C., Mory, P. C., Cathcart, J. B., and Gerachi, P. J., 1977, 

Mineral resources of the Bradwell Bay Wilderness and the Sopchoppy River Study Area, Wakulla County, Florida: U.S. Geological Survey Bulletin 1431, 37 p. 
CLEAR LAKE ROADLESS AREA, FLORIDA 

By SAM H . PATTERSO 1, U.S. GEOLOGICAL S RVEY, and 

THOMAS M. CRANDALL, U.S. BUREAU OF Ml ES 

SUMMARY 

On the basis of a mineral survey in 1980 and 1981 the Clear Lake Roadless 

Area was concluded to offer little or no promise for the occurrence of mineral 

resources. The only commodity that has been mined in the area is clayey sand 

used in stabilizing USFS roads and in highway construction. Although there are 

large clayey sand resources in the Clear Lake Roadless Area, there are virtually 

unlimited resources of this material in the surrounding region. No peat more 

than a few inches thick occurs in the area Limestone underlies all of the Clear 

Lake area but is under thick overburden. The region has been explored for heavy 

minerals and phosphate, but no resources have been found. There appears to be 

little promise for discovery of oil and gas in the Clear Lake area. However, the 

area and nearby lands have not been thoroughly tested for oil and gas, and the 

possibilities for discovery cannot be ruled out. 

CHARACTER AND SETTING 

The Clear Lake Roadless Area occupies about 10 sq 

mi in the Apalachicola National Forest, Leon County, 

Florida, which is in the Big Bend region about 10 mi 

southwest of Tallahassee. The area is bounded on the 

southwest by Florida Highway 267 and on the other 

sides by unimproved USFS roads. 

The entire Clear Lake area is blanketed by unconsolidated sediments overlying a thick sequence of sedimentary rocks that were deposited in the eastern part of 

the Apalachicola embayment. The unconsolidated 

sediments consist of Pleistocene and Holocene clayey 

sand and soil, having a total thickness of about 35 ft. 

The formations that underlie the unconsolidated sediments and are in contact with them are the St. Marks 

and Hawthorn Formations of Miocene age and the 

Jackson Bluff Formation of Pliocene age. The St. Marks 

is composed of carbonate, the Hawthorn of sandstone, 

sandy limestone, and clayey sand, and the Jackson 

Bluff of a very fossiliferous dark clayey sand. The rocks 

that underlie the St. Marks Formation include about 

2800 ft of Oligocene (includes Suwanee Limestone) and 

Paleocene beds and nearly 4000 ft of Cretaceous strata 

Little is known about the older rocks below the Clear 

Lake area, but sedimentary formations of Jurassic and 

Triassic and probably early Paleozoic age as well as 

1

Wi!Jl contributions from C. W. Hendry. Jr .. Florida Bureau of Geology nnd J. W. weeney. 

USBM. 

crystalline rocks are present in the central part of the 

Apalachicola embayment and probably underlie the 

Clear Lake area 

The sedimentary formations underlying the Clear 

Lake area dip gently to the southwest toward the 

Apalachicola embayment which was formed by downwarping of crustal rocks. The central part of the embayment is filled with sediments of Triassic to Quaternary 

age having a thickness of more than 14,000 ft. No faults 

have been recognized in the Clear Lake area However, 

strata have been disturbed in many places by slumping 

into solution cavities. 

MINERAL RESOURCES 

The geology of the area had been investigated by the 

Florida Bureau of Geology (Hendry and Sproul, 1966) 

and the mineral potential of the area was investigated 

by the USGS and the USBM in 1980 and 1981. Reports 

by Hendry and others (1982) and Crandall (1982) summarized herein provide the information on mineralresource potential. 

The only mineral material that has been produced in 

the Clear Lake area is clayey sand used in the construction of Florida Highway 267 and in stabilizing USFS 

roads. Although large quantities of clayey sand resources in the unconsolidated surficial material are present in the Clear Lake area, they are not shown on the 

517 
30° ------------------------------------- ~'~0~"---------------------------------.---------- 84 ' ______ --, 22' .--

30" 

518 

Jackson Bluff Formation (Tertiary) 

Hawthorn Formation (Tertiary) 

St. Marks Formation (Tertiary) 

0 

MILE 

EXPLANATION 

• 

MAP LOCATION 

Contact 

Drill hole or well--Formations penetrated are 

identified by Hendry and Sproul 

( 1966, table 2) 

Entire area is blanketed by Holocene and 

Pleistocene sand and clayey sand 

Figure 151.- Clear Lake Roadless Area, Florida 
map because virtually unlimited quantities of similar 

materials occur in the surrounding areas outside the 

roadless area 

Limestone in the St. Marks Formation occurs under 

about 35 ft of overburden in the eastern one-third of the 

Clear Lake area and under thicker overburden in the 

central and western parts of the area This limestone 

resource is not shown on the map because similar rock 

under thinner overburden occurs in extensive areas east 

of the Clear Lake area The limestone east of the area is 

also closer to potential markets in the Tallahassee area 

Other mineral resources either do not occur in the 

Clear Lake area or are too deeply buried and include 

common clay, fuller's earth, heavy minerals, phosphate, 

and sand and gravel. Very thin deposits of peaty 

material are present in the area, but they are too small 

and impure to be assessed as having mineral-resource 

potential. 

The entire Clear Lake area has been leased for oil and 

gas in the past, but there were no active oil or gas leases 

or applications for leases in the area as of October, 1981. 

According to the reports and records of the Florida Bureau of Geology, many exploratory wells have been 

drilled in search for oil and gas in the region. To date, 

only a few shows of oil have been found, and all of the 

holes have been dry. At least 30 were deeper than 

5000 ft and 15 were deeper than 10,000 ft. The deepest 

hole bottomed at 14,570 ft. Surprisingly, two of the 

shallow holes were reported (Hendry and Sproul, 1966, 

p. 105) to have good shows of oil. These two wells are located less than 20 mi from the Clear Lake Roadless 

Area 

Although there are no reasons for optimism about the 

discovery of oil and gas in and near the Clear Lake area, 

the possibilities cannot be completely ruled out. The 

principal reasons for the unfavorable outlook are the 

large number of dry holes in the region and the probable 

absence of the Jurassic Smackover Formation. Geologists believe that the Smackover Formation has the 

greatest promise for oil and gas in the region because it 

contains the oil and gas produced in the Jay field in the 

westernmost Florida panhandle and nearby fields in 

Alabama (Babcock, 1972). The Smackover has been 

found to be present in several wells southwest of Clear 

Lake and is thought to underlie about 2000 sq mi in the 

region. However, the updip limit of this formation is 

shown by Applegate and others (1978, fig. 1) to be more 

than 15 mi west of the Clear Lake area in Liberty County. Reasons why some possibility remains for oil and 

gas discoveries in the study area include the following: 

(1) the shows of oil in dry holes east of the area, noted in 

the foregoing paragraph; and (2) uncertainty as to 

whether or not formations older than the Smackover 

may contain oil and gas. 

The Clear Lake area has not been thoroughly explored 

for oil and gas and the possibility for either being present still exists. 

SUGGESTIONS FOR FURTHER STUDIES 

The blanket of unconsolidated surficial materials covering the Clear Lake area rules out the acquisition of 

significant additional geologic information by field 

studies, and the Florida Bureau of Geology has published a report on the geology of Leon County (Hendry 

and Sproul, 1966) in which the area is located. Accordingly, further evaluations of the mineral potential of the 

Clear Lake area are not warranted. 

REFERENCES 

Applegate. A. V., Pontigo. F. A., Jr., and Rooke, J. H., 1978, Jurassic 

Smackover oil and gas prospects in the Apalachicola embayment: The Oil and Gas Journal, January 23, p. 80-84. 

Babcock, Clarence, 1972, Oil and gas activities in Florida, 1970: 

Florida Bureau of Geology Information Circular 80, 82 p. 

Crandall, T. M., 1982, Mineral investigations of the Clear Lake RARE 

II Further Planning Area. Leon County, Florida: U.S. Bureau of 

Mines Open File Report MLA 71 - 82,20 p. 

Hendry, C. W., Jr., and Sproul, C. R .. 1966, Geology and groundwater resources of Leon County, Florida: Florida Geological 

Survey Bulletin 4 7. 178 p. 

Hendry. C. W., Jr., Patterson. S. H., Crandall. T. M .. and Sweeney, 

J. W., 1982, Mineral resource potential map of the Clear Lake 

Road.less Area, Leon County, Florida: U.S. Geological Survey 

Miscellaneous Field Studies Map MF- 1479. 

519 
290 

07' 

30" 

520 

81 °42'30" 81 °40' 

MAP LOCATION 

I Buck Lake \ 

I I 

1 _.,,.~ flo/• 1 

l'0nrls V") J \ I \ 

I \ 

: I \ 

I \ l-----------------~ ( _;B w Smk 

0 2 

MILES 

EXPLANATION 

D Citronelle(?) Formation (Pliocene) 

• Drill hole 

X Clayey sand or borrow pit 

Figure 152.-Fnrles Prairie and Buck Lake Road.less Areas, Florida 

,, 

95 
FARLES PRAIRIE AND BUCK LAKE ROADLESS AREAS, FLORIDA 

By SAM H . PATTERSO , U.S. GEOLOGICAL R EY, and 

THOMAS M. CRA DALL, U.S. B REA OF Mr E 

SUMMARY 

Mineral surveys in 1980 and 1981 conducted by the USGS and USBM of the 

Faries Prairie and Buck Lake Roadless Areas showed little promise for the occurrence of metallic mineral or energy resources; the possibility for the occurrence of hydrocarbons, however, cannot be ruled out. The only mineral material 

that has been produced in the roadless areas is clayey sand used in stabilizing 

USFS roads. The large quantities of clayey sand occurring in the areas are not 

identified as resources because virtually unlimited resources are present in the 

surrounding region. Limestone underlies all of the two areas, but is too far from 

markets and under too much overburden for quarrying. Heavy minerals and 

phosphate are present in the two areas but are not sufficiently concentrated to 

be identified as resources. 

CHARACTER AND SETTING 

The Faries Prairie Roadless Area occupies about 3.4 

sq mi and the Buck Lake Roadless Area about 8.9 sq mi 

in the Ocala National Forest, Marion County, Florida 

The areas can be reached from Ocala by taking Florida 

Highway 40 east about 32 mi to Florida Highway 19 

then south on this road to USFS Road 62 which leads 

through the U.S. Navy Tracking Station to the Faries 

Prairie Roadless Area 

The two roadless areas are in the Central Highlands 

physiographic province of Florida, and the topography 

is a modified karst with a thin veneer of windblown sand 

at the surface. Faries Prairie Roadless Area is an area of 

low sand hills in the eastern part and shallow lakes and 

flat prairies in the west. Buck Lake Roadless Area is 

almost entirely an area of low sand hills, and has only a 

few scattered ponds. Altitudes in the two areas range 

from 50 to 140 ft above sea level. 

The mineral potential of the Faries Prairie and Buck 

Lake Roadless Areas was investigated by the USGS 

and the USBM in 1980 and 1981. Reports by Crandall 

(1982), Cathcart and Patterson (1983) and Cathcart and 

others (1983) provide information on the geology and 

mineral potential of the areas. 

The surface of the Faries Prairie and Buck Lake Roadless Areas is blanketed by unconsolidated soil and sand. 

This surficial blanket is no more than 5 ft thick in most 

places, but is as much as 100 ft thick in sink hole fillings. These surficial materials are underlain by a second 

unconsolidated blanket consisting of white, red, and 

orange sand that is 40 to 60 ft thick. The age of this unconsolidated layer is uncertain, but it is probably of 

Pliocene age and has been called the Citronelle(?) Formation. The Citronelle(?) rests unconformably on Miocene strata that consist of an unnamed upper Miocene 

formation and the middle Micoene Hawthorn Formation which is chiefly sand; both contain phosphate. The 

lower part of the Hawthorn contains considerable 

dolomite. The two Miocene units have been removed by 

erosion from parts of the Ocala National Forest, but 

they have a total thickness of as much as 200 ft in the 

Faries Prairie and Buck Lake Roadless Areas. About 

4000 ft of sedimentary rocks ranging in age from 

Cretaceous to Eocene underlie the Hawthorn Formation 

and rest unconformably on an older basement of crystalline and Paleozoic sedimentary rocks. 

MINERAL RESOURCES 

No minerals have been mined in the Faries Prairie 

Roadless Area, and the only production in the Buck 

Lake Roadless Area has been clayey sand used in stabilizing USFS roads. Although large resources of clayey 

sand in the Citronelle(?) Formation are present in the 

two roadless areas, they occur as virtually unlimited 

resources in surrounding areas. 

521 
Phosphate deposits occur in the Hawthorn Formation 

and the unnamed upper Miocene formation in both 

areas. The deposits have been explored by widely 

spaced drill holes, including three holes drilled during 

this study. No significant deposits of phosphate have 

been found in the Ocala National Forest. The P zOs content of samples of pebble fraction was only 13.1 percent 

and the results of analyses of samples collected during 

this investigation failed to indicate the presence of highgrade phosphate and no phosphate resource potential 

was identified. 

Other minerals that are produced in the region of the 

Ocala National Forest either do not occur in the Farles 

Prairie and Buck Lake Roadless Areas or were not identified as resources in this study; these include limestone, 

fuller's earth, kaolin, heavy minerals, and peat. The 

Eocene Ocala Limestone underlies both areas but is too 

deeply buried to be quarried and large resources of this 

limestone are located in places much closer to markets. 

No fuller's earth or kaolin clays of sufficient purity to 

form valuable deposits occur in the two areas. One sample of common clay tested by the USBM had excellent 

ceramic properties, but it came from an interval 86-94 

ft below the surface. Small amounts of heavy minerals 

occur in the unconsolidated surficial material, Citronelle(?) Formation, unnamed upper Miocene formation, 

and Hawthorn Formation. However, no concentrations 

sufficiently rich to be identified as resources were found. 

Organic rich muck and small accumulations of peaty 

material occur in some of the swamps in the two areas, 

but no low-ash peat deposits are present. 

Oil and natural gas are produced from Lower Cretaceous Sunniland Limestone in southern Florida and from 

the Jurassic Smackover Formation in western Panhandle Florida Jurassic beds are not present in the 

Ocala National Forest, and beds of Early Cretaceous 

522 

age, present both to the east and west, are missing in 

the area, where beds of Late Cretaceous age rest on 

Paleozoic rocks. 

Several exploratory holes for oil and gas have been 

drilled in and around the Ocala National Forest, but all 

holes were dry and abandoned. There is little reason for 

optimism regarding possible oil and gas accumulations 

in the subsurface in Faries Prairie and Buck Lake Roadless Areas, because of the number of dry holes in the 

surrounding areas, and because rocks that contain oil 

and gas elsewhere in Florida are not present here. 

SUGGESTIONS FOR FURTHER STUDY 

Because of the blanket of surficial material covering 

the Faries Prairie and Buck Lake Roadless Areas little 

could be accomplished by further field observations, 

and drilling would be required to obtain much more 

information about geology. The principal potential valuable mineral in the area is phosphate, but information 

now available indicates there is little possibility for the 

occurrence of large high-grade deposits. 

REFERENCES 

Cathcart, J. B., and Patterson, S. H., 1983, Geologic map of the 

Faries Prairie and Buck Lake Roadless Areas, Marion County, 

Florida: U.S. Geological Survey Miscellaneous Field Studies Map 

MF- 1591- A, scale 1:24,000. 

Cathcart, J. B., Patterson, S. H., and Crandall, T. M., 1983, Mineral 

resource potential map of the Faries Prairie and Buck Lake Roadless Areas, Marion County, Florida: U.S. Geological Survey 

Miscellaneous Field Studies Map MF-1591 - B, scale 1:24,000. 

Crandall, T.M., 1982, Mineral resources of Faries Prairie and Buck 

Lake RARE II further planning areas, Marion County, Florida: 

U.S. Bureau of Mines Open-File Report MLA 46-82, 19 p. 
NATURAL AREA ROADLESS AREA, FLORIDA 

B y SAM H . PATIERSON, 1 U .. GEOLO !CAL U RVEY, and 

THOM AS M . CRA DALL, U .S. B UREAU OF Mr E 

SUMMARY 

Mineral surveys in 1980 and 1981 of the Natural Area Roadless Area, Florida 

identi~ed a substantiated :esource P?tential for scattered low-grade phospha~ deposits. The area has little prorruse for the occurrence of other mineral 

resources or oil and gas, although the possibilities for the occurrence of these 

two hydrocarbons cannot be ruled out. The only mineral material that has been 

produced in the area is clayey sand used in stabilizing USFS roads, but virtually 

unlimited quantities of similar material are present in the surrounding region. 

Peaty material is present in swamps in the roadless area, but none of it is thick 

or pure and no resource potential was identified. Limestone underlies all of the 

Natural Area Roadless Area but is under too much overburden for quarrying. 

Heavy minerals are present in the area but are not sufficiently concentrated to 

consider the area as having resource potential. 

CHARACTER AND SETTING 

The Natural Area Roadless Area occupies about 6.8 

sq rni in the Osceola National Forest, Baker County, 

Florida The area is 18 rni northeast of Lake City which 

is in northern peninsular Florida The Natural Area 

Roadless Area is bounded by USFS Road 277 on the 

south and road 235 on the west. The surface of the 

roadless area is a flat swampy plain. The highest 

altitude is 133 ft above sea level and the lowest point is 

only about 10 ft lower. 

The mineral potential of the area was investigated by 

the USGS and the USBM in 1980- 81 (Crandall, 1981; 

Cathcart and others, 1983; and Patterson and others 

1983. 

The entire Natural Area Roadless Area is blanketed 

by unconsolidated sediments of Pleistocene and 

Holocene age, that overlie a sequence of Tertiary 

sedimentary rocks. The surficial sediments in swamps 

consist of peaty material and organic-rich muck. The 

shallow soils in the drier areas are rarely more than a 

1 ft thick A horizon and consist chiefly of clayey sands. 

The swamp deposits and shallow soils are underlain by 

25- 35 ft of unconsolidated sand and clayey sand. 

Miocene rocks underlying the unconsolidated beds consist of an unnamed formation and the Hawthorn Forma1

WiLh con tributions from J ames B. Cart.hcart. and Cornelia C. Cameron. USG . 

tion, having a total thickness of 240-280 ft. Both of 

these formations contain phosphate. About 3300 ft of 

sedimentary rocks ranging in age from Cretaceous to 

Eocene underlie the Hawthorn Formation and rest unconformably on an older basement of crystalline and 

Paleozoic sedimentary rocks. 

MINERAL RESOURCES 

The only mineral material that has been produced in 

the Natural Area Roadless Area is clayey sand used in 

stabilizing USFS roads. Although large resources of 

clayey sand in unconsolidated surficial material are 

present in the roadless area, virtually unlimited quantities of similar material occur in surrounding areas. 

Scattered phosphate deposits occur in the Miocene 

Hawthorn Formation and an unnamed upper Miocene 

formation in the Natural Area Roadless Area The 

deposits have been explored by widely spaced drill 

holes. Preference right lease applications for phosphate 

have been filed on large acreages in parts of the Osceola 

National Forest located west and southwest of the 

Natural Area Roadless Area, but no lease applications 

have been filed for tracts within the area Although the 

phosphate in the roadless area is low grade, the entire 

area has a substantiated phosphate resource potential. 

Limestone in the Ocala Limestone underlies the entire 

523 
30° 

24' 

30° 

22' 

524 

82°22' 

<; n p 

MAP LOCATION 

0 

MILE 

Oc: , Bal 

08 

roximate roadless 

boundary 

EXPLANATION 

- Geologic terrane with substantiated 

low-grade phosphate resource 

potential 

X Sand pit 

D Swamp containing peaty material 

r<··. :_.··. I Sandy soil, organic rich and 

· locally water logged 

Contact 

Figure 153.- atural Area Roadless Area, Florida 
area, but is too deeply buried to be amenable to quarry. 

Peat material occurs in swamps in the area, but the 

deposits generally contain more than 25 percent ash, 

the current maximum cut off in commerical quality 

peat. 

Small quantities of heavy minerals occur in unconsolidated surficial sand in the Natural Area Roadless 

Area However, these heavy-mineral accumulations are 

much lower in grade than deposits currently being 

mined in the Trail Ridge district of Florida, and no resource potential was identified. 

According to the reports and records of the Florida 

Bureau of Geology, many exploratory holes have been 

drilled in the region surrounding the Osceola National 

Forest in search for oil and gas. To date, only a few 

shows of oil and gas have been found, and all of the 

holes have been dry. Only three of the 29 holes in the 

region were drilled deeper than 5000 ft; the deepest was 

5862 ft, one hole was 4444 ft deep, and all other holes 

were less than 3500 ft deep. Thirteen of the dry holes 

penetrated Paleozoic strata A driller's log of the St. 

Mary's River Oil Corporation well, located 35 mi northeast of the Natural Area Roadless Area, noted several 

shows of oil at depths between 1812 and 4795 ft and 

evidence of gas at two intervals. 

Although no potential for oil and gas was identified in 

the Natural Area Roadless Area, the possibilities cannot be completely ruled out. The principal reasons for an 

unfavorable outlook are the large number of dry holes in 

the region and the absence of the formations that contain oil and gas in the fields in southern and westernmost Florida The oil in the southern Florida fields is in 

Lower Cretaceous formations, and in the Jay field in the 

western Florida Panhandle it occurs in the Jurassic 

Smackover Formation. In the vicinity of the Osceola 

National Forest, the lowermost Upper Cretaceous formation rests unconformably on Paleozoic rocks. 

Some possibility remains, however, for the occurrence 

of oil and gas in deep rocks in the Natural Area 

Roadless Area The Paleozoic rocks have not been adequately explored in the region of the Osceola National 

Forest, and according to one authority, rocks of 

Paleozoic age in northern Florida and on the adjacent 

continental shelf should contain 100 million barrels of 

oil and 0.5 trillion cu ft of gas. The shows of oil and gas, 

like that in the St. Mary's River Oil Corporation dry 

hole located 35 mi northeast of the roadless area, suggest that valuable quantities of oil and gas may also be 

present in northern Florida The westward thinning of 

Cenozoic and Upper Cretaceous formations and the 

wedging out of Lower Cretaceous beds are excellent conditions for the occurrence of updip pinch-out sedimentary traps. Whether or not traps of this type are present 

in the subsurface of the Osceola Forest is unknown, but 

if they exist, they might contain hydrocarbons. 

SUGGESTIONS FOR FURTHER STUDIES 

Because of the blanket of surficial material covering 

the Natural Area Roadless Area, little could be accomplished by further field investigations and drilling 

would be required to obtain information about the 

geology and to assess the oil and gas potential. Many 

drill holes would be needed to adequately evaluate the 

phosphate potential of the area No reasons for investigating the possibilities for minerals other than 

phosphate are apparent. 

REFERENCES 

Crandall, T. M., 1981, Mineral resources of the atural Area RARE 

II further planning area; Baker County, Florida: U.S. Bureau of 

Mines Open· File Report MLA 30-81. 22 p. 

Cathcart, J. B., Patterson, S. H., and Crandall, T. M., 1983, Mineral 

resource potential map of the Natural Area Roadless Area: U.S. 

Geological Survey Miscellaneou s Field Studies Map 

MF - 1572-B, scale 1:24,000. 

Patterson. S. H., Cathcart, J. B .. Cameron, C. C., and Schruben, P. G., 

1983, Geology of the atural Area and the Big Gum Swamp 

Roadless Areas, Osceola National Forest, Columbia and Baker 

Counties, Florida: U.S. Geological Survey Miscellaneous Field 

Studies Map MF - 1572-A, scale 1:24,000. 

525 
/ 

/ 

JOO 05 .----~·"' 

526 

/ 

Pliocene Jacks6 n B~ luff Format· / 1on 

fJ'- -< 

0 

MILE 

F. Jgure 154.- Savannah Roadless Ar ea, Florida 

f 

( " 

Approximate b 

~01?.t. t'.s 

oundary 

MAP LOCATION 

Ent ire area is blank and Pleistocene clae ted by Holocene 

yey san d 
SAVANNAH ROADLESS AREA, FLORIDA 

By SAM H. PATTERSON ,

1 U.S . G EOLOG ICAL S RVEY and 

' 

THOMAS M. CRANDALL, U.S. B REA OF MIN E 

SUMMARY 

On the basis of a mineral survey in 1980 and 1981 the Savannah Roadless 

Area was appraised to offer little promise for the occurrence of mineral 

resources. The commodities identified in the area are deposits of sand and 

gravel; however, they are deeply buried, far from potential markets, and more 

readily accessible material exists outside the roadless area. The possibility that 

oil and gas might occur in the Jurassic Smackover Formation or in other formations at depth cannot be ruled out. 

CHARACTER AND SETTING 

The Savannah Roadless Area occupies about 3 sq mi 

in the Apalachicola National Forest, Liberty County, 

Florida, which is in the Big Bend region about 50 mi 

southwest of Tallahassee. The area is in lowlands of the 

Gulf Coastal Plain at altitudes of 25- 43 ft. It is bounded 

on two sides by USFS roads and on the third by County 

Highway 379. The area can be reached on County Highway 379 by traveling 6 mi northwest from Sumatra, a 

small village in southern Liberty County located on 

Florida Highway 65. No mineral materials other than 

clayey sand used in surfacing USFS roads and in highway construction have been produced within 25 mi of 

the Savannah area in recent years. In 1981 about 51 percent of the Savannah area was under simultaneous oil 

and gas lease, and an application for an oil and gas lease 

on an additional 6 percent of the area was on file. 

The mineral potential of the Savannah Roadless Area 

was investigated by the USGS and the USBM in 1980 

and 1981. Reports by Patterson and others (1982) and 

Crandall (1982), summarized herein, include the results 

of those studies. 

The entire Savannah area is blanketed by unconsolidated sediments overlying a thick sequence of sedimentary rocks that were deposited in the Apalachicola embayment. The surficial blanketing material consists of a 

thin soil horizon overlying a thickness of about 60 ft of 

Pleistocene-Holocene sand, gravel, and clay strata. The 

surficial materials overlie the Pliocene Jackson Bluff 

Formation, which consists of coarse sand-to gravel-size 

1

Wi1Jl contributions from Walter Schmidt. Florida Bureau of Geology. 

shell fragments, quartz sand, and clay, containing trace 

amounts of phosphate pellets, heavy minerals, and 

glauconite. The Jackson Bluff Formation forms the 

bedrock throughout the area and is underlain by a thick 

sequence of older sedimentary rocks. 

The Savannah area is located in the central part of the 

Apalachicola embayment that was formed by the structural depression of crustal rocks to form a deep basin. 

The embayment was filled by Triassic to Quaternary 

sediments having a total thickness of more than 

14,000 ft. Deeply buried strata along the axis of the embayment plunge about 65 ftJmi to the west-southwest. 

Shallow rocks, that were deposited after the embayment was mostly filled, dip only a few feet per mile 

toward the Gulf of Mexico. No faults have been recognized in the Savannah area 

MINERAL RESOURCES 

The only mineral commodity in the Savannah area is 

a subsurface bed of sand and gravel in the unconsolidated surficial materials (Patterson and others, 1982). 

Cuttings from one drill hole (18 on map) showed this bed 

to be 13 ft thick, lying at a depth of 37 to 50 ft, and to 

consist mostly of remarkably pure angular quartz; only 

17 percent of the sample was finer than coarse sand, and 

28 percent was gravel. Although the sand and gravel is 

more suitable for construction and other uses than that 

produced elsewhere in Florida, it is far from possible 

markets, under excessive thicknesses of overburden and 

more readily available material exists outside the 

roadless area 

527 
Extensive deposits of clayey sand of the type used in 

road construction and stabilizing occur in the Savannah 

area, and the sand is dug intermittently in two pits located 2 mi south of the area The clayey sand in the Savannah area was not identified as having resource 

potential as unlimited resources of such material are 

present in the surrounding region. 

Other industrial minerals-limestone, common clay, 

peat, and fuller's earth-are presently or have in the 

past been mined or investigated in the Big Bend region, 

but they either do not occur in the Savannah Area or are 

deeply buried. 

According to the reports and records of the Florida 

Bureau of Geology many exploratory wells have been 

drilled in search of oil and gas in the Big Bend region of 

Florida To date, only a few shows of oil have been 

found, and all of the holes have been dry. Thirty of the 

holes bottomed at depths of more than 5,000 ft. Of 

these, 15 were deeper than 10,000 ft and the deepest 

bottomed at 14,570 ft. Surprisingly, two shallow dry 

holes, located about 50 mi east of the Savannah Area, 

were reported to have good shows of oil. Oil stains were 

found in the Smackover Formation and in a conglomeratic calcareous sandstone of the Norphlet Formation 

also of Jurassic age in a dry hole located 20 mi westnorthwest of the Savannah area 

Although there are no reasons for optimism about the 

discovery of oil and gas in and near the Savannah area, 

the possibilities cannot be completely ruled out. Oil and 

gas are produced from the Smackover Formation in the 

Jay field in the westernmost Florida panhandle and 

nearby fields in Alabama Therefore, this formation 

may have some potential for oil and gas in the Big Bend 

region. The Smackover Formation, however, has been 

intersected by several dry holes in parts of the Big Bend 

region lying to the east, south, and west of the Savannah area Other reasons for not ruling out the potential 

528 

for oil and gas discovery in the Savannah Area include 

(1) the shows of oil in dry holes in the region noted in the 

foregoing paragraph, (2) uncertainties as to whether or 

not formations older than the Smackover may contain 

oil and gas, and (3) the geologic favorability of the 

region for the occurrence of both structural and sedimentary traps. The Savannah area and surrounding 

region has not been thoroughly explored, and insufficient data were obtained in this study to evaluate the oil 

and gas resource potential. 

SUGGESTIONS FOR FURTHER STUDIES 

Because of the blanket of surficial materials covering 

the Savannah Roadless Area the acquisition of further 

meaningful geologic information would require costly 

core drilling, and there seems to be little likelihood of 

discovery of valuable mineral deposits. The type of 

work that would be fruitful is the regional core drilling 

program now underway by the Florida Bureau of Geology, which includes several widely spaced drill holes. 

The products of this program will include significant improvement in knowledge of stratigraphy, structure, 

geologic history, and water- and mineral-resource potential of the region. 

REFERENCES 

Crandall, T. M., 1982, Mineral investigations of the Savannah RARE 

II Further Planning Area, Leon County, Florida; U.S. Bureau of 

Mines Open File ReportMLA 71 -82,20 p. 

Patterson. S. H., Schmidt, Walter, and Crandall, T. M., 1982, Mineral 

resource potential map of the Savannah Roadless Area, Liberty 

County, Florida; U.S. Geological Survey Miscellaneous Field 

Studies Map MF- 1470, scale 1:24,000. 

G E 0 

85° 

4. . 1 . 5 

. 7 8 • 6 • 

*ATLANTA 

530 

R G 1 

0 

L 

0 

Athens 

Location of areas studied. 

A 

50 

I I I _j 

MILES 

Augusta 

0 

1?t--~~ 
GEORGIA 

Map 

No. Name of Area 

1 Big Frog Wilderness Study Area and additions, Tennessee and GeorgiaSee Tennessee 

8 Blood Mountain Roadless Area 

6 Chattahoochee Roadless Area 

4 Cohutta Wilderness, Georgia and Tennessee, and Hemp Top Roadless 

Area, Georgia 

3 Ellicott Rock Wilderness and additions, South Carolina, North Carolina, 

and Georgia-See South Carolina 

2 Overflow Roadless Area, Georgia and North Carolina 

7 Rich Mountain Roadless Area 

5 Tray Mountain Roadless Area 

531 
532 

,, ,.--..... \ .......... ~~ -. \ 

\ Approximate I , J roadless boundary ~ 

\ 

\ 

/ 

/ 

--~ 

0 

MILES 

/ 

2 

EXPLANATION 

Great Smokey sheet Contact 

Hayesville sheet, schist • • Thrust fault --Sawteeth 

on upper plate Granitic gneiss L_ _ _.J 

Figure 155.-Blood Mountain Road.less Area, Georgia 

.., 
BLOOD MOUNTAIN ROAD LESS AREA, GEORGIA 

By R OBERT P. KOEPPE , 1 U.S. G EOLOG ICAL S R EY and 

' 

MICHELLE K. ARMSTRONG , U.S. B REA F MI NE 

SUMMARY 

A mineral-resource survey made in 1981 of the Blood Mountain Roadless 

Area, Georgia, indicates that there is little promise for the occurrence of mineral 

and energy resources. Natural gas may be present at great depth, perhaps 5 mi 

down and below the overthrust sheets of the Blue Ridge Mountains, but 

presently available information is not adequate to evaluate the resource potential of this commodity. 

CHARACTER AND SETTING 

The Blood Mountain Roadless Area occupies approximately 16 sq mi of Chattahoochee National Forest in 

the Blue Ridge Mountains of northern Georgia The 

area is centered about 12 mi south of Blairsville and 

covers parts of Lumpkin and Union Counties. U.S. 

Highway 19 closely parallels the area s eastern boundary, and Georgia Highways 60 and 180 are near its 

western and northwestern boundaries. A few secondary 

roads, as well as some logging and USFS roads, provide 

limited access to the fringe of the roadless area In addition, a number of foot paths, including the Appalachian 

Trail, provide access to some of the remote parts of the 

roadless area The terrane is heavily forested and characterized by rugged mountainous topography with narrow valleys, sharp ridges, and steep hill slopes. The 

highest altitude is 4458 ft on Blood Mountain and the 

lowest altitude is about 1800 ft on Dicks Creek at the 

southern edge of the area. Tributaries of the north flowing Nottely River, the northwest flowing Toccoa River, 

and the south flowing Chestatee River drain the area 

The Blood Mountain Roadless Area is underlain by 

polydeformed and metamorphosed rocks of the Tallulah 

Falls Formation of Proterozoic age. The Tallulah Falls 

Formation is part of the Hayesville sheet, one of several 

large crustal blocks emplaced by westward-directed 

movement over low-angle thrust faults in the southern 

Blue Ridge Mountains (Nelson, 1982). One of these 

faults, the Hayesville-Fries fault, separates rocks of the 

Hayesville sheet from rocks of the Great Smoky sheet, 

1

Contribul.ion from A. E. elson. USGS. and A. E. Sabin. USBM. 

about 0.5 mi north of the Blood Mountain Roadless 

Area However, rocks of the Great Smoky sheet are not 

exposed in the roadless area 

Rocks of the Tallulah Falls Formation within the 

roadless area consist of biotite gneiss, mica schist, 

metasandstone, quartzite, amphibolite, and minor calcsilicate layers. Granite and granodiorite gneiss are also 

present. In addition, pegmatite veins and pods of 

various sizes are widely dispersed throughout the area 

Migmatite of biotite gneiss and granitic gneiss are 

abundant. Metamorphic index minerals indicate that 

the assemblage is of sillimanite grade. Rocks within the 

roadless area are complexly deformed and large-scale 

fold interference patterns are commonly seen. All the 

rocks are jointed throughout the roadless area, and 

most joints are steeply inclined. Thin pegmatite and 

quartz veins occupy some of the early joints (Nelson, 

1983). 

A mineral-resource survey of the Blood Mountain 

Roadless Area was made by USGS and USBM personnel during the fall and winter of 1981. The survey included reconnaissance geologic mapping (Nelson, 1983), 

geochemical studies (Koeppen and Nelson, 1983), mine 

prospect examination (Armstrong and Sabin, 1983), and 

mineral-resource potential (Koeppen and others, 1983). 

The Federal Government owns 99 percent of the surface rights and about 87 percent of the mineral rights in 

the roadless area. The remainder are privately owned. 

Oil and gas lease applications were filed for approximately the southern two-thirds of the area, and 10-year 

leases were issued for about 1.3 sq mi in May 1982. At 

last report, no drilling for oil or gas has taken place on 

the leased tracts. There are no known prospects or 

mines within the roadless area 

533 
MINERAL RESOURCES 

The Blood Mountain Roadless Area lies within the 

northern Georgia pegmatite district (Lesure and 

Shirley, 1968). Mica occurrences in the roadless area are 

minor, poor quality, and low grade; no potential for mica 

resources was identified. 

Gneiss and schist suitable for crushed rock and aggregate underlie much of the roadless area Good 

sources for these materials abound throughout the 

region, closer to potential markets. 

The geologic studies, reconnaissance geochemical 

survey, and search for prospects (Koeppen and others, 

1983) indicate little promise for the occurrence of other 

mineral resources in the area 

Recent seismic studies (Cook and others, 1979) indicate that Paleozoic sedimentary rocks like those in the 

Tennessee Valley may underlie the overthrust rocks of 

the Blue Ridge Mountains of Georgia The Paleozoic 

rocks are buried by about 5 mi of metamorphic rocks, 

and temperatures and pressures probable at those 

depths suggests that any hydrocarbons present would 

be in the form of natural gas and not oil. The possibility 

of concentrations of gas in these rocks is uncertain; no 

reasonable assessment of the gas potential can be made 

on the basis of available information. 

SUGGESTIONS FOR FURTHER STUDIES 

Further seismic studies and exploratory drilling are 

needed to evaluate the gas potential of this part of the 

Eastern Overthrust Belt. 

534 

REFERENCES 

Armstrong, M. K.. and Sabin, A. E., 1983, Mineral investigation of 

Blood Mountain RARE II Further Planning Area and Raven 

Cliff RARE II Wilderness Area, Lumpkin, Union, and White 

Counties, Georgia: U.S. Bureau of Mines Open-File Report MLA 

2-83,22 p. 

Cook, F. A., Albaugh, D. S., Brown, L. D., Kaufman, Sidney, Oliver, 

J. E., and Hatcher, R. D., Jr., 1979, Thin-skinned tectonics in the 

Crystalline southern Appalachians; COCORP seismic-reflection 

profiling of the Blue Ridge and Piedmont: Geology, v. 7, no. 12, 

p. 563-567. 

Koeppen, R. P., Nelson, A. E., Armstrong, M. K., and Sabin, A. E., 

1983, Mineral resource potential map of the Blood Mountain 

Roadless Area, Union and Lumpkin Counties, Georgia: U.S. 

Geological Survey Miscellaneous Field Studies Map MF- 1503-C, 

1:30,000. 

Koeppen, R. P., and elson. A. E., 1983, Geochemical survey of the 

Blood Mountain Road.Jess Area, Union and Lumpkin Counties, 

Georgia: U.S. Geological Survey Miscellaneous Field Studies 

Map MF-1503-B, 1:30,000. 

Lesure, F. G., and Shirley, L. E., 1968, Mica, in Mineral resources of 

the Appalachian region: U.S. Geological Survey Professional 

Paper 580, p. 311-325. 

Nelson, A. E., 1982, Geologic map of the Tray Mountain Road.Jess 

Area: U.S. Geological Survey Miscellaneous Field Studies Map 

MF -1347-A, scale 1:30,000. 

Nelson, A. E., 1983, Geologic map of the Blood Mountain Road.Jess 

Area, Union and Lumpkin Counties, Georgia: U.S. Geological 

Survey Miscellaneous Field Studies Map MF - 1503-A, scale 

1:30,000. 
CHATTAHOOCHEE ROADLESS AREA, GEORGIA 

By ARTHUR E. ELSO , 1 U .. GEOL GI AL SUR EY, and 

ROBERT A. WELSH , JR. , U.S. BUREAU OF MINE 

SUMMARY 

A mineral survey made in 1981 indicates that the Chattahoochee Roadless 

Area, Georgia, offers little promise for the occurrence of mineral resources even 

though gold, mica, sillimanite, soapstone, dunite, chromite, and nickel have been 

mined nearby, and source rocks for these commodities are present in the 

roadless area Granite gneiss, gneiss, schist, and metasandstone in the roadless 

area are suitable for stone, crushed rock, or aggregate; however, other sources 

for these materials are available outside the roadless area, closer to present 

markets. The potential for the occurrence of hydrocarbons (probably gas) 

beneath the thick regional thrust sheets in this area cannot be adequately 

evaluated from available data 

CHARACTER AND SETTING 

The Chattahoochee Roadless Area occupies approximately 36 sq mi in the Chattahooche National Forest, 

centered about 12 mi southeast of Blairsville, Georgia 

The terrane is heavily forested, has a rugged topography with narrow valleys, sharp ridges, and steep 

slopes. In places, the slopes exceed 45 o, whereas commonly they range from 20 to 30°; rarely are they less 

than 10°. The roadless area occupies parts of Towns, 

White, and Union Counties. The highest altitude is 4045 

ft on Horsetrough Mountain and the lowest is about 

1664 ft in Horton Creek west of Helen in the southern 

part of the area Tributaries of the north-flowing 

Hiwassee River, the south-flowing Chattahoochee 

River, and the northwest-flowing Nottely River drain 

the Chattahoochee Roadless Area 

Georgia State Routes 17, 66, 180, and the Richard 

Russell Highway (348) lead to a few secondary, logging, 

and USFS roads that provide limited access to the 

roadless area In addition, the Appalachian Trail 

traverses part of the area's high ground. 

The Chattahoochee Roadless Area is underlain by 

Precambrian metamorphic rocks that form two thrust 

sheets. The northwest border of the roadless area is 

underlain by part of a narrow thrust sheet of maficultramafic rocks that includes serpentinite, dunite, 

pyroxenite, and gabbro. The rest of the roadless area is 

underlain by rocks of the Hayesville thrust sheet that 

1

WiUt conlribuuons from ROOert P. Koeppen. USGS. and Ronald W. Mikolajczyk. U BM. 

includes mafic and felsic gneisses, schist, metasandstone, and granitic gneiss. About 300ft southeast of the 

roadless area the Shope Fork fault juxtaposes the 

Hayesville sheet against the lower-grade metamorphic 

rocks of the Helen belt (Nelson, 1983), which includes 

metasandstone, schist, and mafic gneiss. 

Rocks underlying the roadless area have been complexly folded and faulted. Some exposures show that 

the rocks have been deformed by as many as five 

generations of folding. The second generation folds form 

the regional folds with northeast-trending fold axes. 

Numerous thrust faults characterized the terrane surrounding the roadless area, but except for the faults 

bounding the Hayesville sheet in and near the roadless 

area, other faults with large displacements were not 

observed. However, numerous small faults with displacements ranging from several inches to 4 ft or more 

are common. Locally some ductile shear and mylonite 

zones are also present. 

Rocks of the Hayesville sheet within the roadless area 

are in the sillimanite zone of regional metamorphism, as 

all compositionally favorable rocks contain sillimanite. 

The rocks are highly migmatitic and contain many irregular granitic masses. In addition, anatectic melt 

material and feldspathic segregations are widespread. 

Sillimanite which is widely distributed is commonly 

present in rocks with a low muscovite content. These 

rocks were probably metamorphosed about 450 to 480 

million years ago, during the Taconic orogeny. The 

granitic rocks and pegmatites were probably intruded 

near the peak of metamorphism. 

535 
536 

34° 

50' 

MAP LOCATION 

0 2 

MILES 

EXPLANATION 

Mafic-ultramafic rocks 

Helen Belt 

Hayesville Thrust Sheet 

• • Thrust fault--Sawteeth on upper plate 

Figure 156.-Chattahoochee Roadless Area, Georgia 
The Hayesville thrust sheet, the mafic-ultramafic 

rocks as well as the adjoining Helen belt together form a 

series of thrust slices that overlie younger Paleozoic 

rocks along a master decollement. This thrust fault 

decollement, based on projections of seismic data, is 

believed to be nearly 5 mi below the surface of the 

roadless area 

The Federal Government owns surface rights to more 

than 99 percent of the roadless area Mineral rights are 

71 percent Federally owned and 29 percent privately 

owned. There is no mining activity of record in the roadless area Oil and gas exploration permits are held on 0.2 

sq mi and applications are pending on about 8.2 sq mi in 

the roadless area 

MINERAL RESOURCES 

The roadless area is underlain by rock types that contain mineral deposits outside the area Within 1 mi of 

the area's boundary, gold, mica, and construction stone 

have been mined (Welsh and Mikolajczyk, 1982; Nelson 

and others, 1983). The most recent mining near the 

roadless area was a small-scale gold placer operation 

located about 3 mi to the southeast in the Helen belt. 

Gold mining in the Helen belt has occurred intermittently for the past 150 years. Placer deposits in 

tributary valleys of the Chattahoochee River as well as 

veins, and saprolite were mined for gold. Within the 

roadless area only one particle of gold was found in the 

stream-sediment samples, and gold resources are considered unlikely. Muscovite mica was mined from 

pegmatites in Union County, where some mica sheets 

were 12 to 15 in. across. Pegmatites in the roadless area 

are small unzoned pods or veins and the observed 

muscovite rarely exceeds 3 in. in diameter. The mica 

and sillimanite from occurrences in the roadless area are 

of poor quality and low grade. A small stone quany is 

present along the eastern boundary of the roadless area 

but has not been recently worked. Much of the rock 

underlying the roadless area is suitable for use as 

crushed stone or aggregate. Good sources for these 

materials also are known closer to present markets outside the roadless area 

Farther to the east and northeast of the roadless area 

in the Hayesville thrust sheet, some bodies of maficultramafic rock have been mined for asbestos, olivine, 

and chromite. Numerous mafic-ultramafic bodies are 

widely dispersed throughout the Hayesville thrust 

sheet; they vary in size, ranging from a few feet in width 

and several tens of feet in length to some that cover 

several square miles. The mafic-ultramafic rocks present along the northwest boundary of the roadless area 

includes thin bands of impure dunite and soapstone; 

sparsely disseminated chromite and nickel are present 

as accessory minerals. Samples from the ultramafic 

rocks show the soapstone and dunite to be of poor quality and the chromite and nickel contents are low; no 

resource potential was identified. 

A reconnaissance geochemical survey was undertaken 

to determine if any unidentified mineral deposits exist 

within the roadless area (Koeppen and Nelson, 1983). 

Samples of bedrock, stream sediment, and panned concentrates were analyzed by 31 element emission spectrographic method. Most of the samples contain normal 

chemical abundances and distribution. Nonmagnetic 

splits from several panned concentrates of streams 

along the southern edge of the area have moderately 

enriched abundance of tin (200 to 300 parts per million), 

but no other evidence was found for concentration of 

metals in rocks of this area It is unlikely that any 

metallic mineral resource occurs within the roadless 

area 

Sedimentary rocks that contain hydrocarbons in the 

Tennessee Valley may form a part of the Paleozoic rocks 

that underlie rocks of the Hayesville thrust sheet, the 

mafic-ultramafic bodies, and the Helen belt in the vicinity of the roadless area The Paleozoic rocks lie below a 

nearly 5 mi thickness of metamorphic rocks in thrust 

sheets of the Blue Ridge. As little is known about these 

rocks, their hydrocarbon resource potential cannot be 

evaluated. 

REFERENCES 

Koeppen, R. P., and Nelson, A. E .. 1983, Geochemical survey of the 

Chattachoochee Roadless Area. Towns, Union, and White Coun· 

ties, Georgia: U.S. Geological Survey Miscellaneous Field 

Studies Map MF - 1502-B, scale 1:30,000. 

Nelson, A. E., 1983, Geologic map of the Chattahoochee Roadless 

Area. Towns, Union, and White Counties, Georgia: U.S. Geolog· 

ical Survey Miscellaneous Field Studies Map MF- 1502-A, scale 

1:30,000. 

Nelson, A. E., Koeppen, R. P. Welsh, R. A., Jr., and Mikolajczyk, 

R. W., 1983, Mineral resource potential map of the Chattahoochee Roadless Area. Towns, Union, and White Counties. Georgia: 

U.S. Geological Survey Miscellaneous Field Studies Map 

MF - 1502- C, scale 1:30,000. 

Welsh, R. A., Jr., and Mikolajczyk, R. W., 1982, Mineral investigation 

of Chattahoochee River RARE I I Further Planning Area. 

Towns, Union, and White Counties, Georgia: U.S. Bureau of 

Mines Open-File Report MLA 140-82,25 p. 

537 
538 

84 ·~o~·--------------------------------------------------------------------------------~s4~·r _· __________ -, 

; .... ·: . . ··. · . . · ... . .. . :: .. ·.: 

.: .. :: ;; 

.. 

road less 

boundary 

'i ·:: .. :.;::·.-· · .... ·.._:::·:.·:·:::.~ .. -::.· :~.··.···; . ::.::·.~~·~:?·.· :: .. :: .... ···:.··· . . ~~,;,;,o,.-........ .;,~ ·;;-:-· : .::.... . • .. .- .. :: ... ::·."·:'.,=.:.::·.· .. ·.··:·: ..... 

Approximate 

boundary 

MAP LOCATION 

5034 ' °L-------------------------------------------------------------------------------------L------------~ 

0 3 

MILES 

EXPLANATION 

CJ Slightly metamorphosed sandstones, 

si ltstone, shale, and conglomerate 

--- Contact 

---Fault 

Shale and siltstone • • • Thrust fault- Sawteeth on upper plate 

Figure 157.-Cohutta Wilderness, Georgia and Tennessee, and Hemp Top Roadless Area, Georgia 
COHUTTA WILDERNESS, GEORGIA AND TENNESSEE 

AND HEMP TOP ROADLESS AREA, GEORGIA 

By jACOB E. GAIR,

1 U.S . GEOLOGICAL t.:~ , and 

GERTRUDE C. GAZDIK, U .S . BUREAU OF MINES 

SUMMARY 

A survey done between 1977 and 1979 has found little or no promise for the 

occurrence of metallic mineral-resources in the Cohutta Wilderness and the adjacent Hemp Top Roadless Area The Cohutta Wilderness is located mainly in 

northern Georgia and extends a small distance into southeastern Tennessee; the 

Hemp Top Roadless Area borders part of the Cohutta Wilderness on the east 

and extends southward from the Georgia-Tennessee line. The study area is 

underlain by slightly metamorphosed folded and faulted sedimentary rocks of 

late Precambrian age. The Ducktown mining district, Tennessee, lies only ten 

miles to the northeast, but apparently the Ducktown mineral-rich zone does not 

reach into the study area No energy-resource potential was identified by this 

survey. 

CHARACTER AND SETTING 

The Cohutta Wilderness is an area of about 55 sq mi 

wholly within rugged mountainous and wooded country 

in northern Georgia and southeastern Tennessee about 

6 mi south of the Ocoee River gorge. The adjacent 

Hemp Top Roadless Area is about 4-112 sq mi in size. 

The north edge of the study area is 22 mi southeast of 

Cleveland, Tennessee, and 10 mi southwest of Ducktown. The most conspicuous landmark in the area, Big 

Frog Mountain, is on the north boundary of the Wilderness. South of the Big Frog Mountain, Hemp Top is a 

prominent high point along the steep-sided, southtrending Blue Ridge on the boundary between the wilderness and the roadless area Several other steep northsouth ridges cross the area The principal streams are 

Jacks River and Conasuaga River which flow generally 

northwestward across the area Unpaved roads reach 

points on the wilderness boundary and extend along 

parts of the boundary, from paved highways that surround the area Most travel within the wilderness must 

be done on foot. 

The study area is underlain by folded and faulted 

slightly metamorphosed sedimentary rocks of late 

Precambrian age that belong to the Ocoee Supergroup. 

'Assisted by J. F. Slack, Richard Ketelle, Andrew Grosz. Timothy Muzik. Thomas Hanley. 

Donald Henry. Ann Stevenson. and Gregory MOI"ley. USGS. and Maynard L. Dunn. J r .. 

USBM. 

In a large part of the area these rocks consist of an interlayered sequence of impure sandstones (mixtures of 

quartz and feldspar sand grains, clay, and mica flakes), 

siltstone, shale, and pebbly conglomerate. Many rock 

layers contain scattered iron sulfide grains of pyrite and 

pyrrhotite (from traces to a few percent), but the rocks 

display no other evidence of metallic mineral content, 

and the iron sulfide content, unaccompanied by significant amounts of base metals, is too low to be classified 

as having a resource potential. These sandstones and 

other sedimentary rocks are complexly faulted by 

thrusting from the east and all the rocks of this interlayered sequence have been moved westward on thrust 

faults. Below the principal thrusts, there are green and 

dark-gray to black pyrite-bearing shales and siltstones. 

These shales and siltstones are found principally in and 

near valley bottoms in the western part of the area 

MINERAL RESOURCES 

A mineral-resource survey of the Cohutta Wilderness 

and Hemp Top Roadless Area was made between 1977 

and 1979 by the USGS and the USBM. Reports on this 

survey have been published (Gair and others, 1982; Gair 

and Slack, 1982; Gair, 1982). 

Rocks of the Ocoee Supergroup contain the massive 

sulfide deposits at Ducktown and smaller deposits such 

539 
as those about 80 mi to the northeast of the study area 

near the Fontana Reservoir. The specific rock formations which contain the copper-zinc and massive ironsulfide mineralization at Ducktown appear to be confined to a belt east of the study area The Ocoee rocks 

are also the source for placer gold deposits at Coker 

Creek a few miles north of Ducktown. The gold particles 

in those placers came either from certain layers of the 

Ocoee or from quartz veins that penetrate the Ocoee 

rocks. Ocoee rocks should not be categorized as having 

mineral-resource potential merely because deposits exist in some places in these rocks. Supporting evidence 

such as visible mineralization or geochemical or 

geophysical anomalies is necessary if the specific areas 

being evaluated are to be classed as having resource 

potential. 

No visible mineralization was seen in the area other 

than the minor disseminated iron sulfides typical of the 

Ocoee rocks, and a few minor concentrations of iron 

oxides near faults. The latter occurrences are similar to 

those in the Alaculsy Valley a few miles west of the 

wilderness, although smaller, and probably result from 

the concentration of limonite along faults formed by 

weathering of iron silicate minerals and the disseminated iron sulfides from the Ocoee rocks. The iron content in these faults is highly variable, volume is small, 

impurities are high, and no iron resource potential was 

identified for these occurrences. 

During the wilderness survey, samples of stream sediment, soil, and rock were collected in the Cohutta 

Wilderness and Hemp Top Roadless Area, and were 

spectrographically analyzed to determine the relative 

amounts of 30 elements in each sample. On the average, 

a few samples of each type were taken from each square 

mile of the study area, and sediment was sampled from 

virtually every stream course longer than 2000 ft. In 

addition, three concentrate samples of heavy minerals 

were obtained by panning stream sediments in the westem part of the Cohutta Wilderness. It is likely that any 

mineral deposit of significant size close enough to the 

surface to be affected by weathering would be respresented by characteristic minerals or trace elements in 

one or another of the materials sampled. Relatively 

large amounts of some trace elements were found in a 

few isolated samples, but most of these occurrences are 

interpreted as not indicating the existence of undiscovered mineral deposits and no mineral-resource potential was identified. 

High background amounts of cobalt and nickel occur 

in several samples within an area in the northeast part 

of the Cohutta Wilderness. The presence in this area of 

high background amounts of these two different trace 

elements that are often associated in nature constitutes 

540 

a weak geochemical anomaly, but no resource potential 

was identified. 

About 36 of the approximately 900 samples collected 

contain barely detectable or small measurable amounts 

of gold. These sample sites are widely separated from 

one another and there is no indication that gold occurrences are localized in any particular part of the study 

area Such a localization would suggest a source of 

significant size which might have resource potential. 

The scattered distribution of gold-bearing samples actually observed and the very small amounts of gold in 

the samples indicate that the gold in the samples 

represents insignificant occurrences- probably isolated 

small quartz veins containing some disseminated flakes 

of gold and (or) local zones in Ocoee sedimentary rock 

that contain small amounts of disseminated gold. There 

is little promise for the occurrence of gold resources in 

this area 

In the western part of the Cohutta Wilderness anomalous amounts of tin were found in several samples of 

soil, rock, and stream sediment, and in the magnetic 

fraction of panned concentrates from three streamsediment samples. The largest values for tin occur in the 

magnetic material most likely in the mineral magnetite. 

The tin resource potential tends to be negated because 

the tin in magnetite is not recoverable. The tin-bearing 

samples are widely separated, with numerous tin-barren 

samples in between, so it is likely that the sources of tin 

are local and small. This consideration and the pre ence 

of the tin in the magnetic parts of the panned concentrate samples suggest that there is little promise for the 

occurrence of tin resources in the western part of the 

wilderness. 

SUGGESTIONS FOR FURTHER STUDIES 

Detailed sampling in the vicinity of the known goldbearing and tin-bearing samples might outline small 

areas of low-grade mineralization, but it is unlikely that 

such mineralization would constitute a significant mineral resource. 

Recent seismic studies (Cook and others, 1979) indicate that the slightly metamorphosed rocks of the 

Cohutta-Hemp Top area have been moved a 100 mi or 

more westward on major thrust faults over younger 

nonmetamorphosed sedimentary rocks. The sedimentary rocks which are buried many thousands of feet 

beneath the surface of the Cohutta area have an 

unknown potential for oil and gas-probably gas at the 

inferred depth of burial and temperatures implicit at 

such depth. This potential could only be verified by a 

program of deep drilling. 
REFERENCES 

Cook, F. A., Albaugh, D. S., Brown, L. D., Kaufman, Sidney, Oliver, 

J. E., and Hatcher, R. D., Jr., 1979, Thin-skinned tectonics in the 

crystalline southern Appalachians-COCORP seismic-reflection 

profiling of the Blue Ridge and Piedmont: Geology, v. 7, 

p. 563- 567. 

Gair, J. E., Gazdik, G. C., and Dunn, M. L., Jr., 1982, Mineral resource 

potential map of the Cohutta Wilderness and the Hemp Top 

Roadless Area, northern Georgia and southeastern Tennessee: 

U.S. Geological Survey Miscellaneous Field Studies Map 

MF- 1415-C, scale 1:48,000. 

Gair, J. E., and Slack, J . F .. 1982, Geology of the Cohutta Wilderness 

and the Hemp Top Roadless Area, northern Georgia and southeastern Tennesee: U.S. Geological Survey Miscellaneous Field 

Studies Map MF- 1415- A, scale 1:48,000. 

Gair, J . E., 1982, Geochemical survey of the Cohutta Wilderness and 

Hemp Top Roadless Area, northern Georgia and southeastern 

Tennessee: U.S. Geological Survey Miscellaneous Field Studies 

Map MF- 1415- B, scale 1:48,000. 

541 
542 

MAP LOCATION 

0 

' \ 

\ 

Ftote: \ ---?"'h \ "'--------

MILES 

EXPLANATION 

I -,,-

'fi~\(-11 Granite and granodiorite gneiss 

_,_ 1 (Proterozoic) 

2 

Schist and gneiss (Proterozoic) 

CJ Granite Schist and Amphibolite (Proterozoic) gneiss and biotite gneiss 

(PrQterozoic) ---- Contact 

Figure 158.- 0verflow Roadless Area, Georgia and North Carolina 
OVERFLOW ROADLESS AREA, GEORGIA AND NORTH CAROLINA 

By R OBERT P. KOEPPEN,

1 U .S. G EO LOG I AL S R EY a nd 

M ICHAEL P. DA I , .S. B REA O F MIN E 

SUMMARY 

The Overflow Roadless Area in the Blue Ridge Mountains of Georgia and 

North Carolina is underlain by complexly folded schist and gneiss of Proterozoic 

age. A mineral-resource survey done between 1980 and 1982 found little 

likelihood for the occurrence of mineral or energy resources in the area. Minor 

isolated localities of mica pegmatite and amethyst gemstone occur in the area 

Gneiss and schist suitable for rock aggregate are present in large quantities, but 

similar rocks abound outside the area Natural gas may possibly be present at 

great depth beneath the overthrust of the Blue Ridge, but presently available information is not adequate to evaluate this potential. 

CHARACTER AND SETTING 

The Overflow Roadless Area consists of 7.5 sq mi in 

the Chattahoochee National Forest of Rabun County, 

Georgia, and 5 sq mi of adjacent Nantahala National 

Forest, Macon County, North Carolina The area is 

centered about 4 mi southwest of Highlands, North 

Carolina, and about 12 mi northeast of Clayton, 

Georgia, in the eastern Blue Ridge Mountains. North 

Carolina Route 106 forms the northern boundary of the 

area, while Georgia and North Carolina Route 28 lies 

somewhat to the east. Three USFS roads, 86B, 86D, 

and 79, provide limited access to the central part of the 

roadless area 

The highest altitude is about 4170 ft on Chinquapin 

Mountain on the northern edge of the area, and the 

lowest altitude is about 1610 ft in the West Fork of the 

Chattooga River at the southern end of the area The 

terrane is heavily forested and characterized by rugged 

topography with sharp to rounded crests capping steep 

valley slopes. In the southern part of the area the 

topography is dominated by the cliff-bound walls of the 

deeply incised West Fork of Chattooga River and its 

tributary, Overflow Creek, which drains the center of 

the roadless area and from which the area takes its 

name. 

Mineral-resource surveys of the Overflow Roadless 

Area were made by the USGS during 1981 and 1982, 

and by the USBM during 1980. This survey included 

'With contributions from A. E. Nelaon. USGS. 

reconnaissance geologic mapping (Nelson and Koeppen, 

1983), geochemical studies, mine and prospect examination, and evaluation of mineral-resource potential. 

The Federal Government owns all surface and mineral 

rights within the Overflow Roadless Area There are 

currently no outstanding prospecting or mining permits 

nor have there been any recent applications. 

The bedrock in the roadless area is the severely 

deformed and metamorphosed Tallulah Falls Formation 

of Galpin (1915), originally sedimentary and minor 

volcanic rocks of Proterozoic age. The principal rock 

types are schist, gneiss, amphibolite, metasandstone, 

metagraywacke, and minor quartzite. Sparce metamorphic index minerals indicate the assemblage is kyanite 

or sillimanite grade. Variable sized bodies of granite, 

granodiorite gneiss, and migmatite, and veins and pods 

of pegmatite and quartz are numerous and widely scattered through the roadless area Several small bodies of 

mafic and ultramafic rock are present nearby and may 

also be present in small undetected pods within the 

area 

Complex fold interference patterns indicate the rocks 

have been deformed by several generations of folding. 

Jointing in the rocks is ubiquitous throughout the roadless area Thrust faults are common in the Southern 

Appalachian Mountains, but faults displacing map 

units in the Overflow Roadless Area have not been observed. Some minor shear zones and faults with relatively small displacements occur in individual 

exposures. 

543 
MINERAL RESOURCES 

The Overflow Roadless Area lies within the westernmost monazite belt of Mertie (1979, p. 66), and immediately west of the Hall County Gold Belt, a 2-mi-wide 

band of isolated auriferous veins and associated stream 

placers (Yeates and others, 1896). A geochemical survey 

of rock, panned concentrate, and stream-sediment 

samples indicates little promise for the occurrence of 

monazite, gold, or other metallic mineral resources in 

the roadless area 

The roadless area includes a part of the Rabun 

pegmatite district, a region of poorly exposed and 

weathered pegmatites (Lesure and Shirley, 1968). 

Greenish-brown bent and ruled sheet mica was encountered in scattered localities within the roadless 

area, but all occurrences are small and low grade. 

Amethyst is present at a small number of localities 

marked by spoil piles along the northern edge of the 

roadless area The amethyst occurs in minor quartz 

veins associated with a small, highly deformed body of 

granitic gneiss present there. The area remains of interest to amateur gemstone collectors, but based on 

reconnaissance examination there seems little likelihood 

for the occurrence of gemstone resources. 

Gneiss and schist in the roadless area are suitable for 

use as crushed rock or aggregate. However, similar 

stone is abundant throughout the region. 

Recent seismic studies (Cook and others, 1979) indicate that Paleozoic, possibly hydrocarbon-bearing, 

sedimentary rocks may underlie the overthrust rocks of 

the Blue Ridge Mountains of Georgia The Paleozoic 

rocks are buried by 5 mi or more of metamorphic rock 

and the implied temperatures and pressures at these 

depths suggest any hydrocarbons present would be in 

the form of natural gas and not oil. The possibility of 

544 

finding concentrations of gas in these rocks cannot be 

evaluated from available information. 

SUGGESTIONS FOR FURTHER STUDIES 

Further seismic studies and exploratory drilling are 

needed to evaluate the natural gas potential of this part 

of the Eastern Overthrust Belt. 

REFERENCES 

Cook, F. A., Albaugh, D. S., Brown, L. D., Kaufman, S. Oliver, J. E .. 

and Hatcher, R. D., Jr., 1979, Thin-skinned tectonics in the crys· 

talline southern Appalachians-COCORP seismic-reflection pr<r 

filing of the Blue Ridge and Piedmont: Geology, v. 7, no. 12, 

p. 563-567. 

Davis, M. P., 1982, Mineral resources of the Overflow further plan· 

ning area, Rabun County, Georgia. and Macan County, orth 

Carolina: U.S. Bureau of Mines, Open·File Report MLA 31 - 82. 

Galpin, S. L., 1915, A preliminary report on the feldspar and mica 

deposits of Georgia: Georgia Geological Survey Bulletin 30. 

Koeppen, R. P., Nelson, A. E .. and Davis, M. P., in press, Mineral 

resource potential map of the Overflow Roadless Area. Rabun 

County, Georgia and Macon County, North Carolina: U.S. Geological Survey Miscellaneous Field Studies Map MF- 1618- A, 

scale 1:48,000. 

Lesure, F. G., and Shirley, L. W., 1968, Mica, in Mineral resources of 

the Appalachian region: U.S. Geological Survey Professional 

Paper 580, p. 311 - 325. 

Mertie, J. B., Jr., 1979, Monazite in the granitic rocks of the 

southeastern Atlantic states-an example of the use of heavy 

minerals in geologic exploration: U.S. Geological Survey Profes· 

sional Paper 1094, 79 p. 

Nelson, A. E., and Koeppen, R. P., 1983, Geologic map of the 

Overflow Roadless Area, Rabun County, Georgia and Macon 

County, North Carolina: U.S. Geological Survey Miscellaneous 

Field Studies Map MF-1608-A, scale 1:48,000. 

Yeates, W. S., McCallie, S. W., and King, F. P., 1896, A preliminary 

report on a part of the gold deposits of Georgia: Geological 

Survey of Georgia Bulletin 4-A, p. 80-100. 
RICH MOUNTAIN ROADLESS AREA, GEORGIA 

By MICHAEL P . FOOSE, U .S. G EOLOGICAL S R EY and 

' 

R OBERT M . T HOMPSO , U. S. B REA OF Mlt ES 

SUMMARY 

A mineral-resource survey of the Rich Mountain Road.less Area, Georgia, carried out in 1981, shows it to have little promise for the occurrence of mineral or 

energy resources. Stone for aggregate resources occur in the area, but abundant 

alternative sources of crushed stone exist in nearby areas. Rocks underlying the 

area are partly correlative with those that are known to host stratabound basemetal deposits, but no evidence for this type of mineralization was found, and no 

resource potential for this type of deposit was identified in this study. Recent 

seismic surveys indicate that natural gas may exist in this region at depths of 

between 5000 and 45,000 ft; deep drilling would be needed to evaluate the potential for this resource. 

CHARACTER AND SETTING 

The approximately 26.4 sq mi which make up the 

Rich Mountain Road.less Area are located in the Chattahoochee National Forest, Gilmer and Fannin Counties, 

Georgia The area is situated between the towns of Blue 

Ridge and Ellijay, Georgia, and has an irregular boundary that is east of U.S. Highway 76, south of County 

Highway 153, and north and west of County Roads 216 

and S1010. Numerous small roads extending in from 

this perimeter provide good access to the edges of the 

road.less area However, only one very rough road provides access to the central part of the area 

Topography is moderately rugged with altitudes 

ranging from 1600 ft to 4080 ft. Slopes steeper than 20 ° 

are common. Although maximum relief is in excess of 

2400 ft, local relief is on the order of 800 to 1800 ft. 

Second growth of hardwood forests cover most ridges, 

while drainages often have heavy growths of laurel and 

rhododendron. Trails and abandoned logging roads 

allow good foot access within most of the road.less area 

The mineral-resource survey of the road.less area was 

made in the fall of 1981 and consisted of geologic mapping, geochemical studies, and examination of mines 

and prospects in and near the area Results of these 

studies have b~n published (Foose, 1983; Foose and 

Sears, 1983; Foose and Thompson, 1983; Thompson and 

Girol, 1982). 

The Federal Government owns about 99 percent of 

the surface rights and 96 percent of the mineral rights in 

the road.less area The outstanding 1 percent of the surface rights, with accompanying mineral rights, are privately owned. Oil and gas lease applications, filed in 

1979 and 1980, include about 96 percent of the Federal 

mineral rights. 

Three rock units are recognized within the road.less 

area The lower two (Hothouse and Dean Formations) 

are predominantly sequences of metasandstones, metasiltstones, and schists of Precambrian age that are part 

of the Great Smoky Group. They are overlain by the 

Cambrian(?) Nantahala Slate which is mostly carbonaceous slates. 

Subsequent to deposition of the original sediments, 

the rocks experienced multiple deformation. The first 

and most intense folding generated northeast-trending, 

step-shaped folds that have anticlines with relatively 

long gently dipping southeast limbs and relatively 

short, steeply dipping northwest limbs. These folds 

form a large anticline that passes through the center of 

the road.less area and is gently cross folded by a later 

period of northwest-trending folds. Fault offsets have 

not been recognized. 

Mineral assemblages are characteristic of the amphibolite facies of metamorphism. Isotopic ages from 

other parts of the Blue Ridge province indicate that 

peak metamorphism occurred about 450 million years 

ago, during the Taconic orogeny. 

The reconnaissance geochemical sampling of this area 

did not reveal evidence of mineralization or even the 

presence of unusual concentrations of metallic elements. 

545 
546 

~---..... I 

I 

0 

Approximate roadless 

boundary 

--'- 08143 

"'--- ~ 

I 

I 

I 

I 

. / -\. ~-,, ~--' 

ff) 

-' 

--

r-J 

y I , __ _.: _____ J 

I 

I 

I 1 

L--""' 

MAP LOCATION 

2 

MILES 

EXPLANATION 

D Dean Formation, mostly schist (Precambrian) 

Hothouse Formation, mostly metasiltstones 

(Precam brian) 

Contact 

Figure 159.-Rich Mountain Roadless Area, Georgia 
Local concentrations of high background values can 

mostly be explained as resulting from chemical variations associated with bedrock. 

Considerable mineral-related activity has occurred adjacent to the roadless area and includes mining of gold, 

iron, manganese, talc, and marble, and prospecting for 

copper and silver. Stone for road aggregate is extracted 

from a quarry on White Path Creek, close to the roadless area's western margin. The sites of all these activities are confined to stratigraphic units that are not 

present in the roadless area, and therefore these activities are not considered to reflect potential for similar 

resources within the roadless area 

MINERAL RESOURCES 

The geologic and geochemical surveys indicate little 

promise for the occurrence of mineral resources within 

the Rich Mountain Roadless Area Sandstones occur 

within parts of the Great Smoky Group and may provide a source of crushed stone. However, little chance 

exists that these would be used as they are relatively 

inaccessible, and occur as discontinuous lenses. More 

easily worked sources of stone are readily available outside the roadless area 

Rocks of the Great Smoky Group host major basemetal sulfide deposits. However, the formation in which 

this stratabound mineralization occurs is stratigraphically below rocks in the roadless area Further, Great 

Smoky Group rocks around Rich Mountain contain only 

trace amounts of sporadically distributed iron sulfides, 

have no significant metal anomalies, and show no 

unusual concentration of minerals that are commonly 

associated with base-metal sulfide deposits. Although a 

possibility exists for resources at depth, no evidence for 

this type of mineralization was identified in this study. 

Gold is reported as occurring in placers along streams 

issuing from the roadless area and in veins located 

south and east of the area Placers on White Path Creek, 

near the roadless area's west margin, produced 5000 

troy oz of gold, and four of the five largest gold nuggets 

found in Georgia, one of which weighed 4.5lbs. Searches 

for a vein source of this gold have been unsuccessful. It 

has been postulated that the source was gold-bearing 

veins that have subsequently been eroded away. 

Gold or its companion element, silver, were not detected in any samples. All samples of vein quartz were 

barren of sulfides and had only trace amounts of metals. 

Careful processing of the heavy fraction of stream 

sediments, both by panning and by laboratory heavyliquid separation, failed to identify concentrations of 

gold. No gold resource potential was identified in this 

study. 

Recent seismic profiles across the southern Appalachians have generated much interest in oil and gas 

exploration. These studies (Cook and others, 1979) show 

the metamorphic rocks in this region to be thrust over 

well-layered sedimentary rocks that occur between 5000 

and 45,000 ft below the surface. The possibility of 

hydrocarbons occurring in these layered sediments is 

under investigation; however, the depth and temperatures at which they occur make existence of liquid 

hydrocarbons unlikely. Natural gas, however, could be 

present. At this time, no reasonable estimate of this 

resource can be made. 

SUGGESTIONS FOR FURTHER STUDIES 

Deep drilling would be necessary to evaluate the 

natural-gas potential of sedimentary rocks at depths of 

5000 to 45,000 ft below the surface. 

REFERENCES 

Cook. F. A., Albaugh, D. S., Brown, L. D .. Kaufman, S., Oliver, J. E., 

and Hatcher, R. D., Jr., 1979, Thin-skinned tectonics in the crys· 

talline southern Appalachlans; COCORP seismic-reflection profiling of the Blue Ridge and Piedmont: Geology, v. 7, no. 12, 

p. 563-567. 

Foose, M. P .. 1983, Geology of the Rich Mountain Roadless Area. 

Gilmer and Fannin Counties, Georgia: U.S. Geological Survey 

Miscellaneous Field Stuclies MF -1586-A, scale 1:48,000. 

Foose, M. P., and Sears, C. M., 1983, Geochemical Survey of the Rich 

Mountain Roadless Area, Gilmer and Fannin Counties, Georgia: 

U.S. Geological Survey Miscellaneous Field Stuclies Map 

MF- 1586- B. 

Foose, M. P. and Thompson, R. M., 1983, Mineral resource potential 

map of the Rich Mountain Roadless Area, Gilmer and Fannin 

Counties, Georgia: U.S. Geological Survey Miscelleaneous Field 

Stuclies Map MF-1586-C, scale 1:48,000. 

Thompson, R. M., and Giro), V. P., 1982, Mineral Investigation of 

Rich Mountain RARE I I Further Planning Area, Gilmer and 

Fannin Counties, Georgia: U.S. Bureau of Mines, Open-File 

ReportMLA 141- 82. 

547 
548 

83°45' 

MAP LOCATION 

34•L ________ __ ___.ci:.::::::::.~-----~:__o'-----

J~ -------' 45' 

0 

MILES 

EXPLANATION 

Mafic-ultramafic rocks 

Helen Belt 

Hayesville thrust sheet 

Fault 

___..,_____.,_ Thrust fault --Sawteeth 

on upper plate 

5 

Figure 160.-Tray Mountain Roadless Area, Georgia 
TRAY MOUNTAIN ROADLESS AREA, GEORGIA 

By ART H UR E. EL 0 , 1 U . . GE LOG ICAL SUR E , and 

M ARK L. C HAT A , U .S . B REA OF Ml E 

SUMMARY 

A mineral survey made in 1981 indicates that the Tray Mountain Roadless 

Area has little promise for the occurrence of metallic mineral resources. Rocks 

underlying the Tray Mountain Roadless Area are suitable for crushed rock or 

aggregate; however, other sources for these materials are available closer to 

present markets. There is a possibility for the occurrence of hydrocarbon 

resources underlying the area at great depth, but no hydrocarbon potential was 

identified. 

CHARACTER AND SETTING 

The Tray Mountain Roadless Area occupies slightly 

more than 57 sq mi in the Chattahooche National 

Forest, about 14 mi west of Clayton, Georgia. The 

roadless area lies in parts of Rabun, Habersham, White, 

and Towns Counties. The terrane is heavily forested and 

has a rugged topography with narrow valleys, sharp 

ridges, and steep slopes. Commonly the hill slopes range 

from 20 ° to 30° but in places the slopes exceed 45 °. The 

highest altitude is 4433 ft on Tray Mountain and the 

lowest is 1910 ft in McClure Creek in the southern part 

of the roadless area Tributaries of the north flowing 

Hiwassee, the southeast flowing Tallulah, and the 

southwest flowing Chattahoochee Rivers drain the 

roadless area Georgia State Routes 17, 197, 356, and 

U.S. Highway 76 lead to a few secondary roads as well 

as some logging and USFS roads and trails that provide 

limited access to the roadless area. The Appalachian 

Trail also traverses part of the area's high ground. 

The roadless area is underlain by metamorphic rocks 

that form parts of two major lithotectonic units, the 

Hayesville thrust sheet and the Helen belt (Nelson, 

1982). A major fault, the Shope Fork fault, separates 

the Hayesville sheet on the northwest from the Helen 

belt on the southeast. Most of the roadless area is 

underlain by rocks of the Hayesville sheet which includes mafic and felsic gneisses, schist, metasandstone, 

and granitic gneiss, all of Proterozoic Z(?) age. The 

Helen belt, which occupies a small area in the southeast 

part of the roadless area is underlain by metasandstone, 

1

Willl con!Jibutions from Robert P. Koeppen. USGS. 

schist, and mafic gneiss of probable Proterozoic Z age. 

Many of the rocks in the Helen belt have been altered to 

a deep saprolite. Several mafic-ultramafic bodies have 

been emplaced along faults into the rocks of the Hayesville sheet and the Helen belt; they include serpentinite, 

dunite, pyroxenite, and gabbro. The you,ngest rock in 

the roadless area is a diabase dike of probable Triassic 

or Jurassic age that intrudes rocks from both the 

Hayesville sheet and the Helen belt. 

Rocks underlying the roadless area have been complexly folded and faulted. Although the rocks have been 

deformed by several generations of folding, the second 

generation folds form the regional folds whose axes 

trend northeast. Besides the Shope Fork fault and the 

faults bounding the mafic-ultramafic bodies, numerous 

faults with small displacements and local shear and 

narrow mylonite zones are also present. 

Both the Hayesville thrust sheet and the Helen belt 

form part of a series of major thrust sheets overlying 

younger Paleozoic rocks along a master decollement. 

This decollement thrust fault, based on projections of 

seismic data, is believed to be nearly 5 mi below the surface in the area 

MINERAL RESOURCES 

The Tray Mountain Roadless Area is underlain by 

rocks that in neighboring areas contain mineral 

deposits. Mica has been mined from numerous widely 

scattered pegmatites that commonly occur throughout 

the Hayesville thrust sheet. Although some small micabearing pegmatites are present within the roadless area, 

549 
large pegmatites containing mica have not been observed. Gold from placer and lode deposits, and massive 

sulfide deposits containing primarily pyrite have been 

mined from rocks in the Helen belt southeast of the 

roadless area However, alluvial concentrates of heavy 

minerals from the roadless area contain only trace 

amounts of gold and there is no evidence that massive 

sulfide deposits occur within the roadless area A heavy 

forest cover conceals much of the rock in the roadless 

area, but where rocks are exposed they show little 

evidence of mineralization, or extensive alteration. 

Farther to the east and northeast of the roadless area 

in the Hayesville thrust sheet, some mafic-ultramafic 

bodies have been mined for asbestos, olivine for foundry 

sand, and chromite. Mafic-ultramafic bodies commonly 

are present in the Hayesville thrust sheet; they vary 

widely in size, ranging from a few feet in width and 

several tens of feet long to some that cover several 

square miles. Three mafic-ultramafic bodies are present 

in the roadless area; two are in the Hayesville thrust 

sheet, and one is in the Helen belt, which is here called 

the Lake Burton body. The Lake Burton body also extends northward beyond the roadless area boundary. 

Olivine has not been identified in either of the two 

bodies present in the Hayesville thrust sheet, but 

olivine together with associated serpentine, nickel, 

chromite, and cobalt are present in the Lake Burton 

body. This body contains an estimated 5.0 million short 

tons of olivine in the roadless area (Nelson and others, 

1983). Although the mafic-ultramafic bodies contain 

metals, no metallic or olivine resource potential was 

identified in this study. 

Analysis of bedrock, stream-sediment, and panned 

concentrate samples, with the exception of ultramafic 

samples from the Lake Burton body, did not reveal 

unusual abundances or distributions of metals or 

elements which might be associated with mineral 

deposits (Koeppen and Nelson, 1983). However, splits 

from panned concentrate samples from six drainages in 

the southwest quadrant of the roadless area have 

anomalously high lead abundances, two to three orders 

of magnitude above the 20 to 100 parts per million mean 

value for panned concentrates in this area Although the 

source of the lead is unknown, absence of other corroborating geologic evidence makes the likelihood of occurrence of a lead-bearing resource in the area unlikely. 

Sedimentary rocks that contain hydrocarbons in the 

Tennessee Valley may underlie the Hayesville thrust 

sheet and the Helen belt in the roadless area at great 

depth. There is a small possibility of obtaining hydr<r 

550 

carbon products from such rocks, but they are untested. 

Much of the rock underlying the roadless area is suitable for use as crushed rock or aggregate, and several 

small quarries for local supplies of these materials are 

present in and near to the roadless area. However, 

because good sources for aggregate and crushed stone 

are close to present markets, there is no immediate use 

for rock in the roadless area as a source for stone. 

All surface rights in the roadless area are owned by 

the Federal Government. Mineral rights for 21 sq mi in 

the roadless area are privately owned, but the remaining 

mineral rights are Federally owned. A 0.6 sq mi mining 

lease for olivine is currently in effect, and oil and gas exploration permits have been applied for on 3.7 sq mi 

(Chatman, 1982, 1983) No mining is currently under 

way within the roadless area. The mining of asbestos, 

limited prospecting for gold, olivine, and some crushed 

rock quarrying are the only mineral activities on record. 

SUGGESTIONS FOR FURTHER STUDIES 

Detailed studies are needed to establish the presence 

or absence and mineral-resource potential of olivine, 

nickel, cobalt, and chrome in the two mafic-ultramafic 

bodies in the Hayesville thrust sheet. 

The cause of the lead anomaly in pan concentrate 

samples taken from the southwest part of the roadless 

area has not been established; the mineral residence and 

source of the anomaly remain to be determined. 

REFERENCES 

Chatman, M. L., 1982, Mineral investigation of Tray Mountain 

RARE I I Further Planning Area, Rabun, Habersham, Towns, 

and White Counties, Georgia: U.S. Bureau of Mines Open-File 

Report MLA 145- 82, 39 p. 

__ 1983, Map showing mines and prospects in the Tray Mountain 

Roadless Area, Rabun, Habersham, Towns, and White Counties, 

Georgia: U.S. Geological Survey Miscellaneous Field Studies 

Map MF-1347-C, scale 1:30,000. 

Koeppen, R. P., and Nelson, A. E., 1983. Geochemical survey of the 

Tray Mountain Roadless Area, Rabun, Habersham, Towns, and 

White Counties, Georgia: U.S. Geological Survey Miscellaneous 

Field Studies Map MF-1347- B, scale 1:30,000. 

Nelson, A. E., 1982, Geologic map of the Tray Mountain Roadless 

Area, northern Georgia: U.S. Geological Survey Miscellaneous 

Field Studies Map MF- 1347- A. 

Nelson, A. E., Koeppen, R. P., and Chatman, M. L., 1983, Mineral 

resource potential map of the Tray Mountain Roadless Area, 

Rabun, Habersham, Towns, and White Counties, Georgia: U.S. 

Geological Survey Miscellaneous Field Studies Map 

MF- 1347- D, scale 1:30,000. 

o U.S . GOVERNI!ENT PR I NTING OFFICE: 1983-680-563/114916 
USGS LIBRARY • RESTON 

1111111 Ill 11111111 1111 111 11 11~11 l\ 1~11 ~111 1 111 ~1111 3 1818 00103581 3