Mineral Resources of the 

Spauldins Wilderness Study Area/

 **~s I ' Lake and Harney Counties, Oregon

U.S. GEOLOGICAL SURVEY BULLETIN 1738-E

'Wt,
AVAILABILITY OF BOOKS AND MAPS OF THE U.S. GEOLOGICAL SURVEY

Instructions on ordering publications of the U.S. Geological Survey, along with prices of the last offerings, are given in the currentyear issues of the monthly catalog "New Publications of the U.S. Geological Survey." Prices of available U.S. Geological Survey 

publications released prior to the current year are listed in the most recent annual "Price and Availability List." Publications that are 

listed in various U.S. Geological Survey catalogs (see back inside cover) but not listed in the most recent annual "Price and Availability 

List" are no longer available.

Reports released through the NTIS may be obtained by writing to the National Technical Information Service, U.S. Department of 

Commerce, Springfield, VA 22161; please include NTIS report number with inquiry.

Order U.S. Geological Survey publications by mail or over the counter from the offices given below.

BY MAIL 

Books

Professional Papers, Bulletins, Water-Supply Papers, Techniques of Water-Resources Investigations, Circulars, publications 

of general interest (such as leaflets, pamphlets, booklets), single 

copies of Earthquakes & Volcanoes, Preliminary Determination of 

Epicenters, and some miscellaneous reports, including some of 

the foregoing series that have gone out of print at the Superintendent of Documents, are obtainable by mail from

U.S. Geological Survey, Map Distribution

Box 25286, MS 306, Federal Center

Denver, CO 80225

Subscriptions to periodicals (Earthquakes & Volcanoes and 

Preliminary Determination of Epicenters) can be obtained ONLY 

from the

Superintendent of Documents

Government Printing Office

Washington, DC 20402

(Check or money order must be payable to Superintendent of 

Documents.)

Maps

For maps, address mail orders to

U.S. Geological Survey, Map Distribution

Box 25286, Bldg. 810, Federal Center

Denver, CO 80225

Residents of Alaska may order maps from

U.S. Geological Survey, Earth Science Information Center

101 Twelfth Ave., Box 12

Fairbanks, AK 99701

OVER THE COUNTER 

Books and Maps

Books and maps of the U.S. Geological Survey are available 

over the counter at the following U.S. Geological Survey offices, 

all of which are authorized agents of the Superintendent of Documents.

 ANCHORAGE, Alaska-^230 University Dr., Rm. 101

 LAKEWOOD, Colorado Federal Center, Bldg. 810

 MENLO PARK, California Bldg. 3, Rm. 3128, 345 Middlefield Rd.

 RESTON, Virginia National Center, Rm. 1C402, 12201 

Sunrise Valley Dr.

 SALT LAKE CITY, Utah Federal Bldg., Rm. 8105, 125 

South State St.

 SPOKANE, Washington U.S. Post Office Bldg., Rm. 135, 

W. 904 Riverside Ave.

 WASHINGTON, D.C. Main Interior Bldg., Rm. 2650, 18th 

and C Sts., NW

Maps Only

Maps may be purchased over the counter at the U.S. Geological Survey offices:

 FAIRBANKS, Alaska New Federal Building, 101 Twelfth 

Ave.

 ROLLA, Missouri 1400 Independence Rd.

 STENNIS SPACE CENTER, Mississippi Bldg. 3101
Chapter E

Mineral Resources of the 

Spaulding Wilderness Study Area, 

Lake and Harney Counties, Oregon

By MICHAEL G. SAWLAN, HARLEY D. KING, and 

DONALD PLOUFF 

U.S. Geological Survey

MICHAELS. MILLER 

U.S. Bureau of Mines

U.S. GEOLOGICAL SURVEY BULLETIN 1738

MINERAL RESOURCES OF WILDERNESS STUDY AREAS: 

SOUTH-CENTRAL OREGON
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY 

Gordon P. Eaton, Director

Any use of trade, product, or firm names

in this publication is for descriptive purposes only

and does not imply endorsement by the U.S. Government

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1995

For sale by

U.S. Geological Survey, Map Distribution 

Box 25286, MS 306, Federal Center 

Denver, CO 80225

Library of Congress Cataloging-in-Publication Data

Mineral resources of the Spaulding Wilderness Study Area, Lake and Harney 

Counties, Oregon/by Michael G. Sawlan ... [etal.].

p. cm. (Mineral resources of wilderness study areas south-central 

Oregon ; ch. E) (U.S. Geological Survey bulletin ; 1738-E)

Includes bibliographical references.

Supt. of Docs, no.: 119.3;1738-E

1. Mines and mineral resources Oregon Spaulding Wilderness. 

2. Spaulding Wilderness (Or.) I. Sawlan, Michael G. II. Series. III. Series: U.S. 

Geological Survey bulletin ; 1738-E. 

TN24.07M62 1994

557.3s dc20 94-15504 

[553'.09795'93] CIP
STUDIES RELATED TO WILDERNESS

Bureau of Land Management Wilderness Study Areas

The Federal Land Policy and Management Act (Public Law 94-579, October 21, 1976) 

requires the U.S. Geological Survey and the U.S. Bureau of Mines to conduct mineral surveys 

on certain areas to determine the mineral values, if any, that may be present. Results must be 

made available to the public and be submitted to the President and the Congress. This report 

presents the results of a mineral survey of the Spaulding Wilderness Study Area (OR-OQ1- 

139), Lake and Hamey Counties, Oregon.

CONTENTS

Summary El 

Abstract El 

Character and setting El 

Identified resources El 

Mineral resource potential E3 

Introduction E3

Location, character, and setting E3 

Previous investigations E3 

Present investigations E5 

Acknowledgments E5 

Appraisal of identified resources E6

Prospects, claims, and mineral occurrences E6 

Metallic commodities E6 

Nonmetallic commodities E6 

Energy resources E6

Assessment of mineral resource potential E7 

Geology E7

Description of lithologic units E7 

Andesite (Ta) E7 

Ash-flow tuff (Tt) E7 

Lower basalt (Tbl) E7 

Lower tuffaceous sedimentary rocks (Tsl) E8 

Upper tuffaceous sedimentary rocks (Ts) E8 

Upper basalt (Tb) E8 

Basalt dikes (Tbi) E8 

Undifferentiated volcanic rocks (Tv) E9 

Aeolian sand (Qd) E9 

Alluvium (Qa) E9 

Structure E9

Alteration and mineralization E9 

Geochemical studies E9 

Introduction E9 

Sample preparation E10 

Analytical methods E10 

Results and interpretations E10 

Geophysical studies Ell 

Gamma-ray survey Ell 

Gravity survey Ell 

Aeromagnetic survey Ell 

Implications for mineral resource potential Ell 

Mineral resource potential Ell 

References cited E13 

Appendixes

Definition of levels of mineral resource potential and certainty of assessment E16 

Resource/reserve classification E17 

Geologic time chart E18

FIGURES

1. Index map showing location of the Spaulding Wilderness Study Area, Lake and 

Harney Counties, Oregon El

2. Map showing generalized geology and mineral resource potential of the Spaulding 

Wilderness Study Area, Lake and Harney Counties, Oregon E4

Contents

Mineral Resources of the Spaulding Wilderness 

Study Area, Lake and Harney Counties, Oregon

By Michael G. Sawlan, Harley D. King, and Donald Plouff 

U.S. Geological Survey

Michael S. Miller 

U.S. Bureau of Mines

SUMMARY 

Abstract

The Spaulding Wilderness Study Area (OR-001-139) is 

located along the east side of Guano Valley in southern Oregon. At the request of the U.S. Bureau of Land Management, 

34,800 acres of the Spaulding Wilderness Study Area was 

evaluated for mineral resources (known) and mineral resource potential (undiscovered). In this report, the area studied is referred to as the "Spaulding Wilderness Study Area" 

or the "study area."

There are no identified resources in the study area. Two 

groups of mining claims and a small prospect pit are located 

in the study area. No workings are found near the claims 

and no mining claims are current. There are no mineral leases and no oil and gas leases or lease applications. The northwestern and southeastern parts of the study area have low 

potential for epithermal (low-temperature) gold and silver 

(precious-metal) resources; trace amounts of gold were detected in alluvium in the northwestern part of the study area, 

and anomalous concentrations of elements commonly associated with precious-metal deposits were found in the southeastern part of the study area. The study area contains 

occurrences of pozzolanic tuff, perlite, and building stone. 

The sand and gravel occurrences in the study area are small 

and of poor quality. The study area has low potential for oil 

and gas. There is no potential for geothermal, uranium, or 

thorium resources.

Harney Counties, Oregon, about 8 mi north of the OregonNevada State line (fig. 1). The study area encompasses 

34,800 acres, mostly mesas and rolling hills east of Guano 

Rim. The northwestern part of the study area includes 

low-lying areas in the north end of Guano Valley.

Access to the study area is via State Highway 140, 

about 10 mi south of the study area; gravel roads and jeep 

trails connect with State Highway 140 and encircle the study 

area. The nearest towns are Adel, Oregon, about 25 mi west 

of the study area, and Denio, Nevada, about 45 mi southeast 

of the study area. National antelope refuges and ranges are 

located south, west, and northwest of the study area. The 

study area lies in the northern Basin and Range province and 

encompasses part of the range between Guano Valley and 

Hawks Valley. Relief in the area is moderate; elevations 

range from about 5,250 ft in Guano Valley to about 6,250 ft 

on the mesas in the central part of the study area.

The study area is underlain by flat-lying to gently dipping middle and late Miocene volcanic rocks (see "Appendixes" for geologic time chart), which include andesite lava 

and tuff breccia, ash-flow tuff, tuffaceous sedimentary rocks, 

and basalt. The western part of the study area is underlain 

mostly by andesite, which forms the steep scarp along 

Guano Rim. The central part of the study area is underlain by 

mesa-forming basalt and tuffaceous sedimentary rock. The 

eastern part is underlain by ash-flow tuff, which forms a 

terrain of gently rolling hills and low-lying bluffs.

Character and Setting

The Spaulding Wilderness Study Area (OR-001-139) 

is located along the east side of Guano Valley in Lake and

Manuscript approved for publication April 1,1994.

Identified Resources

There are no identified resources in the Spaulding 

Wilderness Study Area. County mining records show that 

two groups of mining claims, apparently for the same site, 

were located in the study area. However, none of these 

claims is current and there are no mineral leases. No ongoing mineral exploration is known in or adjacent to the

Mineral Resources of the Spaulding Wilderness Study Area, Lake and Harney Counties, Oregon E1
11 9° 30" 119° 15'

42° 15'

42° 00'

Mountain

Desert Lake

Guano Creek 

Wilderness 

Study Area

APPROXIMATE BOUNDARY

OF

SPAULDING

WILDERNESS STUDY AREA 

,. I Antelope (OR-001-139)

/ -{-' Refuge /- ' 

/r.'j-r

|_ LAKE CO

WASHOE!CO

Charles Sheldon 

Antelope Range

Sheldon National 

Antelope Refuge

i i i i

10 MILES

Figure 1. Index map showing location of Spaulding Wilderness Study Area, Lake and Harney Counties, Oregon. 

Unlabeled dashed lines represent gravel roads and (or) jeep trails.

E2 Mineral Resources of Wilderness Study Areas: South-Central Oregon
study area. The northern part of the study area contains 

occurrences of pozzolanic tuff. These are not regarded as 

resources because markets for pozzolanic tuff are limited 

and similar materials are located close to existing markets. 

Occurrences of stone and small amounts of low-grade perlite are present in and near the study area but also do not 

constitute resources.

Mineral Resource Potential

The northwestern and southeastern parts of the Spaulding Wilderness Study Area have low potential for gold 

and silver resources (fig. 2). Alteration and (or) geochemical anomalies for elements commonly associated with epithermal precious-metal deposits are found in small, 

scattered areas. Trace amounts of free gold are present in 

alluvial gravel in the northwestern part of the study area. 

Analysis of a surficial clast of altered rock from Guano 

Valley reveals a trace amount of gold (4 parts per billion 

(ppb)). Geochemical anomalies of silver and other elements (lead, barium, bismuth, and zinc) typically associated with epithermal precious-metal deposits are present in 

heavy-mineral concentrates of stream sediment samples 

from the southeastern part of the study area, about 2 mi 

southwest of South Corral. Geochemical anomalies of antimony, arsenic, barium, tungsten, and molybdenum are 

also present in rock samples of black, glassy veins in ashflow tuff near Chimney Rock in the eastern part of the 

study area. The presence of manganiferous iron-oxide 

veins in upper Sage Hen canyon in the southern part of 

the study area indicates past hydrothermal activity. Samples from there contain anomalous concentrations of one 

or more of the following elements: arsenic, mercury, barium, cadmium, and bismuth.

The entire study area has low potential for oil and gas 

even though there are no indications in the surface geology to indicate the presence of either hydrocarbon source 

rocks or structural traps. There are no oil and gas or geothermal leases or applications. No geothermal energy or 

uranium and thorium resources were identified.

INTRODUCTION

This mineral survey was requested by the U.S. Bureau of Land Management and is the result of a cooperative effort by the U.S. Geological Survey and the U.S. 

Bureau of Mines. An introduction to the wilderness review 

process, mineral survey methods, and agency responsibilities was provided by Beikman and others (1983). The U.S. 

Bureau of Mines evaluates identified resources at individual mines and known mineralized areas by collecting data 

on current and past mining activities and through field examination of mines, prospects, claims, and mineralized areas. Identified resources are classified according to the 

system modified from that described by McKelvey (1972) 

and the U.S. Bureau of Mines and U.S. Geological Survey 

(1980). Studies by the U.S. Geological Survey are designed to provide a reasonable scientific basis for assessing the potential for undiscovered mineral resources by 

determining geologic units and structures, possible environments of mineral deposition, presence of geochemical 

and geophysical anomalies, and applicable ore-deposit 

models. Goudarzi (1984) discussed mineral assessment 

methodology and terminology as they apply to these surveys. See "Appendixes" for the definition of levels of mineral resource potential and certainty of assessment and for 

the resource/reserve classification.

Location, Character, and Setting

The Spaulding Wilderness Study Area is located in 

the High Lava Plains physiographic province in the northern Basin and Range geologic province. The study area 

encompasses part of the low mountain range between 

Guano Valley to the west and Hawks Valley to the east 

(fig. 1). Much of the study area consists of basalt mesas; 

the terrain in the southeastern part of the study area consists of low rolling hills. A steep, north-northeast-trending 

escarpment, 500 to 800ft high, bounds the east side of 

Guano Valley and coincides with the boundary of the 

west-central part of the study area. The extreme northwestern part of the study area lies in Guano Valley. Relief 

in the study area is moderate; elevations range from about 

5,250 ft in Guano Valley to about 6,250 ft on basalt mesas 

in the central part of the study area. Beatys Butte, Lone 

Grave Butte, and Mahogany Butte (north of area shown in 

fig. 1) are remnants of ancient volcanoes that dominate the 

landscape to the north.

Several antelope Ranges and Refuges lie peripheral to 

the study area (fig. 1). The Hart Mountain National Antelope 

Refuge is about 5 mi west and northwest of the study area. 

The Sheldon National Antelope Refuge and the Charles 

Sheldon Antelope Range include large areas south of the 

study area mostly in Nevada. Indian petroglyphs are found 

in the southernmost part of the study area where potholes in 

basalt along Sage Hen Canyon form small catch basins for 

water. The climate is arid and sparse rainfall results in only 

intermittent stream flow and inundation of shallow ephemeral lakes.

Previous Investigations

The Adel 1° by 2° quadrangle, which includes the 

study area, was previously mapped in reconnaissance at a 

scale of 1:250,000 by Walker and Repenning (1965); this 

map was later compiled in a l:500,000-scale geologic map

Mineral Resources of the Spaulding Wilderness Study Area, Lake and Harney Counties, Oregon E3
119° 22' 30" 119° 15'

_ i

APPROXIMATE 

BOUNDARY

OF

SPAULDING

WILDERNESS

STUDY AREA

(OR-001-139)

Spaulding 

Reservoir

Black Hope 

Claim Group

(entire study area)

L/B _

Au, Ag

4 MILES

Figure 2. Mineral resource potential and generalized geology of Spaulding Wilderness Study Area, Lake and Harney Counties, 

Oregon.

E4 Mineral Resources of Wilderness Study Areas: South-Central Oregon
of eastern Oregon by Walker (1977). The geology of an 

area about 6 mi south of the study area to about 25 mi into 

Nevada was mapped by Greene (1984) for a mineral resource assessment of the Charles Sheldon Wilderness Study 

Area. Diggles and others (1988) reported on the mineral 

resources of the Guano Creek Wilderness Study Area about 

5 mi west of the northwestern part of the study area (fig. 1). 

The study area is included in several regional geophysical and geochemical surveys aimed at assessing potential for uranium resources (Erikson and Currey, 1977; 

Geodata International, 1980, Union Carbide Corp., 1982). 

A summary of the geology, energy resources, and mineral 

resources of the study area was reported by Matthews and 

Blackburn (1983).

EXPLANATION

I___I Area with low mineral resource potential (L)

B

Levels of certainty of assessment 

Data only suggest level of potential

Commodities 

Au Gold 

Ag Silver 

O-G Oil and Gas

Map units

Qa Alluvium (Quaternary) 

Qd Aeolian sand (Quaternary)

TV Undifferentiated volcanic rocks 

(late Miocene?)

Tbi Basalt dikes (middle Miocene)

Tb Upper basalt (middle Miocene to 

early Pliocene)

Ts Upper tuffaceous sedimentary rocks 

(middle Miocene to early Pliocene)

Tsl Lower tuffaceous sedimentary rocks 

(middle Miocene)

Tbl Lower basalt (middle Miocene)

Tt Ash-flow tuff Includes Idaho Canyon 

Tuff of Greene (1984) and tuff of 

Ryegrass Valley (middle Miocene)

Ta Andesite (middle Miocene) 

 Contact

 Fault Ball and bar on downthrown block, 

dotted where concealed

X Claim or prospect

® Mineral occurrence (see sections "Prospects, 

Claims, and Mineral Occurrences" and 

"Alteration and Mineralization")

Figure 2. Continued.

Present Investigations

In 1987, the U.S. Geological Survey (USGS) conducted field investigations which consisted of geologic 

mapping at a scale of 1:24,000, field checking of existing 

maps, interpreting aerial photographs, geochemical sampling, and examining outcrops for evidence of mineralization. In all, 87 rock samples, 49 stream sediment samples, 

and 49 heavy-mineral-concentrate samples panned from 

stream sediment were analyzed at USGS laboratories.

Work by the U.S. Bureau of Mines (USBM) included 

examining literature on the geology, mines, and prospects 

in and near the study area. Federal, State, and county 

records were examined to ascertain the location of mines or 

mineral claims in the study area. Field studies, conducted in 

1986 and 1987, included examining, mapping, and geochemical sampling of prospects, claims, and mineralized 

areas in and adjacent to the study area. Eighteen alluvial 

and 30 rock samples were collected. The alluvial samples 

were concentrated and examined for economic minerals. 

Rock samples were analyzed by private laboratories for a 

suite of elements related to formation of mineral deposits. 

Samples from nonmetallic sources with likely industrial 

uses were analyzed with respect to their pertinent physical 

properties. Samples were checked in the field and in the 

laboratory for radioactivity. Sampling procedures and results of the USBM investigations of the study area are presented by Miller (1988).

Acknowledgments

John R. Benham, William N. Hale, Richard A. Winters, Thomas J. Peters, and J. Douglas Causey (USBM, 

Western Field Operations Center, Spokane, Wash.), and 

Dennis Simontachi (U.S. Bureau of Land Management, 

Lakeview, Oreg.) assisted M.S. Miller in the field. Mark 

Wick assisted M.G. Sawlan in geologic investigations. J.L. 

Jones and T.A. Delaney (USGS, Denver, Colo.) assisted

Mineral Resources of the Spaulding Wilderness Study Area, Lake and Harney Counties, Oregon E5
H.D. King in collecting stream sediment and panned-concentrate samples. D.R. Keitzman assisted Donald Plouff in 

collecting geophysical data. Douglass Troutman and Dennis Simontachi (U.S. Bureau of Land Management, Lakeview, Oreg.) provided maps and logistical information to 

M.G. Sawlan.

APPRAISAL OF IDENTIFIED RESOURCES

By Michael S. Miller 

U.S. Bureau of Mines

Prospects, Claims, and Mineral Occurrences

There is no record of mineral production from within 

the Spaulding Wilderness Study Area. Two groups of mining 

claims have been located in the study area, but none of these 

claims is active. One group of claims was first staked about 

a mile east of Spaulding Reservoir in 1919. In 1943, this 

claim group was relocated to the south in Sage Hen Canyon 

and named the Black Hope claim group (fig. 2). There are 

no identified resources in the Spaulding Wilderness Study 

Area.

Metallic Commodities

An area in the Chimney Rock area (fig. 2) was reported by Erikson and Currey (1977) to contain uranium and 

by the U.S. Department of the Interior (1939, 1941) to 

contain mercury. Uranium and mercury concentrations 

from weakly altered rock in this area are at levels typical 

of tuffs that underlie the surrounding region. Two samples 

of black glassy veins in welded tuff from about 0.5 mi 

northwest of Chimney Rock are weakly anomalous in barium (1,500-5,000 parts per million (ppm)), molybdenum 

(20-39 ppm), and arsenic (5-6 ppm). These veins may be 

similar to manganiferous veins in the upper part of Sage 

Hen canyon, which contain 500 to more than 5,000 ppm 

barium, as much as 20 ppm molybdenum, and as much as 

62 ppm arsenic, based on USGS investigations (see "Geochemical Studies"). Manganese was not analyzed, however, in samples of the veins from near Chimney Rock.

A small unnamed prospect pit lies about 2 mi north 

of Spaulding Reservoir (fig. 1). There, rocks adjacent to a 

basaltic dike exhibit limonite and hematite staining and 

clay alteration. Silver (16 parts per million (ppm)) is 

present in one sample of scoriaceous basalt, and platinum 

(30 ppb) is present in another.

Platinum (less than 15 ppb to as much as 30 ppb) and 

palladium (less than or equal to 2 ppb) are present in 7 of 

8 samples from three unaltered basaltic dikes. Few analyses for platinum and palladium in basalt are available for 

comparison but these platinum and palladium values and 

platinumrpalladium ratios (about 7 to 15) are high compared to those of Siberian flood basalt, for example, which 

contains platinum and palladium in subequal amounts, at 

concentrations typically in the range of 2 to 10 ppb. Platinum and palladium values in basalt from the study area 

are about 200 to 1000 times lower than the minimum 

grade of ore, approximately 5 to 20 ppm, from deposits of 

platinum-group elements that are currently being mined 

(M. Zientek, oral comm., 1992). There are no resources of 

platinum-group minerals in the study area.

Alluvium in the northwestern part of the study area 

contains traces of free gold. Microscopic flakes of gold are 

present in nine 0.3 ft3 alluvial samples. Alluvium at these 

sites is estimated to contain approximately 0.00003 to 

0.0009 troy ounces of gold per yd3, worth about $0.12 to 

0.36 per yd3 at a gold price of $400 per troy ounce (oz). The 

alluvium has no current economic value as a gold placer.

Analyses of five rock samples from the western part 

of the study area show silver in concentrations ranging 

from 5 to 16 ppm. These samples are of pumiceous tuff, a 

basalt dike, scoriaceous basalt, and friable silty sandstone. 

Although minor amounts of limonite, hematite and clay are 

present in these rocks, none contain anomalous concentrations of arsenic, antimony, mercury, or other metals characteristically associated with epithermal precious-metal 

mineralization.

Nonmetallic Commodities

Nonmetallic commodities include uneconomic occurrences of perlite and pozzolan. The Black Hope claims encompass an area in Sage Hen Canyon along a 2-mi-long, 

north-trending basalt dike. The dike cuts tuff that, in a 2- to 

3-ft-wide envelope along the margins of the dike, was partially fused to rhyolite glass during intrusion of the dike; the 

rhyolite glass has since hydrated to form perlite. No workings are found near the claims. Perlitic glass is also present 

in fiamme in densely welded ash-flow tuff outside the southeastern boundary of the study area. Perlite occurrences in 

and near the study area are of poor quality and unsuitable 

for commercial development and use. Tuffaceous rocks in 

the northwestern corner of the study area meet the chemical 

definition of pozzolan established by the American Society 

for Testing and Materials (1985). The pozzolan might be 

suitable as an additive to cement, but detailed testing to 

evaluate compatibility with specific cement mixes would be 

required. Similar pozzolanic rocks are widespread throughout the Basin and Range province and, therefore, it is likely 

that materials closer to markets would be mined before pozzolan from the study area.

Energy Resources

No energy resources were identified in the study area. 

There are no oil and gas or geothermal leases or lease applications for land in the study area.

E6 Mineral Resources of Wilderness Study Areas: South-Central Oregon
ASSESSMENT OF MINERAL RESOURCE 

POTENTIAL

By Michael G. Sawlan, Harley D. King, and

Donald Plouff

U.S. Geological Survey

Geology

The Spaulding Wilderness Study Area lies in the 

northern Basin and Range province, an area characterized 

by north-trending ranges and intervening basins bounded 

by normal faults. The study area includes part of a northtrending range bounded on the west by faults along Guano 

Rim and on the east by Hawks Valley (fig. 1). The study 

area is underlain by flat-lying to gently dipping middle 

Miocene to early Pliocene volcanic and volcaniclastic sedimentary rocks including andesite, two sequences of basalt 

and tuffaceous sedimentary rocks, and ash-flow tuff (fig. 

2). These rocks range in age from about 16 to 5 Ma 

(mega-annum, or million years). This age range is defined 

by K-Ar (potassium-argon) ages cited by Greene (1984), 

and new K-Ar ages acquired during this study (J.E. Conrad, USGS, written commun., 1989) and that of the Guano 

Creek Wilderness Study Area (M.E Diggles, USGS, written commun., 1990).

Surficial deposits in the study area include thin accumulations of alluvial gravel, sand, and silt along drainages 

and in ephemeral lakes. Aeolian sand dunes are present 

southwest of the study area in the eastern part of Guano 

Valley. Small alluvial fans along the scarp east of Guano 

Valley have a conical shape which indicates that relative 

subsidence of Guano Valley, along faults that form the 

scarp of Guano Rim, has occurred in Quaternary time and 

perhaps is ongoing.

Description of Lithologic Units

ANDESITE (Ta)

The oldest rocks exposed in the study area are andesite 

and basalt(?) lava and andesite tuff breccia that underlie the 

western part of the study area, mostly within 2 to 3 mi of 

Guano Rim (fig. 2). These rocks generally dip gently, less 

than 10°, to the southeast. This unit is mostly porphyritic 

andesite with abundant plagioclase phenocrysts, but includes 

sparsely porphyritic basaltic andesite or basalt with phenocrysts of olivine±plagioclase±clinopyroxene. The andesite 

tuff breccia is a rock type commonly attributed to lahars, or 

mudflows, deposited on the distal flanks of andesitic composite volcanoes.

The andesite in the study area and the surrounding 

region is about 17 to 14 Ma old. Two K-Ar ages on andesite from the mouth of Rocky Canyon (fig. 1) adjacent to 

Guano Valley are 16.2+0.5 and 14.2±1.5 Ma (I.E. Conrad,

written commun., 1989). Basaltic andesite from the hills 

along the west side of Guano Valley has been dated at 

17.0±0.5 Ma (M.E Diggles, written commun., 1990). Andesite from Bald Mountain at the south end of Guano Valley (about 2 mi south of the southwest corner of fig. 1) 

has been dated at 15.3+0.9 Ma (E.H. McKee, written commun., 1990, previously cited by Greene, 1984).

ASH-FLOW TUFF (Tt)

Two petrologically distinct ash-flow tuffs are found in 

and adjacent to the study area: poorly welded tuff in Ryegrass 

Valley northeast of the study area, and the Idaho Canyon 

Tuff, which underlies most of the southeastern part of the 

study area. Minor amounts of unwelded lapilli tuff and tuffaceous sedimentary rocks are also included in this unit. In 

the study area, the Idaho Canyon Tuff mostly consists of 

devitrified, vapor-phase altered, moderately welded tuff containing about 6 to 10 percent phenocrysts of alkali feldspar, 

quartz, and lesser amounts of fayalite. Locally, this tuff shows 

dense welding, vitrophyric layers, and poorly welded layers 

containing abundant pumice lapilli. It probably contains 

more than one cooling unit. The Idaho Canyon Tuff extends 

at least 20 mi south into Nevada and its age is about 15.5 to 

15 Ma (Greene, 1984). It overlies the tuff of Craine Creek, 

dated at 15.7+0.5 Ma (Noble and others, 1970), and it underlies the Summit Lake Tuff, dated at 15.110.5 Ma (Noble 

and others, 1970), which are both present in Nevada. Ashflow tuff exposed northeast of the study area, here informally 

named the tuff of Ryegrass Valley, consists of poorly welded 

white tuff containing biotite phenocrysts. This tuff is overlain 

by the lower basalt unit. Stratigraphic relations between the 

Idaho Canyon Tuff and the andesite lavas were not observed.

LOWER BASALT (Tbl)

Gently tilted basalt flows are present in and adjacent to 

the northern part of the study area (fig. 2). In Guano Valley, 

this basalt contains abundant, large plagioclase phenocryststhese lavas may be correlative with the Steens Mountain 

basalt, which is widespread in southeastern Oregon. These 

lavas are cut by northwest-trending faults and dip about 5 

to 15° southwest or northeast. Correlation of the lower basalt 

from the east and west sides of the study area is uncertain. 

Along the east margin of the study area, the basalt contains 

sparse olivine(?) phenocrysts and dips about 5 to 10° southeast. The lower basalt in this area underlies the Idaho Canyon 

Tuff and overlies the biotite-bearing ash-flow tuff that crops 

out in Ryegrass Valley. The age of the lower basalt is not 

certain but is at least 15 Ma, the age of the Idaho Canyon 

Tuff (Greene, 1984). This lower basalt unit locally includes 

tuffaceous sedimentary rocks that are intercalated with the 

basaltic lavas; thicker sections of these sedimentary rocks 

were mapped separately as the lower tuffaceous sedimentary 

rocks unit (unit Tsl).

Mineral Resources of the Spaulding Wilderness Study Area, Lake and Harney Counties, Oregon E7
LOWER TUFFACEOUS SEDIMENTARY ROCKS (Tsl)

This unit includes poorly exposed tuffaceous sedimentary rocks intercalated with the lower basalt. These rocks are 

distinguished from the upper tuffaceous sedimentary rocks 

by their stratigraphic association with the lower basalt (see 

"Upper Tuffaceous Sedimentary Rocks" section).

UPPER TUFFACEOUS SEDIMENTARY ROCKS (Ts)

This unit includes poorly bedded, weakly lithified, friable, and tuffaceous nonmarine sandstone, siltstone, and 

minor amounts of conglomerate. Some beds locally contain 

abundant rhyolite pumice lapilli. These pumice-rich deposits 

may represent airfall or reworked deposits of airfall or unwelded tuff. The poorly lithified rocks of this unit generally 

are preserved only where overlain by basalt. This unit typically is poorly exposed and forms gentle grassy or taluscovered slopes beneath basalt mesas. Mammalian fossils are 

found locally within this unit; during this study, bone fragments were found in the southeastern corner of the study 

area. Both the upper and lower tuffaceous sedimentary rocks 

are poorly exposed, have a similar appearance in the field, 

and are distinguished by stratigraphic position in relation to 

the lower and upper basalts. The upper tuffaceous unit may 

include rocks of the lower tuffaceous unit where intercalated 

basalt is absent and exposures are poor.

UPPER BASALT (Tb)

The upper basalt unit consists of mesa-forming basalt 

in the east-central and southwestern parts of the study 

area, and basalt in Guano Valley. Individual flows are typically 15 to 40 ft thick, are aphyric or contain sparse phenocrysts of olivine±plagioclase, and have a characteristic 

diktytaxitic groundmass texture. At most localities, 1 to 3 

lava flows have a composite thickness of 60 ft. or less. 

These basalts differ markedly in chemical composition 

from the andesite of unit Ta; that is, they have very low 

amounts of potassium and generally high amounts of nickel, chromium, and cobalt compared to most volcanic 

rocks. These basalts belong to the suite of low-potassium 

tholeiitic basalt, which is widespread throughout southern 

Oregon (Hart and others, 1984).

This upper basalt unit includes two groups of basalt 

that are petrographically similar but differ in age. An older 

group of lavas forms the north-trending band of mesas in 

the eastern part of the study area. A younger group of 

lavas includes the basalt mesa between Sage Hen and 

Rocky canyons, the broad basalt mesa southwest of the 

study area, and basalt in Guano Valley (fig. 2).

These basalts are late middle Miocene to early Pliocene, 

but dating of these rocks has been imprecise due to analytical 

difficulties caused by their low K2O (potassium oxide) contents. Basalt belonging to the older group has not been dated

directly but it is probably between 13 and 9 Ma. The older 

group may be correlative with mesa-forming basalt at Gooch 

Table, about 16 mi south of the study area, which has a KAr age of 9.9±1.2Ma (E.H. McKee, USGS, written commun., 1990; cited by Greene, 1984). The age of a basalt dike 

in Sage Hen canyon, which perhaps fed some lavas of the 

older group, is about 13 Ma (see "Basalt Dikes"). A K-Ar 

age of 5.1±1.5 Ma on basalt of the younger group, from the 

mesa south of Spaulding Reservoir, was obtained during this 

study (I.E. Conrad, written commun., 1989).

Basalts of the older group forms gently south-dipping 

mesas that may differ in elevation as much as 220 ft. Although 

only one or two basalt flows are present at most localities, 

differences in abundances of phenocryst minerals between 

mesas suggests that these mesas comprise several different 

lava flows. Individual flows can seldom be correlated across 

most of these mesas and the number of lava flows may differ 

between adjoining mesas. These basalts apparently comprise 

several lava flows that were erupted over a sufficiently long 

span of time for relief to be developed in the underlying 

tuffaceous sediment owing to erosion and (or) faulting. Differences in elevations of the older basalt mesas are attributed, 

in part, to confinement of basalt flows within northwesttrending fluvial channels and downwasting of adjacent, uncovered tuffaceous sediment between basalt eruptions. Accordingly, these basalt mesas likely represent an inversion 

of the topography that existed prior to eruption of the earliest 

basalt flows. That is, basalt that forms the topographically 

highest mesas was emplaced into early-formed channels; 

younger basalts of this group flowed into shallow arroyos 

cut into sediments not covered by older lavas. Although 

differences in elevations of some basalt mesas of this older 

group are attributed, in part, to erosion between eruptions of 

different lava flows, these mesa-forming basalts are also cut 

by northwest-trending faults at Buckaroo Pass in the northern 

part of the study area and east of Sage Hen Canyon in the 

southern part of the study area (fig. 2).

The younger group of basalts of this upper basalt unit 

show an increase in the number and thickness of lava 

flows from the Rocky Canyon area to the south. Probable 

vent areas for these lavas include a small butte about 1.5 

mi north of Sage Hen Butte and perhaps Sage Hen Butte. 

The younger mesa-forming basalt is cut by north-northeast-trending faults along Guano Rim but is not cut by the 

northwest-trending faults (fig. 2).

BASALT DIKES (Tbi)

A 2-mi-long north-trending basalt dike in Sage Hen 

Canyon (fig. 2) has the characteristic diktytaxitic texture and 

low K2O content of the mesa-forming basalts. This dike, 

dated at 12.8±1.3 Ma (I.E. Conrad, USGS, written commun., 

1989), probably represents a feeder to a fissure vent system 

for the older group of mesa-forming basalt. It shows no 

displacement along the northwest-trending fault along Sage

E8 Mineral Resources of Wilderness Study Areas: South-Central Oregon
Hen Canyon near Spaulding Reservoir. Smaller dikes, apparently equivalent to the dike mapped in Sage Hen Canyon, 

are also present in the northern part of the study area.

UNDIFFERENTIATED VOLCANIC ROCKS (Tv)

This unit includes generally thick andesitic to dacitic(?) lava flows that overlie tuffaceous sedimentary rocks 

and ash-flow tuff north of Buckaroo Pass (fig. 2). These 

rocks are probably late Miocene and appear to be derived 

from volcanic centers north of the study area.

AEOLIAN SAND (Qd)

Windblown sand deposits are present on or adjacent 

to basalt in the eastern part of Guano Valley at the base of 

Guano Rim scarp (fig. 2). These sands generally form sinusoidal dunes trending east-west. Locally developed cuspate dunes are convex to the south and indicate a 

northward migration direction of dunes.

ALLUVIUM (Qa)

Alluvial deposits include accumulations of gravel, 

sand and silt along drainages and in Guano Valley. Silt and 

fine sand, probably carried onto the basalt mesas by wind, 

and locally-derived basalt debris are present in shallow depressions in the surfaces of the basalt mesas. These depressions, which intermittently pond with water, are as 

much as 1,500 ft across and about 10 to 25 ft deep.

Structure

Two episodes of faulting have displaced rocks in the 

study area. Older, northwest-trending faults were active in 

the middle and late(?) Miocene. Younger north-northeasttrending faults, related to formation of basins and ranges 

that dominate the present-day regional physiography, cut 

all volcanic strata in the study area.

The older, northwest-trending faults cut all volcanic 

rocks except for younger mesa-forming basalt. In part, 

movement along the northwest-trending faults appears to 

have been concurrent with eruption of mesa-forming basalt in the central part of the study area. Some of these 

mesa-forming basalts show displacement along northwesttrending faults; others appear to have flowed into shallow 

northwest-trending drainages that probably developed in 

grabens and are not offset. The youngest rocks cut by 

northwest-trending faults, the older mesa-forming basalt, 

are between about 13 to 9 Ma. The younger lavas of the 

upper basalt, however, show no displacement along the 

northwest-trending faults. Therefore, movement on the 

northwest-trending faults occurred prior to and probably 

during eruption of the older group of mesa forming basalt, 

which is between about 13 to 9 Ma, but ceased before

eruption of the younger group of mesa-forming basalt at 

about 5 Ma. Minor tilting to the southwest and northeast is 

associated with the northwest-trending faults.

Movement along the younger north-northeast-trending 

faults has formed the 25-mi long scarp along Guano Rim 

(figs. 1 and 2). Normal displacement along this fault system has resulted in subsidence of Guano Valley relative to 

the range the east, and gentle tilting of this range to the 

east-southeast. In several places along this fault zone, narrow fault-bounded blocks about Vi mi wide have rotated 

downward to the north along curvilinear traces of faults 

that bound the south side of the blocks. These block rotations between subparallel faults occur where the main 

fault trace steps to the east. The east-stepping fault pattern 

suggests that the fault system along Guano Rim has a 

component of right-lateral displacement in addition to the 

dominandy vertical displacement. Tentative correlation of 

younger mesa-forming basalt in the Rocky Canyon area 

with basalt in Guano Valley indicates that about 500 ft of 

normal displacement has occurred along this fault zone 

since about 5 Ma. The conical shape of small alluvial fans 

along the Guano Rim scarp suggests that faulting has occurred in Quaternary time and perhaps is ongoing.

Alteration and Mineralization

Alteration of rocks in the study area is generally weak 

and localized. Weak iron-oxide staining is present at sites 

near Chimney Rock, and Miller (1988) reported local ironstaining and clay alteration adjacent to a dike about 2 mi 

north of Spaulding Reservoir. Miller (1988) also reported 

black glassy veins of unspecified mineralogy (goethite? 

and (or) manganese minerals?) north of Chimney Rock. 

Rounded clasts of silicified rock are present north of the 

study area at Buckaroo Pass and in the northwestern part 

of the study area in Guano Valley.

Manganiferous iron-oxide veins are present in upper 

Sage Hen Canyon. The manganiferous veins are dark gray 

to black, earthy, less than 3 in. thick, and continuous for only 

5 to 15 ft. The veins cut tuffaceous sedimentary rocks in 

which a weak iron-oxide halo, about 150 ft long by 40 to 60 

ft wide, developed. The larger veins trend mostly north, 

although smaller, thin (less than 1 in.), brittle to friable green 

and brown veins of amorphous material trend roughly east. 

The margins of the black veins commonly show stubby, 

radiating, granular aggregate forms, as much as 10 in. across 

and 2 in. thick, that probably formed by replacement.

Geochemical Studies 

Introduction

A reconnaissance geochemical survey was conducted 

in the study area by the USGS in the summers of 1987

Mineral Resources of the Spaulding Wilderness Study Area, Lake and Harney Counties, Oregon E9
and 1988. The study consisted of collecting, analyzing, 

and evaluating rock, stream sediment, and heavy-mineralconcentrate samples. Minus-80 mesh (0.007 in.) stream 

sediments, nonmagnetic heavy-mineral concentrates of 

stream sediments, and rock samples were collected. Both a 

minus-80 mesh sample and a nonmagnetic heavy-mineral 

concentrate sample were collected from 49 sites. Eight 

rock samples were collected from five of those sites and 

79 rock samples were collected from other sites. Most of 

the rock samples were taken from outcrops. The stream 

sediments from which the concentrates were derived were 

taken from active alluvium in stream channels.

The stream sediment and nonmagnetic heavy-mineral 

panned-concentrate samples (heavy-mineral concentrates) 

are collected primarily for their ability to reveal metal 

anomalies within drainage basins. Stream sediment samples 

represent a composite of the rock and soil exposed upstream from the sample site. The processing of heavy-mineral concentrates removes common rock-forming minerals 

and retains ore and ore-related minerals. The selective concentration of minerals permits determination of some elements that are not easily detected in bulk stream sediment 

samples.

The rock samples, nearly all of which appeared unaltered and unmineralized, were collected to determine if 

analyses might indicate mineralization. Some samples 

were collected to provide information on background concentrations of elements. In some cases, rock samples were 

collected along fractures to determine if anomalous concentrations of elements had been deposited there. Anomalous values were determined by statistical methods, by 

comparison of mineralized and altered samples with unaltered equivalent rocks, and by comparison of with published data for common rock types.

Sample Preparation

Stream sediment samples were sieved using 80-mesh 

stainless-steel sieves; the minus-80 mesh fraction was 

used for analysis. The heavy-mineral concentrate was obtained by panning minus-10-mesh (0.08 in.) stream sediment to remove most of the quartz, feldspar, organic 

material, and clay-size material. Immersion of this material in bromoform, a liquid having a specific gravity of 2.8, 

removed any light mineral grains remaining after panning. 

The resultant heavy-mineral concentrate was separated, 

using an electromagnet, into three fractions: a magnetic 

fraction, chiefly magnetite; an intermediate fraction consisting of common rock-forming minerals; and a nonmagnetic fraction composed predominantly of light-colored 

rock-forming accessory minerals and primary and secondary ore-forming and ore-related minerals. Using a microsplitter, the nonmagnetic fraction was split into two 

fractions. One of these fractions was analyzed and the 

other was visually examined with a binocular microscope.

Rock samples were crushed and pulverized with ceramic 

plates to a grain size of less than 0.006 in.

Analytical Methods

The rock, stream sediment, and heavy-mineral-concentrate samples were analyzed for 35 elements (antimony, 

arsenic, barium, beryllium, bismuth, boron, cadmium, calcium, chromium, cobalt, copper, gallium, germanium, gold, 

iron, lanthanum, lead, magnesium, manganese, molybdenum, nickel, niobium, phosphorus, sodium, scandium, silver, strontium, thorium, tin, titanium, tungsten, vanadium, 

yttrium, zinc, and zirconium) by a six-step, semiquantitative, direct-current arc emission spectrography method routinely used by the USGS (Grimes and Marranzino, 1968). 

Stream sediments were also analyzed by more sensitive 

techniques for certain elements of special interest. Antimony, arsenic, bismuth, cadmium, and zinc concentrations were 

determined by inductively coupled argon plasma-atomic 

emission spectroscopy (ICAP-AES) (Crock and others, 

1987). Lower limits of determination for these elements are 

shown in parentheses as follows, in ppm: antimony (2), 

arsenic (5), bismuth (2), cadmium (0.1), and zinc (2). Mercury was analyzed by cold vapor atomic-absorption spectrometry (lower limit of determination, 20 ppb) (Crock and 

others, 1987).

Gold concentrations were determined in stream sediment samples and in 10 rock samples by flame atomic absorption (lower limit of determination, 50 ppb); 77 rock 

samples were analyzed for gold by flameless atomic absorption with a heated graphite atomizer (lower limit of determination, 2 ppb). Both methods are described in O'Leary 

and Meier (1986). Gold analyses obtained by these methods 

largely reflect the gold introduced into the rock by mineralization and not the total gold concentrations in the rock; the 

common rock-forming silicates, which may contain trace 

amounts of gold (less than 5 ppb), are not decomposed by 

the method used in gold analysis sample preparation.

Results and Interpretations

Anomalous values for several elements including silver, lead, barium, bismuth, and zinc are present in heavymineral concentrates from an area of about 2 mi2 in the 

southeastern part of the study area, about 1 to 2 mi southwest of South Corral (fig. 2). The area is chiefly underlain 

by welded tuff cut by northwest-trending faults. Anomalous silver values (7 and 70 ppm Ag) are present in two of 

the heavy-mineral concentrates taken from adjacent 

streams. The sample with the higher silver value also contains anomalous values of lead (1,500 ppm), barium 

(2,000 ppm), bismuth (70 ppm), and zinc (700 ppm). Two 

concentrate samples collected upstream from the site with 

the 70 ppm silver value contain 200 and 300 ppm lead but 

no other elements in anomalous concentrations; however,

E10 Mineral Resources of Wilderness Study Areas: South-Central Oregon
samples of welded tuff from these same two sites contain 

moderately anomalous concentrations of copper (100 and 

150 ppm). Anomalous amounts of barium (3,000 to more 

than 10,000 ppm) are present in three other concentrate 

samples from this area and are attributed to small amounts 

of barite in the concentrates. The concentrates from this 

area also contain pyrite; the largest amount of pyrite, 

about 10 percent of the concentrate, is present in the concentrate with the 70 ppm silver value. The abundance of 

silver, lead, and zinc in concentrate samples suggests these 

elements are most likely present as impurities in galena. 

Although no galena was observed in the concentrates, it 

could be present as mineral grains included in pyrite and 

(or) as individual grains that are altered to anglesite, a 

common alteration mineral after galena in surficial environments. Anglesite is colorless or weakly colored and 

could have been easily overlooked during microscopic examination of the concentrates.

The source of barite and pyrite and associated geochemical anomalies in the southeastern part of the study 

area is enigmatic because no visibly altered or mineralized 

rock was observed in nearby areas. The presence of barite 

and the angular, faceted morphology of pyrite grains suggest that these minerals are derived locally and most likely 

have not been transported from distant sources into the 

study area. These minerals may have been eroded from 

fractures or cavities in tuff along northwest-trending faults 

that cut this area but iron-staining, a characteristic result of 

oxidation of iron sulfide, is absent. The small amount of 

pyrite found, however, suggests the presence of only a 

small amount of pyrite in the area, and therefore a noticeable amount of iron staining may not be expected.

In the northwestern part of the study area, where traces of alluvial gold are present (Miller, 1988), no significantly altered rock was observed in outcrop. The alluvial 

gold may possibly be derived from buried mineralized 

rock or, alternatively, may be derived from mineralized 

rock outside the study area and was transported into the 

study area by fluvial processes. In the latter interpretation, 

concentration of gold in alluvium occurred during erosion 

and redeposition of the tuffaceous sediment. Analyses of 

the finer grained tuffaceous sediments shows no geochemical anomalies but rounded, silicified cobbles, apparently 

derived from tuffaceous sedimentary rocks, were found in 

the northern and northwestern parts of the study area. The 

presence of altered clasts, and notably the rounded shape 

of silicified clasts, suggest that the gold in this area may 

have been derived from mineralized rock located some 

distance from the study area.

Nonmagnetic heavy-mineral-concentrate samples from 

two sites along Sage Hen Creek near the southern boundary 

of the study area contain high values of lead (2,000 and 

50,000 ppm). The sample with the highest lead also contains 

antimony, less than 200 ppm. Both the lead and antimony 

can be attributed to bullet fragments or lead shot, which

commonly contain antimony as a hardening agent. A metal 

particle from the sample with the highest lead value was 

determined by x-ray analysis to be a lead artifact. Although 

most of the artifact was removed from the sample prior to 

analysis, oxidized margins of the artifact that were not extracted from the sample most likely contributed lead and 

antimony to the sample that was analyzed.

Anomalous concentrations of several elements are 

present in samples of thin veins collected in Sage Hen Canyon. Most of the veins are dark gray and oxidized. Samples 

generally contain abundant iron oxide and three samples 

contain 5,000 ppm or more manganese. Anomalous arsenic 

is also present in most of these samples; the higher arsenic 

values (28 to 67 ppm) are in samples with high amounts 

of iron (5 to 15 percent), and the lower arsenic values are 

in samples with high amounts of manganese (greater than 

5,000 ppm). Several of these samples also contain anomalous 

amounts of cadmium (1.7 to 6.5 ppm) and molybdenum 

(as much as 20 ppm). The samples with high manganese 

values also contain anomalous amounts of antimony (16 

and 17 ppm), barium (greater than 5,000 ppm), bismuth 

(4 ppm), cobalt (150 ppm in one sample), mercury (0.18 

ppm) and zinc (122 and 123 ppm). These anomalous elements 

were probably enriched by coprecipitation and scavenging 

(adsorption) of the elements by the iron and (or) manganese 

oxides (Chao and Theobald, 1976; Levinson, 1974, p. 134- 

138). As such, the anomalies may be unrelated to mineral 

deposits, and instead are probably the result of enrichment 

of the elements over background concentrations from the 

weathering of unmineralized rock. No gold was detected 

in any of these vein samples at a lower limit of determination 

of 2 ppb. Although black glassy veins from northwest of 

Chimney Rock were not analyzed for manganese, they contain weakly anomalous concentrations of barium, molybdenum, and arsenic (see "Identified Resources"), and they 

may be similar to the manganiferous veins in Sage Hen 

Canyon.

Geophysical Studies

Gamma-ray Survey

The aerial gamma-ray data were compiled by Geodata 

International, Inc. (1980) for the National Uranium Resource 

Evaluation (NURE) program of the U.S. Department of Energy. The survey was flown in east-west lines with 6-mi 

spacing at flight altitudes ranging from 200 to 500 ft above 

the ground. The coverage in the study area consists of 4 

east-west flightlines totaling about 20 mi. Recordings were 

made of gamma-ray flux from radioactive isotopes of uranium, thorium, and potassium. Radioactivity count rates generally were low over the andesite exposed in the southwestern 

part of the study area and the mesa-forming basalt. Radioactivity count rates exceeded the mean background level

Mineral Resources of the Spaulding Wilderness Study Area, Lake and Hamey Counties, Oregon Ell
over rhyolitic rocks in the study area, including tuffaceous 

sedimentary rocks and ash-flow tuff. However, these count 

rates are attributed to generally higher uranium and thorium 

concentrations in-the rhyolite compared to average crustal 

rocks and to the basalt and andesite in other parts of the 

study area. No locality was identified where the concentration 

of either uranium or thorium is high enough to indicate 

the presence of uranium or thorium resources.

Gravity Survey

Gravity data were previously available at two sites 

along the edge of and about 1 mi south of the study area 

(National Geophysical Data Center, 1984). In 1986, the 

USGS established 6 gravity stations along the margins of 

the study area and 25 stations within 5 mi of the study 

area (Plouff, 1987). A gravity-anomaly map shows that 

gravity anomalies interpolated within the study area increase to the northwest by about 12 milligals in 10 mi. 

The source of the gravity gradient is probably a contrast in 

density between rock masses buried deeply beneath the 

surface. A local small-amplitude gravity high is located 

near the west corner of the study area.

Aeromagnetic Survey

A regional aeromagnetic survey was flown over the 

study area at a constant barometric elevation of 9,000 ft 

above sea level with east-west flightline spacings of about 

2 mi (U.S. Geological Survey, 1972). An aeromagnetic 

low with two minima covers most of the study area. The 

shape and location of the aeromagnetic low correlate with 

areas underlain by andesite and ash-flow tuff. Therefore, 

these rocks probably erupted and cooled at a time when 

the Earth's magnetic field was reversed. The pattern of the 

magnetic low is interrupted by a north-trending magnetic 

high through the central part of the study area over outcrops of normally magnetized mesa-forming basalt.

Implications for Mineral Resource Potential

The geophysical data provide no constraints on the 

distribution of altered or mineralized rock in the study 

area. Altered areas are typically only several feet wide in 

the study area; these relatively small features are not detected with geophysical data collected on widely spaced 

flightlines or from widely distributed stations. No extensions of known sites of alteration were found.

MINERAL RESOURCE POTENTIAL

The mineral resource potential of the Spaulding Wilderness Study Area was assessed on the basis of geologic

investigations, geochemical and geophysical studies, and a 

study of prospects and claims in the area of reported mineral 

occurrences and deposits in the region. The northwestern 

and southeastern parts of the study area have low potential 

for epithermal gold and silver resources, with a certainty 

level of B. This assessment is based on the presence of 

localized gold or altered areas and (or) the presence of geochemical anomalies associated with precious-metal mineralization. Geochemical anomalies in silver, lead, zinc, 

bismuth, and the ore-related minerals barite and pyrite are 

present in nonmagnetic heavy-mineral concentrates from the 

southeastern part of the study area, and trace amounts of free 

gold are present in alluvial sand and gravel samples from 

the northwestern part of the study area. The source of these 

geochemical and mineral anomalies may differ for the northwestern and southeastern parts of the study area.

The presence of rounded clasts of silicified rock in 

the northwestern part of the study area suggests that the 

source of gold in this area may be detrital clasts of altered 

and mineralized rock. No similar rocks were found in outcrop and the rounding of these clasts suggests significant 

transport distances. The altered clasts probably were eroded from tuffaceous sedimentary rocks, which had a provenance outside the study area. Most, if not all, of the study 

area was at one time covered by tuffaceous sediment. 

Hence, the geochemical anomalies and traces of alluvial 

gold may be related to sources outside the study area. 

Scattered weak alteration zones suggest that minor hydrothermal alteration has affected parts of this area.

In the southeastern part of the study area, the presence in stream-sediment samples of faceted ore-related 

minerals showing little evidence of abrasion suggests that 

hydrothermal alteration has affected this part of the study 

area and that a local bedrock source is likely. Alternatively, the pyrite and barite present in the southeastern part of 

the study area may represent reworked lag deposits that 

remained after erosion of tuffaceous sediment off the 

welded tuff and were incorporated into present-day alluvium. This latter explanation is consistent with the general 

lack of alteration in exposed rocks in the area and the dispersed, low-level geochemical anomalies indicated by 

analysis of alluvial material, but is difficult to reconcile 

with the angular shape of crystal fragments of relatively 

soft minerals, such as barite, that were found in stream 

sediment samples.

The geochemical anomalies of elements such as mercury, arsenic, antimony, lead, copper, zinc, bismuth, and 

cadmium do not indicate potential resources for deposits 

of these elements. Concentrations of these elements are far 

below economic levels, and they are viewed as accessory 

constituents of an element suite related to epithermal precious-metal mineralization.

Tuffaceous rocks that pass nominal tests for use as 

pozzolan, which could possibly be used as additives to cement, are found in the northern part of the study area. These

El 2 Mineral Resources of Wilderness Study Areas: South-Central Oregon
rocks, however, would require detailed testing for compatibility with various cements. In addition, considering that the 

value of pozzolan depends largely on proximity to market 

and that similar rocks are widespread throughout the western 

United States, it is unlikely that these rocks will ever be 

mined. Perlite is present in small amounts in and near the 

study area but is of poor quality. The stone in the study area 

has no special aesthetic characteristics or physical properties 

that make it particularly desirable for decorative or construction uses. The pozzolanic rocks, perlite, and stone are regarded as occurrences only and have no resource potential.

There is low oil and gas potential in the study area 

(Fouch, 1982, 1983). The tuffaceous sedimentary rocks, the 

only likely source rock for hydrocarbons, do not contain 

significant amounts of organic material. There are no geologic indications of oil and gas or structural traps for hydrocarbon accumulation in or around the study area; hence, the 

assessment of low potential may be too high. If oil and gas 

are present at depth in the area, then they are buried beneath 

the volcanic section and could only be found with detailed 

geophysical surveys and drilling. The certainty of assessment, therefore, is B.

The study area has no geothermal energy potential, 

certainty level D (Muffler, 1979). No young volcanic centers are located in the area. The youngest volcanic rocks in 

the study area are the younger mesa-forming basalts, 

which are about 5 Ma. No fossil or active hot springs are 

present in the area.

The study area has no uranium or thorium mineral 

resource potential, certainty level D. Aerial gamma-ray 

surveys indicate slightly high amounts of uranium and 

thorium in rhyolitic rocks in the study area, but these levels are typical of rhyolitic rocks in the Basin and Range 

province. Field scintillometer readings and laboratory 

checks for radioactivity of heavy mineral fractions of alluvial material showed no anomalous readings.

REFERENCES CITED

American Society for Testing and Materials, 1985, Fly ash and 

raw or calcined natural pozzolan for use as a mineral admixture in portland cement concrete: 1985 annual book of 

ASTM Standards, part 10, section 4, construction; concrete 

and mineral aggregates: Philadelphia, Pennsylvania, American Society for Testing and Materials, designation C 618-85.

Beikman, H.M., Hinkle, M.E., Frieders, Twila, Marcus, S.M., 

and Edward, J.R., 1983, Mineral surveys by the Geological 

Survey and the Bureau of Mines of Bureau of Land Management Wilderness Study Areas: U.S. Geological Survey Circular 901, 28 p.

Chao, T.T., and Theobald, P.K., 1976, The significance of secondary iron and manganese oxides in geochemical exploration: Economic Geology, v. 71, p. 1560-1569.

Crock, J.G., Briggs, PH., Jackson, L.L, and Lichte, F.E., 1987, 

Analytical methods for the analysis of stream sediments and

rocks from wilderness study areas: U.S. Geological Survey 

Open-File Report 87-84, 35 p.

Diggles, M.F., King, H.D., Plouff, Donald, Conrad, J.E., Sawatzky, 

D.L., and Benjamin, D.A., 1988, Mineral Resources of the 

Guano Creek Wilderness Study Area, Lake County, Oregon: 

U.S. Geological Survey Open-File Report 88-0297, 12 p.

Erikson, E.H., and Currey, W.E., 1977, Preliminary study of the 

uranium favorability of Tertiary rocks, southeastern Oregon: 

eastern Klamath, southern Lake, Harney, and western Malheur Counties: Bendix Field Engineering Corporation, Grand 

Junction, Colo., prepared for the U.S. Department of Energy 

under contract EY-76-C-13-1664, GJBX-92 (77), 24 p., map 

scale 1:500,000.

Fouch, T.D., 1982, Petroleum potential of wilderness lands 

Oregon: U.S. Geological Survey Miscellaneous Geologic Investigations Map 1-1544, scale 1:1,000,000.

Fouch, T.D., 1983, Petroleum potential of wilderness lands 

Oregon: U.S. Geological Survey Circular 902-J, 5 p.

Geodata International, Inc., 1980, Aerial radiometric and magnetic survey, National Topographic Map, Adel, Oregon: U.S. 

Department of Energy Open-File Report GJBX-104 (80), 

v. 2, 145 p.

Goudarzi, G.H., 1984, Guide to preparation of mineral survey 

reports on public lands: U.S. Geological Survey Open-File 

Report 84-787, 51 p.

Greene, R.C., 1984, Mineral resources of the Charles Sheldon 

Wilderness Study Area, Humboldt and Washoe Counties, Nevada, and Lake and Harney Counties, Oregon: U.S. Geological 

Survey Bulletin 1538, 139 p., 2 plates, scale 1:125,000.

Grimes, D.J., and Marranzino, A.P., 1968, Direct-current arc and 

alternating-current spark emission spectrographic field methods for the semiquantitative analysis of geologic materials: 

U.S. Geological Survey Circular 591, 6 p.

Hart, W.K., Aronson, J.L., and Mertzman, S.A., 1984, Area! distribution and age of low-K, high-alumina olivine tholeiite 

magmatism in the northwestern Great Basin: Geological Society of America Bulletin, v. 95, p. 186-195.

Levinson, A.A., 1974, Introduction to exploration geochemistry: 

Wilmette, 111., Applied Publishing Ltd., 614 p.

Matthews, G.W, and Blackburn, W.H., 1983, Assessment of geology, energy, and mineral resources, Guano Valley GRA 

(OR-010-24), Lake and Harney Counties, Oregon: Lakewood, Colorado, Terradata, 34 p.

McKelvey, V.E., 1972, Mineral resource estimates and public 

policy: American Scientist, v. 60, p. 32-40.

Miller, M.S., 1988, Mineral resources of the Spaulding Wilderness Study Area, Lake and Harney Counties, Oregon: U.S. 

Bureau of Mines Minerals Land Assessment Open-File Report MLA 23-88, 30 p.

Muffler, L.J.P., ed., 1979, Assessment of geothermal resources of 

the United States-1978: U.S. Geological Survey Circular 

790, 163 p.

National Geophysical Data Center, 1984, DMA gravity file of the 

U.S.: National Oceanic and Atmospheric Administration, 

Boulder, Colo., 2 magnetic tapes.

Noble, D.C., McKee, E.H., Smith, J.G., and Korringa, M.K., 

1970, Stratigraphy and geochronology of Miocene volcanic 

rocks in northwestern Nevada, in Geological Survey Research 1970: U.S. Geological Survey Professional Paper 

700-D, p. D23-D32.

Mineral Resources of the Spaulding Wilderness Study Area, Lake and Harney Counties, Oregon El 3
O'Leary, R.M., and Meier, A.L., 1986, Analytical methods used 

in geochemical exploration, 1984: U.S. Geological Survey 

Circular 948, 48 p.

Plouff, Donald, 1987, Gravity observations by the U.S. Geological Survey in northwest Nevada, southeast Oregon, and 

northeast California, 1984-1986: U.S. Geological Survey 

Open-File Report 87-639, 33 p.

Union Carbide Corporation, 1982, Hydrogeochemical and stream 

sediment reconnaissance basic data for Adel, Jordan Valley, 

and Twin Falls quadrangles, Oregon, Idaho: prepared for the 

U.S. Department of Energy, Grand Junction, Colorado under 

contract W-7405 eng 26, GJBX-170 (82), K/UR-450, 73 p.

U.S. Bureau of Mines and U.S. Geological Survey, 1980, Principles of a resource/reserve classification for minerals: U.S. 

Geological Survey Circular 831, 5 p.

U.S. Department of the Interior, 1939, Pacific northwest mineral 

occurrences: Bonneville project, 25 p.

 1941, Pacific northwest mineral occurrences: Bonneville 

project, 51 p.

U.S. Geological Survey, 1972, Aeromagnetic map of the Adel 

and parts of the Burns, Boise, and Jordan Valley 1° by 2° 

quadrangles, Oregon: U.S. Geological Survey Open-File Report, scale 1:250,000.

Walker, G.W., 1977, Geologic map of Oregon east of the 121st 

meridian: U.S. Geological Survey Miscellaneous Geologic 

Investigations Map 1-902, scale 1:500,000.

Walker, G.W., and Repenning, C.A., 1965, Reconnaissance geologic map of the Adel quadrangle, Lake, Harney, and Malheur 

Counties, Oregon: U.S. Geological Survey Miscellaneous Geologic Investigations Map 1-446, scale 1:250,000.

El 4 Mineral Resources of Wilderness Study Areas: South-Central Oregon
APPENDIXES
DEFINITION OF LEVELS OF MINERAL RESOURCE POTENTIAL 

AND CERTAINTY OF ASSESSMENT

LEVELS OF RESOURCE POTENTIAL

H HIGH mineral resource potential is assigned to areas where geologic, geochemical, and geophysical characteristics indicate a geologic environment favorable for resource occurrence, where interpretations of data 

indicate a high degree of likelihood for resource accumulation, where data support mineral-deposit models 

indicating presence of resources, and where evidence indicates that mineral concentration has taken place. 

Assignment of high resource potential to an area requires some positive knowledge that mineral-forming 

processes have been active in t least part of the area.

M MODERATE mineral resource potential is assigned to areas where geologic, geochemical, and geophysical 

characteristics indicate a geologic environment favorable for resource occurrence, where interpretations of 

data indicate reasonable likelihood for resource accumulation, an (or) where an application of mineraldeposit models indicates favorable ground for the specified type(s) of deposits.

L LOW mineral resource potential is assigned to areas where geologic, geochemical, and geophysical characteristics define a geologic environment in which the existence of resources is permissive. This broad 

category embraces areas with dispersed but insignificantly mineralized rock, as well as areas with little or 

not indication of having been mineralized.

N NO mineral resource potential is a category reserved for a specific type of resource in a well-defined area.

U UNKNOWN mineral resource potential is assigned to areas where information is inadequate to assign a 

low, moderate, or high level of resource potential.

LEVELS OF CERTAINTY

A Available information is not adequate for determination of the level of mineral resource potential.

B Available information only suggests the level of mineral resource potential.

C Available information gives a good indication of the level of mineral resource potential.

D Available information clearly defines the level of mineral resource potential.

A

U/A

UNKNOWN POTENTIAL

B

H/B

HIGH POTENTIAL

M/B

MODERATE POTENTIAL

L/B

LOW POTENTIAL

C

H/C

HIGH POTENTIAL

M/C

MODERATE POTENTIAL

L/C

LOW POTENTIAL

D

H/D

HIGH POTENTIAL

M/D

MODERATE POTENTIAL

L/D

LOW POTENTIAL

N/D

NO POTENTIAL

o

Q.

LU

U

C*.

D

oen

LU

o

_I

LU 

>

LEVEL OF CERTAINTY

Abstracted with minor modifications from:

Taylor, R.B., and Steven, T.A., 1983, Definition of mineral resource potential: Economic Geology, v. 78, no. 6, p. 1268-1270.

Taylor, R.B., Stoneman, R.J., and Marsh, S.P., 1984, An assessment of the mineral resource potential of the San Isabel National Forest, south-central Colorado: U.S.

Geological Survey Bulletin 1638, p. 40-42. 

Goudarzi, G.H., compiler, 1984, Guide to preparation of mineral survey reports on public lands: U.S. Geological Survey Open-File Report 84-0787, p. 7, 8.

El 6 Mineral Resources of Wilderness Study Areas: South-Central Oregon
RESOURCE/RESERVE CLASSIFICATION

ECONOMIC

MARGINALLY 

ECONOMIC

SUBECONOMIC

IDENTIFIED

Demonstrated

Measured Indicated

i 

Reserves

i

i i

Marginal

Reserves i i

Demonstrated 

Subeconomic 

Resources

RESOURCES

Inferred

Inferred 

Reserves

Inferred 

Marginal 

Reserves

Inferred 

Subeconomic 

Resources

UNDISCOVERED RESOURCES

Probability Range

Hypothetical Speculative

i

 

t

Major elements of mineral resource classification, excluding reserve base and inferred reserve base. Modified from McKelvey, V.E., 1972, Mineral 

resource estimates and public policy: American Scientist, v. 60, p. 32-40; and U.S. Bureau of Mines and U.S. Geological Survey, 1980, Principles 

of a resource/reserve classification for minerals: U.S. Geological Survey Circular 831, p. 5.

Mineral Resources of the Spaulding Wilderness Study Area, Lake and Harney Counties, Oregon El 7
GEOLOGIC TIME CHART

Terms and boundary ages used by the U.S. Geological Survey in this report

EON

Phanerozoic

Proterozoic

Archean

pre-Archean2

ERA

Cenozoic

Mesozoic

Paleozoic

Late Proterozoic

Middle Proterozoic

Early Proterozoic

Late Archean

Middle Archean

Early Archean

PERIOD

Neogene

Subperiod

Tertiary

Subperiod

Cretaceous

Jurassic

Triassic

Permian

Pennsylvanian 

Carboniferous

Mississippian

Devonian

Silurian

Ordovician

Cambrian

_______ (3800?) -

EPOCH

Holocene

Pleistocene

Pliocene

Miocene

Oligocene

Eocene

Pal eocene

Late 

Early

Late 

Middle 

Early

Late 

Middle 

Early

Late 

Early

Late 

Middle 

Early

Late 

Early

Late 

Middle 

Early

Late 

Middle 

Early

Late 

Middle 

Early

Late 

Middle 

Early

AGE ESTIMATES OF 

BOUNDARIES IN 

MILLION YEARS (Ma)

0.010

1.7

5

24

to

55

66

 96

1 1Q

205

-?4O

oon

-330

Ififl

410

435

COO

1 C7O

onn

1600

 2500

onnn

 3400

.dccn

1 Rocks older than 570 Ma also called Precambrian, a time term without specific rank. 

Informal time term without specific rank.

El 8 Mineral Resources of Wilderness Study Areas: South-Central Oregon
Mineral Resources of 

Wilderness Study Areas: 

South-Central Oregon

This volume was published as separate chapters A-E

U.S. GEOLOGICAL SURVEY BULLETIN 1738
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY 

Gordon P. Eaton, Director
CONTENTS

[Letters designate the separately published chapters]

(A) Mineral Resources of the Devil's Garden Lava Bed, Squaw Ridge Lava Bed, and 

Four Craters Lava Bed Wilderness Study Areas, Lake County, Oregon, by 

William J. Keith, Harley D. King, Mark E. Gettings, and Fredrick L. Johnson.

(B) Mineral Resources of the Orejana Canyon Wilderness Study Area, Harney County, 

Oregon, by James E. Conrad, Harley D. King, Mark E. Gettings, Michael F. 

Diggles, Don L. Sawatzky, and David A. Benjamin.

(C) Mineral Resources of the Abert Rim Wilderness Study Area, Lake County,

Oregon, by Maureen G. Sherlock, Mark E. Gettings, Harley D. King, and Terry 

R. Neumann.

(D) Mineral Resources of the Diablo Mountain Wilderness Study Area, Lake County, 

Oregon, by Michael F. Diggles, Harley D. King, Mark E. Gettings, James E. 

Conrad, Don L. Sawatzky, Gerilyn S. Soreghan, Thomas J. Peters, and Spencee L. 

Willett.

(E) Mineral Resources of the Spaulding Wilderness Study Area, Lake and Harney 

Counties, Oregon, by Michael G. Sawlan, Harley D. King, Donald Plouff, and 

Michael S. Miller.

*u.s. GOVERtimir EKEOTING OFFICE: 1995-683-048A0015

SELECTED SERIES OF U.S. GEOLOGICAL SURVEY PUBLICATIONS

Periodicals

Earthquakes & Volcanoes (issued bimonthly). 

Preliminary Determination of Epicenters (issued monthly).

Technical Books and Reports

Professional Papers are mainly comprehensive scientific reports of wide and lasting interest and importance to professional 

scientists and engineers. Included are reports on the results of 

resource studies and of topographic, hydrologic, and geologic 

investigations. They also include collections of related papers 

addressing different aspects of a single scientific topic.

Bulletins contain significant data and interpretations that are of 

lasting scientific interest but are generally more limited in scope or 

geographic coverage than Professional Papers. They include the 

results of resource studies and of geologic and topographic investigations, as well as collections of short papers related to a specific 

topic.

Water-Supply Papers are comprehensive reports that present 

significant interpretive results of hydrologic investigations of wide 

interest to professional geologists, hydrologists, and engineers. The 

series covers investigations in all phases of hydrology, including 

hydrogeology, availability of water, quality of water, and use of 

water.

Circulars present administrative information or important scientific information of wide popular interest in a format designed for 

distribution at no cost to the public. Information is usually of shortterm interest.

Water-Resource Investigations Reports are papers of an interpretive nature made available to the public outside the formal USGS 

publications series. Copies are reproduced on request unlike formal 

USGS publications, and they are also available for public inspection 

at depositories indicated in USGS catalogs.

Open-File Reports include unpublished manuscript reports, 

maps, and other material that are made available for public consultation at depositories. They are a nonpermanent form of publication 

that may be cited in other publications as sources of information.

Maps

Geologic Quadrangle Maps are multicolor geologic maps on 

topographic bases in 7 1/2- or 15-minute quadrangle formats (scales 

mainly 1:24,000 or 1:62,500) showing bedrock, surficial, or engineering geology. Maps generally include brief texts; some maps 

include structure and columnar sections only.

Geophysical Investigations Maps are on topographic or planimetric bases at various scales; they show results of surveys using 

geophysical techniques, such as gravity, magnetic, seismic, or 

radioactivity, which reflect subsurface structures that are of economic or geologic significance. Many maps include correlations 

with the geology.

Miscellaneous Investigations Series Maps are on planimetric 

or topographic bases of regular and irregular areas at various scales; 

they present a wide variety of format and subject matter. The series 

also includes 7 1/2-minute quadrangle photogeologic maps on 

planimetric bases that show geology as interpreted from aerial 

photographs. Series also includes maps of Mars and the Moon.

Coal Investigations Maps are geologic maps on topographic or 

planimetric bases at various scales showing bedrock or surficial 

geology, stratigraphy, and structural relations in certain coal-resource 

areas.

Oil and Gas Investigations Charts show stratigraphic information for certain oil and gas fields and other areas having petroleum 

potential.

Miscellaneous Field Studies Maps are multicolor or black-andwhite maps on topographic or planimetric bases on quadrangle or 

irregular areas at various scales. Pre-1971 maps show bedrock 

geology in relation to specific mining or mineral-deposit problems; 

post-1971 maps are primarily black-and-white maps on various 

subjects, such as environmental studies or wilderness mineral investigations.

Hydrologic Investigations Atlases are multicolor orblack-andwhite maps on topographic or planimetric bases presenting a wide 

range of geohydrologic data of both regular and irregular areas; 

principal scale is 1:24,000, and regional studies are at 1:250,000 

scale or smaller.

Catalogs

Permanent catalogs, as well as some others, giving comprehensive listings of U.S. Geological Survey publications are available 

under the conditions indicated below from the U.S. Geological 

Survey, Books and Open-File Reports Sales, Federal Center, Box 

25286, Denver, CO 80225. (See latest Price and Availability List.)

"Publications of the Geological Survey, 1879-1961" may be 

purchased by mail and over the counter in paperback book form and 

as a set of microfiche.

"Publications of the Geological Survey, 1962-1970" may be 

purchased by mail and over the counter in paperback book form and 

as a set of microfiche.

"Publications of the Geological Survey, 1971-1981" may be 

purchased by mail and over the counter in paperback book form (two 

volumes, publications listing and index) and as a set of microfiche.

Supplements for 1982,1983,1984,1985,1986, and for subsequent years since the last permanent catalog may be purchased by 

mail and over the counter in paperback book form.

State catalogs, "List of U.S. Geological Survey Geologic and 

Water-Supply Reports and Maps For (State)," may be purchased by 

mail and over the counter in paperback booklet form only.

"Price and Availability List of U.S. Geological Survey Publications," issued annually, is available free of charge in paperback 

booklet form only.

Selected copies of a monthly catalog "New Publications of the 

U.S. Geological Survey" are available free of charge by mail or may 

be obtained over the counter in paperback booklet form only. Those 

wishing a free subscription to the monthly catalog "New Publications of the U.S. Geological Survey" should write to the U.S. 

Geological Survey, 582 National Center, Reston, VA 22092.

Note.-Prices of Government publications listed in older catalogs, announcements, and publications may be incorrect. Therefore, 

the prices charged may differ from the prices in catalogs, announcements, and publications.