58TH CoNGREss, } 

~d Session. 

,Professional Paper No. 27 

HOUSE OF REPRESENTATIVES . . j DocuMENT 

1 No. 715. 

Serres . . . { A, Economic Geology, 35 

B, Descriptive Geology, 39 

DEPARTMENT OF THE INTERIOR 

UNITED STATES GEOLOGICAL SURVEY 

CHARLES D. WALCOTT, DIRECTOR 

A 

GEOLOGICAL RECONNAISSANCE 

ACROSS THE 

BITTERROOT RANGE .LL\_ND CLEARWATER 

MOUNTAINS IN MONTANA 

AND IDAHO 

BY 

W ALI}EMA-R LINDGREN 

WASHINGTON 

GOVERNMENT PRINTING OFFICE 

1904 
, 

' ; 

.• 
CONTENTS. 

Page. 

Introduction ......•..........•...................................•• ______ ••.•••• _ •••••• -. 9 

Situation ____ . __ ........ _ ... _ . __ .......................... _ .. _ .... _ • _ . .. _ ... ___ .. __ • . . 9 

Maps and literature __ ... ____ ... ___ .. __ . ________ .... · .. _. _ .. ·. __ . ________ .• _. _. ____ .• ___ . 10 

Field work _ . _ .... _ .... ___ .... _ .. ~ _ ... _ ............... _ .. _ ..... __ .. _. _ ..•... ___ .. ___ . _ 12 

Topography _. _ .... _ ............ __ ... _. _ .. _ ............ _ . _ L .. _______ •• _ ••• __ ••.• _ •. __ • _ .. _ _ 12 

Descriptive geology __ ... _____ .... _ .. _ .. _ ...... __ ...... _ .... __ . __ .... __ ... __ ...... _ .. _..... 15 

General features ....... _ ....•. _ . __ .. __ . _ .............. _ ..... _ . _ ........ _ ....... ___ . __ . 15 

Sedimentary formations ...... _. _. _ ... __________ .. _ .. ________ . __ .. __ . _ .. ____ .. _. _. . 15 

·Granite __ .. ___ . __ .. _ .. _ ....... _ .. _. __ .. ___ ~ _ ....... _ .... ___ ..... ..... _. _._. _. __ ... 17 

Extent _ . _ ....... _ .... _ .................... _ ... _ ................ _ ... · ... _ . . 17 

Character . _ .....• ____ ......... _ ...... _ ........... _ . _ ............. ___ . __ ~ _ 17 

Age . ______ .. _-........... ____ . _______ .. _ .......... .. _ .. ...... ..... ___ ... _ _ 20 

Dikes in granite._ .................. _ ............. _ ...... _ ........ _........ 20 

Gneiss .... ____ __ .. __ ....... __ ............ _ ................. ___ .... _ . ____ . _ .. _ . _ . . 20 

Tertiary lavas ....... __ . _ .... __ .... __ ...... _ ........ ______________ . ---.. ----- -. _ --- 23 

Rhyolite . _________ .. __ .. _________ .. _ .... ___ .. ___ . _____ -.-.. _ .. _. ________ -.- 23 

Basalt. ________ __ .... __ ... . _. __ ..... _. ___ ....... __ ... _._ .. _ ...... _ ... _ ... _ 24 

Quaternary formations ............. _ .................... _ ... _ . _ ........... _ . . . . . . . 25 

Geological history ............ _ . _ .... _ .. _ . _ .... _ .. _ ... ___ ................. _ . . . . . . . . 26 

Bitterroot Valley . _ . ___ .. _ . ...... _ . _ ...... _ . _ .... _ .. ___ . __ ..... _ . _ . ___ ..... _____ . __ . _ . 28 

Topography _ ............... -,-.. __ .. _ ........... _ .............. ______ . _ .. ___ . _..... 28 

Culture and vegetation ____ . ___________ . ____________ _ . __ .. ______ .. _ ., _________ . ___ . _ 29 

Geology ____ . _ . ____ . _ . _____ . ___ . ______ ... _ . __ ... ____ . ____ .. _______ . __ . __ . ____ .. __ . 29 

Quaternary . _____ .. __ ~ __ . _ ..... _____ . __ .. __ ... __ . _ . ______ .. __ . ___ . _____ .... _ . . 29 

Eastern foothills ____ . __ .. _ . _____ _ .. _ . .. _ .. ______ . ___ . _ . _ . ___ . _ . _ ..... __ .. _ .. __ • __ . _ .. _ 30 

Topography . __ .. _ .. ___ . _____ .. ____ .. ____ . _. __ ... _. _________ . ____ ....... -. __ . . . . . . 30 

Geology. ___ .. _ . _ .. __ .... ____ .. ___ ..... ______ .. _ . ___ .. ____ . _______ . ___ ........ _ _ _ _ 31 

Sedimentary series . _. __ .... ___ .. ___ . ___ . _ .. _. _. ___ . _ .. _____________ •. ______ .... 31 

Contacts. __________ .. _. ____________________________ . _________ ...... ___ . _ .. __ ... 31 

Granitic rocks . ____________________________ __ .. _ . ___ . ________ .. ______ . _ _ _ _ _ _ _ _ 32 

Dikes ____________________________ . ____________________ . ___ .. _ ... _ ... _ .. _____ . 32 

Rhyolite . _. ___ . ____ . _____ . ___________ . _ . _ .. _____ .. _. _. _. ____________ ... _. __ .. 32 

Lolo Fork and north end of Bitterroot Range . ____ . _ . __ . __ -.. _. _. _________ .. __ ....... __ ... 33 

Topography .. ___ . ________________ . _________ .. ___ ..... __ . _ .... _. _. ____ . _______ . _ _ _ 33 

Geology ~ ______________________ . __ . _____ ..... _______ ... _ . _ . ___ . _________________ . . 34 

Sedimentary series _ . ____ ____ . ___ . ___ . _ . _______ . _____________________________ ~ . 34: 

Lolo contact ___ . __ . _ . . ____________ ~ ~ __________ · ___________ . ___ ... __________ . _ _ _ 36 . 
4 CONTENTS. 

Descriptive geology-Continued. 

Lolo Fork and north end of Bitterroot Range-Continued. 

Geology-Continued. 

Carlton Creek contact_._._._. ____ .. _. _ .. _ .. ___ . _ ... ____ .. _. _ .•••. · ............ . 

Gneiss of St. Marys Peak._._ . _ ..... _ .. _. _ ..................•............ _ .... . 

Granite; quartz-monzonite._ ........... __ ......... _ ... _ .. _. __ .......... ______ -. 

Qua ternary ____ . _ . _ .. __ .. __ ..... ______ . _ . _ .. ____ .. ___ . _______ . _ . _ . _____ .. ____ . 

Bitterroot Range._._. __ ... __ ~. __________________ ..... ________ . ____ . _______ .. ___ . _____ . 

Topography ..... ____ ... __ . _ .. __________ ... __ . __ . _. __ . ____ . _____ .. ____ . ___ ... ____ . 

Geology ___ . ___ ." . __ . _____ . " __ . _______________________________ ..... ____________ .. ___ _ 

- Sedimentary series. ______ ... ___ . _____ ......... __ .... _ ........ _ ..... _ ......... . 

,Granite and gneiss ... _ ...... _ ......................... ___ . _________ . __ .. --- _ .. _ .. 

North end of the range. __ . ___ .... _ ...... __ ._ ......... · ......... ---_ . -- .. -.. 

Mill Creek section . ____ .............. · ..... ____ . _ . _ .. _ . ·. _ ...... ___ . _ .- ____ - -

Lost Horse section _ . __ . _ .. ________ .... ____ . _________ . ____ . _ . _ . _______ . ___ . 

Rock Creek section ________ .. _ .. ___ . __________ ~ ____ . ______ .... _________ . _ . 

Trapper Creek section. ____ ._ .. ________ . __ ._. ____ ... ___ ... ___ ... _. __ ._. ___ _ 

South end of the range _________ .. _. _ .. __ • _. _ .. _ .. ____ ... ___ . ___ .. _________ _ 

Structure and physiography . _. _ . ___ . _ .. _. _ ....•. _ .... __ .. ______ . ________ . __ ... 

Glaciation ______ . _____ ._ . ____ .. ; __ .... ___ . _ .. ______ . _. ___ . __ . _. _____________ .. 

South Fork of Bitterroot River. ______________ . _ .. ___ . _ .. _________ . __ . _____ .. ____ . _. :. _. 

Topography .. _ ... _ .. _ . _____ .. ___ . ________ . _____ ..... _ .. ___ ~ __ ... ____ ... ____ ... _. _ 

Geology ____ ... _ . _ .. _ .. _ .. __ . _____________________________ ~ -' _____________________ _ 

Granite . __ . ____ ~ ____ . ___ . ____________ ... ____ . ___ . _ .. _ . _________ .. _ · ____ .. _ .•. _ 

Sedimentary series . ____ . __ . ______________ . ________ . _ " ___ ...... _ ... _: . __ ...... _ 

Tertiary volcanic rocks. __ . _________ . ______________ . ___ ... ______ . _ ... ___ . _ .. __ . 

Quaternary _________ . ____ ... ___ . __ .. ___ . _ .. _ . _ ... _ . __ . _ . _____ .. _ ... ___ ........ . 

Clearwater Mountains . ___ ........... __________________ . ___ . ___ ...... __ ............... . 

Topography .. ____ ..... ___ ... _______ .. __ ... _ .... _ ........... ___ .. __ ... __ . _. _ . ____ _ 

. Ridges _ ... _ . __ . _ . ____ · ...... ____ . _ . _ ........... _ . . . . . . . . . - -........... -. -- - - - -

. Canyons ... __ ... _ ... __ ... ________________ . ______ . _ . _________ .. ________ . ___ .. __ 

Geology ... ___ .. __ . ____ . ______________________ · ________________________________ • __ _ 

Granite " _ .... __ . ___ . ________________ ... ·-.. _. ____ . __ ~ _ . _ .. ______ . _____ ... _ .... 

Gneiss _ . _ .... __ . ____ . __ ... ________ . __________ .. ____ l _____ . __ .... __ . __ ... ____ . S~dimentary rocks . ___ . ________ ... _________ .. _. ________________ .. ____ . _____ ... 

Tertiary gravels .. _ . _____ ..... _ . __ .. _. __ .. _______ . ______ - ___ .. ____ ----· ____ ----

Glaciation _ . _ . _____ . __ .. _ . _____ . _ . ____________________ . __ .. _____ . _________ .. _ . 

The lava plateau __ .... ___ .. _ . _____ . ________________ . _ . ___ . _____ . __ . _ . _______________ . _ 

Topography ... _ .... __ ... ___ .. _____ .. _. _ ... __ .. ___ . ________ . ___ . _____ . _. _ .. ____ ... _ 

Geology _ ......... ___ .... _ .. _ ... ___ . ____ .. ___________ . ______ . ____________ . _______ _ 

Pre-Tertiary formations ________ .. ___ . _ . _ . ____ . _ .. ____ . __ . ___ . _____ . __ .. _______ . 

Basalt flows ___ .. _ .- __ .. __ . ___ ...... ____ ... __ -·- _. _. _. _. _ .. ___ -..... -- -----. __ --

Structure and physiography of the plateau ... _ ... ___ .. __ .... __ .... _ . _ .. _ .. _ . _ . _ . 

Orogenic disturbances ___ .......... _. __ . ____ . __ .... _ .. ____ ._._._ .. __ .... ___ . 

Epeirogenic disturbances ... _ .. ____ ...... _____ . _ . _, ...... . . __ ......... ___ .. 

Place of eruption of the basalt. _ . _ .. __ .. _______ . _ . __ ... ___ .. __ . ___ ... ___ .. ____ _ 

Coeur d'Alene Mountains ... ___ ....... _._ .. ___ . ____ . __ ._ .... ___ ...... __ .~ . .... _____ . __ _ 

Page. 

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55 

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56 

57 

58 

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74 

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80 

81 
CONTENTS. 5 

Page. 

Economic geology. __ . __ . ____ . _____ ..................•••...•. ·_ ...•••.•. _ ••••••••. -- -... -.. . 82 

General features . __________ . __ .......... _ . . . . . . . . . . . • . . . . . . • . . • • • • • . • . • • . . . • • . . . . . . . . . 82 

Character of mineral deposits_ .......... ................••..••••. _--- ... -.-. 82 

Distribution of deposits_ ... _. ___ . ________ ... ___ . ___ • ___ • _____ .. ----- .. -.. -- 82 

Character of ore. _ .... ___ .... _ ... _ ... _ .. _____ .. _ . _ . __ • _____ • - .. - - -- -.. - - - - - 83 

History and production. ____ . ___ . ____ ..... _ .... ____ .... ____ -.. __ -. _ -... ---. 84 

Geological relations ___ .. __ . _ ....... ___ . _____ . _ .. __ . __ ....... -. -- .. - -.. -- -- 85 

North end of Bitterroot Range. _________ . ___ ._ ..... _____ . _________ .. __ ........... _ ... -. 86 

Lolo Fork ________ ..... _ .. _ ..... __ .... _ .. _. ____ . ... ___ ....•. ......•... _... 86 

Mormon and Carlton creeks •.... _____ . ______ ..... _ ........ _ ....•••. -----... 86 

Curlew mine. _________ . __ ..... ___ . ____ . _ .. __ . _ ... __ .......••.. _ ....... ---- 86 

Pleasant View prospects .... _____ ...... ______ ._ ... _._ ....... -- .... -- .. ---.. 87 

Upper South Fork of the Bitterroot·--------------------------------------------------- 88 

Trapper Creek------------------------------------------------------------ 88 

Slate Creek ~ ___ .. __ . ___ ... _ ..... _ ... _ ... __ .. •. _ . ____ •.• _ •...•.........• _ . . 88 

Hughes Creek . ___ .. ___ . _ .......••......... _ ...... _. _ .•............. ~. _... 88 

Mineral Point ______ ..... ___ . _ .. _ .... _ ...... _ ...• _ ........ ..•. _. . . . . . . . . . . 89 

l\1ineral Hill. _ ... _______ ..... __ •.. __ .... _ ... . _ ........ _ ... _. _ ........... _ . 90 

Gibbonsville district ________ .. _ .... __ ............•.......... _ ............ ____ ...... _.. 90 

Elk City district. ____ . _ . _ .... _ ..... _ ...•.• _ .......... ____ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 

Placer mines __ .. _____ . _ .. _ .. __ . _ .................... _ . __ . _ .... ___ ....... _ . . . . . . . . . 91 

Red River _____ . ______ ....... _ .........•.. __ ........ __ . . __ .... _ .. _ ..... __ . 91 

An1erican Hill .. _ ... __ . __ ............. _ .. _ ......... _ .. _ ......... . _........ 93 

Tiernan Diggings _____ .. _ . .. ____ .. ~ ... . _ . . . _ . _ . _ Jo • ••• ____ ••••••• __ • • • • • • • • 94 

Buffalo Hill ______ . _ ..... _ .. . . _. _. _ .. . __ . ______________ .......... _ .. _ ... _. 94 

Crooked River. _________ .. _ . _ . _ ... __ . _ .. ____ ..... . _______ ...... __ .... . . _.. 95 

Little Elk Creek __ .. ..... _. _ •................ _ ...• __ ...... _ ... _.......... 95 

Newsome Creek basin . _ .......... . . _ ... __ . ______ . . . . . . . . . . . . . . . . . . . . . . . . . 96 

Quartz veins. _____ . _ .... ______ . ________ . __ ... __ .......... _ .. _ ......... _ . _ .. . .. __ . . 96 

Dixie district _______________ .. .. _ ..... _ ......... _ ...•.. ___ . _____ . ___ " ... _ . _ .... __ ... _-_ 98 

Buffalo Hump district .... _. ___ . . .... , __ .............. ___ ... _____ .......... _ .... _. _ _ _ _ 99 

Pierce district . ___ . ____ ... ____ ... _ .. . ________ . .... . ....... _ ... _ ....... _____ .. __ . . . . . . . 102 

Placers ________________ .......... __ ....... _ . ___ ....... __ ... _ . . . . . . . . . ........ _ _ _ _ _ 102 

Quartz veins. __ . __ ._ ... . ____ ... _ .. ____ ._. ___ .. ____ ......................... __ ._... 103 

Musselshell and Lolo creeks ...... ____ .. ___ . ___ . _ .......... __ " __ •... __ • _. . ............ 105 

Deposits between Clearwater and Snake rivers ... _._ ...... _ .. __ .. _ ......... _____ ... _._. 105 

Near Harpster and Mount Idaho----------------------------------------- 105 

Cottonwood Buttes .. _____________ ..•. __ . _ ....... _ ..... _ ..•.. __ .. _ ..... ~ _. 106 

The lower Clearwater ___ . _ .. _ •................ __ ...•. _ .. ___ ..•.• _ •.. __ .. _ 107 

Canyons of Snake and Salmon rivers •......... _. __ ..•...•....... _ ... ____ . _ 107 

Coeur d'Alene Mountains .. ___ . ___ .. ________ .. __ . _. ___ ... ___ .. __ .... _ ....•. __ . _....... 108 

Gold deposits ...••... . . . . _.- __ . _____________ . ____ . _____ . ______ .• _ .. _ .. -. ______ . ____ . 108 

Lead-silver veins .. __ ... __ ... ___ . _ ...... _ .•.. _ ••• _ ....... __ ....................... 108 

Lignite .. ___ .... _ ........ . .. __ .. _ ................................ _ •...... _ " ...... _ _ _ _ _ 111 

Mineral springs .. _ .. _'_ .. _._._ . ... . .. _ ... _ ......... _ .... _ ........... _ ....... _......... 113 

Summary .... _ ..... _ .... __ .. __ ....... __ . _. __ .. _ . __ . __ ... __ .....................•.......... 114 

Index ............. : .... _ ...... ___ ..... _ ...... .......... _ ..... _ .•...••..•... _ .......... _ . . 117 

I Ij L U S T R A T I 0 N S. 

Page 

PLATE I. Map of a part of central Idaho, from Lewiston to the Bitterroot Range .. _._ .. _ •••• -. 1 

II. Map of a part of the Bitterroot Range, Montana and Idaho _____ ~ __________________ • 1 

III. Map showing central part of Bitterroot Range, from Hamilton quadrangle._. ___ ._... 1 

IV. Profiles across the Bitterroot Range, Clearwater Mountains, and Columbia lava plateau. 1 

V. Photomicrographs of gneiss or granite-schist __________________________ .. __ . ______ .. 2 

VI. A, Detail of gneiss cliffs 0n north side of Mill Creek Canyon, near mouth; B, View 

south from Hamilton, showing regular slope. of gneiss zone of Bitterroot Mountains. 4 

VII. A, Upper valley of Mill Creek, Bitterroot Range, looking east from main divide; 

B, View south fro~ Ward Peak, Bitterroot Range _____ . _____ . __ . _ ..... __ . ____ .. 4 

VIII. A, View north from Ward Peak, Bitterroot Range, across the canyons of Roaring 

Lion and Sawtooth creeks; B, Como Peaks, seen from Como Lake, Bitterroot 

Mountains ____________________________________________ . ______________ .. ______ • _ 4 

IX. A, Trapper Peak, showing gradual slope of gneiss zone to the left, and glacial 

amphi~heater in tP,e center; B, orest of lodgepole pine (Pinus murrayana), Como 

trail, Bitterroot Mountains. __________ ~ ______________________________ . ____ ... _.. 4 

X. Panoramic view of Bitterroot Range from terrace northeast of Darby, showing bottom lands and terraces along the river, the moraines in front of the canyons, 

and the even slope of the gneiss zone along the southern end of the range. ___ _ 

XL A, Forest of cedar ( Thuja plicata), Cedar Creek, Clearwater Mountains; B, Granite 

Peak, near Bilk M~untain, Clearwater Mountains ___________ . __________________ .. 

XII. A, View southwest from Grave Peak, Clearwater Mountains, showing glacial lakes; 

B, Walton Lake, near Grave Peak, Clearwater Mountains ________________________ _ 

XIII. Canyon of Snake River, looking north from point near Waha _. ___ .. ______ .. _______ _ 

XIV. Lewiston Plateau, looking north from near Waha ______ ___________________________ • 

XV. A, American Hill placer mine, Elk City, Idaho; B, Iron Crown quartz mill, Newsome 

Creek, Idaho ________________ ___________________________________________________ _ 

FIG. 1. Index map showing extent of reconnaissance ________________________ . _____ : __ ._-----

2. Bitterroot Range, looking northwest from Hamilton, showing gentle eastward dip of gneiss 

zone and deeply incised canyons of Blodgett and Mill creeks, with precip'itous sides. _ 

3. South end of Bitterroot Range, showing gradual eastern slope of gneiss zone south of 

Tincup Creek, moraines. in foreground, from point near Darby __________ . ___________ . 

4. View south across Salmon River Canyon from south slope of Caseknife Mountain, showing plateau character of Salmon River Mountains. _______ . _______________________ ---

5. Salmon River Canyon seen from diorite point at Holdenried ranch, near Keuterville, 

looking southeast, upstream, toward White Bird ___________ . ______ . ________ . ______ _ 

6. View north from Rocky Ridge, on the Lolo Ridge over the Coeur d'Alene Mountains, 

showing the continued plateau character north o£ the Clearwater Mountains ________ _ 

7. Map of the upper South Fork of Clearwater River, showing location of the mining districts __ __ - - -- - - - - - - - - - - -- - - - ~ - - - - -- - -- - - - -- - - -- - - -- -- - -- - -· - - - -- - -- - - - - - - · - --- -- -

8. Sketch map of the Buffalo Hump mining region _________ . __ .•. _____ . ___ . .. . . . .. ___ _ _ 
LETTER OF TRANSMITTAL. 

DEPARTMENT OF THE INTERIOR, 

UNITED STATES GEOLOGICAL SuRVEY, 

Washington, D. 0., June 3, 1903. 

SIR: I have the honor to transmit herewith the manuscript of a· report entitled 

''A Geological Reconnaissance across the Bitterroot Range and Clearwater Mountains in Montana and Idaho, by Mr. Waldemar Lindgren." The report contains the 

results of a rapid reconnaissance made in August, September, and ·october, 1899, 

covering an area of 12,000 square miles in Idaho, Montana, a:nd Oregon. The 

region is one concerning the geology of which little iilformation is available, and 

this report, while merely a reconnaissance, Rhould be of material assistance in the 

development of the economic resources of the region. 

Very respectfully, 

Ron. CHARLES D. WALCOTT, 

Director United States Geological Survey. 

8 

- .-( 

c. w. HAYES, 

Geologist itn Oharge of Geology. 
A GEOLOGICAL RECONNAISSANCE ACROSS THE BITTERROOT 

RANGE AND THE CLEAR\VATER MOUNTAINS IN MONTANA AND 

IDAHO. 

By w ALDEMAR LINDGREN. 

INTRODUCTION. 

SITUATION. 

This report describes, in a preliminary way, a belt of country extending 

westward from the Bitterroot Valley, across the dividing range and the rugged 

mountains of the Clearwater system, down to the fertile plateau~ which border 

the canyon of Snake River. It thus presents a reconnais~ance section from 

western Montana across northern Idaho, and deals chiefly with areas about which, 

thus far, little geological information has been available. 

In spite of the forbidding aspect of these mountains, the earliest explorers 

of the Cordilleran region, Lewis and Clarke, led their expedition across them, 

choosing the Lolo trail from the Bitterroot Valley to the present site of Lewiston, where they wintered. This was in 1805. For many decades after this the 

wild solitudes remained the exclusive hunting ground of the Nez Perce Indians; 

but in 1860 the gold fields of Elk City and Oro Fino were discovered, and in that 

year began the gradual settlement of the Bitterroot Valley on the east and the lower 

Clearwater country on the west. An army of gold ~eekers invaded the Clearwater 

Mountains, but, failing to find gold placer~ outside of the old camps, soon abandoned the search. The two Indian trails connecting Idaho with l\1orftana, the 

Lolo and the Nez Perce, which were much used at first, gradually became less 

frequented. The Indians and the few trappers who wintered in the snowy 

forests were the only occupants of these mountains, which, on account of their 

isolation, formed one of the finest game ·preserves of the West, where the moose, 

the elk, and the bear roamed in great numbers. 

In 1~77 the lower Clearwater country was the scene of the Nez Perce Indian 

war, and the march of the United States troops across the Lolo trail after the 

Indians forms one of the memorable. episodes of this unfortunate conflict. In 1896 

9 
10 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

there was established the present United States forest ·reserve, which embraces the 

larger part of the Clearwater drainage. During the last few years the reserve has 

been patrolled -by Government rangers in order to prevent forest fires, which 

in the past have caused such destruction within this area, and in order to check 

the indiscriminate slaughter of wild game which has gone on during the last ten 

or fifteen · yea1•s. The Bitterroot V all~y ,has gradually been settled, and to-day its 

orchards and fields form . one of the most attractive parts of Montan~ . . In 1897 

the Nez Perce Reservation, which had long been a barrier to the settlement of 

the lower Clearwater, was thrown open, and the high prairies between the Clearwater and the Snake have been transformed into a rich and important farming 

country. 

MAPS AND LITERATURE. 

Until a recent date the topography of the Clearwater Mountains was only 

imperfectly known. The first approximately reliable data are contained in the 

map of the Department of 'the Columbia issued in 1881 by the Engineer Corps, 

United State.s Army, which was compiled by Lieut. T. · W. Symons. During 1897 

Mr. J. B. Lippincott made, for th~ United States Geological Survey, a · reconnais- . 

sance 'map of the newly created forest reserve, on the scale of 6 miles to the inch. 

'This excellent work is the chief basis of the maps published since then and is also 

used in thi:; paper, s'omewhat reduced in scale. Many of the photographs in this 

report were taken by }\lr. Lippincott in 189'7. In 1897-98 the Hamilton quadrangle (Montana and Idaho) was mapped by Messrs. S. S. Gannett, E. C. Barnard, 

and A : B. Searle for the United States Geological Survey. The map of this 

quadrangle includes the crest of the central part of the Bitterroot Range; it is 

published on the scale of 1:125000, or about 2 ·miles to 1 inch, and it .has 100-foot 

contour intervals. These, together with the cadastral surveys of the United 

States General Land Office (General Land Office, Department of. the Interior, 

map of Idaho, 1898) of the eastern and w~stern margins of the area involved, , 

form the basis of . the maps accompanying th,is report. PL I, which shows the 

region covered by this reconnaissance, is compiled from the Geological Survey 

map by Lippincott and the -Lan? Office map of Ipaho. The contours west of 

the western bound~ry of the for~st r~serve w~re sketched by myself. from 

numerous aneroid observations. 

The reports dealing with the w-hole, or parts. of tl;l.is region are as follows: 

RussELL, I. C., A reconnaissance in southeastern Washington: w .ater-Sup . .and Irr. Paper No. 4, 

U. S. Geol. Survey, 1897. 

Contains description of the' c~nyon of S~ake River below Lewiston. 

GooDE, R. U., The Bitte:r~oot Forest Reserve: Nat. G~og. Mag., 'VOL 9, 1898; pp. 387-400, No. 9. 

Contains general description of reserve and definition of· mountain systems. 
TERTI

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MAPS AND LITERATURE. 11 

LEIBERG, J. B., The Bitterroot Forest Reserve: Nineteenth Ann. Rept. U. S. Geol. Survey, pt. 5, 

1899, pp. 253-282. 

Describes topography and forests of the Clearwater Mountains. 

LINDGREN, WALDEMAR, The gold and silver veins of Silver City, De Lamar, and other mining 

districts in Idaho: Twentieth Ann. Rept. U. S. Geol.. Survey, pt. 3, 1900, pp. 67-256. 

A reconnaissance south of the Clearwater Mountains and partly connecting with the area 

described in the present report. Describes also the gold-mining camp of Florence and the canyon · 

of Salmon River west of it. 

RussELL, I. C., Geology and water resources of Nez Perce County, Idaho: Water-Sup. and Irr. 

Papers Nos. 53 and 54, U. S. Geol. Survey, 1901. 

Describes the lower Clearwater region, chiefly occupied by the Columbia River lava. Also 

contains accounts of underlying formations and of the canyons of Salmon and Snake rivers. 

WHITTLE, C. L., The Buffalo Hump mining district: Eng. and Min. Jour., vol. 68, 1899, pp. 215, 216. 

Contains a short description of this mining camp. 

FINLAY, J. R., The mining industry of the Cceur d'Alene, Idaho: Trans. Am. Inst. Min. Eng., 

February and May, 1902. 

Many scattered notes regarding mining operations and production are found 

in the early reports to the United States .Government by J. Ross Browne and 

R. W. Raymond, as well as in subsequent reports by the Bureau of the Mint 

on . the production of gold and silver. 

FIELD WORK. 

The area ·embraced in the present reconnaissance contains about 12,000 square 

miles, of which 6,500 square miles are included in the Bitterroot Forest Reserve. 

Beginning at the confluence of Bitterroot River and Lolo Fork, the boundary of 

this area extends south to the head of the South Fork of the Bitterroot River; 

then it follows the divide between the Salmon and the Clearwater t@ Buffalo Hump; 

then it runs northwestward to Mount Idaho, Grangeville, and the lower canyon 

of the Salmon, then to Lewiston, and from there eastward to Pierce; then it follows the divide between the Lochsa Fork and the North Fork of the Clearwater 

to Lolo Pass, and down the Lolo Fork to its mouth. (Pl. I and fig. 1, p. 1~.) 

The field work occupied the time between July 22 and 9ctober 21, 1899. 

Dur.ing this time Mr. H. R. Johnson, of Stanford University, rendered efficient 

geological aid, and during my temporary absence, from September 22 to October 

8, had charge of the party examining the western part of the Lolo trail and the 

Crags. From ·August 1 to September 11 I had also the valuable assistance of 

Mr. G. W. Stose, to whom especially many observations on the upper Bitterroot 

Valley are due. The general route led first north from Hamilton along the 

Bitterroot Range to some miles beyond Lolo Pass, thence back to Hamilton and 

across the range over the. Lost Horse trail. Returning, the southern part of the 

range was examined, and from Darby the route led up the Bitterroot R.iver to 

its head; thence along the divide .between the Salmon and the Clearwater to Elk 
12 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

City and Buffalo I;Iump; thence across the high prairie south of Lewiston, up the 

main fork of the Clearwater to the Crags; finally, to Pierce and up to Rocky 

Ridge on the Lolo trail. Many parts of the area were not visited and the whole 

examination partakes of the character of a rapid reconnaissance. Fortunately, 

Scale 10,t:;O~::E3===5EO 3:::E3::=J==iC:======10:CO======:::::i200 MILES 

FIG. I.-Index map showing extent of reconnaissance. 

the route was laid out in a manner to obtain, in spite of this, a ~airly accurate 

conception of the general geological structure of the whole region. 

TOPOGRAPHY. 

The nomenclature of the main ranges in these parts of Idaho and Montana is 

not yet.· settled, and it will, therefore, first be necessary to define the mountain 

system'S involved. The whole area lies in the watershed of the Columbia River. 
U S. GEOLOGICAL SURVEY 

7137 

I 

l1--· 

Topogrd phy oy J B Lippi nco 

i>~ ·l 

U'~ -= 

Perce~ 

~~ =r -··->sa e Cone 

·' ' · / / 

PROFESSIONAL PA ER NO 27 Pl . II 

t.;ofoPeak 

rrpek 

z 

< 

0 

a: 

~ . .J . I TIN R 20 ( i 

rf i 

~-·----+-i J 

/ . 

. t1· 

I 

I 

.f 

,,·· -· 

/ 

.'-!J.>"'-!""---"'-"'-"""'t-"L'""'i n"'e"-_L . 

.. -"'/ wiw 

\ 

:i?;-

· ....... 

/ "y 

--~ 

~ 

/ . _/ 

i>~.- ' 

------4~&------------~----------------~3L0.----------------------------1L~--------------------------~IIt "\ 

\HT OF THE BTTTJ<:H R OT HA.."'\l GE 

lDAlTO AND ~v10~TANA 

0 

Sb:<'ldt ·· o niOIIt·s 

JULIUS D IEtt & CO. Un'l N .Y 
TOPOGRAPHY. 13 

As is well known, the main divide of the Rocky Mountains is followed by the 

boundary line between Montana and Idaho from the Yellowstone Park westward 

to Gibbons Pass, near the southeastern corner of this reconnaissance area; thence 

the main divide bends sharply northeast, while for over 200 miles northward the 

boundary follows the divide between the tributaries of Snake River on the west 

and Clark Fork of the Columbia on the east, the principal affluent of the latter 

being the Bitterroot River. 

It is proposed to give the name of the Coeur d'Alene Mountains to the broad 

complex exten~ing 100 miles from Pend Oreille Lake southeasterly to the head 

of the North Fork of the Clearwater, a short distance north of Lolo Pass. This 

range, which reaches elevations o~ only 7,000 or 7,500 feet, is drained westward 

by the Coeur d'Alene, St. Joseph, and St. Marys rivers, all emptying into the 

Coeur d'Alene Lake, and thence into the Columbia by way of Spokane River. 

At the western foot of this range extend the high plateaus of the Palouse country. 

The eastern slope of the Coeur d'Alene lVIountains is only from 10 to 25 miles 

wide, and the .creeks drain directly into Missoula River or the Clark Fork. 

From Lolo Fork to the head of the V\7 est Fork of the Bitt~rroot River (also 

called Nez Perce Fork) extends the Bitterroot Range. It is extremely well defined, 

topographically and geologically, is about 60 miles long, and trends exactly north 

and south. In many places it attains elevations of over 9,000 feet, and near the 

southern end culminates in Trapper Peak (elevation, 10,175 feet). 

Eastward the Bitterroot Range descends steeply toward the valley of the same 

name·. Westward its slopes soon merge into the Clearwater Mountains. 

By the name Clearwater Mountains it is proposed to designate that broad, 

mountainous country comprised within the drainage of the C1earwater River. The 

Clearwater Mountains occupy a rough square with a side of about 70 miles, and at 

their westward margin descend rapidly to the high plateaus of \he lower Salmon 

and Snake rivers. The highest peaks rarely exceed 8,000 feet in elevation. 

The Clearwater Mountains are continued southward in the Salmon River 

Mountains. These have the same general characteristics and occupy a large 

portion of central Idaho. The Salmon River is supposed to be the dividinz line 

between these two regions. 

The divisions here outlined are on the whole similar to those used by thb 

United States Engineers in their map of the Department of the Columbia of 1881, 

but differ from those employed on the map of Idaho of the General Land Office, 

on which the Bitterroot Mountains cover the area between Mullans Pass in the 

Coeur d'Alene Mountains and Nez Perce Pass. 

R. U. Goode (see list of literature, p. 10) gives the general name of. Bitterroot 

Mountains to the whole uplift from near Pend Oreille Lake to the pass at the 
/ 

14 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

head of Bitterroot River, near the North Fork of the Salmon, and makes the 

C~eur d'Ale~e and Clearwater mountains subdivisions of this general term. On 

account of the strongly pronounced individuality of that part of the range between 

the Lolo and Nez Perce passes, which unquestionably has always been designated by 

the name of the ''Bitterroot Range," I do not like to accept so wide a definition. 

The Clearwater Mountains thus form a part of the great mountain region of 

central Idaho, a vast uplift extending from the Snake River Valley on the south 

well up toward the British P?Ssessions on the north. Like' the Salmon River 

Mountains on the south and the Coeur d'Alene Mountains on the north, they are 

deeply dissected by a canyon syst~m . of rarely equaled extent and depth. The · 

principal ridges between the streams, generally broad and flat, but sometimes also 

dissected into sharper crests and peaks, attain throughout about the same eleva.tion, 

averaging perhaps 7,000 feet, and varying between 8,000 and 6,000 feet. Their 

combined crest lines would form an undulating plain differing littl~ in elevation 

in the various parts of · the · Clearwater Mountains; in other ~ords, sloping very 

little, .if any, in any given direction. From their westerly margin the mountains 

slope rapidly to the lava plateau, which has an elevation of 3,000 to 3,500 feet. 

Along the Salmon River the high mountain plateau extends farther westward, and 

its last ramparts overlook the great bend o£ that river, rising 6,500 feet above 

its water line. The plateau character of the combined ridge lines is clearly seen 

in figs. 4 and 6 (pp. 60, 69). We must regard this surface as the result of erosion. 

The country was worn down to a comparatively gentle . topographic feature, then 

uplifted and_ deeply dissected by canyons. Foremost of these is the great canyon 

of the, Salmon, which, .like a mighty V -shaped trench, is cut to a dep~h of from 

4~000 to 5,000 fe~t practi~ally across the w~ole width of Idaho, 100 miles in a 

straight line, and f~r more along the course of the river. It interposes a formidable obstacle to intercourse betwe~n the southern ~nd northern parts of the · 

State. Only 011e wagon ~oad crosses it, and that can be tra.versed by only lightly 

loaded vehjcfes. Within a few miles of Snake River the Salmon bends suddenly 

northwarti and parallels the Snake for a distance of 40 miles, and then fina_lly 

joins it, after making a wide curve convex toward the north. Until a point some 

di ance below the great bend is reached the canyon is entirely cut in pre-Ter-

·dary rocks and antedates 'the flows of the Columbia River lava. No bottom 

lands worthy of the name line · the main part of the canyon, and many parts of 

the gorge are entirely inaccessible. Disaster has frequently overtaken those who 

have · tried to navigate its wild rapids. The river is still largely eroding its 

bed. Below Freedom its course ·. was changed by the Tertiary lavas. 

The lower portion .. of the·· Clearwater River in the Columbia River lava 

closely parallels the Salmon, and its course is undoubtedly due to the same deter-
R. U.Goode, Geographer in charge 

Triangulatio n by S.S. Gannett 

Topography by E.C.Barnard and A.B.Searle 

Surveyed in 1897- 98 

CENTRAL PART 0~ BITTERROOT RANGE 

FROM MAP OF HAMILTON QUADRANGLE 

Scale 

k= E:~~o====~~==== ~2~~~~3======~~====~5miles Cont our interval 100 f eet· 

Datam is 5.1 rea above mP£tn sea level 

Profiles along the lines B B 

and CC are shown on Plate IV 
SEDIMENTARY FORMATIONS. 15 

mining 'cause-that is, to the obstructing Tertiary flows of basalt. The Clearwater 

drainage system is much more branching, and though the trenches of the principal 

forks, the Lochsa and the Selway, are fully 4,000 feet deep and often inaccessible 

along the stream beds, they lack the grandeur of the single canyon of the Salmon. 

As seen from the map (Pl. I), the Clearwater splits In a number of branches, and, 

in fact, drains practically the whole area discussed in this paper. When the 

river enters the plateau of Columbia River lava the canyons are much less deep, 

but are much more sharply incised than the flaring trenches of the Clearwater 

Mountains. 

Between ·the Lolo and Nez Perce passes, very close to the Montana boundary 

line, the mountains increase rapidly in elevation and form the narrow and sharply 

defined Bitterroot Range, which eastward soon slopes down to the equally pronounced 

depression of Bitterroot Valley. 

The Bitterroot Range can best be likened to a · long and narrow block raised 

2,000 feet above the general elevation of the old Clearwater Plateau. North and 

south of it fragments of this plateau seem to continue for a still undetermi~ed 

distance into Montana. 

The Bitterroot River heads on the ridge north of the Salmon River Canyon. 

In its upper course, as far north as the southern end pf the Bitterroot Range, the 

river and its branches have evidently dissected the same old Clearwater Plateau. 

It soon, however, enters the wide and level Bitterroot Valley and continues northward in this for over 60 miles. North of the mouth of Lolo Fork 'the bordering 

ridges again rise to · the general level of the Clearwater Plateau. Gently sloping 

ridges face the Bitterroot Valley on the east, while on the west rises the high 

block of the Bitterroot Mountains, sloping down to the valley by a long, even 

declivity of . 18° , and indicating by its geologic and topographic features its important tectonic character as a fault plane. • 

DESCRIPTIVE GEOLOGY. 

GENERAL FEATURES. 

SEDIMENTARY E'ORMATIONS. 

In a broad way the distribution of the pte-Tertiary sedimentary formation& in 

the region under consideration is as follows: Practically the entire area of th~ 

Bitterroot and Clearwater mountains is occupied by granite with some gneiss. 

West of the Clearwater River, and only imperfectly exposed below the lava, is an 

extensive sedimentary area adjoining this granite; snialle.r sedimentary areas are 

exposed on Lolo Fork and on the head of the South Fork of Bitterroot River. 

In no place have well-defined fossils been foup.d, but there is some foundation for 
16 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

the belief that the two last-named areas on the eas~ sid,e are very old, possibly preCambrian, while the western area probably includes Triassic, Carboniferous, and 

possibly still older sediments. 

The sedimentary series of the Lolo Fork, in the northeast corner of the area, 

consists of moderately metamorphosed quartzites, limestone, and banded slates, some 

of them of a purple color. This apparently conformable but evidently folded, overturned, and repeated series has a northwesterly or west-northwesterly strike and a 

prevailing northeasterly dip of 30° to 45° , and borders south and west against later 

granit~ with intrusive contact. The chief interest of this series lies in the fact that 

it is probably the southward end of the similar very extensive area which in the 

Coeur d'Alene section, 75 miles farther north, occupies the whole width of the Coeur 

d'Alene Mountains from the lake of the same name up to . Mullan Pass, and thence 

down to the Clark Fork of the Columbia by way of S.t. Regis de Borgia River. 

Throughout, .this Coeur d'Alene series has a west-northwest or northwesterly strike 

and usually a moderate northeasterly dip. No fossils have ,been found in it, and my 

belief is that it should be coordinated with the thick pre-Cambrian series of central 

Montana. 

Small exposures of the same or a similar series are noted along the foothills 

of the Bitterroot Valley and again on the Skalkaho and Weeping Child Creek, 

where they also border intrusive granite. 

A series of quartzites or quartzitic schists and slates occupies a considerable 

area at the very head of the South Fork of the Bitterroot and extends at least as 

far as Gibbonsville, ldab0, on the east. They appear to be thrown into flat folds 

dipping east or west at moderate angles. They are probably intrudeq by granite 

and certainly by granite-porphyry on the north, and border against older gneisses 

on the south. 

At the western foot of the Clearwater Mountains the m<:>st prominent sedimentary terrane is composed of black slates, limestones, quartzitic slates, and 

associated partly schistose and probably effusive greenstones which are found on 

the South Fork of the Clearwater and which extend only a short distance north of 

Harpsterf?. This series has a persistent northeasterly strike and steep dip, and 

evidently· forms the northern continuation of beds of the same strike exposed at 

intertals below the Columbia River basalt on the lower Salmon, in the Seven 

Defils, and, over 100 miles distant, near Huntington. Triassic foss.ils have been 

found in the Seven Devils, a and a large part of this long area of sediments is 

believed to be of Triassic age. Still farther west sedimentary rocks of unknown 

age, but probably Paleozoic or Mesozoic, are exposed near the junction of the 

Salmon and Snake rivers, in the Cottonwood Buttes, and in Clearwater Canyon 

a Twenty-second Ann. Rept. u, S. Geol. Survey, pt. 3, 1902, p. 581. 
U.S.GEOLOGICAL SURVEY 

w 10,000 Lolo CTY'A!k 

Colum?ia River basalt 

l 

0~----- ~---.1..---;:: ---G~_r_a~n~i_t~e -~--____ ___ 

5,000 

Sea-level 

w 10,000 

spoo 

PROFILE A-A 

PROFILE C-C ( See PlaLe III ) 

Shennan Pk. 

Granite 

PROFESSIONAL PAPER NO. 27 PL.IV 

PROFILE B- B (See Plate III) 

w El, Capil£uv ComoFI<.. E 

:- . ! _____/'- BiUerrootRiver IO,OOO~IJivi.tf.e > . ~ 

1 _ Moraines i Terraces ' : 

S<•~Ji -'----P-r_o_b_a_b_l_y __ a_l_l __ g_r_a_n_i_t_e _ _ _ _ __ ~---- -------------....__-~_~_--_~_:::_-_~-~_:_~_:_.:::;___~_~_::.._~_-_~_=_:;,..._ _ ·' ·-.....::;: -' --~_ '' "·'_:~_- ''··:_~_:o.;::·C·,_~<_·'_''"_'"'_··'·'·'_'"'_'•..:.•·'-_''_""_··" ,, _ •. ,_· .•._~·._•! ~..._ t PROFILE D-D 

HORIZONTAL Al'<"TI VERTICAL SCALE FOR PROFILES A-A, B-8, C-C, D-D 

Probably a l l granite 

Biuerroot Range 

St.JiJseph, Pk. 

E 10,000 

5POO 

-.._"":, G.neiss 'zone 

"<-""~e 

--~ Grave~~erraces 

Lolo PtLSs • 

--~ --- G r8an d ite G ra'";;\~~~·Bi ~;~~ :'al •~.,., 

------ -- ---------------~P_r~o~b~a~b_~l.~y,_-=a~I_I~~S~~a~..:.n~_t~e--~------~G~r_a=-n~i~t_e=-----------------l_d_e_r_g_n_e_is_s _______ _._~_-..:.~~~c:: --~~~~S2~----'- 0 

PROFILE. E- E (.See Pla.te I) 

Probably a II g r a. n t e 

PROFILE F- F (See Plate I ) 

Di.a.bi Peal"' 

I 

E 

Bitterroot 

Val ley Gravel terraces 

10,000 

5,000 

PROFILES ... <\CROSS THE BITTERR~OOT Rc\NGE, THE CLEAR\,\TATER ~fOUNTAINS, AND THE COLUMBIA RNER LA\C<\ PLATE.Lt\U 

HORIZONTAL AND VERTICAL SCALE FOR PROFILES 

5 0 5 

E-E, F-F 

15 

.JULIUS BIEN & CO.UTH.N.Y. 

·I 

I 
GRANITIC ROOKS. 17 

between Contact railroad station and the mouth of the North Fork. They consist 

of quartzites, sandstones, conglomerates, limestones, and shales, as well as large 

masses of associated old and partly altered and schistose lavas (greenstones). The 

structure of this series is little known except that the dips are generally steep 

and the strike has a general northerly direction. 

At Oro Fino, North Fork, and Pierce are gneisses, mica-schists, and occasional 

crystalline limestones bordering the intrusive granite of the Clearwater Mountains. 

These are surely partly at least of sedimentary origin, but their age is unknown . 

. GRANITE. a 

Extent.-Granitic rocks prevail in the Bitterroot Range ltnd in the Clearwater 

Mountains, and form a central mass of vast extent, bounded in the four corners of 

the region covered by this reconnaissance by smaller areas of different sedimentary 

series. To the north of this region the extent of the granite is not well known. 

But as the granite is absent in the Coeur d'Alene section (p. 81) it is probable that 

the main area does not continue far north of Lolo Ridge except as detached masses. 

Southward this granite cont:iJnues through all of central Idaho as a broad belt, and 

finally disappears below the sediments of Snake River Valley. It does not reach 

Snake River at any place between Huntington and Lewiston. It forms on the whole 

an elongated area 300 miles from north to south and f>O to 100 miles from east to 

west, constituting one of the largest granitic batholiths of this continent. 

Within the margins of this reconnaissance it occupies the whole of the Bitterroot Range except its extreme northern end. Along the foot of this range it 

acquires gneissoid structure, owing to orographic forces. It even appears in the 

eastern foothills of the Bitterroot Val1ey, and is there al~o slightly gneissoid in 

structure. Westward it occupies the whole center of the Clearwater Mountains 

from Lolo Ridge down to Salmon River, but along the latter contains many included 

areas of an older gneiss. Between Oro Fino and Stuart, on the Clearwater, a 

projecting arm of the granite extends far westward underneath the lava to the 

southeastern part of the Cottonwood Buttes, and possibly even to the Salmon River 

Canyon west of Grangeville. 

Oharacter.-On the whole, this extensive area of granite shows grest constancy 

in its petrographic character. It is a normal granular rock, sometimes roughly 

porphyritic by the development of large orthoclase crystals up to 3 em. in diameter. 

The color is almost always light gray, the outcrops assuming a yellowish-gray color, 

which in glaciated districts changes to a brilliant white or light-gray tone. Biotite 

is always present in small foils, and over large areas muscovite also enters into the 

a The coarser granular, massive, igneous rocks occurring in this region consist chiefiy of quartz-monzonites with 

frequent facies of true granite with prevailing alkali feldspar. The two kinds of rocks can not easily be distinguished in 

the field, and it has therefore been found necessary to speak of them collectively as" granite." The distinction between 

them is emphasized only in detailed petrvgraphic descriptions. 

5995-No. 27-04-2 
18 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

composition; quartz is abundant in medium-size grain:3, while the feldspars are 

. represented by both orthoclase and oligoclase, the latter usually in large quantity. 

Perthite is also frequently encountered, and more rarely microcline. The rock 

contains far too much oligoclase to be classed as a normal granite and should be 

rather characterized a~ a quartz-monzonite. Modifications more closely allied to 

granodiorite, diorite, and granite occur in subordinate quantity~· 

The granite is typically developed near the head of Mill Creek, Bitterroot Range, 

where it is a light-g·ray, medium-grained rock, with small foils of biotite and a little 

muscovite. A few larger crystals of orthoclase reach one-half inch in length. 

Under the microscope the roek shows much quartz, a little normal orthoclase, and 

·many large grains of microperthite. An acrdic oligoclase with very narrow striations 

is very abundant. .Biotite and museovite occur in scattered straight foils. Few 

accessories except zircon and apatite were noted, though titanite occurs abundantly 

in basic concretions in the same granite. The structure is typically granitic; the 

oligoclaRe is in part idiomorphic and sometimes included in the perthite. An 

analysis of this rock is given in the table below, together with such analyses of rocks 

as are available from the southern end of this great granitic batholith. 

Analyses of granitic rocks from Idaho. 

I. II. III. IV. v. 

Si02 ••••••••• ______ · __ - __ - . ________ -- ____ - - -- 72.07 69.56 68.42 65.23 57.78 

Al20 3

• ______ • _________ - _____ - __________ - -- _·_ 15.51 15.29 15.01 16.94 16.28 

Fe20 3 .. __ •••••••••••••••••••••••••••••• · •••• __ . 31 . 86 . 97 1. 60 1.02 

Feo _______________________________________ _ 1. 01 2.06 1. 93 1. 91 4.92 

MgO . ___ -- _ - - -... -.. - - - - - --- - - - " --- ----- --- . 35 . 69 1. 21 1. 31 4.60 

.cao _____________________________ • __________ _ 1. 93 2.81 2.60 3.85 6.1

65 

N a

2

0 ___________ -.- _________________________ . 4.02 3.97 3.22 3.57 3.25 

K 20- -- - _ -- - - - - - - - - - - -- - -- - -- - -- -- - - - - · - --- 4.09 3.36 4.25 3.02 2.22 

H 20 below 110° C __________________________ _ 

H 2

0 above 110° C .. ____________________ . ___ _ 

.03 } { a.86 . 30 .54 .18 . 34 

. 73 . 88 .92 

Ti02 _______ •• _. _ .•. ---- •• ----- ---- • - •••• - _ .-- .16 . 55 .50 . 66 1. 07 

C02 ••• ---------------------------.-------.--

P205 ... _ .. _. ____ ... __ . __________ . __ ..... _._ _ _ . 11 . 16 

None. -----·---· .20 -25 .15 

.13 .19 I . 30 ' 

s- ---------. ---·--------------.--------------._ ---------- ---------- . 02 --------·- .02 

NiO and CoO _. _____ . _. _______________ . __ . _______ . ____ ... ____ .. _ None. ---- ............... .02 

MnO ....... _______ ... ____ ... ____ . _. ___ .... _ _ Trace. ____ . ____ _ . 06 Trace . .15 

BaO .... _ . _____ . ___ . __ . ___ .. ______ ~ . __ ' ___ . _ _ _ ______ . _ . . ________ . .12 .19 .12 

SrO . . _ . _ . _ . - _ . - _ -- __ . -. - - _ ... _ . _ . ___ . __ . . __ . _ . _ . _ _ _ _ ___ ... __ _ . 03 ---------..- .07 

Li20 .. _ .. __ . ____ ..... ____ . __ . _ • ___ . _ . _ .... _________ · ______ . _____ . Trace. ---------- Trace. 

99. 89 100. 17 99.94 99. 78 99.88 

a Loss on ignition. 
GRANITIC ROOKS. 19 

I. Quartz-monzonite. Near head of Mill Creek, Bitterroot Range, Montana. W. F. Hillebrand, 

analyst. 

II. Quartz-monzonite, No. 46, Boise collection. Shafer Butte, Boise County, Idaho. George 

Steiger, analyst. Twentieth Ann. Rept. U. S. Geol. Survey, pt. 3, 1900, p. 82. 

III. Quartz-monzonite, No. 25, Hailey collection. Democrat mine, near Hailey, Blaine County, 

Idaho. 'V. F. Hillebrand, analyst. Twentieth Ann. Rept. U. S. Geol. Survey, pt. 3, 1900, 

p. 82. 

IV. Granodiorite, No. 79, Boise collection. Silver Wreath tunnel, Willow Creek mining district, 

Boise County, Idaho. George Steiger, analyst. Twentieth Ann. Rept. U. S. Geol. Survey, 

pt. 3, 1900, p. 82. 

V. Diorite, No. 32, Hailey collection. Crmsus mine, near Hailey, Blaine County, Idaho. vV. F. 

Hillebrand, analyst. Twentieth Ann. Rept. U. S. Geol. Survey,. pt. 3, p. 82. 

The approximately calculated composition of the rocks is as follows: 

Calculated composition of rocks from Idaho. 

Quartz ____ .. __ . _ .. _ ... ______ . _ .. ___ . ___ . __ . 

_ Orthoclase molecule ........ _ ............... . 

Albite molecule ............................ . 

Anorthite molecule ..................... _ .. . 

Biotite a .•••••.•••••.. _ .•.•.••.•••••• _ •••••• 

Apatite ....... _ ............................ . 

Titanite ................................... . 

Magnetite ..... __ ...... _ ............. _ ..... . 

I. II. 

28. 73 

20.04 

33.'98 

8.36 

b8. 03 

. 27 

.29 

.17 

28.04 

15.84 

33.54 

11.15 

7.55 

. 37 

1.13 

. 93 

Calcite ............................... _ .. __ .. _ ••. __ . _ .......... . 

Pyrite .. _ ...... __ . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . ........ . 

Hygroscopic water .......... _ ......... _..... . 03 . 36 

Excess combined water. .................... ___ ....... . 27 

Total .......... _ .......... _ ....... ___ . 99.90 99.18 

III. IV. 

29.21 25.00 

18.07 11.21 

27.19 30.25 

9.53 13.88 

12.36 15.99 

.47 .44 

. 88 1. 65 

. 31 . 61 

.45 . 57 

.03 ---------- .54 .18 

.32 ----------

99.36 99.78 

v. 

8.45 

7.57 

26.20 

20.45 

C32. 55 

. 69 

1. 29 

1.48 

. 33 

. 03 

. 34 

. 51 

99.89 

a Molecular ratio assumed: MgO: Si02: Ti02: Al20 3: Fe20 3: FeO: CaO: K20: H20=1: 2.44: .06: .75: .14: .88: .04: .42: .76. 

b Biotite, 5.03; muscovite, 3.00. Molecular ratio of biotite in this analysis figures out to MgO: Si02 : Al20 3 : Fe20a: FeO: 

CaO: K20: H20: Ti02=1: 3.64: 1.11: .14: 1.52: .04: .42: 1.04: .06 ' 

c Biotite, diallage, hypersthene, hornblende. 

The analysis of the rock from the Bitterroot Range shows so great similarity 

to II and III, both of which are representative · rocks, that no special calculation 

seems necessary. It contains the same amount of quattz and a more sodic oligoclase, while the potash feldspar is slightly increased, a little muscovite being 

present in I. Analyses IV and V represent local basic modifications. The five 

analyses form a series with gradually lowered Si02, constant Al, and increasing 

Fe, Mg, Ca. The first three rocks should doubtless be considered as quartzmonzonites, though I distinctly approaches the granites. 

In the Bittm ':'oot Mountains streaks of basic magmatic segregations often 

appear, characterized by biotite and hornblende, quartz, orthoclase, oligoclase, 
20 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDA.HO. 

and andesine, together with ·much titanite. Almost normal granites with prevailing orthoclase were observed west of Little Salmon Meadows and on the head 

of Crooked River. Dioritic modifications were observed near the schist contact 

at Pierce, and in the . Clearwater Canyon near Greers Ferry. At the latter place 

a very fine diorite-pegmatite, consisting of hornblende and a plagioclase of 

medium acidity, is exposed in a railroad cut near the river. 

A.ge.-The intrusive character of the granitic batholith is apparent at all 

places where it adjoins adjacent formations. The petrographic character is, on 

the whole, so constant that ·it seems probable that the whole area is ~f the 

same age, and a geological unit. The age can not be determined with certainty 

on account of the absence of fossils in the surrounding formations. In the 

southern part of the batholith, near Hailey, on Wood River, it has been shown 

that the intrusion is certainly post-Carboniferous. a As it has been shown (p. 16) 

that · the sedimentary series on the South Fork of the Clearwater, near Harpster, 

is very probably Triassic, a post-Triassic age may, with the same degree of certainty, be attributed to the great granitic batholith. 

Dikes in granite.-On the whol~, dikes are not common in the principal 

granite area embraced in this report, even pegmatites and aplites being rare. 

In the eastern foothills of the Bitterroot Valley-, however, and along the South 

Fork of Bitterroot River dikes of granite-porphyry and rhyolite are very abundant 

in the granite. The shattered gneiss areas of Horse Creek and Salmon Mountain, 

as well as the IJ?.Ore compact areas of Elk City, contain also an abundance of 

pegmatitic, granitic, and dioritic dikes. The gneiss is sometimes injected by a 

great number of narrow pegmatite dikelets which have suffered a crumpling at 

the same. time as the surrounding foliated rocks. 

GNEISS.b 

In a prevailing terrane of intrusive granite the Bitterroot and the Clearwater mountains contain numerous areas of gneissoid rocks of very differing ages. 

Some are later than the granite, of which they indeed, are only a modification, 

caused by peculiarly applied stresses. If the conclusion as to the age of the 

granite is correct, these gneisses are post-Triassic. Others are of much greater 

age, being probably older than the associated sediments, which are themselves 

older than the granite. In these sediments no fqssils have bee~ found, and their 

trl.1e horizon is thus doubtful. Very likely, however, parts or all of this second 

series of gneisses may be of pre-Cambrian age. 

The first and most extensive gneiss area is ·that which follows the wellmarked eastern slope of the Bitterroots, and which is clearly nothing hut a sheet 

a Twentieth Ann. Rept. U. S. Geol. Survey, pt. 3, 1900, p. 79. 

b The word gneiss is here used without limitations as to age and origin. 
GNEISSOID ROCKS. 21 

of pressed and deformed granite. · It is usually a light-gray, granular, and schistose 

rock, and consists of lenticular squeezed aggregates of oligoclase and quartz 

and deformed orthoclase crystals, separated by somewhat curved aggregates of 

new-formed biotite and muscovite. The primary constituents are the same as 

those o£ the granite. All transit\ons toward massive granite m21Jy be seen. 

Excessive compression results ·in finer-grained and darker micaceous schists. 

This gneiss is characterized by abundant slipping planes, which show movements 

parallel to the dip, and on which large pla~es of muscovite have often formed. 

As far as the observations showed, this gneiss is never crumpled and folded like 

the older gneisses. 

The incipient gneissoid structure may be well observed in the gneissoid 

granite o£ Lost Horse Pass near Twin Lakes. (Pl. V.) Macroscopically it is lightgray granular rock of mJdium grain. The schistose structure is not prominent, 

but indicated by the distribution of the biotite and the lenticular shape of larger 

feldspar crystals. Under the microscope the large grains consist of quartz, 

o:tthoclase, and oligoclase, very similar to those in the normal granite. The 

biotite is largely recry tallize~~ and converted to ·stringy. aggregates of the same 

mineral partly changed into chlorite. Some muscovite is ·also present. There 

is an abundant development f new allotriomorphic fine-grained aggregates along . 

winding and curving shearin planes. This aggregate consists of feldspar 1 mostly 

without striations, and quart ; there is also much micropegmatite, and in places 

a coarse · poikilitic structure. Black iron ore in irregular, sometimes pressed, 

grains as well as apatite and zircon' are accessories. 

About halfway up Lost orse Creek similar but more schistose rocks were 

observed. Their appearaq.ce under the microscope is similar to the specimens 

just described; in addition the larger grains are greatly crushed with much cataclastic structure. The normal gneiss from JVIill Creek, 2 miles above the mouth 

of the canyon, is a plainly schistose rock with large orthoclase crystals pressed 

into partly lenticular shape. Biotite and a little muscovite lie · in flat aggregates 

between streak's of pressed feldspar and quartz. There is much cataclastic action 

and formation of new allotriomorphic aggregates along wavy lines, which indicate schistosity. Large feldspar and quartz grains, when crossed by these lines, 

are greatly crushed. On the whole, however, the rock has great similarity to 

the normal Bitterroot granite. 

Stronger crushing action near the mouth of the canyons simply results in 

emphasizing the characteristics already · referred to. The sinuous lines along 

which most active recrystallizing movement is in progress multiply, and at last 

the whole rock is. transformed into a fine-grained aggregate traversed by wavy 

streaks of finely distributed biotite and a little muscovite, and in this mass lie as 

1 -
22 BITTERROOT .AND CLE.ARW .ATER MOUNTAINS, MONT.-IDAHO. 

pseudophenocrysts the irregular, more frequently lenticular remains of larger 

grains. These are often cut by parallel cracks which dip about 70° E., and 

which are sometimes opened and filled by sEcondary quartz, suggesting a stretching movement. 

Still further pressure results in dark, fine-grained bands in the coarser gneiss, 

which under the microscope appear to be suffused by extr~mely finely d1vided 

biotite with allotriomorphic feldspar and quartz. This mass contains small, 

rounded residua of larger grains, and the whole imitates fairly successfully · a 

fine-grained ·clastic rock. 

The second gneiss area is that of St. Marys Peak in the northern center of 

the range ·and probably underlying the sedimentary Lolo series. This dark-gray 

gneiss is very rich in black ·mica and weathers to reddish outcrops. It is usually 

crumpled and includes portions or streaks of exceedingly micaceous schists. The 

dip is usually steep toward the west. The origin of the rock is uncertain. 

On the east side of the Bitterroot Valley the granite, which is presumably 

but not certainly of the ::;arne age as the normal Bitterroot granite, contains I 

frequent, well-defined inclusions of a crumpled gneiss, like that of St. Marys Peak. 

It is believed that this gneiss is composed of fragments of a more extensive 

formation which had been shattered by the granit~. In places the granite itself 

is somewhat schistose. Dip and strike of these roughly gneissoid rocks, as well 

as those of the inclusions, are characteristically variable. 

The next big gneiss area is found at the very head of the South Fork of the 

Bitterroot, adjoining the quartzitic series of that valley, which probably is identical 

with that of the Lolo Fork; the contact, ·though difficult to interpret, probably 

indicates that the gneiss underlies the sedimentary formation. This gneiss, which 

is cut by many granite dikes, consists of medium-grained aggregates of quartz 

and feldspar with some larger deformed crystals of the same kind. The abundant 

aggregates of muscovite and biotite run in irregular bands, curving around the 

lenticular patches of quartz and feldspar. It is often contorted and sometimes 

of coarse grain. It contains much microcline and little plagioclase. The schis- . 

tosity is variable, but most frequently it dips 40° E. 

A similar gneiss area, perhaps connecting southward with the one just described, 

is found on Salmon Mountain; it is extensively broken and intruded by granite 

dikes. Both these areas are pretty surely dynamo-metarrorphosed granitic rocks 

of mhch greater age than the Bitterroot granite. 

A mucl:~ larger gneiss area is that of Elk City. It is elliptical in form 

and extends 40 miles north and south and 24 miles east and west. It borders 

almost everywhere against granite, the contact plainly showing the intrusive 

nature of the latter rock. The gneiss of this area is uniform in character; it is 
TERTIARY LAVAS. 

of light-gray color, roughly schistose, and consists of a granular mass of white 

feldspar and quartz, occasionally with larger orthoclase crystals; the aggregates 

of biotite indicate the schistosity. Microscopically the rock was found to consist 

of quartz, much microcline, grains of oligoclase or andesine, together with much 

black mica and someti,mes a little hornblende. Crumpling and folding perpendicular to the schistosity are usually characteristic. Intruded narrow dikes of 

granite or pegmatite have often suffered the same crumpling. This rock also is 

clearly a dynamo-metamorphic form of a very old granite. The dip is generally 

flat, but characteristically variable. 

An area of gneiss with equally variable strike and dip and also adjoined by 

intrusive granite begins at Pierce. Similar rocks occur in the lower part of the 

canyon of the North Fork of the Clearwater and at Oro Fino, along the main 

stream. Mica-schists, sometimes garnetiferous, and (at Oro Fino) limestone beds 

also occur with gneissoid rocks and the series is probably made up partly of 

highly altered sedimentary rocks, partly of sheared intrusives, both older than the 

Bitterroot granite. The intense and equally distributed metamorphism of tbis 

series is probably not due to the adjoining granite, but rather to regional causes. 

TERTIARY LAVAS. 

The distribution of younger igneous rocks in this region is peculiar. A line 

of rhyolitic eruptions of moderate volume follows the Bitterroot Valley. No 

basalts or andesites are known to exist here. Within the whole extent of the 

Bitterroot and the Clearwater Mount~ jus no surface lavas of any kind have been 

found, but at the foot of these same mountains is spread out a veritable flood of 

Miocene basalts, covering thousands of square miles. Neither rhyolites nor 

andesites are known from this part of the country. 

Rhya.lite.-Beginning at the north the fin,t small area of rhyolite is found a 

few miles west of Florence in the Bitterroot Valley, forming a low ridge near 

the first foothills. Forty miles farther south a much larger area is exposed in 

the bluffs on the east side of the river, forming a succession of tuffaceous, 

vitreous, and felsitic flows several hundred feet thick. This rock breaks through 

the granite and gneiss of the eastern foothills and many long dikes in the vicinity 

indicate its- manner of eruption. 

Dikes of granite-porphyry, many of which have a somewhat rhyolitic habit, 

occur along the South Fork above the junction. Between Blue tT oint and Overwhich creeks, well up toward the head of the stream, another not very thick 

rhyolite flow is met with, a small area still remaining on the summit of Crown 

Peak or Castle Rock south of Nez Perce Pass. It filled the bottom of the valley 

to a depth of several hundred feet. In its upper part sedimentary beds and- lignite 
24 BIT'TERROOT AND OLEARWATER :MOUNTAINS, MONT.-IDAHO. 

seams are intercalated in the felsitic flows. Still higher up near the head of the 

river, on Lick Creek, a succession of flows of glassy, felsitic, and tuffaceous 

rhyolite is met with; this came down from some point on the divide betw:een 

the South and East forks. 

While the general habit of these rocks unquestionably is that of rhyolites, 

the general prevalence of phenocrysts of oligoclase suggests that they contain a 

a large a~ount of soda. No analyses have been made. The age is probably 

Mioeene or Pliocene. 

Basalt.-From the last heights along the western margin of the Clearwater 

Mountains the vast plateau of the Columbia River basalt, covering thousands of 

square miles, spreads out in a magnificent view. The old Clearwater Plateau, 

dsing to 7,000 feet above the sea, heavily forested, and deeply trenched by 

canyons, breaks· off with rapid slope, and at its foot extends another plateau, much 

better defined, 4,000 feet lower, but still 3,000 feet above the sea, its open fields in 

strong contrast to the dark-green Clearwater forests. The canyons are in reality 

much sharper incised than those of the older plateau, but seen from this point of 

v.iew become indistinct. With a knowledge of the geological structure of the lava 

plateau, we can easily imagine how the molten rock in rapidly succeeding flows 

swept over and buried the foothills, perhaps at most permitting isolated high 

points to project above the lava, until at last these horizo~tal basaltic sheets had 

frequently attained a thickness of 2,000 feet and in a few pla~es even of 4,000 feet. 

The enormous volume of congealed magma along the foot of the mountains 

dammed the old canyons of the rivers and forced the streams in their lower 

courses to seek new channels. New drainage systems were laid out on the basalt 

plateau; and corrading rivers cleared the partly filled canyons of the damming 

]ava and excavated ne~ trenches in the basaltic fields. 

The basalt is a normal rock of its kind, usually au olivine-basalt, with a tendency 

to diabasic granular structure, glass remaining between the grains. Each of the 

many individu~l flows is ordinarily scoriaceous on top and more massive in the center. In a few places waterlaid clays and sands, with local ]ignites, are intercalated, 

doubtless accumulated by the rivers during lulls in the eruptions. Beds of t~:ff are 

absent. 

The age of this basalt is generally conceded to be Miocene. The evidence, 

consisting mostly of fossil plants in interbedded sediments, has been gathered 

from various points and examined, chiefly by Professors Knowlton and Merriam. a 

~o new evidence as to the age of this basalt has been obtained during this 

reconnaissance. 

The original surface of the basalt was no doubt approximately level over large 

areas; still we are. not justified in applying hydrostatic laws to the fluid rock, and 

· a Knowlton, F. H., Bull. U.S. Geol. Survey No. 108, 1893, pp. 103-104. 

.. 
QUATERNARY 'DEPOSITS. '25 

it is very likely that if a focus of eruption was located high up on a mountain 

side the flows might have an initial dip of several degrees down to the level at which 

the main valleys were:f:looded. No positive evidence as to ~he manner of eruption 

has been obtained. As a 'negative bit of evidence it may be stated that no ~asalt 

dikes of any kind have been found along the western margin of the Clear,water 

Mountains. The only focus thus far discovered along the eastern shore of the 

basalt plain is that described in a previous publication a and located at elevations of 

up to 8,000 feet on the eastern slope of the Eagle Creek Range, in Oregon. As 

has been surmised from the great fluidity of the lavas, the magma seems to have 

been emitted frory. a great number of short dike fissures in quiet and continuous 

streams. 

Orographic dislocations have caused two folds in the level surface of the lava 

plateau. ·Most important among these is, first, the synclinal depression centering 

in Lewiston and bordered on the north by the monoclinal fold of the Clearwater 

escarpment; and second, the gentle anticline of the Craig 1\tlountains, , separating 

the Lewiston Plateau from Camas Prairie. 

Slow earth movements on a grand scale are also believed to have affected the 

lava plateau. The principal movement seems to be a universal depression, perhaps 

induced by the extrusion of vast basalt masses from the interior. From a study 

of the courses and canyons of the antecedent rivers, like the Snake and the Salmon, 

it is surmised that certain marginal portio~s of the plateau may have been raised 

above the original level and that the. extraordinarily deep canyons have resulted 

from an erosive trenching progressing simultaneously with this uplift. 

QUATERNARY FORMATIONS. 

The distinctly Quaternary deposits of this region are principally those connected with glaciation. Heavy moraines lie at the foot of the southern part of · 

the Bitterroot Range, and glacial accumulations are found in all the valleys 

descending eastward and westward from their crests., From the Nez Perce to 

the Lolo Pa:::;s this range was covered by a .sheet of neve . and ice. Smaller 

moraines indicating a local glaciation are found on Salmon Mountain, The Crags, 

Buffalo Hump, Grave Peak, Rhodes Peak, and the Rocky Ridge, but over a 

larger part of the Clearwater .Mountains below an elevation of 7,000 feet, as 

well as along Lolo Fork and the South Fork of the Bitterroot River there is 

no indication of glaciation. It is also believed that the larger part of the Coeur 

d'Alene Mountains was free from ice during the Glacial epoch. South of 

Mullan Pass and generally near the highest points there i8 some evidence of . . . local glacial basins. In this more nort~erly region the limit of glaciation seems 

to lie a little lower than in the Clearwater Mountains. 

aLindgren, W., Twenty-second Ann. Rept. U.S. Geol. Survey, pt. 3, 1902, pp. 740-742. 
26 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

Deep gravels accumulated in the valley of the Bitterroot River and its branch 

streams during the Glacial epoch and, since its close, have been gradually exca- . 

vated q,nd terraced. The bottom lands along the rivers and the dried-lake basins 

in the ·]·1aciated district are the most recent Quaternary deposits. 

GEOLOGICAL HISTORY. 

An exact statement of the geological history of this region is difficult to give 

on account of the few exactly determinable datum planes. There are really only 

two determinatlons of time on which we may rely. The first is the date of 

the Columbia River lava as Mio~ene; the second is the Glacial epoch as early 

Quaternary. Back of the Columbia River lava the a·ges given for the sedimentatjons, intrusions, and dislocations are only tentative. 

The oldest rocks known are probably the gneisses of the Clearwater Mountains; more recent than these are the sediments of supposed pre-Cambrian, 

Carboniferous, and Triassic age. We may conceive a post-Triassic uplift of 

great importance, followed or accompanied by vast intrusions of granite, the 

granite of the Bitterroot, Clearwater, Salmon, and. Coeur d'Alene mountains. 

We may further, with great probability, a~sume a long-continued erosion, 

which planed down this uplift to the moderate relief of the Clearwater, Salmon, 

and Coeur d'Alene plateaus, and which exposed the intrusive granite . by the 

removal of great masses of covering sediments. 

Going one step further, it is necessary to assume a second great and evenlydistributed uplift which raised this eroded surface several thousand feet above 

the sea, an uplift of post-Triassic and pre-Miocene age. This was probably 

accompanied by breaks along what is now the western margin of the plateau, and 

was· necessarily followed by the establishment of the systems of the Bitterroot, 

Clearwater, and the Salmon rivers. These streams trenched the plateau broadly 

and deeply, with the result that their canyons during the Miocene epoch were cut 

to a depth equal t~ that of the present day. The relatio~s of the Columbia River 

lava to the old topography prove this on the western side, and similar evidence 

is adduced for the South Fork of the Bitterroot, by the fact that the rhyolites 

there filled a valley coinciding in depth and configuration with that of to-day. 

Going back a little further from the Miocene datum plane, perhaps to a 

time when the Bitterroot· River first flowed over the uplifted plateau, which 

probably reached far into Montana, a disloca.Mon of great importance occurred 

along what is now the Bitterroot Range.: 1'his dislocation, the beginning of 

which perhaps scarcely antedated the close of · the Cretaceous period, extended 

for 60 miles north and south, only bend~ng westward close to its southern end .. 

This fault plane was inclined eastward at angles up to 26° from the horizontal, 

and the rocks along it bear evidence both. of molecular and molar movement~ 
G EO LOGICAL HISTORY. 

the former expressed in schistosity~ the latter in striated slipping planes. The 

direction of the movement was that o~ a normal fault, and seemed to have been 

of a stretching. and shearing character. The foot wall seems to have moved up 

as expressed by the ra:ising of the Bitterroot Range above the general level 

of the Clearwater Plateau. The hanging wall seems to have moved down as 

expressed by the apparently structural trough of the Bitterroot Valley. The 

minimum amount of the dislocation along the plane of fault is 2 or 3 miles; the 

minimum horizontal component would be but little less, while the corresponding 

vertical component is ab<;>ut 5,000 feet. The evidence finally shows that movement along this dislocation has proceeded for a very long time, and probably still 

continues along certain parts of the fault. The flat dip of the fault plane has 

naturally aided the preservation of the record. 

During the latter part of the l\1iocene epoch~ important events happened. 

The western foot of the Clearwater Mountains was flooded by basalt, poured out 

through fissures in enormous volume. The foothills were covered by rapidly 

succeeding outbursts of very fluid lava, piled up in a great number of thin 

flows, which had a maximum thickness of 4,000 feet, and finally reached a level 

of about 3,000 feet above the sea, as the land stands to-day. The lower river 

courses were entirely changed; while the canyons of the Clearwater Mountains, 

though dammed by basalt~ still preserved their form and direction. 

The last part of Tertiary time, and perhaps the beginning of the Pleistocene, 

was occupied by the rivers on the western slope in undoing the constructive work 

of the earlier eruptions. Steep and sharply incised canyons were eroded along 

new stream courses along the lower Clearwater and the Salmon rivers, while 

the trunk stream of the Snake River cut out an entirely new course from Wieser 

(at the lower ~nd of the Great Snake River Valley) to its mouth. The canyons 

were cleared of accumulations, and at the beginning of the Glacial epoch the 

rivers of the western slope had trenched their canyons very nearly to the depth 

they have to-day. The filling of the canyons by lava had probably~ in most 

cases; produced accumulation of gravel terraces along the upper parts of the 

watersheds, and of such character are probably the auriferous terrace gravels 

of Elk City, on the South Fork of the Clearwater, the highest level of which 

reaches 4, 500 feet in elevation. In the lower stream courses the pre-Miocene 

drainage channels now lie below the bottom of the present streams; from this it 

seems probable that a large part of the field of the Columbia River lava has 

undergone a su'bsidence since the time of the eruptions; a subsidence probably 

caused by the eruption of , large masses of magma from the interior of the earth. 

Minor folds have occurred in the once horizontal lava beds, as near Lewiston. 

Finally, the courses of the Snake River and the lower part of Salmon River seem 

to indicate that an uplift has occurred along certain TUarginal parts of the lava 
28 BITTERROOT .AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

plateau; the deepening of the canyon keeping step with the rate of the · uplift. 

Only on such a supposition can we account for the abnormally deep canyons, 

which sometimes are cut 5,000 feet below the plateau surface. 

On the eastern slope the happenings of late Tertiary time are less easily 

traceable, but it is probable that the damming· by basalt of the Clark Fork of the 

Columbia and the subsidence of BitterrootValley along the great fault made a lake 

basin of this valley for a limited time. 

One of the last events in the geological history is the glaciation which dur.ing 

. the later part of the Quaternary period covered the whole Bitterroot Range with 

ice and snow and produced the extremely rugged forms which now characterize 

its surface region. Glaciers extended to the mouth of the ea~stern canyons of 'the 

range and also far down into the Clearwater drainag-e. Great moraines were 

accumulated· at the southern end of the Bitterroot Mountains. The Clearwater 

Mountains were not uniformly glaciated, but . contained numerous small glaci-al 

centers, such as The Crags, Grave Peak, Rocky . Ridge, Salmon Mountain, ·and 

the Buffalo Hump region. From causes not clearly recognized as yet, the L~lo 

Fork, the main valley, ana the South Fork of the Bitterroot River were during 

the Glacial epoch· filled with gravels to a height of 400 or 500 .feet above the 

present level of the stream. Similarly, we find evidence of a damming of the 

Snake and the Salmon canyons, with accompanying accumulation of ·sands and 

gravels to a depth of about 300 feet. Less evidence of this kind is available 

from the Clearwater system, though this also must have been similarly filled. 

Finally these accumulations were removed, and during this clearing out the 

terraces and bottom lands which now line the Bitterroot Valley were formed; 

gravel bars were left in places along the lower Clearwater, the Salmon, and the 

Snake; morainal material was worked over and terminal moraines trenched; 

basins of glacial lakes were filled and converted into meadows. . 

Beyond this there has been only a slight deepening of the canyons of the 

great rivers . . In glacial regions the marks of the ice seem as • if dating from 

yesterday. Except in the region of the Coh;tmbia River lava, the rivers have 

deepened their channels but little since early Tertiary time. The influences causing 

this retardation are the Miocene lava dams, the post-Miocene subsidence, and the 

obstructions to the rivers during the Glacial epoch. 

BITTERROOT VALLEY. 

' TOPOGRAPHY. 

Bitterroot Valley extends, properly speaking, from the point where the Lolo 

Fork enters the ·Bitterroot River to a point 5 miles south of Darby, where the 

river splits into two main branches. It is a well-marked depression about 65 miles 

long and up to 9 miles wide in its broadest portion, with a nearly north-south 
BITTE'RROOT VALLEY. 29 

direction. In the upper 15 miles its width is only from 2 to 4 miles. Westward 

the Bitterroot Range rises with its remarkably even slope and deeply incised · 

canyons, while eastward, with gentler slope and far less pronounced outlines, are 

the foothills which gradually lead up to the main divide of the Rocky Mountains 

toward Phillipsburg. The Bitterroot River pursues its course in a northerly 

direction with an average grade of 20 feet per mile, receiving many tributaries 

from the western mountains and a few from the much more arid eastern foothills. 

Those from the west, which generally have an east-west direction within the range, 

are usually sharply deflected northeasterly, where they debouch into the valley. 

CULTURE AND VEGETATION. 

Owing to a moderate elevation of from 3,900 to 3,150 feet, good soils, and 

excellent water supply, the Bitterroot Valley forms one of the most prosperous 

agricultural areas of Montana. There are many little towns, the largest among 

which is Hamilton, picturesquely situated in the middle of the valley, with 

beautiful view across to the serrated and snowy ridges of the Bitterroot. The 

hardier fruits thrive, as well as cereals and forage plants, but irrigation is 

everywhere necessary. Along the river is a moderate growth of deciduous _trees 

and a few pines; the gravel terraces and the eastern foothills are partly open; 

while the lower hills of the Bitterroot Range are covered by thick timber. 

The forests and soils of this region have been described in much detail by Mr. 

J. B. Leiberg. a 

·, 

GEOLOGY. 

QUATERNARY. 

A large amount of Quaternary deposits lie in the deep trough of the 

Bitterroot Valley, and there is evidence that it was once filled to a much 'higher 

level than at present. The greater part of this material is doubtless derived from 

the moraines and glacial streams which came down from the valleys of the 

western range, but much of it has also been brought down from the canyons of 

the upper river. . 

At the forks of the river, 25 miles south of Hamilton, the alluvial bottom 

lands are about 1 mile wide and continue with the same width downstream toward 

Grantsdale. From this point northward to the end of the valley the bottom lands 

are ordinarily several miles wide. These latest alluvial depqsits are throughout 

the valley flanked by gravelly terraces, often several miles wide. Near the forks 

of the river and upstream toward Darby there are at least two prominent 

terraces on the west side at elevations of 100 and 200 feet above the river. 

In some places these are sharply defined and at others merge into the slopes of 

the valley. The highest is at an elevation ·of about 4,100 feet. Near the river 

aNineteenth Ann. Rept. U. S. Geol. Survey, pt. 5, 1899, pp. 253-282. 
30 BITTERROO'l' AND OLEARW ATER MOUNTAINS, MONT.-IDAHO. 

are lower gravel terraces, 8 and 30 feet above the water level. The upper 

terrace leans againRt gradually rising hills of heavy moraines. On the east side 

there are few terraces south of Grantsdale, for the river is closely crowded 

against the rocky foothills of that side. From Grantsdale north the terraces 

become wider. East of Roaring Lion Creek there is a 30-foot terrace on the 

west side of the river, with a gradual slope covered with heavy gravel wash, which 

extends to the first moraine at the mouth of the canyon, which is 400 feet above 

·the river and at an elevation of 4,000 f~et. Simila,· relations obtain at the mouth 

of Mill Creek, except that the gravel is finer and more sandy. 

At various places between Curlew mine and the mouth of Bear Creek the 

gravel terrace contains much quartzite in large cobbles, the origin of which seems 

somewhat doubtful, as there is not much quartzite in place close by. At the 

Curlew mine the gradual gravel slope reaches up from the river to the foothills, 

200 feet above. On a spur 500 feet above the mine and 700 feet above the ,river 

-lies a patch of well-washed gravel, the elevation of which (4,033 feet) must indicate the height to which the valley was once filled. Immediately north of Big 

Creek the gravel again reaches up to an elevation of 4,000 feet. 

Near Florence, in the northern part of the valley, the gravel terrace skirts 

the river, the hanks being 20 feet high in places. From the Curlew mine north 

the gravel contains much coarse, micaceous gneiss and the sands are full of mica. 

The evidence, as far as it goes, indicates that during the Glacial epoch the Bitterroot Valley was filled with gravels and sands to an elevation of about 4,000 feet 

along the margins, and that the grade of the river was then less than at present. 

No direct evidence of the former existence of a lake within the valley has 

been found. The east side, however, has not been carefully examined, and from the 

genera1 configuration it would se~m possible that this depression, like many other 

intermontane valleys of this region, was occupied by a lake in late Tertiary time. a 

It seems, highly imprpb3tble that the Bitterroot Valley, at least north of 

Grantsdale, has been formed by erosion alone. It bears too many characteristics 

of structurttl valleys, and it seems not out of the way to tentatively associate its 

origin with that of the great range to the west of it. This subject will be 

referred to again in the description of the mountains. 

EASTERN FOOTHILLS. 

TOPOGRAPHY. 

As far south as Skalkaho Creek the foothills on the · eastern side of Bitterroot Valley are low, ascending gradually in many 'low spurs from gravel terraces. 

"The crest line lies about 30 miles · east of the valley, but as a continuous ridge 

a Mr. Bailey Willis states (orally) that he found soft, clayey beds, probably of lacustrine origin, on the north side of 

Skalkaho Creek, in the first foothills, a few miles from Hamilton. These beds dip westward at an angle of 30°. 
EASTJ£RN FOOTHILLS. 31 

is scarcely so definite and well marked as the summit of the western watershed. 

The ultimate divide is the main range of the Rocky :Mountains, but the intermediary ranges, radiating in all directions, form so many separate divides that 

the central backbone is lost sight of. The canyons that enter the valley from the 

east are not so numerous nor so regularly arranged as are the western affiuents. 

The divides between them rise from the valley with easy gradients, presenting 

fronts many miles in width that are seamed and scarred with shallow and irregular 

gulcheb, sometimes cutting back several miles in the fronting portion of the spur." a 

South of Skalkaho Creek the spurs advance close to the river, presenting ~steep 

front in places over 1,000 feet high. The irregular maze of closely crowded ridges 

gradually attains elevations of over 7,000 feet in the complex of hills a few miles 

east of Darby, which still is many miles distant from the main divide. 

GEOLOGY. 

SEDIMENTARY SERIES. 

While the prevailing rock east of the river appears to be a granite or gneiss, 

there are also considerable areas of a sedimentary series, chiefly quartzite or calcareous quartzite. The age of this series is iri doubt, as no fossils have been 

found, but there is considerable similarity to certain parts of the Lolo Fork 

series and the rocks may well be of the same age. As on Lolo Fork, the con:-

tacts with the granitic rocks indicate the intrusive character and later age of the 

latter. 

In the foothills east of Victor the first outcrops of older rocks consist of 

compact quartzites dipping 27° to 48° W. ,Larger areas of quartzite appear in 

Skalkaho and Weeping Child creeks, a few miles distant from the valley. On 

Skalkaho Creek the beds dip 45° to 55° N. or NE. On Weeping Child C~eek 

about 5 miles above its mouth it'! a narrow belt of quartzite, with a dip of 85° 

NW. This continues across to Skalkaho on the north and can be followed southwesterly across the spurs to a steep bluff on the Bitterroot River, a short distance 

north of Como post-office, where the dip is 38° SE. Small croppings of quartzite 

are even found in places below the gravel terrace on the west side of the river. 

Beyond the first belt of quartzite on Weeping Child Creek granite or gneiss is 

exposed for a distance of 2 or 3 miles; the quartzites then come in again with 

varying though generally. flat dip, and near the Hot Springs are interstratified 

with micaceous schists. The series is evidently both folded and faulted. 

CONTACTS. 

On both creeks the contacts with the granitic rocks are well exposed and 

show that the latter are of unquestionable intrusive character. At the main contact 

on Skalkaho Creek the quartzite is magnificently intruded by b'ranching dikes of 

aLeiberg, J. B., Nineteenth Ann. Rept, U.S. Geql. Survey, pt. 5, 1899, p. 256. 
32 BITTERROOT .AND OLEARW ATER MOUNTAINS, MONT.-IDAHO. 

normal granitic rock; near the ,granite the quartzite contains bands of biotiteschi~ts and is largely converted into banded hornfels with malacolite and biotite. 

Inclusions. of these rocks are also contained in the granite. In places the granite 

dikes are pegmatites with Vtuch quartz. At the first contact in V\.,. eeping Child. 

Creek the same phenomena are seen. Many of the granitic dikes here follow the 

bedding planes of the q tiartzite, w bile in the section described above they mainly 

break ·. across them. The same contact metamorphic rocks are noted. 

GRANITIC ROCKS. 

The larger part of the foothills east of the river is occupied by granites ancl. 

gneiss, the relations of which seem rather complicated. Much of the granite is a 

normal, massive, light-yellowish gray rock similar to that of the central Bitterroot 

Range and, like that, containing both biotite and muscovite. The grain is apt to 

vary and some specimens contain large orthoclase crystals. Such rocks are found 

on the lower Skalkaho and southeast of Darby. Larger and smaller fragments 

of gneissoid rock, rich in black mica and with contorted planes. of schistosity, 

frequently occur as inclusions in this granite. Over large areas the granite itself 

has acquired a roughly schistose structure. This is seen on. lower V\r eeping Child 

Creek, where the schistosity has an east-west direction, and in the hills east of 

Darby, where it strikes from N. 15° W. toN. 50° E., the dip being either w:esterly 

or easterly from 45° to 60° . 

The most probable interpretation of these facts is that an old pre-Cambrian 

series of quartzite and of still older true gneisses was intruded by granite similar 

in age and type tO the Bitterroot granite. While large quartzite areas are left, 

the contorted inclusions are the only remnants of the gneisses. The granite has 

subsequently by irregularly acting forces acquired local rough schistosity in various 

directions. The included gneiss 'fragments can not reasonably be interpreted as 

contact metamorphic parts of the quartzite series. The roughly gneissoid granites 

are very different from the strongly compressed gneisses of the Bitterroot · Range 

and probably did not result from the same kind of stresses which were active at 

that place. 

DIKES. 

The granitic rocks contain abundant dikes of granite-porphyry, dark dioriteporphyry, and rhyolite. 

RHYOLITE. 

For a few miles south of Como post-office the east side of the river up to 

a height of 1,000 feet is lined by precipitous bluffs which are formed by a series 

of rhyolite flows dipping about 45° to 60° SE. A thickness of several hundred · 
LOLO F'ORK. 33 

feet is exposed and the succession from the base up is as follows, the flows 

resting on gneissoid rock: 

Section near Como post-office. 

( 1) Columnar rhyolitic tuff, weathering soft. 

(2) White rhyolitic tuff, weathering soft. 

( 3) Red felsophyre, weathering brown. 

( 4) Soft white rhyolite. 

( 5) Massive white rhyolite. 

(6) White breccia, with dark bands. 

(7) Red felsophyre, with green and black bands of vitrophyre. Rhyolite is also found in a 

few places on the west side of the river covered by Quaternary terrace gravel. 

LOLO FORK AND NORTH END OF BITTERROOT RANGE. 

TOPOGRAPHY. I 

At Lolo post-office, 35 miles north of Hamilton and 10 miles south of Missoula, the foothills of the Bitterroot Valley advance close to the stream, and 

this point may be considered as the end of the valley, properly speaking. Near 

the same place is the northern termination of the Bitterroot Range. From Lolo 

Peak, about 9,000 feet in elevation, the slopes descend abruptly to~ard Lolo 

Fork, an important tributary of the Bitterroot River; north of Lolo Fork the 

complicated system of timbered ridges which mark the beginning of the Coeur 

d'Alene Mountains rarely attain 7,000 feet above the sea. 

Along Lolo . Fork for a few miles above its mouth the b'ottom lands have a 

maximum width of one-half mile, and are bordered on both sides by gradually 

rising hills. Soon, however, a canyon ·begins with flat though narrow bottom, 

and this is practically continuous to the head, the slopes rising steeply on both 

sides for a few hundred feet, continuing then along more gently indined ridges. 

About 20 miles from the mouth an important tributary is received from the 

north, and near this place the valley widens and contains sG>me meadow labd at an 

elevation of 3, 700 feet. A well-marked terrace is noted 500 feet above the valley, 

and from this the long ridges gradually . ascend to elevations of 6,000 feet or 

more. An excellent view is afforded from them southeasterly toward the snow 

• . :fields and serrated peaks of the Bitterroots, and northwesterly over the monotonous, heavily timbered ridges of the Coeur d'Alene Moul1tains, scarred by the 

tracks of extensive forest :fires. 

Above the North Fork the canyon continues for 10 miles to Hot Springs where 

the stream forks again, one branch extending 10 miles westward and heading near 

Rhodes Peak, while the oth.er comes down with northerly direction from Lolo Pass, 

8 miles distant. 

5995-No. 27-04-3 
34 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

Lolo Fork thus runs from west to east just north of the Bitterroot Range and 

may be considered to mark the boundary between this range and . the southern part 

of what, in this report, has been called the Coeur d'Alene Mountains. Its length is 

about 40 miles, and its southern fork cuts in back of the main divide of the Bitterroot 

Range. A wagon road leads up to the Hot Springs (elevation 4,100 feet), a favorite 

summer resort with baths, and at this place the Lolo trail begins. In 1899 this part 

of the trail was in very bad condition, due to fallen timber between which the 

path runs in most eccentric ,curves. A gradually ascending ridge leads up to the 

divide which has an elevation of only about 5,200 feet. Lolo Pass is a broad, flat 

depression between the westerly spurs of the Bitterroots and the projecting ridges 

of Rhodes Peak in the Clearwater Mountains. Deep soil and extremely thick forest 

with underbrush cover the hills, between whieh extend a series of swampy meadows. 

A fe~ miles westward .the trail crosses the North Fork of the Lochsa Fork and 

views are obtained over the Clearwater Mountains, heavily forested, with deep 

though not precipitous canyons and with slightly undulating skyline. In many 

places white exposures of granite gleam in the openings of the forests. 

GEOLOGY. 

SEDIMENTARY SERIES. 

For a distance of 20 miles in a straight line westward from its mouth Lolo Fork 

cuts· across a sedimentary series with a general northwesterly strike and prevailing 

northeasterly dip. Near Hot Springs this series is cut off by intrusive granite, the 

contact line thence curving southward toward Lolo Pass. This same series occupies 

the extreme northern slopes of the Bitterroot Range and .probably also Lolo Peak. 

Along the eastern front of the range it reaches down to the mouth of Carlton 

Canyon, 7 miles south of Lolo Fork, where it again is cut off by intrusive granite; 

thence the contact probably extends westward toward Lolo Pass. The micaceous, 

contorted gneiss of St. Marys possibly connects with the sedimentary area. 

These sedimentary beds, which may be provisionally designated as the Lolo 

series, derive additional interest from their probable identity and continuity with 

the series occupying the entire width of the Coeur d'Alene Mountains, 90 miles 

northward, and extending from the lake of the same name on the west to Clark Fork 

of the Columbia on the east. In neither case bas the age been established, no trace 

of fossils having thus far been found. That the beds are very old is evident; they 

may even be pre-Cambrian. 

The stup.y of the series began at the mouth of Lolo Fork close to the Lolo 

post-office. ' Cherty limestone and quartzite crop here with northwesterly strike, 

adjoined 1 mile farther up the fork by a narrow belt of purple shale or slate. 

Three miles above begins the mouth a broad belt of quartzite-schist with north-
LOLO FORK. 35 

westerly strike and a dip of 83° NE. Going up Mormon Gulch, which empties 

into the fork near its mouth and heads near Lolo Peak, shales and cherty limestone are noted; these beds have a southwesterly dip of 55°; above them on the 

same gulch begins the same micaceous quartzite-schist which was observed on 

the main fork and , which contains a few aplitic dikes. 

In the main fork the quartzitic schists continue for several miles. The 

schist, which is clearly of sedimentary origin, splits easily in slabs coated with 

muscovite. Just below vVesterman's ranch, 5 miles from the mouth of the river, 

a belt of thick-bedded quartzites crosses the canyon. The next part of the 

series continues for 2 miles and consists of calcareous quartzite with some shaly 

limestone, with same northwesterly strike and northeasterly dip. Half a mile 

above W oodmans Creek this is adjoined by heavy bedded quartzite, continuous 

for 1t miles. The canyon now becomes narrower, and schists of a greenish color, 

probably largely altered eruptives, predominate. One mile below Spark's ranch 

a dike of quartz-diorite crosses the canyon; above this. a white quartzitic schist 

is extensively developed, striking N. 44° to 74° "\V., and dipping 35° to 45° NE. 

A long ridge north of Spark's ranch was ascended to a point 2,000 feet above 

the valley and the series was here found to strike much more northerly, ranging 

from due N. to N. 15° W., and dipping about 20° W., implying some kind of a 

break between this part and the rocks exposed in the canyon. The beds are 

banded, calcareous rocks, greenstone-schists, and a large amount of purple slates, 

very similar to those near the mouth of Lolo Fork. 

The white quartzitic schists continue with the same dip for several miles 

above Spark's, when they run over into cherty banded and streaked calcareous 

quartzites which do not appear very much altered. In spite of careful search no 

definite fossils were found. One dike of diorite-porphyry was observed on the north 

side of the river. Tb 3 remaining distance of about 6 miles up to the granite 

contact near Hot Springs is occupied by banded and calcareous quartzites, interstratified with dark slates. While this series contains lime, it is not so distinctly 

calcareous as that exposed at the mouth of W oodmans Creek. The strike swings 

more to the west, being from N. 60° to 80° W. Th~ dip is prevailingly from 

15° to 45° NNE. In a straight line the distance from the· mouth of the fork up 

to the contact is 20 miles, but except in the lower part the river does not cut 

squarely across the strike. No estimate of thickness of this series can be 

attempted on the basis of the foregoing observations, but it is apparent that it 

must be considerable, even allowing for folding, faulting, and repetition. There 

is a noticeable absence of pyritic impregnation, quartz veins, and dikes. While 

the series contains some sheared eruptives, there is certainly no great amount of 

this kind of rock. 
36 BITTERROOT AND CLE.ARW .ATER MOUNTAINS, MONT.-ID.AHO. 

LOLO CONTACT. 

Just below Hot Springs, near the mouth of Granite Creek, is a sharp contact, 

though ' the actual contact plane is not well exposed and the drainage basin above . 

this point is occupied by granite. The contact crosses Granite Cre~k near its 

mouth, and thence for many miles continues with a general direction of. N. 80° 

W. To the south the contact changes its direction and appears to follow pretty 

close to Lolo Fork. Near Lolo Pass irregular areas of metamorphosed sediments 

were observed. The thick vegetation and deep soil give few opportunities for 

study of the rocks. 

For several hundred feet from the contact the quartzitic slates are very crystalline, and minerals and structure typical of contact phenomena have developed in 

them. The e~posures on the ridge east of the Hot Springs are not good, but at 

the contact the slates are very micaceous. The calcareous rocks have been altered 

to malacolite-hornfels, while the pure quartzite has obtained a dense :flinty structure. A granite-porphyry with bipyramidal quartz crystals often appears on the 

immediate contact. The excellent outcrops, 1,200 feet below Hot Springs in the 

creek, show greenish crystalline schists, stri)ring north-south and dipping 80° W. 

These schists contain many small dikes of mu_scovite-granite, aplite, and pegmatite, 

some containing tourmllline. A specimen 20 feet from the actual contact which 

is covered shows a biotite-andalusite hornfels with abundant tourmaline. The 

alteration decreases rapidly, though a specimen collected 1,000 feet below the contact, on Lolo Fork, appearing like a dark-gray, tJ.inty quartzite, still shows 

the structure of hornfels and contains tourmaline. Half a mile below the contact 

banded slates appear with normal' strike and dip, and very little altered, the chief 

evidence being little spots and knots on the cleavage faces. A few dikes of 

granite-porphyry were no~ed at this place. 

The intrusive character of the granite into the Lolo sedimentary series is the 

main point established. 

CARLTON CREEK CONTACT. 

As might be expected, the quartzitic schists and quartzites of the lower Lolo 

Fork continue with northwe_sterly strike ac~os~ the ridge between that river and 

the main Bitterroot Range, and are found along the foothills for 7 miles south of 

the junction. Quartzite is exposed to a point three-fourths of a mile north of the 

mouth of Carlton Creek Canyon, where k.notty slates are interbedded and show 

strikes of N. 45° W., dip 45° NE. The slates are micaceous and contain in places 

abundant narrow dikes of pegmatitic and aplitic granite 5 to 6 inches wide, 

chiefly intruded parallel to the coinciding planes of schistosity and bedding. 

Going southward, more ·quartzite follows, and at Carlton Creek the contact of the 
U S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 27 PL. V 

A 

B 

c 

PHOTOM ICRO GRAPHS OF GNEISS OR GRAN I TE-S CH I ST. 

A, Gneiss or g ranite-schist from near mouth of Tin Cup Canyon ; ord inary light, X 20. 

H, Same as A; crossed nico ls, X 20. 

C, Gneiss or granite-sch ist from ne ar mouth of Sawtooth Canyon: ordinary light , X 20. 
. . 
LOLO FORK. 37 

sedimentary series with the granitic is reached. One of the interesting points of 

this contact is that the intrusive rock here consists of the normal gneiss of the 

Bitterroot front slopes, itself a dynamo-metamorphic development of granite. 

At this place the gneiss is imperfectly schistose, but the dip is from 15° to 18° E., 

as at most points farther south. About 2 miles above the mouth of the canyon 

this gn iss seems to gradually change into the normal granite abundantly exposed 

on the slopes facing north. The exact place of contact between gneiss or granite 

and quartzite .is somewhat in doubt, so gradually increasing is the injection of 

the latter by pegmatite and granitic rocks. That this contact, too, is intrusive 

admits of no doubt, and it is accompanied by a mo!e intense contact metamorphism than at Hot Springs on Lolo Fork, probably, because the series is here 

fractured across the bedding planes. In some places the interstratified clay slates 

are converted to gneissoid mica-schists. . The zone of metamorphism extends at 

least three-fourths of a mile northward from the contact. 

<;/NEISS OF ST. MARYS PEAK. 

Eighteen miles south of the northern end of the range, St. Marys Peak rises 

to an elevation of 9,p00 feet or: 6,000 feet above the level of ·the valley. As 

usual in these mountains the culminating points are situated a few miles east of 

the main divide. The long ascent from the valley leads over the usual sheared 

granite of the front of the range, with its constant easterly dip. But at about 

an elevation of 7,000 this changes without clearly exposed contact to a very contorted and entirely different gneiss, very rich in black mica and weathering with 

1~eddish color. Streaks and patches with fairly well-marked ou~~ines of finegrained, also contorted, mica-schist are embedded in this. These rocks have, on 

St. l\farys Peak, a northerly strike and a westerly dip of about 70°. The area 

clearly extends southward across Big Creek. As evidenced by the detritus 

brought down to the valley by the creeks, similar rocks also occupy considerable 

areas to the north of the peak. A short distance westward the normal granite 

begins, and is well exposed in the glaciated outcrops. The age and origin of the I 

St. Marys gneiss has not been determined. A possible explanation is to consider 

it simply as an extreme facies of contact metamorphic action on the Lolo series, 

and this view receives some support from the fact that small amounts· of somewhat similar rocks were observed at the Carlton Creek contact. But the area is 

too uniform and large and the absence of quartzites is too conspicuou.s to allow 

this explanation to stand. Considering the relations in the southeastern and 

southwestern parts of the Clearwater Mountains, it is more probable that· it is 

an independent and older gneiss, very likely of Archean age, which underlies the 

Lolo series and which, .like those beds, was invaded and ruptured by intrusive 

granite. 
38 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

GRANITE; QUARTZ-MONZONITE. 

A granite · of the normal appearance of the Bitterroot variety occupies the 

drainage basin of Lolo Fork, above Hot Springs, and of Granite Creek. The 

rock which near the Springs forms light-gray, large, partly rounded, outcrops of 

typical form, is coarse grained and contains both biotite and muscovite. An 

analysis would probably bring out its close relationship to quartz-monzonite. It 

contains much grayish orthoclase, besides perthite and a little microcline as well 

as an acid oligoclase. The character seems ~onstant as far as observations were 

extended. A few miles west of Lolo Pass a few outcrops of pyroxenite were 

noted; beyond this the normal muscovite-granite begins again, and from the 

appearance of the outcrops, seems to occupy the whole of the last end of Lolo 

ridge in the Clearwater Mountains and the larger part of the country visible to 

the south of the Lochsa Fork, including the prominent mass of Grave Creek. 

QUATERNARY. 

The only deposits belonging to the Quaternary period~ noted in the Lolo 

drainage, are the narrow meadow lands appearing at intervals in the usually fiat 

bottom of the Lolo Fork and the high terrace near Sparks's ranch. While in 

the lower part of the stream no gravel terraces were observed, an extensive bench 

of coarse gravel, deeply cut by the river and its gulches, forms a prominent 

feature near the junction of the first important branch from the north, 14 miles 

above the mouth of the river. Steep declivities lead up from the bottom lands to 

this terrace, which probably occupies an area of several square miles on both sides 

of the river. The well-washed g,ravel begins at an elevation of 400 feet above the 

stream and reaches up to 550 feet (elevation 4,300 feet); above it rise long, gently 

sloping ridges of slate and other sedimentary rocks. 

This occurrence is interesting as it shows that during some part of the 

Quaternary period Lolo Fork, like the main Bitterroot River, was filled by sands 

and gravels to an elevation several hundred feet above the present river bottom. 

No evidence of glaciation was noted along Lolo Fork, though it is probable 

that the ice streams of the Bitterroot Range extended westward to a point near 

Lolo Pass and that the meadow lands at that place are of glacial origin. 

BITTERROOT RANGE. 

TOPOGRAPHY. 

As defined in this report, the Bitterroot Range extends from the head of 

West Fork of Bitterroot River and the Nez Perce Pass on the south a distance 

of 65 miles almost due north to Lolo Fork. Its imposing front, with deep 

c,anyons and snow-flecked serrated , ridges, overlooks the Bitterroot Valley on the 
BITTERROOT RANGE. 39 

east, while westward its slopes soon merge' into the dissected high plateau of the 

Clearwater Mountains. Its height is considerable, though many ranges of the 

west easily exceed it in this respect. Near the southern end El Capitan and 

Trapper Peak nearly reach or exceed 10,000 feet, but the average elevations of 

its highest summits is more nearly 9,000 feet. These elevations are very constant 

throughout the range, which thus rises somewhat less than 6,000 feet above 

Bitterroot Valley. North of Lolo Peak and south of Boulder Peak the elevations 

decrease conspicuously, few points exceeding 8,000 feet south of the Boulder Peak 

or 7, 000 feet north of Lolo Peak. The range is characterized by some very 

singular and com;tant topographic features, of which the most striking, perhaps, 

is the regular and even slope toward the valley. From Lolo Peak to Nez Perce 

FIG. 2.-Bitterroot Range, looking northwest from Hamilton; showing gentle eastward dip of gneiss zone and 

deeply incised canyons of Blodgett and Mill creeks, with precipitous sides. 

Pass this slope is nearly constant at angles ranging from 18° to 26° . Its width 

varies from 2 to 4 miles. Pls. IV, VI, B, VII, B, IX, A, and X and figs. 2 and 3 

show the appearance of this slope from various points in the valley. · From the 

summit of this slope, east-west ridges extend toward Clearwater to the divide which 

forms the boundary line between Montana and Idaho. These ridges are usually 

narrow, extremely jagged, and rough, but their highest peaks do not vary much in 

elevation. In some places, as near Ward Peak (Pl. III), the highest elevations 

of the range are nearer to the valley than to the main divide. Ordinarily~ bowever, the highest summits of the range are halfway between the valley and the 

divide, the peaks along the divide never reaching 9,000 feet and ordinarily 

ranging in elevation from 7,500 to 8,500 feet. The saddles on the divide are from 

7,000 to 7,500 feet in elevation, except in the case of the gap at the head of Lost 
40 BITTERROOT AND CLE.ARW .ATER MOUNTAINS, MONT.-ID.AHO. 

Horse Creek, which sinks to 6,600. Both Lolo Pass and the N;ez Perce Pass are 

still lower, the former only attaining 5,300 feet. Thus_ the summit "of the range 

lies several miles to the east of the Clearwater divide. (See profiles, Pl. IV.) 

Another remarkable feature is in the direction and character of the drainage. 

Se(:m from any convenient place in the valley, for instance, from ?rantsdale, _the 

bold, even slope sweeps along the face of the range as a single tectonic plane; the 

canyons, like those of Blodgett and Mill creeks, appear as deep gashes, scarcely 

interrupting the continuity of the front. They are narrow, especially hear the 

mouth, the walls in many cases being abrupt precipices. About twenty canyons, 

closely spaced, score the east slope of the Bitterroot Mountains. ·In most cases their 

streams are· remarkably straight, flowi!l~ from west to east, without important 

FIG. 3.-South end of Bitterroot Range from point near Darby; showing gradual eastern slope of gneiss zone south 

of Tincup Creek. 'Moraines are shown in foreground. 

branches, and separated by almost equally straight ridges, with narrow, jagged 

summits. Especially fine instances ?f this arrangement are furnished by the four 

_or five creeks west of Hamilton. (Pl. III.) Broadly U-shaped in their upper 

courses (Pl. VII, A), due to energetic glacial action, they generally na~row to 

V -shaped incisions near the mouth. Near the head we note a general tendency to 

turn southward. By far most ·of their tributary gulches are received from · the 

south, while the slopes to the north of the canyons generally present unbroken 

fronts. Lost Horse Creek is rather an exception to the rule, as it splits, not far 

. from the mouth, into three branches. Along the main divide ·and sometimes also 

. on the secondary east-west ridges small glacial lakes are found in abundance. 
BITTERROOT RANGE. 41 

Jointing of the rock, erosion, and glacial action contribute to a~ excessive roughness of topographic detail, making the range one of the most inaccessible. Continuous travel along the divides is impossible, on horseback or on foot. In the creek 

bottoms, treacherous, swampy areas, a slender but impenetrable growth of lodgepole 

pine, tangled underbrush, and fallen logs make travel difficult, even along the few 

trails which cross the range or ascend the gulches. Between Lolo and Nez Perce 

passes the only safe horse trail across the range is that leading up Lost Horse 

Creek, and even this is far from being an easy one. 

Ordinarily mountain ranges adjoining thickly populated valleys abound in trails 

or even roads, and are .well known and frequented by the inhabitants of the plains. 

But the Bitterroot Range is different; its lofty summits are without the attractions 

of flowery meadows and easy paths; only the hunter and the explorer penetrate its 

wilderness. The lower slopes are covered by thick forests which gradually become 

more sparse as elevations increas~ and the white granite begins to gleam between the 

dark pines; finally vegetation almost ceases and the summit region spreads out with 

a maze of peaks and broken ridges of dazzling bright granite, flecked by still more 

brilliant snow fields. (Pis. VII, B, and VIII, A.) 

The main divide, distant from. 8 to 15 miles from the first. foothills, is, as 

stated above, a succession of sharp, craggy peaks alternating with deep saddles 

at the head of the large canyons. Especially in the southern portion of the 

range it is irregular, swinging from east to west with curves. t~e radius of which 

is from 1 to 2 miles. On a smaller scale the same thing is repeated on the 

secondary east-west divides of the eastern slope, the secondary canyons ·cutting 

deep recesses in them, narrow, precipitous of grade in their lower part, and 

openip.g into wide glacial cirques near their head. 

The western slope of the range is even more rug~ed than the eastern. ''The 

immediate slopes from the crest are here very abrupt, are cut up by immense 

gorges, and abound in precipices and extensive rock slides to such a degree that 

they are entirely impassable." a West ward these ridges soon descend to the level 

of the dissected high plateau of the Clearwater Mountains, and the glacial cirques 

contract to the winding, narrow, and inaccessible canyons of that system. 

GEOLOGY. 

SEDIMENTARY SERIES. 

Except near its extreme northern end the Bitterroot Range is almost 

exclut:~ively built up of granite and gneiss. The Lolo sedimentary series and 

the St. Marys gneiss have already been described in the preceding section. South 

of Carlton Creek no sedimentary rocks are known from the interior mass and 

only a few smaller areas have been observed along the first foothills. 

aLeiberg, J. B., Twentieth Ann. Rept. U.S. Geol. Survey, pt. 5, 1900, p. 319. 
42 BITTERROOT AND CLEAR,W ATER MOUNTAINS, MONT.-IDAHO. 

The largest sedimentary area is that near Curlew mine; it occupies less than 

2 -square miles and really forms foothills projecting beyond the normal line of 

the base of the range. It begins j ~st south of Big Creek and continues 

southward for 2 miles, having ail average width of half a mile. The rocks, 

which are not very well exposed, are chiefly quartzite, or calcareous quartzite, 

in places converted into a fine-grained, dark-brown, . contact-metamorphosed 

hornfels. Throughout the rocks are exceedingly crushed and broken, and rarely 

._ ""--- show their strike and dip. At one place, on the ditch toward Big Creek, was 

-- iiote<L._~ dark lime shale with a southwesterly dip of 60° . On the west the 

contact w1fu tl:!:~ gneiss runs nearly straight north and south and is a fault plane. -.;: 

A dislocation occurred along this line in_ 1898 and is still visible on the surface 

o.f a gently sloping ridg :._ It extends for 1,500 fee_t · and is partly an open 

fissure, the down throw being -OQ._ the eastern ~ide and amo~nting to 1 or 2 feet. 

No well-defined sedimentary roc~s have been found along the footh~lls for 

-a long distance s~uth . of this area: Near the mouth of Sawtooth Gulch finegrained rocks occur interbedded with the ordinary gneiss, but they seem only to 

be varying dynamo-metamorphic developme~ts of granites of slightly differing 

texture. Between Chaffin and Tincup creeks, near the south end of the range, 

extends a short ridge parallel to the trend of the mountains and of somewhat 

complicated structure. Much of it is made up of a fine-grained, almost flinty 

rock, largely consisting of quartz; this has a bedding or jointing, dipping 40° 

east. The same ridge also contains a coarse gneissoid rock, roughly schistose, 

and similar to the imperfect gneisses east of Darby. The schistosity strikes eastwest, and the dip is 30° north; some of this gneiss is of fine grain. 

GRANITE AND GNEISS. 

It has already been stated that the range almost entirely consists of granitic 

arid gneissoid rocks. The arrangement of these corresponds to the topographic 

development described above in this manner: The central mass is almost throughout a normal biotite-muscovite-granite; the regular eastern slope, even and continuous from Nez Perce Pass to Lolo Peak, is formed by a sheet of gneiss, dipping 

from 18° to 26° E. like that slope. The gneiss is a modification of the interior 

granite-in other words, · is granite made schistose by pressure, and westward 

. graduall;r changes into the massive granite. This gneiss is not only schistose, but 

also 'fuil of slipping planes, parallel to the schistosity, and on these slipping 

· planes are commonly closely massed striations parallel to the dip of the gneiss. 

The structural importance of these remarkable facts will be discussed in a later 

· paragraph (p. 47). In this , place such detailed observations as are available will 

first be recorded. 
U. S. GEOLOGICAL SURVEY PROFESSiONAL PAPER NO. 27 PL. 1/ I 

A DETAIL OF GNEISS CLIFF ON NORTH SIDE OF MILL CREEK 

CANYON , NEAR MOUTH. 

Cliff 1,500 feet high. 

B. VIEW SOUTH FROM HAMIL TON. 

Shows regular slope of gne1ss zone of Bitterroot Mountains. Ward Peak is SEen in th e ce nter backgrou nd, and below it the ridge between Roaring Lion a nd 

Sawtooth creeks. 

U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 27 PL. VII 

A. UPPER VA LLEY O F MILL CR EEK, BITTERROOT RANG E, LOOKING § AST FROM MAIN DIVIDE. 

Note pronou need U-sh ape of va lley, narrow1ng toward the lowe r part. The p re vail ing rock is gran ite. 

B. VIEW SOUTH FROM WARD PEAK, BITT ERROOT RANGE. 

El Ca p1tan In center backgrou nd. 

U. S. GtOLOGICAL SU RYEY PROFESSIONAL PAPER NO. 27 PL. vi:l 

I A. VI EW NORTH FROM WARD PEAK, B IT TE RROOT RANGE, ACROSS CANYON S OF ROAR IN G LION AND SAWTOOTH 

CREEKS. 

B. COMO PEAKS FROM COMO LA KE, BITTE RR OOT MOUNTAINS. 
I. 
BITTERROOT RANG E. 43 

North end of the range.-Going from north to south the gneiss Is first 

observed at the mouth of Carlton Creek Canyon. It is here imperfectly schistose, 

dipping 15° to 18° E., and the belt is not wide. 

Two miles farther up normal granite crops on the south side. As described 

on page 36, the gneiss borders the quartzite of the Lolo series, and the contact 

shows it to be of intrusive character. 

A few miles farther south, due west of Florence, the gneiss has locally a 

steeper eastward dip of 30° to 35° , and fine cliffs of these rocks are seen, where 

the canyon walls cut the front plane of· the range, 2,000 feet above the val1ey. 

Large white granite cliffs appear higher up in the canyon. The exposures in 

the lower part of Big Creek along the Curlew mine ditch are excellent; the 

gneiss dips 20° E., striking a few degrees east of north exactly parallel to the local 

trend of the foothills; the rock is medium-grained, dark gray, and very much 

sheared, .the larger feldspars being pressed into lenticular shape and surrounded 

by films of fine-grained biotite. Striated slipping planes are very frequent, the 

striations being s.trictly parallel to the dip of the gneiss; large foils of secondary 

muscovite have in many places developed on the planes of schistosity. 

At Bear Creek a small area of massive granite lJes in the first foothills, but 

immediately west of this the normal gneiss begins and is well exposed with 

easterly dip of 18° at the entrance to the canyon, above the moraines. 

Mill Creek section.-A good section is obtained along Mill Creek, the almost 

perpendicular bluffs of the lower canyon offering excellent opportunities for observation. The dip of the gneiss is from 15° to 25° E., probably averaging 18°. It 

seems a little steeper near the valley and flattens out slightly toward the west. 

Horizontally the width of the gneissoid zone is 1t miles, corresponding to a thickness of about one-hal£ mile. In petrographic character the gneiss is similar to that 

from all points described above. It is medium to coarse grained, consisting of 

elongated aggregates of gray feldspar and quartz separated and surrounded by 

streaks of black and white mica. Striated slipping planes are very common, as are 

also elongated pressed orthoclase crystals up to 1 inch in length. As the canyon 

is ascended the gneissoid structure becomes less apparent and about 2 miles above 

its mouth, where the whole bluff is beautifully exposed, the bottom is in granite 

and schistosity sets in by degrees toward the top. Much of the gneiss has the 

same grain as the granite; some layers are, however, finer grained and darker 

in color. This is clearly not due to any diversity of material, but only to the 

degree of crushing and compression. Some layers are so much sheared as to 

constitute a dark slaty mass traversed by innumerable wavy slipping planes. The 

petrographic examination, as well as that in the field, allows no doubt as to the 

original identity of granite and gneiss. From this point westward to the divide and 

\ 
44 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

:far beyond it granite is the only rock present. The prevailing variety is medium 

to coarse grained, the average size of the grains being about 5 mm. ~ it contains 

much grayish quartz and whitish orthoclase or perthite and oligoclase, and besides 

small quantities of both biotite and muscovite in small foils, the :former usually 

prevailing. Porphyritic orthoclase crystals up to 1t inches in length are of 

:frequent occurrence,. The outcrops are brilliantly white; the rock weathers 

with a thin hard and white crust, :fresher in appearance than the inside, the softer 

texture and slightly yellowish color of which becomes apparent when the surface 

is broken off the large glaciated outcrops. The granite in many places contains 

many streaks . ("schlieren") and masses of darker, :finer grained rock, with more 

biotite and som~times rich in titanite. Usually they appear as if kneaded into 

the normal rock and ex~ibit a pseudo-schistose, contorted appearance probably 

due to :fluidal structure. These masses are probably more basic, differentiated, 

and early oooled parts· of the magma. Pegmatitic masses and dik~s of all 

descriptions are conspicuously absent. 

An east-west perpendicular jointing of · the .gneiss zone is a very common 

feature, producing the perpen'dicular walls of th~ canyons. In the granite the 

same structure is not so persistent. There is much · jointiiig, to which the pinnacles of the ridges are largely due, but no striking regularity is exhibited. On 

glaciated outcrops an exfoliation is often noticeable, causing the surface to scale 

off in concentric, slightly curved slabs. 

Like most of the canyons, Mill Creek bends south near its source and a small 

glacial lake, surrounded by a cirque of bare granite cliffs forms its head. On 

ascending this cliff, which is about 1,000 feet high, an excellent view is obtained 

over almost the whole extent of the Clearwater Mountains. rhe bare, glaciated 

outcrops seen in the maze of sharp peaks and serrated ridges northward as far as 

Big Creek and southward as far as Lost Horse justify the conclusion that the whole 

range is built up of granite. Westward the same kind of outcrops are seen on 

successive ridges as far as Grave Peak, which is a prominent granite point rising . 

from a lower forested plateau. Rhodes Peak and at least parts of the Lolo Ridge 

appear to be of the same material. Similiarily, The Crags are clearly of granite. 

The whole gives a remarkable illustration of the extent of this rock. 

Gneiss of usual structure and dip of 18° to 20° E. appears in the lower parts of 

Roaring Lion and Sawtooth creeks and numerous granite bowlders give evidence of 

the prevalence of this rock in the upper parts of the canyons. 

Lost Horse section.-West of the heavy moraine piled up at the mouth of Lost 

Horse Canyon a high cliff of gneiss appears on the north side. The rock has the 

, same structure and appearance as described above, but the dip is distinctly less. 

On the :first cliff it is only 5° E. As usual many striated slipping planes lie parallel 
BITTERROOT RANG E. 45 

to the schistosity. On the south side, the dip is 15° an at the forks o£ the creek 

10°. Smooth, glaciated ,outcrops begin 2 miles from e mouth. The section is 

different from that of Mill Creek inasmuch as the schistos,ty has a much smaller ciip 

and probably in consequence of this extends much farthkr westward. At the bjg 

slide 11 miles from the mouth the rock is still a gneissoid kranite, though the almost 

horizontal schistosity is much less distinct than at the !mouth and sometimes is 

recognizable only with difficulty. Slipping planes occur yery sparingly. The iock 

in the 1,500-foot bluff northeast of Twin Lakes, at the low divide (elevation 6,600 

feet) still exhibits a slight but unmistakable schistosity ipping 8° W., instead of 

east. A~most .the only macr~scopical indications of the st ·ucture are the parallelism 

of the mwa fmls and the elliptical form of the large orthjoclase crystals. The rock 

is otherwise identical with th~ Mill Creek type, only hJving a somewhat smaller 

amount of muscovite. Like that type, it weathers to illiantly white crusts. It 

contains, also; a few dikes of slightly sheared pegmatite and some of the same 

ill-defined basic streaks as noted on Mill Creek. Parallel tf the schistosity is a fairly 

well-defined jointing, the plan~s of which in places shol striations parallel to the 

dip. A few less continuous jmnts, also with striations p'rallel to the dip, cross the 

first set, and dip about 20° E. There is, o.lso, a well-defined east-west jointing, 

nearly perpendicular, or dipping 60° N. _On these plane also occasional striations 

may be seen. A fine view is obtained westward down .cross the deep U-shaped 

depression of Moose Creek, dark with thick lodgepole-p ne forest and surrounded 

by steep cliffs of white, granitic rock. 

Rock Creek section.-The next canyon south is that of Rock Creek, resembling · 

the others in its straight east-west course and deeply incifl ed valley. Qutting into a 

more elevated part of the range, the slopes in its central 1 art are exceptionally high 

in some places, being as much as 4,000 feet. While the ain fork has a fairly even 

grade, the south fork heading in the glacial cirques belo1 El Capitan descends over 

precipitous cliffs to the junction. Jn the first cliffs nort~ of Como Lake the gneiss 

is very schistose, but in varying degree, some belts being reduced to the appearances 

of a mica-schist, while others still show clearly the porpiyritic orthoclase crystals. 

The dip is 22° E. Local bends in the schistosity were 1bserved changing the dip 

from steep to :flat and back again to the normal inclinatiop. The heavy falls of the 

South Fork descend over gneiss with :flat easterly dip. Orl the main creek the gneiss I 

continues with dip of 15° E. for 2 miles above the lake. 'lrhe moraines at the mouth 

of the canyon contain abundant granite bowlders. Gne ss was again noted in the 

lower part of Tincup Canyon and has here a dip of 27f E. The observations on 

Rock Creek and Tincup Creek were mainly by Mr. G. ,. Stose. Neither El Capitan nor t~e Como peaks were ascended. From their appe ranee it is likely that they 

consist of gneissoid rocks with :flat dips. 
46 :BITTERROOT .AND OLE.ARW .ATER MOUNTAINS, MONT.-ID.AHO. 

Trapper Creek section.-A few miles south of the forks of the Bitterroot, Trapper Creek empties into the South Fork after a short course of about 6 miles, the 

eastern slope of the range narrowing considerably south of Tincup Creek. Trapper 

Creek heads among the cirques of the peak of the same name, the highest elevation 

in the range (Pl. IX, A), and a heavy moraine has accumulated in front of its canyon. 

Near its mouth the prevailing rock is the granite of . the eastern foothills (p. 32), cut 

by frequent dikes of granite-porphyry. This continues for one-fourth of a mile 

above the mouth. The moraines, containing some gneiss but chiefly granite bowlders, 

cover the underlying formation; 3 miles up from the main river the first high 

bluffs on the north side consist of gneiss, partly normal with the characteristic drawnout feldspar crystals, partly more crushed and chloritic; a few slipping planes with 

usual direction of striations were observed. The dip averages 15°, but varies in detail 

from 10° to 40°. One mile farther up -there is no gneiss in the lower outcrops, but 

only a coarse granite, while the debris fallen from the top of the bluff still consists 

of gneiss. The granite shows a few joint planes dipping 20° E. From points well 

up on the slope fine views are obtained up toward the sharp peaks and cirques at the 

head of the creek, all apparently granite, while the front slope of the range, 

beautifully shown by its line of intersection with the south side of the canyon trench, 

clearly consists of a sheet of gneiss gradually carried up to points with elevations of 

about 8,000 feet. Beyond, the cliffs break off westward and granite prevails. 

South end of the range.-South of Trapper Creek the strike of the gneiss 

sheet swings to north-northeast, the dip remaining the same or about 15° (fig. 3). 

The even slope of the frontal plane is carried up at this angle to the very divide, the 

descent to the Bitterroot River being here less than 6 miles. The deeply incised 

Boulder Canyon is passed 8 miles above Trapper Creek; in a few miles more the 

vVest or Nez Perce Fork is reached. This valley opens up wide and broad in 

contrast to the narrow canyons of the main river, or South Fork, above the junction, 

and from high points in this vicinity a most interesting view is obtained, showing 

the manner of termination of the range. . At the junction of the forks and for 

several miles along the West Fork, which is followed by the Nez Perce trail, 

massive granite prevails, penetrated by many dikes of granite-porphyry. 

From the vicinity of Boulder Creek the front plane of the range begins to 

swing in a still more easterly direction, but is continued with the same· general 

dip and forms the whole northern slope of the West Fork Valley. 

The first creek coming down this slope about 2 miles above the junction of 

the rivers was ascended by Mr. Stose, who found the first outcrops about 800 

feet above the valley. Here the normal Bitterroot gneiss is encountered with a 

strike of N. 52° E., and a dip of 40° SE. Besides this, there is a rough bedding 

dipping 8° SW., and joi:qt planes with evidence of slipping, which strike N. 75° 

E. and dip steeply to the north. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. Z7 PL. IX 

A. TRAPPER PEAK, SHOWING GRADUAL SLOPE OF GNEISS ZONE TO THE LEFT AN D GLACIAL AM PITH EATER IN CENTER. 

R. FOREST OF LODGEPOLE PINE ( PI N US MURRAYANA ), COMO TRAIL, BITTERROOT MOUNTAINS. 
' 
BITTERROOT RANGE. l . 47 

Beyond this point the frontal plane is seen to con inue for several miles I 

farther west, turning gradually to an almost east-west strike. Gneiss appears to 

occupy this whole slope to the summit or main divide and Jthe dip of the schists is 

clearly seen to conform to the slope of the plane. Towar the head of the West 

Fork it appears as if this gneiss gradually merged into the prevalent granitic 

mass. This is the conspicuous southern termination of the Bitterroot Range. 

South of the \Vest Fork geology and topography underg a complete change. 

STRUCTURE AND PHYSIOGRAPHY. 

The topographic description 'of the range has shown he existence of a most 

persistent plane dipping 15° to 26° E., which forms the slope- inclined toward 

the valley, and which continues with due north-south direction from Lolo Peak 

to Boulder Creek, where at the southern end of the ranJ e it gradually swings 

westward, retaining the same dip, now turned southerly. l A short distance west 

of the bend the plane appears to die out. It can not h ve been produced by 

erosion, and the only alternative is to consider it as a I structural plane. An 

examination of the geology reveals the fact that this plani, is formed by a layer 

of gneiss, which petrographic methods show to have been tlerived by compressive 

or shearing stress from the normal massive granite forminJ the mass of the range. 

The gneiss zone conforms in strike and dip with the structural plane, and moreover 

shows persistently and uniformly, by little slickensides and striations, evidence 

of a movement parallel to the dip of the gneiss and the structural plane. The 

aggregate movement along all these slipping planes may well have been very 

large. \Vhile the gneiss zone usually is thin, and ordinarily less than 3,000 feet 

in width perpendicularly to the strike plane, it flattens in the Lost Horse section, 

and a roughly gneissoid granite with nearly horizontal schistosity extends westward at this place as far as the main divide. The strong~st schistosity and the 

most closely massed slipping planes always occur farthest east along the structural 

fronting plane. 

The only conclusion which can be drawn from these facts, remarkable and \ 

unique as far as my Knowledge goes, is that a uniform dislocation of great 

extent has taken place all along the east slope of the range. The main dislocation 

was accompanied partly by direct movement on minute and numberless fault 

planes (slipping planes) and partly by molecular movements long enough sustained to produce a typical schistose structure within the affected zone. The 

unusual feature in this dislocation is the intimate combination o£ actual fault 

planes with schistose structure, showing in the clearest manner, to my mind, the 

transitions between schistosity and jointing, and between molecular and molar 

movement, and indicating that both result from the same force. Taking all the 

data into consideration, it does not seem as if the depth at which this schistose 
48 BITTERROOT .AND CLE.ARW ATER MOUNTAINS, MONT.-ID.AHO. 

structure was produced could have been inore than . a few thousand feet at the 

utmost. Any attempt to place the formation of this schistosity at great depths 

from the surface must lead to wholly improb~ble depths of erosion and amplitude 

of faulting movement. Another unusual feature consists in the :fiat dip of the 

fault plane; this fiat dip is no doubt the cause of the remarkable topographic 

preservation of the fault plane. 

The minimum of . actual movement on the fault plane is clearly measured by 

. the width ?f the gneiss zone along this plane from the summits to the base of the 

mountains, a distance. of 2 or 3 miles. The vertical component of this movement 

would be 4,000 to 6,000 feet, and this again must be considered as a minimum. 

_Admitted that we have here a fiat fault of great extent, the next question is 

as to the absolute direction of the movement. That the relative movement took 

place parallel to the dip of the gneiss is clear beyond question from the observed 

facts. It was first thought that the deformation . of feldspar crystals in the gneiss 

would elucidate this problem. No satisfactory answer was obtained in this way, 

though more detailed studies perhaps would be productive of better results. The 

deformation of the crystals seemed to have proceeded under such heavy pressure 

that a :flow rather than a break resulted, and it was impossible to tell whether 

the hanging wall had relatively moved up or down. The slickensided slipping 

planes, on the other hand, never break across a crystal, but follow in gentle curves 

the aggregate of recrystallized mica scales, on ·which, of course, the movement 

was most easy. 

Approached from a different direction some elucidation of this problem might 

possibly be attained. Throughout the Salmon River Mountains, as well as in the 

Clearwater and the Coeur d'Alene mountains, the configuration o'f the ridge lines 

shows that they ma..y be considered as the remnants of a gently undulating plateau 

raised by epeirogenic forces and dissected by active erosion. The average elevation 

of this wide plateau of central Idaho is perhaps 7,000 feet. It extends far north 

and south of the Bitterroot Mountains, which stand as a boldly raised block 1,000 

to 3,000 feet above this level. It se·ems unavoidable to connect this uplift with 

the fault at the base · of the range, and thus we arrive at the conclusion that the 

foot-wall side of the fault has been raised relatively to the hanging side; in other 

words, the fault is a normal one. Considering again that the Bitterroot Valley 

is an extremely well-marked and probably very deep depression almost coextensive 

with the range, and that borings would probably show it to be a structural 

depression without outlet, we come again to the conclusion that the hangi~g has 

subsided relatively to the foot of· the fault; in other words the fault is probably 

a normal one. 

There are interesting ~acts which prove that this subsidence has taken place and 

that it has not even yet ceased. At the Curlew mine, located in the first foothills 
BITTERROOT RANGE. 49 

in the northern part of the range (p. 86), mining operations have disclosed a fault 

dipping 45° E., along which a body of galena ores was found and mined. I am 

reliably informed that this fault separates the lime and quartzite of the foot wall 

from a hanging wall of gravels with logs of carbonized wood. A heavy clay seam 

lies along the fault. This fault is exposed to a vertical depth of 500 feet. As 

stated, the first foothills here consist of limestone and quartzite of uncertain r _se; 

these rocks have not been rendered schistose like the granite, but are thorouL_hly 

crushed. The hill back of the mine is cut by slipping planes, and a little higher up 

the narrow zone of limestone and quartzite borders along a fault contact toward the 

normal gneissoid zone. Along this contact, far removed from mining operations, a 

fault took place in 1898, the downthrow being on the eastern side; the throw is still 

visible along a distance of 1,500 feet north and south, and amounted to 1 or 2 feet. 

Still another line of evidence points in the same direction. As described above, 

(p. 40) many straight canyons furrow the east slope of the Bitterroot Mountains. 

They have a very steep inclination, but below the upper zone of glaciation in which 

falls over granite ledges are frequent, there is no reason why they should not have 

average regular gradients. Wh~le this holds good in most cases, there are in some 

places curious anomalies. Where Mill Creek emerges from the range, for instance, 

the first mile of canyon has a grade of 400 feet in 1 mile, while the regular grade 

is 200 feet. 

For several miles south of the mouth of Carlton Creek Canyon, also in the 

northern part of the Bitterroots, a distinct escarpment perhaps a· few hundred feet 

high, runs along the foot of the range. An exceedingly heavy fall of 600 feet in 1 

mile marks the ·mouth of the canyon, the lower part of this distance being over 

morainal bowlder heaps, the upper part over gneissoid bed rock. 

It seems thus that during recent or even during the present time, short and 

irregular displacements occur along the foot of the range and in all cases the downthrow is on the valley side. 

From all that precedes it is plain that the east front of the Bitterroot Range is 

determined by an enormous flat fault. It further follows with great probability, 

that the fault is of normal character, and that the dislocation is a double one, 

involving at the same time downward movement of the hanging and upward movement of ' the foot. On the west side of the Bitterroot Mountains the upward movement of the block seems to have been so distributed as to leave few indications of 

its presence. Such double movements, involving a simultaneous raising of the heaved 

block and sinking of the thrown one, are probably not uncommon. Studies along 

the east slope of the Sierra Nevada have led me to believe that the movement along 

this break has been of this character. a The flat dip of the fault plane indicates 

a J our. Geol., vol. 4., 1896, p . 899. 

5995-No. 27-04-4 
50 BITTERROOT .AND OLE.ARW .ATER MOUNTAINS, MON:r.-ID.AHO. 

pretty clearly that gravity does not alone suffice to explain this movement, for as 

pointed out by Mr. G. F. Becker,a friction would overcome gravity on a slope of the 

fault plane of 45° . 

In presenting these conclusions I am not unmindful of the cursory character 

of the field work and fully appreciate that more detailed examinations will throw a 

mt:ch more vivid light on the extremely interesting questions of mountain building 

and rock structure involved. The main facts seem so plain, however, that they_ 

scarcely admit of any other interpretation than that advanced. It is believed that 

the Bitterroot Range will always remain one of the most important localities in the 

world for the study of the development of schistosity and distributed faults. 

It seems unavoidable to recognize the intimate and inseparable relation between 

schistosity an9. faulting, or, in other words, between molecular and molar rock 

movements, in the sheared zone of the Bitterroot Range. The striated slipping 

planes of the granite-schist are often very closely massed, as many as twelve of them 

sometimes occurring in a thickness of an inch. Their surfaces are covered with 

micaceous aggregates or large, new-formed flakes of muscovite, and they curve gently 

about the lenticular, pressed aggregates of former larger feldspar or quartz grains. 

The latter are sometimes broken by a series of small fissures inclined about 45° to 

the plane of schistosity and filled with secondary quartz. (Pl. V, A, B.) Many of 

the slipping planes form blind joints, nonpersistent or gradually fading. · 

The two differing views of th~ relation of schistosity and jointing may be 

briefly recalled: Mr. Van Hise holds b that the two are distinct phenomena. In 

the upper or "zone of fracture" of the earth's crust, bedding fractures, faults, 

joints, fissility, etc., are formed 'almost wholly by the breaking of individual 

minerals and by differential movements between them. Rock flowage, producing 

·schistosity, mainly occurs in a very deep-seated zone by innumerable fractures 

of the mineral particles, or by recrystallization; in brief, it is a molecular movement in . which mass fractures play a subordinate part. 

Q;n the other hand, Mr. G. F. Beckerc holds that there is no essential difference 

between jointing, cleavage, and schistosity, all of those phenomena being due to 

weakening of the cohesive force on planes of maximum slide or maximum tangential 

strain. Accordingly, schistosity and jointing, molecular and molar movement, 

may both be produced at the same time, and molecular movement is not necessarily confined to great depth. The observations in the Bitterroot Range seem 

to confirm Mr. Becker's views. 

a Bull. Geol. Soc. Am., vol. 4, 1893, p . 47_ 

b VanHise, C. R., Principles of North American pre-Cambrian geology, with an appendix on flow and fracture of 

rocks as related to structure, by L. M. Hoskins: Sixteenth Ann. Rept. U. S. Geol. Survey, p't. 1, 1896, p. 589. 

cBecker, G. F ., Finite homogen eous strain, flow and rupture of rocks:, Bull. Geol. Soc. Am ., vol. 4, 1893, pp. 13-90. 
GLACIATION IN BITTERROOT RANGE. 51 

If we should tentatively endeavor to outline the history of the Bitterroot 

Range it would perhaps be something like this: 

During the Cretaceous or earliest part of the Tertiary period the surface of 

the high plateau of the Clearwater lVIountains extended across this whole region 

and included a large part of western Montana. On this uplifted plateau a 

drainage system had been outlined, and of such origin, we may assume, was the 

Bitterroot River. The divide toward the Clearwater drainage was situated along 

the present summit of the range about 10 miles, east of the present position of 

the same divide. The elevation of this divide was 2,000 to 3,000 feet lower 

than at present. 

Now followed the great break along the line of the Bitterroot River. A 

fault plane was formed with flat easterly dip and a movement of probably at 

least 20,000 feet along the dip of that plane took place. This movement had the 

twofold effect of raising the Bitterroot Range to its present position on the west 

and of deepening the depression of the Bitterroot Valley. 

The g·ently sloping structural front plane of the Bitterroot Range being thus 

established a new constructional drainage was at once laid out on the even surface and naturally the creeks would be numeroq.s and straight, just as we :find 

them to-day similar in direction but more deeply incised. Grade and precipitation combined to increase their corrading activity; soon they were robbing ' the 

streams of the then broad plateau on the Clearwater side and the divide migrated 

westward to its present position with the gradual capture of new territory. The 

general bending toward the south, common at the head of the Bitterroot 

streams, is no doubt due to that same prevailing tendency in the headwaters of 

the old captured Clearwater streams. 

Finally, as the last important stage, the neve :fields increased in size and soon 

a continuous ice sheet covered the summit region. During the Glacial epoch the 

summits were carved out to the bewildering mass of craggy aretes separated by 

precipitous cirques which now crown these mountain'3. 

GLACIATION. 

There is excellent evidence that during the Glacial epoch the Bitterroot Range 

along its whole extent was COVered by a 'COntinUOUS sheet of neve, from which 

glacier tongues extended down into every important valley. It forms thus one 

oi the very largest glaciated areas known in the Cordilleran region of the United 

States, and only rivaled in extent by the glaciers of the Sierra Nevada and the 

Cascade Range. There is no evidence of glaciation along the Lolo Fork of the 

Bitterroot River; nor is it probable that any but local foci of glaciation existed 

from Lolo Fork northward along the Coeur d'Alene Mountains. Similarly the 
52 BITTERROOT AND CLEARWATERr-MOUNTAINS, MONT.-IDAHO. 

Nez Perce Fork, or West Fork, at the southern terminus of the range, is free from 

glaciation, and no evidence of anything but very local accumulations of ice were 

noted upon the headwaters of the South Fork south of Nez Perce Pass. 

The U-shaped form of the valleys, the moraines accumulated in front of 

their canyons and within their troughs, the polished outcrops of granite through-. 

out their extent, all bear undoubted testimony to the existence of this ice sheet. 

The main canyons as well as the tributary' gulches terminate everywhere in 

glacial cirques. In short, all the familiar phenomena of extensive glaciated areas 

are represented in the Bitterroot Range on a grand, instructive scale. . Only the 

highest peaks and ridges appear to have projected above the general level of 

ice and sand and between the projecting glacier tongues. The foothills of the 

range also rose to an elevation of 2,000 feet above the valley below the line 

of permanent snows. 

Not in all cases did the glaciers extend down to the mouth of the canyons 

where they opened on the valley. There is clearly evidence of increasing 

strength of the glacial action toward the southern end of the range. Here 

large morainal masses several square miles in extent and with ridges sometimes a thousand feet in height lie in front of the foothills .. 

Beginning from the north, the Carlton Canyon was first examined. The 

canyon pass is narrow and V -shaped, and it is doubtful whether any of the material 

in front of it is of true glacial origin. Heavy masses of bowlders lie on both 

sides of the canyon at its mouth and extend in fan shape for a distance of 

half a mile. Possibly these accumulations are the result of local cloud-bursts or 

torrential action; · 

At the mouth of Big Creek Canyon the gravel terraces extend up to the 

foothills of gneiss, and there are no accumulations of bowlders in front of the 

canyon. Its lower part is V -shaped and sharply incised without polished outcrops or other indications of glaciation. 

At the mouth of Mill Creek Canyon a sloping plain of gravel and sand 

extends down to the river 400 feet lower. Over this gravelly slope Mill Creek 

flows in a shallow cut at most 30 feet deep. 

The first signs of glacial action are seen at Sears's ranch, near the foothills, 

and consist of a big pile of granite bowlders, some of them 8 feet in diameter. A 

very heavy moraine lies on the south side of the creek near the same place and close 

to the mouth of the canyon. The surface forms of these bowlder masses indicate 

unquestionably their morainal origin. Little ridges and shallow ponds abound. The 

height of this moraine is several hundred feet, and on its southern side no rock in 

place appears for a distance of half a mile farther west, while on the northern 

side outcrops begin much lower down. Near the mouth the canyon presents no 
U. S GEOLOGICAL SURVEY 

. .... 

• ""' ""'-o 

, 

r' 

BITTERROOT RANGE FROM ERRACE NORTHEAST OF DARBY 

PROFESSIONAL PAPER No. 27 PL.' X 

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.• . 
GLACIATION IN BITTERROOT RANGE. 53 

trace of actual ice erosion either in the wearing or rounding of the outcrops, so 

that it is not probable that the ice stream it~elf reached this point. 

Like all the Bitterroot canyons, the grade of Mill Creek is very heavy. On 

the gravel planes in front of the range it is 200 feet to the mile. At the mouth 

of the canyon for a distance of about 1 mile it is much heavier, amounting to 400 

feet in that distance. Above this the grade is somewhat lighter, until several 

miles farther up an abrupt fall of over 200 feet occurs below the place known 

as ''the great slide." 

Above the great slide the grade is again fairly moderate up to the lake, 

and amounts to approximately 200 feet per mile. Morainal matter fills the 

comparatively narrow bottom of the canyon for a distance of 1 or 2 miles above 

the mouth. At about this distance the valley becomes much more U-shaped, 

and frequently smooth and flat rocks occupy the creek bottom. The width of 

the valley increases westward, the bottom is filled by morainal material and 

supports a thick growth of lodgepole pine besides rising more steeply and frequently showing polished surfaces of granite. An interesting feature is the 

nearly perpendicular cliff a thousand feet in height which follows the north side 

of Mill Creek for 3 miles above its mouth. Pls. VI, B, and VII, A, illustrate 

the topographic features of these and the shape of the canyon. Great slides of 

angular granite blocks descend into the canyon at many places, and sometimes 

on the forested slope~ are long clearings illustrating the devastating power of 

snowslides. 

At the head of the canyon a small lake dammed by morainal material 

occupies a large glacial cirque surrounded by polished slopes of granite. Even 

the saddle on the divide a thousand feet above the lake shows evidence of 

glacial polish. It seems that the ne:ve fields covered everything along the 

summit region except the highest peaks. 

Blodgett, Sawtooth, and Roaring Lion creeks are almost exact counterparts 

of Mill Creek. The remarkably straight and sharp ridge between Sawtooth 

and Roaring Lion is illustrated on Pl. VII, A, as viewed from Wards Peak. In 

aU cases the moraines accumulated at the lower end of the canyons are comparatively insignificant. 

South of Wards Peak .the conditions change. Lost Horse, Rock, Tincup, 

and Chaffin creeks are all distinguished by great development of lateral and 

terminal moraines, the extent of which are illustrated by the panoramic view 

on Pl. X, taken by Mr. G. vV. Stose from the terrace northeast of Darby on the 

east side of the river. The plate shows the bottom lands and low terraces along 

the river, abo-ye which rise the grassy and open high terraces; these again lean 

against broad and rounded morainal hills, heavily forested, as a rule. Back 
54 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

of these rise the jagged peaks and ridges of granite and gneiss. Pl. I shows 

the areal extent .of the heavy moraines of the south end of the range. At the 

mouth of Lost Horse Canyon moraines occupy several square miles, the most 

prominent one forming an 800-foot ridge on the south side, reaching up to an 

elevation of 5, 000 feet. The creek has cut through the terminal moraine, and 

· gravel terraces skirt the east front o~ the moraines 200 feet above the river. 

The canyons of the forks of Lost Horse Creek are practically duplications of 

t~ose of Mill Creek, the bottoms being U -shaped and often showing extensive 

and smooth· surfaces of ice-worn granite, and elsew.here occupied by a thick 

growth of lodgepole pine. The sides are precipitous cliffs with many enormous 

rock slides. Near the head of the Middle Fork lies a heavy bottom moraine 

which has dammed the Twin Lakes at Lost Horse Pass. 

In a similar manner, high lateral moraines have been piled up on · both sides 

of Rock Creek. The terminal moraine has been partly cut through by the stream, 

but above it still lies the beautiful sheet of water dammed by it, which is called 

Como Lake. From its pine-clad shores a magnificent view is obtained up toward 

the jagged summits of Como Peak, 5,000 feet above the lake. (Pl. VIII, B.) At 

the mouth of Tincup Canyon similar though smaller moraines have accumulated. 

The ice stream was deflected southward,. so that the lateral moraine on the north 

side swings around in a graceful curve. 

From this point southward the distance to . the muin divide is less, and the 

glaciers were correspondingly smaller. 

The moraines of Trapper Creek form a fine semicircle, opening southward. 

They are 3 miles 1 long and 300 feet high~ and extend almost to the Bitterroot 

River. The laRt large tributary from the western slope of the Bitterroots is 

Boulder Creek, the moraines . of which p:roject to the river and have forced it to 

cut a cliff in the eastern foothills. 

The 200-foot gravel terrace skirts the moraines down to the junction of the 

two main forks of the river and continues for some distance up the East Fork, 

while the South Fork south. of Chaffin Creek enters a narrow canyon. 

From all appearances, the glaciation of this range extended to a very recent 

date. While in all cases, excepting Rock Creek, the principal creeks have trenched 

the terminal moraines, but little evidence of erosion is to be seen beyond this 

cutting, and in many places higher up ,these torrential streams still flow over 

broad and fiat glaciated outcrops, not yet having had time to excayate new 

canyons in them. The surface of the moraines is often remarkably smooth, due 

no doubt to the sandy and crumbling character of the granite, and is generally 

covered by a fine growth of yellow pine. 
SOUTH FORK OF BITTERROOT RIVER. 55 

On the western side of the range the glaciers must have been still more 

extensive than on the slope facing east. The canyon system is here more branching; the precipitation was also probably heavier. The result would be that 

several ice streams would meet, and, coalescing, extend far down intq the Clearwater drainage. Just how far west they reached has not been ascertained, but 

from the available infor~ation as to th~ size of the glacial cirques at the summit 

and the conditions of the rivers farther down it is probable that along the 

Lochsa, Moose Creek, and Selway forks this distance was about 20 miles from the 

main divide. Very likely the neve fields of the northern part of the Bitterroots 

extended across to Grave Peak, 15 miles distant from the main divide. 

SOUTH FORK OF BITTERROOT RIVER. 

TOPOGRAPHY. 

At the junction of the East and South forks of Bitterroot River the valley 

is still an open one, with bottom lands 1 mile wide and broad gravel terraces, 

the latter continuing for several miles up along the easterly branch of the 

stream. Broad and partly timbered ridges ascend with comparatively easy slope 

from the East Fork, their summits forming a nearly level sky-line 2,000 or 8,000 

feet above the valley. A low granite ridge projects from the Bitterrroot foothills, connecting with the mountains surrounding the East Fork, and across this 

ridge the South Fork breaks in a narrow canyon, suggesting that a former 

valley, nearer to the Bitterroot Range, has been filled by morainal debris and 

a new trench excavated through the gyanite ridge in post-Glacial time. ·For a 

distance of 15 miles above this canyon the South Fork flows in a narrow valley 

which, however, opens up a little immediately south of the canyon through the 

granitic ridge mentioned. The bottom, though narrow, is fl.at, and occasionally 

fragments of a low terrace appear above the stream. Where the Nez Perce trail 

leaves the South Fork the West Fork Valley branches and forms a wide, open 

depression. Above the West Fork the main branch continues narrow, with flat . 

bottom and sides rising steeply for a few hundred feet up to a sloping bench, 

from which heavily forested broad ridges run up to a similar main divide very 

different from the narrow aretes and pinnacles of the Bitterroot ridges. These 

conditions continue for several miles above the West Fork to near Hughes Creek 

(elevation, 5,000 feet), where the valley opens to a width of half a mile and is 

surrounded by bluffs of rock 1,000 feet high. Above this creek the Bitterroot 

River splits in many branches and the rounded forest-covered ridges of the 

Salmon River divide are soon reached. The highest elevation of this is found at 

Blue Nose Mou~tain, which attains 8,300 feet, but the av'erage height of the 

dividing ridge is considerably less. 
56 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

GEOLOGY. 

GRANITE. 

For a distance of 25 miles above the main junction of the rivers, or up to 

the vicinity of Blue Joint Creek, granitic rocks prevail in the canyon of the 

South Fork. This granite is, on the whole, similar to that described from the 

eastern foothills of the Bitterroot Valley. Its contact with the southern quartzite 

is not well exposed, and nothing definite can thus be said about the relations of 

the two rocks. The granite is rich in dikes of granite-porphyry, sometimes 

appearing very similar to rhyolite. 

In the first canyon above the main junction a coarse biotite-granite prevails, 

with a few inclusions of gneissoid rock. At the mouth of Trapper Creek the 

granite contains many dikes or _irregular masses of reddish granite-porphyry. 

Three miles above this creek a coarse granite with very large feldspar crystals 

was noted, and again opposite Boulder Creek are cliffs of the same reddish rock. 

Similar coarse, reddish biotite-granite, rich in orthoclase, appears near Rumbo 

Creek, here containing many di~es of. granite-porphyry, a rock which is especially 

abundant in the gravels of this creek. Large masses of alternating graniteporphyry and granite outcrop for 2 miles above this point. 

Mr. Stose ascended the West Fork on the Nez Perce trail for several miles 

and reported first granite with streaks and inclusions of gneissoid rocks similar -

to the exposures east of Darby and farther up much granite-porphyry, together 

with pegmatitic rocks and some contorted gneiss. The sheared granite of the 

long slope from the Bitterroot Mountains, north of the West Fork, has already 

been referred to (p. 46). 

SEDIMENTARY SERIES. 

An extensive series of sedimentary rock of doubtful age is encountered on 

the upper South Fork of the Bitterroot. It begins near the mouth of Blue 

Joint Creek, a tributary with several branches coming down from the west about 

10 miles above the point where the Nez Perce trail leaves the valley of the 

South Fork. White and heavy-bedded quartzites prevail, the strike belng 

northwest, the dip 80° S. A long ridge leads from Blue Joint Creek up to the 

high points south of Nez Perce Pass, called Crown Peak or Castle Rock, and 

Bare Cone; going up, the quartzite is soon replaced by a belt of granite with 

many dikes of granite-porphyry. Then quartzite containing many dikes of 

granite-porphyry begins again and occuries the high ridges of Bare Cone, having 

an elevation of about 8,000 feet. The summit of Crown Peak is formed by a 

neck of rhyolite. , 

Above Blue Joint Creek the same heavy-bedded quartzite continues up to 

near the head of the river at Mineral Point, and its precipitous bluffs follow the 
SOUTH lfORK OF BITTERROOT RIVER. 57 

stream for several miles. The same rock occupies almost the whole of the 

Hughes Creek drainage, and probably also reaches up to the Clearwater divide, 

8 miles distant towara the east. 

At Mineral Point Meadows are quartzitic schists with varying dip, generally 

·about 30° ; the dip is northward at the lower end of the meadows, changing to 

east or south near Copper Queen mine. The schist is here more micaceous and 

fissile, but still distinctly sedimentary. Going upstream the schists become still 

more micaceous. A little coarsely crystalline limestone is met on the road along 

Beaver Creek one-fourth mile above its mouth. Many dikes of granite-porphyry 

and diorite-porphyry appear here. One mile above the mouth on the same creek 

the schists change to typical gneiss. The contact is apparently not of intrusive 

character, but the two kinds of rock rather appear as if welded together. Probably 

the quartzitic schists rested on gneiss, and the exact contact line has bec(Jme 

blurred by action of metamorphic processes As stated above, there is nothing 

to prove the age of the sediments, except the probability that they once rested 

on a gneiss which has the characteristics of an Archean series. The similar 

conditions might justify a guess that the quartzites are of the same age as the 

Lolo series, possibly pre-Cambrian. The slates and quartzite are known to 

extend for many miles eastward, or at least as far as Gibbonsville, 12 miles distant 

from Bitterroot River, where Mr. "V. H. Weed observed a ~eries of steel-gray 

quartzitic schists dipping 35:) to 65° W. 

TERTIARY VOLCANIC ROCKS. 

Although some of the dikes in the granite for the first 20 miles south of the 

main fork of the Bitterroot River are somewhat rhyolitic in aspect, no areas of this 

rock are encountered until near the mouth of Blue Joint Creek. At this point a 

flow of normal rhyolite filled the valley to a depth of several hundred feet and is 

now eroded to high bluffs showing on both sides. A small mass of rhyolite forms the 

summit of Crown Peak or Castle Rock. Areas of this rock are also found on Slate 

Creek, on the west side of the valley, and south of Blue Joint Creek this rhyolite 

may even reach the Clearwater divide. On Coal Creek, coming in from the west, 2 

miles above Blue Joint, Mr. Stose found the rhyolite extending up to at least 1,000 

feet above the valley. In its uppermost part it contains thin interbedded clays with 

seams of lignite (see p. 112). 

The next exposure of volcanic rock is found 10 miles farther up, on Lick Creek, 

on the east side of Mineral Point mining district. These thick flows ?f rhyolite, 

which extend at least 1,000 feet above the valley, consist of several flows, some 

glassy, others felsitic. In part they are interstratified with tuffs or sedimentary 

material resembling lake beds, the latter containing traces of lignite and some 
58 BITTERROOT .AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

Unio shells. According to Mr. W. H. Weed much rhyolite is also seen along the 

East Fork of Bitterroot River. 

While there is no direct proof of the age of the rhyolite, it is probable that, 

like nearly all of that rock in Montana, it is of middle Tertiary or Miocene age. Its 

topographic extent is perhaps the most interesting feature, as it clearly proves that 

the configuration, depth of canyon, etc., in the upper· South Fork were about the 

same as at the present time . . As far as this forl~ is ·Concerned, subsequent events 

have consisted rather of repeated fillings and retrenchings of the pre-Miocene 

excavations than of any important deepening of the channel. 

QUATERNARY. 

The Quaternary deposits along the South Fork of the Bitterroot are limited 

to the bottom lands and terraces along the river. Though the bottom lands are 

narrow and of slight extent, they persi~tently follow the river, indicating a recent 

damming, which deprived the river of its full erosive power. In few places the 

water flows over exposed bed rock. Above these alluvial areas are several terraces, 

preserved in fragments, indicating that at a comparatively recent date gravels 

filled the canyon to a depth of over 500 feet. The analogy with Lolo Fork 

(p. 38) is apparent. In the lower South Fork one direct cause for the accumulation of gravels above is found in the fact that during the Glacial epoch the 

moraines of Trapper and Boulder creeks produced effectual dams of considerable 

height. Whether this is sufficient or whether the uniform filling of Lolo, the 

Bitterroot Valley, and the South Fork to a height of 400 to 500 feet above the 

present water level was due to more universal causes acting farther down on the 

Clark Fork of the Columbia can not be regarded as fully settled. The erosion 

which followed the maximum of deposition was clearly of active character and is 

responsible for the st~ep bluffs which now in many cases skirt the river. 

As stated above, three terraces, 30, 100, and 200 feet above the river, form 

the broad valley at the junction of the two forks. Immediately above this the 

South Fork emerges from a narrow canyon extending for a few miles and then 

opening up a little at intervals. A low terrace, 20 feet above the river, follows 

closely, and in places are remnants of another . 200 feet above the ' stream. · 

At the mouth of West Fork the lower terrace is well developed, and another of 

gravel and silt appears on the west side 200 feet above the river. Near the 

mouth of Blue Joint Creek gravel was noted from 500 to 550 feet above the 

river. At the mouth of Hughes Creek gravel bars are found at 20, 50, 200, and 

500 feet above the river, thus reaching up ~o elevations of 5,660 feet . 

• 
TOPOGRAPHY OF OLEARW A'.rER MOUNTAINS. 59 

CLEARWATER MOUNTAINS. 

TOPOGRAPHY. 

As defined above (p. 13) the Clearwater Mountains forn1 a roughly rectangular 

area 70 miles wide and 100. miles long (from north to south) bounded on the 

south by Salmon River, on the north by the North Fork of the Clearwater, 

on the east by the Bitterroot Range, and on the west by the Columbia lava 

plateau which begins a short distance east of the South Fork and the main 

Clearwater River. This broad area of about 7,000 square miles can not be 

regarded as a mountain range due to orographic forces acting along certain 

lines, but must be considered as due to a continental uplift acting evenly over 

the. whole area. It is, briefly, an elevated plateau, of approximately uniform 

height, now so deeply dissected by such an intricate system of canyons that at 

first glance it has almost lost its once doubtless prominent plateau featurBs. 

RIDGES. 

Three primary divides extend westward across the whole width of the Clearwater 

Mountains from the backbone of the Bitterroot Range. The most northerly is the 

ridge between the North Fork and the Lochsa Fork. Immediately west of the 

broad, low depression of Lolo Pass this divide rises to elevations of from 6,000 to 

7,000 feet, and its bleak summits of white granite with scattered dark groups 

of firs extend for 50 miles west-southwest, maintaining about the same height. 

From near Rocky ~idge it slopes gently with many low spurs, within a distance 

of 18 miles, down to the basalt plateaus of Weippe, which are situa~d about 3,000 

feet above sea level. 

The Lochsa-Selway divide, of about the same length, is more broken and 

irregu!ar; and its peaks are also higher. From the Bitterroot Range it forms a 

succession of points and high ridges, such as Grave Peak (elevation 8,287 feet), 

Diablo Peak (elevation 7,531 feet), and near the western end of the ridge, The 

Crags (elevation 7,923 feet). Ten miles west from the bare granite points of the 

Crags, the thickly forested ridge descends abruptly to the junction of Lochsa and 

Selway forks~ Toward its head the Selway Fork splits in a great number of 

branches, separated by complicated ridge .systems. Many of these head toward 

the Salmon River divide, which is a high ridge with many and sharp curves due 

to tributaries cutting into it from north and south. 

The Salmon River divide begins a few miles northwest of Blue Nose Peak 

(at the head of the South Fork of the Bitterroot) and continues westward for fully 

80 miles as a high, broad, ridge, sparsely timbered and sometimes with swampy 

meadows surmounted by a few points exceeding 8,000 feet in elevation. Above 
60 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

the general level rises a bare reef of rocks extending for 12 miles north and south 

and marked by the three points of Caseknife Mountain, Salmon Peak (elevation 

8,881 feet), and McGruder Mountain. This reef is sculptured by glacial erosion 

and the gulches leading up to it end in rocky ampitheaters. From _ the slopes 

magnificent views are obtained of the western Clearwater region and the Salmon 

River Canyon and the mountains south of it. This is illustrated by fig. 1, reproduced from a photograph by Mr. J. B. Lippincott, which shows well the plateau 

character of the broad forested but fire-scarr~d ridges west of Salmon Mountain 

eontinued south of the 4,500-'foot gash of the canyon by an equally well-marked 

general surface level. From the main divide long backbones reach out toward 

FIG. 4.-View south across Salmon River Canyon, from south slope of ~aseknife Mountain, showing plateau 

character of Salmon River Mountains. 

the canyon and suddenly break off in precipitous descents. This sort of country 

continues for 40 miles west of Salmon Mountajh to Buffalo Hump. The lonely 

trail follows the ridge for 24 miles in a bee line, but much more than that, 

counting its windings through fir-covered saddles and over bare rocky ridges. It 

crosses Little Salmon Creek near its head, the swampy meadows surrounded by 

·thick timber having an elevation of only 5,200 feet, but ascends immediately 

west of this creek to the plateau elevations of over 7,000 feet. At intervab 

views are obtained north and east over the Selway drainage-a labyrinth of 

forested ridges sloping gradually at first toward the separating canyons and then 

dropping off to the streams in precipitous descents. Against the skyline are 
TOPOGRAPHY OF CLEARWATER MOUNTAINS. 61 

sometimes visible the snowy crests of the Bitterroot · Mountains, among which 

towers the isolated El Capitan. 

West of Little Salmon Creek the ridge branches. The divide between the 

South Fork and the Selway continues with the same characteristics west-northwest. 

The mass of Bilk Mountain and Indian Park projects northward, overlooking the 

Selway Canyon, while the main part of this ridge extends north of Elk City and 

culminates in Anderson Peak, Bald · Mountain, and Pilot Knob, all about 7,000 

feet high. From the two latter points the plateau of the Clearwater Mountains 

descends abruptly to that of the Columbia River lava, 4,000 feet lower. 

The view from Bald Mountain is instructive and impressive-even magnificentbut, unfortunately, not easily shown in a photograph. Eastward lie the Clearwater 

Mountains, with comp~ratively level crests and a maze of canyons and ridges, a 

wild and lonely country across which the trail leads for 115 miles, the first 80 

of which does not disclose a settlement or even a miner's cabin, while westward, 

and 4,000 feet below, spreads the undulating plateau of Camas and Kamiah 

prairies, checkered with waving wheat fields or wild grass, yellow or golden 

brown at this autumn time. Rarely are wilderness and culture brought into so 

close contact upon such a tremendous scale. Nothing but this high lava plain is 

visible as far as the eye reaches toward the west, far into the State of Washington. 

The southerly ridge, forming the divide between the South Fork and the 

Salmon River, continues 35 miles west of Little ·Salmon Creek with the same 

general aspect of broad forested ridges, with long and gentle slopes toward the 

north and abrupt descent southward toward the great canyon of the Salmon; 

then the high isolated complex of Buffalo Hump rises above it to 8,800 feet in 

elevation. West of Buft'alo Hump the ridge divides again. One branch bends 

northward and drops off suddenly to Camas Prairie at Mount Idaho, while the 

other one continues 30 miles west, sagging to a gentle plateau of 6,000 feet 

elevation at Florence, rising again in the great bend of Salmon River to 8,000 

feet, and then suddenly dropping off 6,000 feet into the canyon of that river. 

From this most westerly point of the Clearwater Mountains, across the deep 

chasm of the Salmon and Snake canyons, the skyline is formed by the lava 

plateau, which here is higher, reaching 5,000 or even 6,000 feet in elevation. To 

the south, across the Salmon River, rise the first spurs of the Seven Devils, an 

outlying group of sharp peaks, surrounded on the south and west by the Columbia 

River lava, but connecting on the east with the Salmon River Mountains. 

CANYONS. 

The widely branching forks of the Clearwater River, which empties into the 

Snake at Lewiston, drain a territory of nearly 8,000 square miles. The streams 

flow throughout in deeply incised canyons, usually so narrow and rocky as to 
62 BITTERROOT .AND CLE.ARW .ATER MOUNTAINS, MONT.-ID.AHO. 

rarely afford space for a trail along the water line. Only along its lowest course 

from Stuart to Lewiston is the Clearwater lined at intervals with small strips of 

bottom lands. For 60 or 70 miles above Lewiston it has , cut a trench 1,000 to 

2,000 feet deep, with precipitous slopes, through the 4orizontal beds of the 

Columbia River lava; beyond this limit begin the Clearwater Mountains, and in 

this province the canyons ai'e less precipitous but far deeper, 4,000 feet being 

a common vertical distance between the summit oJ the ridges and the bed of ~he 

stream. The slopes are fairly gentle for some distance from the summits, but 

become much steeper farther down toward the bottom. Forty miles above Lewis-

, ton the Clearwater receives the North FoTk, whi.ch drains a large territory, its 

headwaters reaching the Montana-Idaho boundary line. This fork lies almost 

entirely outside the territory covered by this reconnaissance. Forty miles farther 

up the riyer again divides; the Middle Fork continues 25 miles due east in a deep 

canyon cut through the westerly ramparts of the Clearwater Mountains and then 

forks again. The northerly branch, Lochsa Fork, heads near Lolo Pass and-flows 

through a canyon 4,000 feet deep, receiving few tributaries from either side. The 

southerly branch, called the Selway Fork, drains the larger part of the ·western 

slope of the Bitterroot Mountains and splits up in a maze of branching and winding 

streams. The South Fork, finally, which is considerably smaller, and has a less 

deeply trenched canyon, heads near the Salmon .River divide, first flowing in a 

westerly direction, changing at Mount Idaho to a northerly course. 

The grade of the rivers is by no means excessively great, that of Lochsa 

and Selway forks varying between 25 and 40 feet per mile through the main part 

of the mountains. Close to the Bitterroot Mountains the grade becomes much . ' steeper and the b_ranches finally head in the great glacial cirques on the west 

side of the Bitterroot Range. 

A peculiar feature throughout this region is that the rivers receive their 

largest tributaries from the south and that near their headwaters they have a 

tendency to bend to the south. 

The Salmon River throughout this region flows in a deep canyon without 

appreciable amounts of bottom lands. This trench is less split up into branches 

and is even more impressive than that of the Clearwater, its sides being also more 

precipitous. From Shoup to Freedom, a distance of at least 130 miles, the 

canyon is from 4,000 to 5,000 feet deep and about 10 miles wide, and has cut 

through the great uplifts <;>f pre-Tertiary rocks. From FreedoD). to its mouth 

the river flows for about 60 miles through a high plateau of. Columbia Riv:er 

lava, older rocks being, however, generally exposed in the bottom of its canyon. 

Snake Rivei· is the main trunk stream of this region, and here forms the 

boundary of Idaho on one side and Oregon and Washington on the other side. 

_/ 
GEOLOGY · OF OLE.ARW .ATER. MOUNT INS. 63 

It first receives the Salmon and, 40 miles farther down, the Clearwater. Through-

- out this region it flows through the Columbia lava · plateau in a deeply incised 

canyon, usually with steep sides. This canyon "may be divided into two welldefined sections of about equal length. Throughout the southern half of its 

course the river is in the bottom of a magnificent canyon with deeply sculptured 

walls 4,000 feet high and about 15 miles wide at the top. The rim rock at the 

crest of the walls on each side is formed by the edges of a lava sheet which 

immediately underlies the surface of Craig Mountain and of another similar 

plateau in Oregon. The northern half of the portion of the canyon referred to 

is narrow, being perhaps 2 miles wi~e at the top, ahd is cut in nearly horizontally bedded lava sheets; the walls, which are so steep that they appear vertical, 

-are about 2,000 feet in height." a (Pl. XIII.) 

GEOLOGY. 

GRANITE. 

From all available information granitic rocks of massive structure prevail 

over the whole extent of the Clearwater Mountains. Gneisses appear only at 

Pierce, Elk City, Salmon Mountain, and Horse Creek in areas of moderate extent, 

everywhere shattered and intruded by granite dikes. The Clearwater granite is, 

in general, a light-gray · granular rock containing biotite and some muscovite, 

quartz, orthoclase, and a large quantity of oligoclase, indicating a relationship to 

the quartz-monzonites. The grain varies from coarse to medium, and larger 

orthoclase crystals up to 1 inch in diameter . are sometimes present. The quantity 

of soda-lime feldspar is also variable, and in a few places the rock is a normal 

granite. Pegmatitic dikes are not very common except in some portions of the 

gneissoid areas. The structure is usually massive, though an incipient schistosity 

is noted in some places, bei~g especially frequent in dikes contained in the gneiss. 

From Lolo Pass, St. Marys Peak, and the summits at the head of Mill 

Creek the white outcrops of vast granite areas are seen far to the west. The 

Grave Peak complex and the whole of Lolo Ridge are probably of granitic 

character. The rock from Sherman Peak, on the western slopes, is a normal rock 

with much biotite and a little muscovite, orthoclase, and microperthite and a 

large quantity of oligoclase. A few smaller feldspar prisms are labradorite. 

Near Pierce; on Oro Fino Creek, the granite is slightly schistose and dioritic 

modifications occur near the contact of the true gneisses, beginning a short distance 

below the town. 

The Crags form the last high projecting point on the Lochsa-Selway divide. 

This rock, like the one just described, is closely allied to the quartz-monzonites. 

a Russell, I. C., Water-Sup. and Irr.j Paper No. 53, U. S. Geol. Survey, 1903, p. 63. 
64 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

Orthoclase and perthite · are present in smaller quantity, but there is much oligoclase; biotite occurs in small foils. 

The complex of Bilk Mountain was not Yisited, but from appearance, 

reports, and photographs by Mr. Lippincott granite is here the prevailing if 

not the exclusively occurring rock. (Pl. XI, B.) 

At Lost Horse Pass, described ·above (p. 44), the granite shows evidence of 

schistose structure and is cut by many joint planes. Granitic rocks. also prevail 

for a long distance west of that pass. 

On the ·Salmon ~iver divide granite begins on Ho:t;se Creek, and is cut by 

many dikes of granitic and dioritic porphyries. The rock is here of the normal 

Bitterroot type but varie_s in grain. West of the gneiss area of Salmon 

Mountain light-gray biotite granite . prevails. again, . but contains many sharply 

defined ~ inclusions of gneiss and occasional dikes of granite-porphyry. On the 

ridge east of Little Salmon River the granite has a slightly gneissoid structure~ 

From this point to Ryans Meadows on the Red River, where the wagon road 

to Elk . City begins, granite prevails. A specimen 4 miles west of Little Salmon 

Meadows is a coarse biotite-granite, orthoclase prevailing over the plagioclase, 

which seems to be an andesine. In the . scant outcrops inclusions of micaceous and 

often contorted gneiss are common, indicating, perhaps, the vicinity of a larger 

gneiss area. Many of these gneiss fragments are injected in the small pegmatitic 

dikes parallel to the schistosity. After the large _gneiss area of Elk City has 

been trayersed the road leads down from Summit House to Harpster on the 

Clearwater. Granite adjoins the gneiss here and occupies the western slope 

toward the river down to an elevation of 3,800 feet, where the granite borders 

with intrusive contact against black slates and limestone of probably Triassic age 

(p. 73): 

Granite occupies large areas again on the head of Crooked River. A specimen from the Homestake mine is a coarse biotite-muscovite rock, containing 

abundant microcline and a small amount of oligoclase. It is clearly a typical 

granite, comparatively rare in this region. 

On the other hand, at Buffalo Hump the light-gray granular rock contains 

very little muscovite, very abundant -olig·oclase, and probably also andesine; it is 

evidently a quartz-monzonite. The Floren.ce granite is similar, while at Warren 

(south of Salmon River) there is much muscovite .and a smaller quantity of sodalime · feldspar. GNEISS. 

· The gneiss areas lie embedded at various places in the granite, dikes of which 

are . ab~ndant · in the schistose ro_ck. Ordinarily it is a_ biotite-microcline-gneiss 

which evidently is d~r~~ed froma g~anite; crushing and folding on a small scale are 

very frequent. The dip, usually moderate, is characteristically variable. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 27 PL. XI 

.d. FOREST OF CEDAR (THUJA PLICATA), CEDAR CREEK, CLEARWATER MOUNTAINS. 

B. GRANITE PEAK NEAR BILK MOUNTAIN, CLEARWATER MOUNTAINS. 

GEOLOGY OF CLEARW .ATER MOUNTAINS. 65 

Beginning on the north a series of coarse micaceous and hornblendic banded 

gneisses appear on Oro Fino Creek just below the mining camp of Pierce (p. 102). 

Their strike is N. 70° W., the dip being nearly vertical. South of Pierce on 

Musselshell Creek and thence up to Sherman Peak granite prevails, but smaller 

areas of gneissoid rocks, probably inclusions, are encountered in places. 

South of this begins the greatest gneiss area of this region, extending 40 miles 

long and 20 miles wide across the Middle and South forks of the Clearwater. Most 

common is an often crumpled biotite-microcline-gneiss with characteristically 

variable strike and dip, the latter from 20° to 90° . Coming from the east on the 

Nez Perce trail this gneiss is first met at Ryans l\'Ieadows and continues to Elk City, 

15 miles distant. It is coarse, rich in mica, and often crumpled perpendicularly to 

the strike. The gneissoid structure is chiefly caused by the parallel arrangement 

' of the mica foils, to less extent by the elongation of other constituents. Microscopically it consists of much microcline, orthoclase, and quartz, with less amount 

of plagioclase of medium acidity. There is further biotite with some hornblende, 

titanite, and epidote, the latter seemingly primary. Sometimes the mica foils 

curve around the white constituents, giving the rock an ocellar structure. It is 

well exposed in the bed rock of American Hill placer mine (p. 93) and here contains ' bands of fine-grained very micaceous rock and many narrow pegmatite dikes 

parallel to the schistosity. Dikes and gneiss are greatly contorted and crumpled. 

At Buffalo Hill placer mine the bed rock is similar gneiss but is cut in all directions 

by granite dikes. On Crooked River gneiss with micaceous streaks continues to 

a point 2 miles below the Badger mill, where it is replaced by intrusive reddish 

granite. Similar micaceous gneisses prevail between Elk City and Newsome and 

continue, cut by granite dikes, to a point 2 miles west of Mountain House, on 

the main road, where it is cut out by intrusive granite. Three and one-half miles 

west of the same place a narrow wedge of gneiss crosses the road, but granite 

again sets in and continues to near the foot of the grade to the Clearwater River. 

The Middle Fork cuts across this gneiss area from Stuart eastward to beyond 

the Lochsa and Selway· forks. Six miles above Stuart granitic gneiss begins; St 

miles above are greenish schists striking N. 30° W. and dipping 70° WSW. Then 

follows micaceous gneiss up to the forks of the river. The point of the ridge 

between these is of gneiss, but 6 miles west of the Crags the trail crosses into the 

granite which forms the Crags. Near the contract the gneiss is cut by dikes of 

granite and pegmatite. 

East of the Elk City gneiss area the granite contains many gneissoid inclusions. 

No large areas are, however, encountered until the great reef of Salmon Mountain 

is crossed. This consists chiefly of gneiss, extending probably all the way from 

Caseknife Mountain on the edge of the Salmon River Canyon north to McGruder 

Mountain. The whole mass is a banded and contorted micaceous gneiss, striking 

5995--~o. 27--04----5 
66 BITTERROOT AND CLEARWATER MOUNTAINS, MONT,-IDAHO. 

northeast and dipping steeply northwest. A specimen from the top of Caseknife 

Mountain is a gray and medium-grained gneiss consisting of allotriomorphic quartz, 

orthoclase and andesine with ·many foils of dark-brown biotite. Granitic injections 

of aplite, hornblendic granite, granite-porphyry, etc., are very extensive. 

Good exposures were seen by Mr. Stose in the glaciated gulch leading up to 

Caseknife Mountain . from Salmon River on the southeast. · Numerous slipping 

planes suggest mo~ement along the schistosity. In places the gneiss is much 

folded, quartz veins crossing the schistosity partaking in this movement. Intrusive 

granite dikes are common and have been made gneissoid parallel to the schistosity. 

On the ridge eastward between Salmon Mountain and Horse Creek granite 

prevails but contains very sharply defined and .broken shattered fragments of 

gneiss: 

The most easterly area of gneiss begins on Horse Creek and extends up to 

the divide between Salmon and Bitterroot rivers, including the mining district of 

Mineral Hill (p. 90). This area which may possibly connect with that of Salmon 

Mountain along the deep . canyon of Salmon River, borders against intrusive 

granite on the west, and probably. underlies the sedimentary series of the. head of 

the SoU:th Fork of the BitterrQot on the east. Th,e gneiss is often coarse and dark 

gray and shows ocellar struct~re due to the curving bands of biotite. It consists 

of ~iotite, quartz, much microcline, and a small amount of plagioclase. Many 

bands are highly micaceous and sometimes contorted. The strike of this gneiss 

at the Horse Creek mi~es is north· and south; the dip 40° E. The poor outcrops 

rarely permit good determinations, and a secondary cleavage often makes it 

difficult to find the true schistosity. Many dikes of granite-porphyry and granite 

cut this series. 

SEDIMENTARY ROCKS. 

Only few and small areas of sedimentary rocks have thus far been noted 

in the Clearwater Mountains, granite prevailing everywhere with smaller areas 

of gneiss. The probably pre-Cambrian areas of Lolo Fork and South Fork of 

Bitterroot River apparently do not enter the watershed of the Clearwater River, 

though continuing close up to its limits. On the western side a small area of 

dark-gray, fine-grained quartzites is found on Relief Creek between Crooked 

River and Red River, south of Elk City. Nothing is known as to their relations 

with the surrounding gneisses. Pebbles of this rock are very common at the Buffalo 

Hill hydraulic mine on American River (see p. 94). The only other sedimentary 

rocks encountered form irregular inclusions in the granite of Buffalo Hump (see 

p. 98). They are slates, quartzites, and limestones of unknown age, shattered by 

granitic dikes and greatly contact metamorphosed to mica-schists, hornfels, and 

garnetiferous products. :Many of these rocks contain microscopic tourmaline. 

GEOLOGY OF OLEARW ATER J\fOUNTAINS. 67 

TERTIARY GRAVELS. 

The great flows of the Columbia River lava dammed the old drainage ways 

to 'present elevation of about 3,000 or 3,200 feet. The natural result was heavy 

accumulations of gravels in the lower reaches of the Clearwater streams. Remaining 

benches of such gravels are beautifully developed in the Elk City mining district 

(p. 91), where the highest of these attains an elevation of 4,500 feet. Similar 

conditions existed, closer to the valley? ~t Pierce, where the highest remaining 

gravel benches reach elevation of 3,300 to 3,500 feet (p. 102). Remains of gravel~ 

are also found on the ridge between Lolo and Musselshell creeks at an elevation 

of 3, 700 feet. 

GLACIATION • 

. The .large confluent ice sheet which once covered the · whole of the Ditterroot 

Range has been described in some detail on a previous page (p. 51). 

Within the Clearwater l\!Iountains no evidence of such general and widespread 

glaciation is found, due of course to the fact that the mountains rarely attain an 

elevation equal to that of the Bitterroots. The glaciation in the Clearwater 

Mountains is confined to a few isolated localities, and evidences of its existence 

appear wherever any considerable area of country exceeds 8,000 feet in elevation. 

Beginning on the north the first center of ·glaciation is met at Rhodes Peak 

on the Lolo Ridge, from which doubtless small glaciers extended in several 

directions. Going west another local center from which small glaciers radiated 

appears at Bald Mountain and Castle Butte. Finally, a few miles farther west 

on the slopes of Rocky Ridge three or four smaller glaciers appear to have 

descended the streams leading up to that peak. 

The ridge between Lochsa and Selway forks of the Clearwater is rougher 

and higher than the Lolo Ridge, and Grave Peak was evidently the center of an 

extensive glaciation, the ice streams descending in all directions from it. It is 

probable that this ice field was connected by way of Diablo Pe_ak with the main 

ice-covered area of the Bitterroot Mountains. The glacial lakes near Grave Peak 

are shown on Pl. XII. 

Still farther west the Crags near the end of the ridge rise to an elevation of 

over 7,900 feet. Small glaciers doubtless descended from their summits. 

On the southern divide between Salmon River and Selway Fork the effects of 

glaciation are only prominent around two centers. The first one is Salmon Mountain reaching 8,881 feet. From the broad shoulders of this mountain wide glacial 

cirques descend in several · directions. The glaciated area here probably covered 

20 or 30 square miles. The divide from this point eastward to the head of the South 

Fork of the Bitterroot is very high and local glaciers may well have existed in 

some places. 
68 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

From Salmon Mountain westward for 40 miles the summit:; of the ridges are 

broad and show no effect of ice sculpture, although the elevation often rises above 

1,000 feet. Forty miles due west of Salmon Mountain a high complex o~ granitic 

hills rises to a height of 8,810 feet, the highest point being called Buffalo Hump. A 

neve field covering several square miles existed here and glaciers extended eastward 

for several miles . down into Lake Creek, which drains into Salmon River, and 

westward at least an equal distance into Sheep Creek, also draining toward the same 

$tream. \ 

West from the line drawn from Buffalo Hump north toward Rocky Ridge on 

the Lolo trail the country slopes rapidly toward the plateaus of Columbia River 

lava, and no evidences whatever of a former glaciation are observed. 

FIG. 5.-8almon River Canyon seen from diorite point at Holdenreid ranch, near Keuterville; looking southeast, 

upstream, toward White Bird. Diorite continues across river; granite hills of Mount Idaho in left background; 

horizontal basalt flows elsewhere. 

THE LAVA PLATEAU.a 

TOPOGRAPHY. 

From the western heights of the Clearwater Mountains a rapid descent leads 

down to a volcanic plateau occupying vast areas in Idaho, Oregon, and Washington. 

Geologically, this is formed by a great number of thin, horizontal basaltic sheets, 

and the formation is called the Columbia River lava. Between the North Fork and 

·Harpster (on the South Fork), a distance of 50 miles, this· plateau has a marginal 

~hwation of about 3,000 feet, and a strip of it, up to 10 miles wide, lies on the east 

_side of the· Clearwater River, largely open a·nd grassy on . the south, more heavily 

timbered toward the :Q6rth. West of the 1,000 to 1,500 foot trench· of the Clearwater 

the direct continuation of this lava plateau is found in the broad, open Camas and 

a As this region has been described in considerable detail by Prof. I. C. Russell in Water-Supply and Irrigation Papers, 

Nos. 53 and 54, U. S. Geol. Survey, especially in regard to the Columbia River lava and the water supply dependent on it, 

the reader is referred to that valuable report for detailed information on these subjects. 

, 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 27 PL. XI I 

A . VIEW SOUTHWEST FROM GRAVE PEAK, CLEARWATER MOUNTAINS, SHOWING GLACIAL LAKES. 

B. WALTON LAKE, NEAR GRAVE PEAK, CLEARWATER MOUNTAINS. 

TOPOGRAPHY OF THE LAVA PLATEAU. 69 

Kamiah prairies, varying in elevation from 3,000 to 3,500 :feet; the two are separated 

by the abrupt Lawyers Canyon, named after a Nez Perce chief prominent in the 

war of , 1877. vYest of Camas Prairie rise the hills of the Cottonwood Buttes, 

points of older rocks projecting through the lava sheets to an elevation of over 4,500 

:feet. To the southwest of Kamiah Prairie and separated from the Cottonwood 

Buttes by a high gap (elevation 4,000 feet) extends Craig Mountain, a broad domeshaped swell of the lava attaining nearly 5,000 feet. The latter overlooks the deep 

canyon which the Snake has cut through the lava sheets. The Cottonwood Buttes 

overlook the similar deep gash cut by the Salmon, fig. 5, both canyons being about 

3,000 feet deep. The lava plateau covers the point between the two great rivers, 

FIG. 6.-View north of Rocky Ridge on the Lolo Ridge over 

plateau character north of the 0.1P•nw.olt.Pr 

but has here an elevation of 4, 000 feet. overs the whole adjacent part of 

Washington and Oregon, the elevations teau increasing southward from 

3,000 feet opposite Waha to 4,000 feet or more on e Grande Ronde and the Imnaha, 

important tributaries received by the Snake from the west. South of Grangeville 

the Clearwater Mountains rise boldly. North of Kamiah Prairie the lava plateau 

descends to the Lewiston Plateau, which has an vation of about 1,500 feet. 

Near Oro Fino, the Clearwater River sharply and flows for 40 miles 

almost due west to Lewiston, where it joins the Snake. The latter river itself 

makes a sudden turn of 90° at Lewiston, and considerable distance into Washington follows the east-west direction of its tri This east-west direction 
70 BITTERROOT .AND CLE.ARW .ATER MOUNTAINS, MONT.-ID.AHO. 

of the rivers stands in some causal connection with the bold scarp of the U pion-

. town plateau which all along follows their north side; the general elevation of 

the latter plateau is 2,500 to 3,000 feet and the steep slope carries it down 1,500 

to 2, 000 feet to river level. 

GEOLOGY. 

PRE-TERTIARY FORMATIONS. 

An examination of the many deeply cut canyons within the province of the 

Columbia River lava soon reveals the fact that the underlying surface of older 

pre-Miocene rocks is extremely uneven and that t];le bottoms of the ,main streams 

before the time of the lava flows were at a lower level than they are at present. 

Thus the old rocks are irregularly exposed in many canyons and again at other 

places west of the main slope of the Clearwater Mountains where they are partly 

or wholly surrounded by the volcanic flows which rise above the general level 

of their surface. a 

The series of rocks exposed below the .lava is of a very complex character 

and consists of slates, sandstones, limestones, greenstone-schists, gneiss, diorite, 

and granite, the detached exposures making the study difficult. It is pretty 

clear, however, that two or three systems of bedded rocks are present. The 

first and oldest is chiefly exposed on the North Fork and at Oro Fino and consists of true gpeisses and mica-schists, sometimes with intercalated limestone; it 

bears the marks of extensive regional metamorphism and is probably very old, 

possibly pre-Cambrian, and should be classed with the gneisses of Pierce and Elk 

City. The second and younger series is exposed on the Cottonwood Buttes and 

in the great canyon of the Snake; it is distinctly sedimentary, containing limestone, sandstone, and black slates, much disturbed but of imperfectly known 

structure, and associated with it are large masses of greenstones partly schistose 

and tuffaceous. . . A third division consists of the also distinctly sedimentary rocks of Salmon 

River · Canyon, Mount Idaho, and Harpster, which continue up to this point from 

the Sever). Devils with persi.stent northeasterly strike. This division, which may· 

be Identical in age with the second series, is believed to be of Mesozoic-Triassic 

age. Granite and ·diorite, forming a spur of the · great area of . this kind of 

the Clearwater Mountains, has been intruded on a large scale into these three 

divisions of sediments. A bay of these rocks extends ·from Pierce, crossing 

the Clearwater near Kamiah and Greers Ferry, to eastern part of the Cottonwood Buttes, probably reaching the canyon of the Salmon west of Grangeville. 

a For these projecting points of more ancient rocks, islands as it were in the lava floods, Professo:r Russell has 

proposed the name of "Steptoes," from a butte of that name north of the area here considered. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 27 PL. XIII 

E R IVE R, LO O KING NORTH F ROM POINT NEAR WAHA. 

basalt 2, 0 00 f~et thick. Clea rwate r e scarp ment is seen in background 

(Pholograph by I. C . Russe ll. ) 

GEOLOGY OF THE LAVA PLATEAU. 71 

0£ all the mPin underlying rock formations this is doubtless the youngest. An , 

approximately correct map of the exposures below the lava may be seen on Pl. I. 

Beginning with Snake River, the first exposure of pre-Neocene rocks is 

noted in the basalt canyon of the Snake River, 26 miles below Lewiston. It is 

a coarse light-gray gneiss, apparently a sheared granite wi~h large pressed aggregate of orthoclase and quartz, surrounded by flaky films of biotite and hornblende. 

The exposure is one-half mile long and rises 250 feet above the river. On the 

Clearwater no exposures of old rocks are seen until 25 miles above Lewiston 

and 3 miles below Contact, from which pla.ce the · exposures continue for 8 miles 

until a point above Oro Fino. · In Bedrock Creek and Big Canyon, quartzites 

and greenstone-schists are exposed, seemingly identical with the Cottonwood 

Butte series and having a strike of N. 25° V\T., the dip being 30° E. 

At the mouth <;>f the North Fork, Professor Ru~~ell a found diorite, gneiss, · 

and micaceous garnetiferous schists striking a little west of north and dipping 

70° to 80° E. One and one-half miles above the mouth of North Fork the rock 

is a fine-grained gneiss with bands of whitish quartzite. The strike is N. 70° 

W ., the dip 65° NNE. A short distance above the town of Oro Fino the rocks 

are micaceous quartzite and mica-schists, containing a coarsely crystalline limestone in, well-defined beds 120 feet wide, which may be followed for lt miles 

southward, where it is narrow, and one-fourth mile northward. The strike is 

N. 25° E., and the dip 78° ESE. Two and one-half miles above Oro Fino the 

micaceous quartzites and mica-schists strike N. 55° W., dipping steeply southwest. Near the mouth of Ford Creek basalt covers the bottom of the canyon. 

South of Ford Creek, about Greers Ferry and the mouth of Lolo Creek, the 

prevailing rock is a massive granite or diorite, some of it at Greers Ferry being 

a very beautiful coarse pegmatite, consisting of plagioclase .and hornblende. A 

few miles above Kamiah the granite disappears below the basalt, which now for 

10 miles or until a few miles below Harpster, forms the bed of the river. 

Small bed-rock exposures ·occur on the top of the plateau near Fletcher, 

on the head of Big Canyon, and on Mission Creek, where limestone has 'been 

observed by Professor Russell. b 

The Cottonwood Buttes are, as stated above, a series of pine-clad hills projecting somewhat over 1,000 feet above the lava plateau of Camas Prairie. The 

western and highest part consists of prevailing greenstone-schists, alternating 

with massive greenstones and smaller areas of partly tu:ffaceou~ clay slate and 

quartzitic slates, the latter fairly being well exposed on the road from CottonaWater-Sup, and Irr. Paper No. 53, U. S. Geol. Survey, 1903, p. 24. 

b Water-Sup. and Irr. Paper No. 54, U.S. Geol. Survey, 1903, p. 120. Analyses are h ere given of limestones from Snake 

River, Mission Creek, and Oro Fino. All are practically pure carbonate of calcium, the last named only containing 3 per 

cent magnesia. 
7·2 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDADO • . 

wood to Keuterville. The greenstones appear to be old lavas of andesitic or 

basaltic character. The strike is northeasterly, the dip being at a high angle and 

rarely determinable with exactness. Eastward the older rocks continue for several miles out into the lower country toward Greer Creek and Columbus, but is 

here principally granite and granite-porphyry. Immediately south of these 

buttes the plateau breaks off into the great canyon of the Salmon. A narrow 

and shallow rim of basalt flows, separates the old rocks of Cottonwood Buttes 

from this great trench, and from prominent points on the edge of the canyon a 

magnificent view is obtained (fig. 5). The rocks are here chiefly greenstone-schists 

with some massive dark and medium-grained diorite. The Cottonwood Buttes are 

recognized as a great reef of the sublava series continuing across the canyon 

with a southwesterly direction. Across the Salmon River the highest point of 

the old spur is only 2,000 feet above the sea and is covered with 2,000 feet 

· of basalt. 

In the Salmon Canyon bed rock is exposed for at least 30 miles between a 

point southwest of Keuterville and White Bird Creek. Little is known as to its 

character. Professor Russell states that below Keuterville there is much of a 

light-colored igneous rock. Limestone is reported from a point in the bottom of 

the canyon between Rocky Canyon and White Bird Creek. 

At Denver, one of the lowest points on the Camas Prairie (elevation 3,125 

feet) and situated on the divide between the Salmon and the Clearwater, bore 

holes have penetrated 240 feet of lava and struck, according to reports, a granitic 

rock at that depth, water under considerable artesian pressure being also obtained, 

rising to a point 150 feet below the surface and indicating a bed-rock depression 

with supply from the direction of the Cottonwood Buttes or Mourit Idaho. 

The bed-rock exposures along the Snake River above Lewiston have been 

described by Professor Russell, a and an abstract of his statement is given below. 

The first outcrops of older rocks in the canyon occur 12 miles above Lewiston, 

west of Waha. A bluff of diorite-porphyry rises here on the east side of the 

canyon below the lava to a height of 3,300 feet above the river; a .lower bluff 

of the same kind appears on the west side of the canyon. A few miles farther 

up, at the mouth of Grande Ronde River, the underlying rocks appear again 

with rough topograp)lic form, the summits of the old topography attaining a 

height of 2,500 feet above the river and being covered by 1,500 feet of horizontal ' 

basalt flows. The rocks are thin-bedded limestones (with indefinite fossils), schists, 

and diorite. The dip is generally northward at angles of 40°-45°, sometimes 

also vertical. The rocks beneath the basalt are exposed in the lower 2,000 feet 

of the canyon all the way up to a few llliles above where the Salmon River 

aWater-Sup. and Irr. Paper No. 53, U. S. Geol. Survey, 1903, p. 26. 
GEOLOGY Olf THE LAVA PLATEAU.. 73 

enters. They were examined by Mr. Russell at Cottonwood Creek a few miles 

below the mouth of the ·Salmon; he states that the stratified rocks are much 

disturbed but generally strike northeast-southwest with variable dip. Sandstone 

conglomerates, 1 shale, and limestone were observed. Intrusive rocks, diorite, and 

diabase-porphyry also occur. Quartzite and diorite were noted near the junction 

of the Salmon and the Snake. 

It remains to describe the interesting series of rocks from the canyon of the 

Salmon above White Bird, from Mount Idaho and from the South Fork of the 

Clearwater. 

One hundred and ten miles south-southwest of Grangeville, at Huntington, 

Oreg., at the beginning of the great canyon of the Snake, first appears a series 

of slates and limestones with great masses of interbedded old lavas. These rocks, 

which continue for 30 miles along the canyon, have a northeasterly strike and prevailing northwesterly moderate dip. Their age is not positively known. Farther . 

north this series is covered by Neocene basalts. The same, or at any rate, a very 

similar series appears at the Heald mining district and in the Seven Devils, Idaho, 

old surface lavas with intercalated slates and limestones prevailing. Fossils found 

in the Seven Devils indicate with certainty a Triassic age. a 

Thirty miles northeast of the Seven Devils a similar series of sediments and 

associated igneous rocks is excellently exposed along the Salmon River Canyon, b 

near Freedom, the interval between these two locations being occupied by high, 

rugged ridges as yet unexplored. The prevailing series in this part of the Salmon 1 

River Canyon consists of clay slates and persistent beds of crystalline limestone 

with associated partly sheared greenstones (chiefly old surface lavas), having a 

general northeasterly strike and a southeasterly dip of about 45°. No fossils were 

found here. Granites and diorites, exposed in places below the horizontal lava 

sheets, and belonging to the great intrmlive area of central Idaho, adjoin the 

whole series on the Idaho side from near V\7 eiser, Idaho, the contact clearly having 

a northeasterly trend. The same contact is exposed east of Salmon River, as 

shown on Pl. IX of the Twentieth Annual Report of the United States Geological 

Survey, pt. 3, and also on Pl. I, this report. Extensive contact metamorphism 

marks the strip of slates adjoining the granitP.. In places, as above the great bend 

of the Salmon, 10 miles below where the wagon road to Florence crosses the 

canyon, gneissoid rocks are present along the contact in su~h volume as to suggest 

that they may possibly be part of an independent formation instead of contact 

metamorphic sediments. 

aLindgren, W., The gold belt of the Blue .Mountains of Oregon: Twenty-second Ann. Revt. U.S. Geol. Survey, pt. 

3, Pl. LXIV, p. 581. The gold and silver veins of Silver City, De Lamar, and other mining districts in Idaho: Twentieth 

Ann. Rept. U.S. Geol. Survey, pt. 3, Pl. IX, pp. 87-89. 

bLindgren, Twentieth Ann. Rept. U.S. Geol. Survey, pt. 3,1900, p. 581. 
7 4 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

Along the road from Mount Idaho to Florence, a few miles south of the 

former town, granite and some schists are exposed below the lava contact. 

East of l\1ount Idaho, in the canyon of the South Fork of the Clearwater 

o~curs a series of sediments which seem to be the direct continuation of those 

of the Salmon River Canyon. Mount Idaho is situated ' on the basaltic plateau, 

but in the canyon immediately east of it and 1,500 feet lower greenstone-schists, 

with bands of clay slate having a northeasterly strike, prevail. They are well 

exposed betw~en the Dewey mine (p. 105) and Hinckley's ranch. A few injected 

granite dikes were observed in the schists. On the steeply rising hills east of 

the river at Hinckley's greenstone-schists first prevail, but 1,600 feet above the 

stream a strong and persistent belt of crystalline limestone is crossed, adjoined 

on the east by heavy masses of black and gray banded quartzitic slates. 

At Harpster, 10 miles f~rther down the South Fork, dark-green, mediumgrained diorite is exposed in the bottom of the canyon below the lava, and continues 

for a few miles beyond that place until the lava dips below the river level. 

Prospectors affirmed that the diorite continues for 4 miles above the Harpster 

bridge. Above this there is said to be an alternation of limestone, slate, and 

greenstone. 

The most northerly exposure of this important northeasterly striking series 

is found on the road 5 miles east of Harpster. At an elevation of 3,850 feet, 

at the foot of a long grade descending over granite from Summit House and 

near the beginning of the lava plateau, appear outcrops of finely laminated clay · 

slates striking N. 60° E. and containing well-defined dikes of granite. Two miles 

south of this point Mr. Johnson found a bed of pure white crystalline limestone 

60 feet thick associated with decomposed greenish slates. This limestone would 

· seem to be in the northeasterly continuation of the bed noted east of Hinckley's 

ranch; it had been utilized for quicklime, as indicated by a kiln built at the .. 

. outcrop. 

Northeast of this point the sedimentary series is replaced by an apparently 

far older gneissoid series. The similarity of this whole northeasterly striking 

series from Huntington to the South Fork of the Clearwater and the definite 

identification at the Seven Devils warrant the belief that it is throughout, largely 

at least, of Triassic age. 

BASALT FLOWS. 

Topographically and geologically basalt is the most impo~tant component rock 

of the high plateau spread out at the foot of the Clearwater Mountains. As 

already indicated, the plateau is chiefly built up of a great number of horizontal 

basaltic flows, to which Professor Russell has given the formation name of the 

Columbia River lava. On the rolling surfaces of the high prairies little is seen 
GEOLOGY OF THE LAVA PLATEAU. 75 

of this formation except the deep, fertile, dark-brown soil, to which it easily 

dis integrates. 

Along the walls of the many abrupt canyons which trench the formation its 

composition is beautifully and clearly revealed. The cliffs and slopes, of somber 

dark-brown color, present a great number of horizontal, long, and persistent lines 

delimiting the individual flows and due to their varying resisting power toward 

erosion. Each flow is from 25 to 150 feet thick, the upper and sometimes also 

the lower part of each being more scoriaceous than the central part. Throughout 

the prevailing rock is a basalt, a though varying. much, for while some flows are 

very glassy others are almost granular and have a diabasic structure. These 

differences are no doubt due to differing conditions of cooling. A columnar 

structure, due to vertical contraction joints, is observed in places. 

In fresh specimens the basalt is nearly black, sometimes yesicular, more frequently massive. Typical specimens from the Clearwater Canyon, 4 miles below 

Contact and from the mouth of Potlatch Creek, are massive, black rocks of fine 

gi·ain, and containing prisms of labradorite up to one-half inch long. In thin 

section they prove to be olivine-basalt of diabasic granular structure, but also 

containing between the grains some dark-brown glass. Porphyritic labradorite 

crystals are on the whole very common in many flows. The basalts from the 

plateau of the Columbia River lava near the Seven Devils; Eagle Creek Range, 

and Boise are entirely similar. 

The only analysis of the Columbia River lava thus far available is a partial 

one, by Prof. Geo. P. Merrill, of a basalt from Walla Walla, and runs as follows:b 

Analysis of basalt from Walla Walla, Wash. 

Si 0 2 •••••••••••••••••••••••••••••••••• _ •••••••••••• • _ • • • • • • • • • • • • • • • • • • • • • • • • • 4 7. 35 

~::~: } - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - _·- - - - - -- - - - - - - - - - - - - - -- - - - -- - - - -- - 34. 38 

MgO ............•................. .: _ .. __ .. _ .. ____ ..... __ .. __ . . . . . . . . . . . . . . . • . 4. 43 

CaO. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8. 27 

N a20 ....... .- ...................... _.. . . . . . . . . . . . . . . . . ... . . . . . . . • . . • . . . . . . . . . . . 2. 55 

K 20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1. 33 

Loss on ignition ................. __ .... __ ...... __ ......... _. __ ..... __ . _______ .. . 95 

99.26 

The persistence in petrographic characters over large areas is noteworthy. 

The age of the basalt flows would seem to be Miocene from the paleo-botanical evidence thus far available. (See p. 24.) Possibly Eocene eruptions make 

up a part of the formations hitherto grottped under the name o£ Columbia 

River lava. 

a Russell, I. C., and Diller, J. S., Water-Sup. and Irr. Paper No.4, 1897, p. 43. Lindgren, W., 'f·wentieth Ann. Rept. 

U.S. Geol. Survey, pt. 3, 1900, p. 90-93; Twenty-second Ann. Rept. U.S. Geol. Survey, pt. 3, 1902, pp. 592- 593; Geologic Atlas 

U.S., folio No. 45, Boise, Idaho. 

b'Water-Sup. and Irr. Paper No. 53, U.S. Geol. Survey, 1903, p. 44. 
76 BITTERROOT AND CLEARW .ATER MOUNTAINS, MONT.-IDAHO. 

Intercalated between the basalt flows are occasionally found thin beds of 

white volcanic dust of rhyolitic character. Professor Russell menti?ns such 

occurrences from each side of Potlatch Canyon; beneath the Candle Rocks, on 

the left bank of Snake River below Lewiston; near Swallow Rock, between 

Clarkston and Asotin; also on Asotin and Captain John Creek in the canyon of 

the Snake above Lewiston.a 

W aterlaid beds, consisting of clays and sands swept down from the surrounding mountains, occur in some places between the lava flows. Basaltic tuffs 

are practically absent. Professor Russell states that on Small's ranch, on the 

Lewiston Plateau~ the drill encountered 60 feet. of sand and 90 to 100 feet of 

clay below 210 feet of basalt, these sediments being again underlain by basalt. 

These sedimentary, intercalated beds can be traced over a large extent of country in the northern and western portions of Nez . Perce County and adjacent 

portions of Washington and Oregon. They probably extend to the foothills of 

the Bitterroot Mountains, but as there are other similar layers in that 1egion 

they have not been identified east of Craig Mountain. b At Cottonwood, on the 

· Camas Prairie, gravel 56 feet deep has been penetrated below a surface sheet of 

60 to 70 feet of basalt. 

Along the canyon of the Clearwater River, from Stuart to Peck, there are 

indications of a thick sheet of sandstone and allied rocks at an elevation of about 

800 feet below the general surface of the plateau. The true relations are often 

obscured by landslides. The same, or a similar complex, 200-300 feet thick, is 

shown throughout the length of Oro Fino Creek from its mouth to near Pierce 

along the walls of the canyon. These beds begin about 750 feet below the surface of the plateau, as along the Clearwater Canyon landslides are very common. 

Again, sandstone and carbonaceous slate occur at the same level on Little Canyon 

Creek, draining a part of the broad plateau south of Oro Fino. · Finally, on 

Potlatch Creek, which joins the Clearwater from the north about 18 n1iles east 

of Lewiston; a moderate thickness of sedimentary beds and volcanic dust appears 

in the basaltic series, 3 miles 3!bove the mouth o{ the canyon. c "The Uniontown 

Plateau is underlain all along its southern border, and apparently throughout 

practically its entire area, by horizontal sheets of basalt, which include at least 

one important bed of clay, sand, and gravel, at a depth of about 160 feet below the 

surface." d 

STRUCTURE AND PHYSIOGRAPHY OF THE PLATEAU. 

Orogen'ic dist rbances.-Like any other series of horizontally deposited beds 

the Colui:nbia River lava is likely to be deformed into folds, and like any other 

a For analysis of this see Water-Sup. and Irr. Paper No.' 53, U.S. Geol. Survey, 1903, p. 34. 

b Water-Sup. and Irr. Paper No. 53, U. S. Geol. Survey, 1903, p. 35. 

c Ibid., pp. 38-39. 

dlbid., p. 57. 
d Uniontown plateau are seen in th e backgrdund. ( Photograph by I. C. Russe ll.) 

GEOLOGY OF THE LAY A l,LATEAU. 77 

terrane it may of course be broken and faulted by orogenic forces. Comparatively little such folding or faulting has taken place, indicating a general absence 

of tangential compressive stresses. This seems to hold good, not only of the lava 

plateau, but also of the higher and older largely granitic plateau of the Coeur 

d'Alene, Clearwater, and Salmon River Mountains. The whole of central Idaho 

should perhaps be regarded as a rigid crust block, but little folded or faulted 

since Mesozoic time. 

Some disturbances of· the Columbia River lava have, however, occurred in 

this region. Along the foot of the Clearwater Mountains the top of the lava 

flows is generally found at an elevation of 3,000 feet above the sea. Practically 

the same elevations obtain on the Camas and Kamiah prairies and on the Uniontown 

Plateau, and this level may be regarded as the surface of the sea of molten rock. 

Fifteen hundred feet lower than the general level is the Lewiston Plateau, 

bordered on the north by the Clearwater escarpment. Up to 1,500 feet higher 

than this level, is Craig Mountain, a long, broad lava swell, extending in a westnorthwest direction between the Snake and the Clearwater. (Pl. I.) B_oth of thes~ 

features Professor Russell regards as monoclinal folds. a The Lewiston Plateau is 

part of a synclinal . trough, bordered on the north by the monoclinal fold of the 

Clearwater escarpment (Pl. XIV). Craig Mountain is a gentle anticline separating 

the Lewiston Plateau from Camas Prairie. (Pl. I.) 

Epeirogenic disturbances:-In a previous paragraph it has been shown that 

the combined ridge lines of the Clearwater Mountains (and also of part at least of 

the Salmon River Mountains south of the stream of the same name) would form 

a broad plateau surface, with an average elevation of about 7,000 feet. In places 

this plateau was depressed to 6,000 feet, while in other places irregular groups of 

hills rose to 1,000 feet above the average level. A slight westward slope probably 

existed and was the determining factor in the general plan of the rivers. This 

surface was evidently a surface of erosion, an old topography reduced from still 

older mountain systems, and lifted, like the rest of the great Idaho mountain 

mass, by epeirogenic processes long before the Miocene epoch to the position of 

a high plateau in which r ejuvenated rivers could begin new and active processes 

of canyon cutting. The rather sudden descent from this old plateau to the later 

one of the Miocene lava is noteworthy. It can scarcely be due to erosion, but 

is rather due to deformation of the crust as suggested in the case of the similar 

steep descent of the plateau of the Boise Mountains to the lower valley of 

the Snake River.b The general character of this plateau between Florence and 

Buflalo Hump, and its contrast against the deep canyon of the Salmon River, is 

clearly shown on Pl. IX of the Twentieth Annual Report of the United States 

Geological Survey, pt. 3. 

a Water-Sup. and Irr. Paper No. 53, U.S. Geol. Survey, 1903, pp. 54-61. bGeologic Atlas U.S., folio No. 45, Boise, Idaho. 
78 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

By following the contact line of the Columbia River lava and the older 

formations of the Clearwater Mountains, it soon. becomes evident that the basalt 

flooded the foothills to an approximate elevation of 3,000 feet; further, that the 

foothills of the Cle&rwater Mountains which it covered often had a sharply 

accentuated topography, and that the lowest points of the main streams of the 

old pre-Miocene system were considerably lower than the bottom of the drainage 

of to-day. The present streams of the region, the Clearwater and the Salmon, 

flow through the mountains in canyons which have a depth of from 3,000 to 

5, 000 feet. The course of the upper and main parts of these streams could 

have been but little Influenced by the floods of basalt even had they filled their 

canyons up to a level of 3,000 above the sea. They would in short time have 

reexcavated th~ir canyons in the lava covering the bottom, and the main features 

of the great canyons would not have been changed. Only the lowest river 

· course~~ below a point where the lava flooded the divides of the canyons, would 

have been different. , 

vVe thus come to regard the whole canyon system of the main fork of the 

Salmon above Freedom and the similar system of the Clearwater above Stuart and 

Harpster as a very old one, laid out as a constructive drainage on the slightly 

westward sloping plateau of the Clearwater Mountains. Its canyons were 

excavated almost to their present depth in 1\tliocene time, before the Columbia 

River lava had flooded their lower reaches. Probably the grade was somewhat 

steeper, the post-Miocene erosion having succeeded in gradually reducing their 

gradient. The preser:t steep slopes of the canyon walls have been retained, and 

are most emphasized near the stream lines because of the damming of the lower 

reaches to elevations of 3,000 feet during the Miocene. 

Below the point where the lavas covered one or both of the confining ridges 

of the canyon the new river course would probably leave the direction of the old 

valley and follow the chance inequalities of the lava plain. A second series of 

constructive drainage would thus be outlined, and of this kind is the canyon of the 

Clearwater below I:Iarpster, the canyon of the Salmon below Freedom, and the · 

great canyon of the Snake River in practically its entire course between Huntington, 

Oreg., and its junction with the Columbia. In the Clearwater River, lava is first 

encountered in the bottom of the stream a few miles below Harpster. Consulting 

Pl. I, we may conclude that the Miocene canyon turned westward from this 

point and continued below Lawyers C~nyon. From here it either extended northwesterly , below Big Canyon toward Lewiston, or, less probably, followed the 

depression between Craig Mountain and Cottonwood Butte in a southwesterly 

direction. Beyond Big Canyon all is covered by basalt~ and the direction of the 

old river is copsequently impossible to determine from surface indications. That 

an important tributary" joined this river below the Lewiston Plateau is indicated 
GEOLOGY OF THE LAVA PLATEAU. 79 

by the deep depression, bringing lava to the bottom of the Clearwater Canyon 

between Greers Ferrv and Oro Fino. . ~ 

In a similar way the pre-Miocene trench of th.e Sal:non River must have continued below the lava plateau between the Snake and the Salmon, and probably 

crossed the present canyon of the Salmon a few miles above its mouth and · the 

Snake River Canyon between Grande Ronde and W aha. 

As stated above, the canyon of the Snake River is of :Miocene date and differs 

entirely from the pre-Miocene valley through which the drainage of the great 

Snake River Valley found its outlet. The relations of lava and bed rock along 

the course of the Snake River Canyon from Huntington down indicate that this 

pre-Miocene trench began near Weiser, Idaho, crossed the present canyon about 

the mouth of Pine Creek, and continued northwesterly between the Seven Devils 

and the Eagle Creek Range. 

Wherever along canyon8 the contact lines between lavas and older rocks reveal 

the old topography its accentuated character is prominent. It is thus at Waha, 

at the mouth of the Grande Ronde, at Freedom, and at Harpster. In the lower 

reaches of the rivers the old channels were cut deeper down into the bed rock 

than the present trenches have been enabled to ·do, although they have -been 

excavated so deep that at present the river at Lewiston is only about 725 feet 

above the sea. This leads us to the conclusion that the region of the Columbia 

River lava along the mountains of Idaho has been depressed, and that it is a field 

, of subsidence of epeirogenic character. This hypothesis I first formulated in a 

report dealing with the general geology of south-centraJ Idaho ct and repeated · it in 

a later report on the Blue Mountains of Oregon. b Professor Russell has_ also 

arrived at the same conclusion. c 

The problem would be less difficult if the surface of the lava everywhere 

approximately followed the 3,000-foot contour, as it mostly does along the foot 

of the Clearwater Mountains, but such is not always the case. On Mount Idaho and 

on the plateau between the Salmon and. the Snake the basalt flows rise to elevations 

of 4,000 and 5,000 feet. Near the SevenDevils and the Eagle Creek Range they 

even attain 6,000 and 7,000 feet. Professor Russell c reasons that because the ,lava 

sheet is in places 4,000 feet thick the top sheet must have had at least that 

elm .,.ation above the sea, unless the old land surface was below the level of the 

sea, which is admittedly improbable. From this it might be expected that, since 

the lava sheets in eastern ·vvashington and Oregon and adjacent portions of Idaho 

are still horizontal, the surface of the plateaus thus formed should have an elevation of at least 4,000 feet above the sea. Instead, we find in numerous instances 

that the general elevation of the plateaus underlain by essentially horizontal lava 

a Twentieth Ann. Rept. U.S. Geol. Survey, pt. 3, 1900, p. 96. 

bTwenty-second Ann. Rept. U.S. Geol. Survey, pt. 3, 1902, p. 598. 

cWater-Sup. and Irr. Paper No. 53, U.S. Geol. Survey, 1901, p. 54. 
80 BITTERROOT AND CLEARWATER MOUNTAINS, MONT,-IDAHO. 

sheets Is between 3,000 and 3,300 .feet. This difference between the present 

elevation of the locally undisturbed plateaus and what is assumed to have been 

their original position indicates a subsidence of about 1,000 feet, which may have 

gone on during the time in which the lava was being extruded or may have occurred 

in part or wholly since the last sheet was spread out. Proceeding on the same 

lines, Professor Russell concludes that where slightly inclined strata of lava are 

found which stand high above the general level of 4,000 feet they have been 

upraised, and vice versa. The above line· of reasoning starts with the assumption 

that the basalt spread out under hydrostatic conditions. This can not be unqualifiedly admitted to be true; for it seems well possible that !lear the points of 

eruption the sheets may have been piled up to gently sloping accumulations considerably thicker than elsewhere. 

It is certain, however, that the course of the whole canyon of the Snake River 

and of the lower canyon of the Salmon River is difficult to explain except on the 

assumption that they were originally laid out over an approximately level plateau 

which has been gradually raised simultaneously with the cutting of the canyon, 

thus giving them the character of antecedent streams. The course of the Snake 

River Canyon has been established across the high plateaus at present 5,000 to 

7,000 feet above the sea, whereas if no uplifts had occurred other directions would 

seem to have offered a far more natural outlet for the stream. 

In conclusion it is believed that the region of the Columbia River lava has 

suffered a general subsidence accompanied by more localized uplifts. 

PLACE OF ERUPTION OF THE BASALT. 

There is no evidence of the existence of ash cones or tuff volcanoes within 

this part of the Columbia River lava formation, and it is thus more probable that 

the eruption of the fluid rock took place, without explosive action, from fissures 

from w_hich the basalt flowed readily and continuously. No dikes of basalt were, 

however, observed in the foothills of the Clearwater Mountains, and we are thus 

forced to seek the focus of the eruption elsewhere. Only one local center of 

eruption has thus far been discovered. This locality is in the Eagle Creek Range, 

Oregon, and has been des~ribed in detail in a previous report. a A perfect network 

of basalt dikes here intersect the schists and granites near Cornucopia at elevations 

of about 7,000 to 8,000 feet, and immediately below this place the lava plateau 

begins. 

While the total thickness of the sheets sometimes reaches 4,000 feet, the 

average depth of the Columbia River lava is ordinarily much less in the region 

here described, 3,000 feet being probably the maximum and 2,000 feet possibly 

the average. 

a Twenty-second Ann. Rept. U.S. Geol. Survey, pt. 3, 1902, pp. 740-745. 
GEOI,OGY OF THE OOEUR D'ALENE MOUNTAINS. 81 

COEUR D'ALENE MOUNTAINS. 

The geology of these mountains is practically unknown, and this may be the 

excuse for publishing the following brief notes taken during 1899, on a trip 

from Lewiston to Spokane and thence across to Montana by way of Mullan Pass. 

A short stay was made at the Coeur d'Alene mines, and such notes regarding 

these important lead deposits as are available will be found on page 108. 

Going north from Lewiston on a branch of the Northern Pacific Railway one 

soon ascends the Uniontown Plateau, which has an elevation of 2,500 feet, and the 

route continues for 50 miles northward just west of the Washington-Idaho line, 

over a rolling open country of Columbia River lava, well cultivated and forming 

a ·part of the rich wheat lands of the "Palouse country." Spurs of older rocks 

project from the Coeur d'Alene Mountains and points of the same in places reach 

up above the general surface of the lava plateau. Of the former kind are the 

Cedar Mountains, near Moscow, Idaho, consisting of quartzite and granite, and 

the Tekoa Spur from the Moose Creek Mountains, which consists of slate. Of the 

latter kind are several quartzite points north of Pullman, as well as the Steptoe 

and Kamiack buttes described by Russell. a Fifteen miles from Spokane the road 

crosses an area of very decomposed granite, locally used for the manufacture of 

fire bricks, and descends to the Spokane River, which near Spokane is flanked 

by basalt flows. These are underlain by fluviatile or lacustrine clays, which are 

probably younger than the Columbia River lava. 

From Tekoa a branch road runs up to Coeur d'Alene Lake and thence eastward 

across Mullan Pass into Montana. Along this line th~ formations seen are as 

follows: 

After crossing slates and quartzites, a spur frorp the small complex known 

as the Moo~e Creek Mountain, the basalt begins again near Coeur d'Alene Lake and 

rises to bluffs forming a plateau 500 feet above the water (elevation about 2,500 

feet). The Columbia l·Uver lava continues up the Coeur d'Alene River a few 

miles east of the lake, and then begins a sedimentary series of great thickness, which 

continues with west-northwest or northwest strike almost uninterruptedly to 

Missoula, Mont. The mountains consist of a maze of steep, narrow ridges, 1,000 

to 3,000 feet high, the level crest lines of which have an elevation of from 5,000 to 

6,500 feet. This region should be regarded as a very extensively dissected 

plateau. At first banded quartzitic slates prevail. North of Wardner the prevailing strike of the slates is N. 62° W. and the dip about 50° NNE. At 'Vardner 

the rock is a heavy-bedded gray quartzite, of medium grain; the bedding planes 

strike N. 7oc W. with a dip of 60° SSW. Quartzite continues up to Burke and 

a Water-Sup. and Irr. PapE>r No. 34, U.S. Geol. Survey, 1900. 

5995-N o. 27-04-6 
82 BITTERROOT AND CIJEARW ATER MOUNTAINS, MONT.-IDAHO• 

,Mullan, occasionally with narrow intercalated bands of clay slate. A mass of 

granite breaks through the quartzite between Niriemile Creek and Canyon Cre.ek 

at Burke and is believed to stand in some genetic connection with the ore deposits. 

Possibly this granite continues northward to Murray, where gold placers and 

veins have been found. From Mullan Pass the railroad follows down the St. 

Regis de Borgia River for 30 miles, where it joins the Missoula; from this point 

it skirts. along the Missoula River for 60 miles to a point near the town of the 

same name. The general direction of the road ,, is east-southeast from Mullan 

Pass. Along this whole distance the prevailing rock are banded quartzites and 

slates, which strike northwest 'and dip variably but generally at 30° to 50° 

NE . . Interbedded with the quartzites 30 miles west of Missoula are purple slates 

similar to those found on Lolo Fork. 

The whole series from Missoula to Coeur d'Alene Lake is evidently folded 

and compressed, and its thickness must be very great. Its age is unknown, but 

may well "9e pre-Cambrian. 

ECONOMIC GEOLOGY. 

GENERAL FEATURES. 

Character of mineral deposits.-The valuable mineral deposits occurring in 

the area described in this report chiefly consist of fissure veins containing gold, 

together with associated placers, derived from the disintegration of the ve~ns. 

Deposits · containing lead and copper, usually also silver, occur also in several 

scattered places. Coal of an inferior quality has also been ·found in the upper 

Bitterroot Valley and in the lower Clearwater dr~inage. The lead-silver veins 

of the Coeur d'Alene Mountains are outside of · the limits of this reconnaissance. 

Distribution of dtposits.-The metalliferous deposits are grouped in two belts. 

The first is along the western side of the Bitterroot Mountains, chiefly in Montana; 

the second is along the western foot of the Clearwater Mountains, in Idaho. 

The deposits of each of these two belts are again principally grouped in two 

regions forming the four corners of the mountain area involved, while the central 

part of the Clearwater Mountains appears to be practically barren. The four 

metalliferous areas are distributed as ,follows: The first occupies the lower Lolo 

Fork and the northern end of the Bitterroot Mountains; the second is found on 

the headwaters of the South Fork of Bitterroot River, and reaches over into 

Idaho, connecting with the mineral belts at Shoup and Gibbonsville; the third, the 

most important area, includes Elk C1ty, Buffalo Hump, Dixie, and Florence, as 

well as numerous places along the South Fork of Clearwater River; the fourth 

area centers in Pierqe, but also extends to the headwaters of Lolo Creek on the 

south and to the North Fork of the Clearwater on the north. 
CHARACTER OF ORE DEPOSITS. 83· 

Character .of ore.-The primary. deposits are almost exclus]vely fissure veins 

and with them are associated extensive placers of an age ranging from Miocene or 

Pliocene to recent. In the northern Bitterroot .lVlountains and on Lolo Fork veins 

occurring in pre-Cambrian (~) schists chiefly contain copper, lead, and silver, 

although some gold is ~lso found on Lolo Fork. The Curlew mine at the eastern 

foot of the Bitterroot Mountains contains argentiferous galena, and is located 

on a fissure between limestone (pre-Cambrian~) as the foot wall and, according 

to accounts, Pleistocene valley gravels as a hanging wall. The mine is not worked 

at the present time. On the upper Bitterroot River veins cutting porphyry 

likewise chiefly carry copper and silver, while argentiferous galena is also known 

from the Monitor mine, worked on a vein in gneiss on the divide between Bitterroot and Salmon rivers. Gold-bearing gravels have been mined for many years 

on Hughes Creek. Southward this belt connects with the gold-bearing deposits 

at Gibbonsville and Shoup. The rocks at Hughes Creek and Gibbonsville are 

pre-Cam brian ( ~) quartzites and slates. 

West of these districts extends a wide granite area which as far as known is 

barren of mineral deposits. There can be no doubt that the Clearwater drainage 

was very thoroughly prospected for placers during the early days of mining, but 

outside of the South Fork very little of value has been found. In the upper part 

of the mountains the glaciation would naturally have swept away any placer 

deposits which may have existed, and in this denuded portion it is not impossible 

that veins may be found.' Nothing of much value has been encountered up to 

the present time. A large vein containing silver is reported to occur on Rhodes 

Peak north of the Lolo trail. Along the Salmon River the conditions are probably more favorable and prospecting in the isolated region betwe~n Dixie and 

Shoup might possibly develop something of value. 

As stated before, the western belt chiefly contains gold; only a few scattered 

copper deposits are known. The placers of Elk City and Florence are well 

known in the history of Idaho and are still worked to some extent. Veins 

which furnish the material for these placers are known to occur in all these 

localities; the principal mining districts are Florence, Dixie, Elk City, and Newsome Creek. The veins, chiefly . occurring in gneiss, are almost exclusively of 

quartzose character and contain from 1 to 10 per cent of sulphurets, besides 

more or less native gold. The Buffalo Hump distr~ct, discovered in 1898, is situated on the high divide between the Clearwater and the Salmon, and contains in 

granite and slate many strong quartz veins, with a varying percentage of free gold 

and auriferous sulphides. Active work is in progress there at the present time. 

The northwestern _mineral-bearing area contains pla<eers along Lolo Creek, Musselshell Creek, and Oro Fino Creek. .lVlany quartz veins of similar character to 
84 BI1'TERROOT .A.ND CLEARWATER MOUNTAINS, MONT.-ID.A.HO. 

those from the· southwestern belt are also worked in these districts. The:y are 

generally incased in schists; more rarely in granite. Veins of sulphide ores, containing gold and copper, occur in amphibolite close to .!Vlount Idaho. 

History and production.-The deposits on the eastern slope of mountains have 

not proved of great importance and have chiefly . been discovered and worked at 

a comparatively recent time. The total production of all the mines on this side of 

the mountains probably does not exceed $1,000,000, of which the larger part has 

been derived from the Curlew mine on the north and from the placers of Hughes 

· Creek, near the head of Bitterroot River. The important gold belt on the western. slope was discovered about 1860, and very actively worked during 'the following 

years. Oro Fino, or Pierce, is reported to be the earliest discovery in Idaho. It 

was found in 1860, and during that season twenty-five men wintered there. The 

gravel near Pierce was not remarkably rich, but paid fairly well in 1861 and 

1&62.a In 1874 Pierce produced $70,000. Soon after this, however, the discoveries' in Montana drew most of the miners away from this place, and in 1867 but 

little mining was going on. Since that time, however, the placers and quartz 

mines have been worked each year, although in a somewhat desultory manner. 

The total production is impossible to ascertain, but probably has not exceeded a 

few million dollars. 

During late years placer mining has been carried on both in the low stream 

gravels and on the benches. There has also been a considerable activity 1ll quartz 

mining, and several small. mills have been built. The output of the placer mines 

in 1902 is estimated at $30,000, and that of the quartz veins at the same amount. 

Elk City and vicinity proved to be of greater richness. Few quartz mines 

have been worked there, practically the whole production being derived from the 

placers. In 1863 or 1864 the white miners began to leave this field, which they 

considered about worked out, and for nearly thirty years there were only two or 

three of them left in the district, which was almost entirely turned over to the 

Chinese. In 1892 the white miners began to come back, and the. Chinese simultaneously disappeared, very few of the latter being left now. A certain amount of 

placer work is still done in this vicinity each year, chiefly on bench gravels. 

The bars of the Clearwater River, which were worked extensively during the 

early days, are still occasionally washed. Regarding the total output of Elk City 

no satisfactory figures are availa~le, but not unlikely the production amounts to 

between $5,000,000 and $10,000,000. 

After the first few years of abundant production the output fell rapidly. In 

1874 Elk City (including Newsome Creek and Clearwater station) produced 

$120,000. From 1882 to' 1887 the Elk City district produced from $35,000 to 

$73,000 per annum. During the recent years the output has again increased, due 

«Browne, J. Ross, Report on Mineral Resources, Washington, 1868. 
PRODUCTION OF ORE. 85 

to the introduction of dredging and hydraulic operation, and during the last years 

has probably been from $20,000 to $40,000. Very similar were the conditions 

during later years in Florence, which camp has been described in a previous 

report.a The total output of Florence was, however, considerably larger than at 

Elk City. 

Florence, Warren, and Elk City are situated in Idaho County. According 

to the mint reports this county has, since 1880, produced an average of $200,000 

per annum, or a total of about $6,000,000. Something like one-half o£ this amount 

probably comes from Warren, leaving $3,000,000 for the two last camps ·for the 

last twenty years. Pierce is located in Shoshone County.b 

It is somewhat surprising that in spite of the recent activity in prospecting and working quartz veins the production of Idaho County should have 

decreased during the last few years. The mint reports give for Idaho County: 

Production of precious metals in Idaho County, Idaho. 

1895- - - -- - - - -.- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- -- $243, 700 

1896- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 155, 350 

1897- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - " - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - . - - - - 236, 500 

1898- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 203, 500 

1899- - - - -- ~ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --- - - - - - - - - - - - - - - - - - - " 166, 000 

1900_---------------------------------------------------------------------- 152,000 

1901_------------.. --- - ---------------- .. ------------------------------------ 161, 500 

1902_---------------------------------------------------------------------- 157,023 

Geological relations.-Nearly all of. the vein deposits occur in granite-gneiss 

or metamorphic slates and schists; the prevailing strike of the veins seems to be 

in an east-west direction. The granite, which is the prevailing rock, represents 

the northward continuation of the great area of central Idaho north of Snake 

River. Gold-bearing veins occur both within this area and along its contacts 

with the surrounding older sedimentary rocks. 

Within the region here discussed a peculiar relation obtains. The large 

central areas of granite, whether sheared, as along the eastern margin of the 

Bitterroot Mountains, or massive, as usually is the case, seem conspicuously barren of deposits. The vein systems appear in or close to the four smaller areas of 

sedimentary or metamorphic rocks which are found at the periphery of the great 

central granite area. It is thus in the quartzitic series of Lolo Fork, in the 

quartzites, slates, and gneisses of the upper South Fork of the Bitterroot, and in · 

the old gneiss areas of Elk City and Pierce. While the age of the ·quartz veins is 

not established beyond doubt, it is probable that they were formed during the 

latter part of the :Mesozoic era. 

aThe gold and silver veins of Silver City, De Lamar, and other mining districts in Idaho: Twentieth Ann. Rept. 

U. S. Geol. Survey, pt. 3, 1900, p. 233. 

b Ibid. , p. 238. 
86 BITTERROOT .AND CLEARWATER MOUNTAINS~ MONT,-ID.AHO. 

NORTH END OF BITTERROOT RANGE. 

Lolo Fork.-The gravels of Lolo Fork are said to contain a little placer gold, 

although there are no evidences of extensive workings. Quartz veins containing 

gold and copper are found in the calcareous quartzites 5 miles above the mouth 

of the river. One of these, called the Chickerman vein, crops' half a mile below 

"-Testerman's ranch. The quartz contains a little chalcopyrite and an 8-stamp mill 

was erected on the property in 1889. There is no evidence, however, of longcontinued working. One mile below Westerman's, on the south side of the 

river, is another quartz vein containing copper minerals and referred to as the 

Sherman and Lattimer claim. 

Som.e copper prospects are located 9 miles above _ the inouth of the river and 

2t miles above "\\Testerman's ranch. The best prospects are contained in the limestone in W oodmans Creek, a tributary entering Lolo Fork -from the north. A 

quarter of a mile ~rom the river a vein crosses the gulch with a northeasterly 

strike. The decomposed croppings were worked in arrastre many years ago, the 

shallow oxidized zone having produc~d about .$5,000. The tunnels driven in from 

Woodmans Creek have developed some good-looking copper ore, chiefly containing 

chalcopyrite and bornite. Five carloads of ore are said to have been shipped. 

About a thousand feet above this vein a dike of dioritic rock 10 feet wide appears 

in the bottom of the canyon. This rock contains chalcopyrite and specularite 

scattered through its mass. 

Mormon and Carlton creeks.-Several quartz prospects have been located on 

Mormon Creek, which heads near Lolo Creek and empties near the mouth of 

Lolo Fork. There is a considerable evidence of mineralization in this vicinity, 

and the zone is probably the continuation of the vein systems described from the 

lower · L~lo Fork. 

One mile north of Carlton Creek the quartzites bear evidence of some miner· 

alization along the foothills of the Bitterroot Range, and this again may be 

considered to be a general continuation of the mineral belt referred to above. 

Few other prospects are known in this vicinity. It is stated, however, that 

galena veips have been found and prospected high up in the mountains on. Bas~ 

Creek, a short distance north of St. Marys Peak. 

Curlew mine.-This deposit, which has produced a considerable amount of 

silver~bearing lead ore, is situated in the· first foothills of the Bitterroot ~ange, 

at an elevation of 3,533 feet, 14 miles north. of Hamilton and just south of the· 

mouth of Big _Creek Canyon. The mine is situated at the very point where the 

first foothills emerge from the Pleistocene of the valley. For a distance of half 

a mile ·west of the mine the rocks consist chiefly of limestones and quartzites, 

both usually much shattered and without clearly defined bedding. In places the 
ORE DEPOSITS OF BITTERROOT RANGE. 87 

quartzites grade over into typical contact metamorphic hornfels. The normal 

gneiss of the Bitterroot Mountains adjoins the quartzite and is well exposed along 

the canyon of Big Creek, the dip being, as usual, 25° E. 

The deposit was not discovered until 1888, and was worked from that time 

until 1893. The total production is reported to have been $800,000. The principal developments consist of a perpendicular shaft 500 feet deep with crosscuts 

on several levels to the vein. The deposit shows few distinct· outcrops, but as 

developed by mine operations strikes north and south and dips 45° E. The 

working~ are naturally not accessible at the present time, the shafts being filled 

with water, and the information here given was communicated to me by the 

former foreman of the mine, Mr. Thomas Corvan. The ore principally consists 

of galena; the first-class ore contained 55 per cent lead, 125 ounces of silver, and 

from $2 to $7 gold per ton. The ore body was found along a well-defined fissure 

on an average 10 feet wide and was all along on the east side protected by a thick 

water-tight cover of clay. Drifts penetrating this clay broke into gravel and 

sand containing much carbonized wood. 

From this information, which is doubtlet-3s correct, it would appear that the 

vein occupies a fault fissure between the quartzite and the Pleistocene gravels of 

the valley. This, besides being most unusual from a mining standpoint, has a 

structural significance which has been further discussed on page 48. 

A few hundred feet west of the shaft is a prominent outcrop showing traces 

of copper, lead, silver, and gold. ·This is probably part of a vein which continues 

southward for half a mile to the Whippoorwill claim; it is in badly crushed lime 

and quartzite the entire distance. Northward this second vein continues to the 

east Curlew shaft where it was mined by the Curlew Company and found to 

contain a rich body of galena ore; $200,000 are said to have been extracted from 

this shaft. 

The Pleasant V?:ew prospects.-Several quartz veins containing silver have been 

prospected in the first foothills of the Bitterroot Range about 10 miles northnorthwest of Hamilton and at an elevation of about 3,900 feet. The country 

rock is a granite forming a small area in front of the usual gneiss of the Bitterroot Range. The prospects are not worked at the present time and the developments are qot extensive, chiefly consisting of two or three shafts of a maximum 

depth of 100 feet. Th.ere is one especially strong quartz vein with a northeasterly direction. The ore consists of quartz containing a little pyrite and tetrahedrite. The values are chiefly in silver. 
88 BITTERROOT .AND OLE.ARW .ATER MOUNTAINS, MONT.-IDAHO. 

UPPER SOUTH FORK OF THE BITTERROOT. 

Trapper Oreek.-No deposits are known to occur south of the locality just 

described until the southern end of the range is reached; no placers have been 

worked and the creeks appear to be barren of even traces of gold. A quartz 

vein was noted on Trapper Creek, near the south end of the range and about 

3t miles from the mouth of the canyon. This is a shear zone 6 to 8 feet wide, 

occurring in granite, and containing several stringers of quartz. The strike is 

north-south and the vein stands nearly vertical. An assay was made of the 

quartz from this prospect, the result showing 0.06 ounce of gold and 0.30 ounce of 

silver per ton. No deposits of any kind have been reported from the Nez Perce 

Pass, or the creek leading up to the pass. 

Slate Oreek.-About 18 miles $Outh of the forks of the river Slate Creek 

joins it from the east. On this tributary are located several veins which were 

visited by Mr. G. W. Stose. The elevation at the mouth of Slate Creek is 

4, 700 feet. Near the entrance to the gulch are four or five cuts on the north 

slope on quartz- veins containing .. calcite and tetrahedrite. These prospects are 

contained in granite-porphyry. On Slate Creek, several miles above its mouth, 

a well-defined vein crosses it with a direction a little west of north. On this 

vein, which cuts through granite, quartzite, and porphyry several locations have 

been made. The one next the creek is called the Moon mine, and is continued 

southward into the "Tiptop."· At this place is exposed 6 feet of quartz dipping steeply to the west. The ore contains bornite, chalcopyrite, and tetrahedrite. 

The third. location visited is '' Dynamo" which is deyeloped by a shaft 35 feet 

deep. Other prospects are located a short distance north of the Dynamo and ; 

among them is mentioned the Empire and the Carney. These are said to contain galena and chalcopyrite. · It is not known that any of the prospects on Slate 

Creek have any considerable production to their credit. 

Hughes Oreek.-Eight miles south of Slate Creek, and about 10 miles north 

of the Salmon River divide, Hughes Creek joins Bitterroot River from the 

east. At its mouth is located the post-office of Alta (elevation 5,160 feet). The 

rock exposed here and for long distances above on the. gulch is a heavy-bedded 

quartzite. For· about 10 miles above the mouth the creek has a rather wide 

bottom with occasional meadows. In places the width of the bottom lands is 

a quarter of a mile. . The walls of the canyon ascend with steep slope to a 

thousand feet or more above the bottom. Hughes Creek is known since . the . 

early days of mining as gold-bearing, and a continuous string of claims cover 

the bottom from the mouth up to the divide, 15 miles distant. For 10 miles 

above the mouth the gravels are deep, and bed rock has not been reached. At 

present the principal operations are carried on in the upper part of the creek. 
ORE DEPOSITS OF BITTERROOT RANGE. 89 

The gold is generally coarse and occurs in flat grains accompanied by garnets 

and black sand. All along, gravel terraces accompany the watercourse, although 

in many places they have been removed by erosion. Near the mouth there is 

a gravel bar 50 feet above the stream, and another one 200 feet above the same. 

Evidences of still higher gravel bars are found up to an elevation of 500 feet 

above the bottom, and many claims are located on these high bars. Whether 

any of these occupying larger areas near the mouth . of the creek will pay for 

working itl not certain. 

In 1899 at least three companies were working the creek, the first consisting of Orton, Molloy & Co. These men were ground sluicing-shoveling the 

material into the sluice bbxes. A little higher up are the Keating claims. One 

mile above this the \\rood Placer Company was beginning operations on a larger 

scale, using an elevator. In 1902 it was reported that the Yvood Placer mines 

had been purchased by eastern capital and that a 4-mile ditch was being constructed which will furnish a pressure of 300 feet. The company expects to 

operate two giants. Stream tin is frequently found with the gold in this creek. 

Johnson Creek, a few miles above Hughes Creek, is also said to contain a 

little gold. 

Mineral Point.-This mining district is located about 6 miles north of the 

Salmon River divide, near the head of Bitterroot River, at the point where the 

stream splits up in several branches. The elevation is about 5,560 feet. The 

formation consists of quartzitic and chloritic schists. A number of copper- bearing 

veins have been located in this -vicinity, and ' some small shipments are said to 

have been made. The first prospects are located on Woods Creek, about 1 mile 

west of the main ri-ver. The croppings are found near the contact of the quartzite 

with gneiss or pegmatitic granite. The de-velopments are -very slight. The rusty, 

decomposed ore shows pyrite, limonite, and azurite. The principal prospect in 

the Mineral Point district is said to oe the Copper Queen, located near the road 

at the upper end of the meadows on the main fork. The ores are principally · 

chalcopyrite, containing a little gold and sil-ver; none of the gold is free. The 

showings on the surface were good, but a 400-foot tunnel run 100 feet below the 

croppings only de-veloped schists impregnated with pyrite containing a little gold 

and copper. The best ore of the Copper Queen contained, it is said, from 5 to 20 

per cent of copper and 11 ounces of sil-ver, with a few dollars in gold per ton. 

Many other irregular -veins of quartz stained with copper and showing e-vidence· 

of considerable pressure and deformation were noted in the vicinity. 

Up toward the adjacent district of :Mineral Hill are se-veral -veins in granite 

or g·neiss containing galena and arsenopyrite with from 6 to 24 ounces of silver 

per ton. The pre-vailing strike is northeast and southwest, while the -veins generally dip 70° S. 
90 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

Mineral Hilt.-This district adjoins Mineral Point on the south and is chiefly 

located on the upper slopes of the hills which descend toward Salmon River. 

South of it, and almost connecting with it, is the gold-mining district of Shoup, . 

in the canyon of the Salmon River. This, however, was not visited. 

The veins of Mineral Hill are chiefly located in the . upper part of Owl Creek, 

on the ridge south of Blue Nose Mountain, and also in the upper part of Horse · 

Creek. The veins occur in a coarse gneiss cut by many dikes of granite. The 

only prospect worked in 1899 wa~ the Monitor, located at the head of Owl Creek, 

at an elevation of 7,500 feet. A ' road was being built about this place :from 

the headwaters of Bitterroot River. The Monitor is a 5-foot quartz vein .with 

an east-west strike and containing scattered bunches of galena. A shaft was sunk 

on it to a depth of 50 feet and a considerable amount of· ore has been shipped. 

It contained lead, with up to 100 ounces of silver, and a little gold~ 

Near the head of Horse Creek, at an elevation o~ 6,900 feet, are several veins 

striking east and west and dipping 40° N. The quartz contains a little galena and 

pyrite and is slightly copper stained. Several tunnels have been run on these 

veins which, however, at the time of visit, appeared to be abandoned. 

GIBBONSVILLE DISTRICT. 

The Gibbonsville mining district is located in Idaho, on a tributary of Salmon 

River, and only about 10 miles distant in a straight line east of the Mineral 

Hill district just described. Gold-bearing quartz veins are found near Gibbonsville, and have been worked for many years with varying success. Some years 

ago the American Development and . Mining Company, who owned the principal 

mines in the di~trict, introduced barrel chlorination to treat the ores. This 

was not found to be in ·all respects satisfactory, and lately a cyanide process 

has taken its place. The district was visited by Mr. W. H. Weed in 1898, who 

kindly put the following notes at my disposal: The rocks at Gibbonsville are 

steely gray, quartzose, and micaceous slates, thinly laminated. The slates strike 

north and south, and dip from 35° to 65° to the east or to the west. . The quartz 

veins run nearly east and west, sometimes southeast and northwest, while the dip 

is northerly. The main tunnel by th~ American Development and Mining Company cuts at least six veins, with sharp, smooth walls, varying in thickness from 

a few inches up to 15 inches. The quartz carries abundant pyrite, and contains 

from $30 to $50 in gold, tog.ether with about $1 in silver. The oxidized part of 

the veins is free-milling, while below that zone very little native gold appears. 

Occasionally the quartz veins are banded or ribboned by parallel fracture planes. 

While the veins are very persistent, they are not uniformly ore-bearing, and no 

absolute regularity of the distribution of the ore has been observed. 
. ' 

PLACERS OF ELK CITY DISTRICT. 

ELK CITY DISTRICT. 

PLACER MINES. 

91 

Important placer mines have been worked for many years on the upper 

·tributaries of the South Fork of the Clearwater, th!s w~ole producing region being 

referred to as the "Elk City district." Placers occur on Red River and its 

numerous tributaries, on Red Horse Creek, American Creek, and Elk Creek; finally, 

on Crooked River, Moose Creek, and Newsome Creek. Below this point the .gravel 

bars of the South Fork have been mined for many miles-at least, in placesas far down as Stuart, at its junction with the main fork of the Clearwater. 

The Elk City diggings were discovered in 1861. During the following years 

the activity was great, and the production doubtless amounted to several mil1ion 

dollars. The gravels in the bottoms of the streams were generally too low to be 

easily reached, and most of the operations were confined to the high bars and 

gravel terraces. In many places in the vicinity of Elk City the so-called ''skim" 

diggings yielded largely, this class of deposits embracing the shallow concentrations of placer gold over large areas within a foot or two of the surface. For 

many years after the first few seasons of heavy production the camp was turned 

over to the Chinese. Renewed interests in the placers were, however, taken by 

white men during the last ten y·ears, and in 1899 several deposits ;vere actively 

worked on a fairly large scale. 

The production of this district has been referred to on page 84. Suffice it 

to say that since 1875 it has yielded something like $30,000 to $70,000 per annum. 

As there is a fairly large amount of workable deposits remaining, a moderate 

output will probably be continued for many years; very likely, however, with a 

decreasing tendency. A map on a larger scale is shown in fig. 7. 

_Red River.-Coming down into Red River from the Nez Perce trail much 

quartz-gravel is seen in the main stream and its tributaries. In many of the latter 

are abundant ~vidences of old and extensive placer mining. At French Creek, 

a tributary entering Red River from the north a short distance belo~ the post-

. office of Raymond, and at an elevation of about 4,500 feet, a dredger was working the old tailings and the gravels underneath them. This dredger is owned by 

the same company which was operating the hydraulic mine at American Hill. 

Along Red River, bottom lands and meadows extend from Ryan's ranch for 

6 miles down. Below this point the river flows in a narrow canyon, opening up 

again near the mouth of American River and Elk Creek. Many placer mines 

are located along the gulch gravels of Red Horse Creek, which heads near Anderson Butte and empties at the lower end of the Red River meadows. Within 

this upper basin just described there are few evidences of terraces · or high 
92 BITTERROOT AND CLEARWATER MOUNTAINS, MONT • .-IDAHO. 

I 

gravels, but a different condition of affairs appears ·as soon as the basin of Elk 

Creek and the American River is entered. 

J FIG. 7--Map of upper South Fork of Clearwater River, showing location of mining districts. 

The basin of Elk Creek and American River is occupied by a system of 

gravel benches filling the basin to an elevation of somewhat over 4,500 feet. 
PLACERS OF ELK CITY DISTRICT. 93 

From any prominent point the level of this gravel terrace is seen to skirt the 

valley for a long distance westward, and the higher mountains of Newsome Creek 

rise with more decided slope from this general level of deposition. For 2 or 3 

miles above its mouth Elk Creek, emptying into the South Fork of the Clearwater from the north, contains broad bottom lands and meadows. A first 

bench is marked fairly clearly 50 feet above the creek and is covered with wellwashed quartz grav~l. This bench is well exposed at the little settlement of 

Elk City. On Little Elk Creek, about 3 miles above its mouth, the bottom 

lands narrow, and gravel ridges 100 feet high rise on both sides of the stream. 

At about 325 feet above Elk City, or an elevation of 4,525 feet, the abovenlentioned prominent level of deposition is reached. This terrace of well-washed 

gravel is seen to skirt the ridges separating Elk Creek from Newsome Creek 

and continues across the divide between Elk Creek and the headwaters of 

American River. Remains of this same gravel terrace are also found in the 

Crooked River basin, although here a more active erosion has removed a larger 

part of these old deposits. 

American Hill.-The most prominent gravel mine worked in 1899 is located 

at American Hill 1 mile southeast of Elk City, at an elevation of 4,200 feet, the 

elevation at Elk City in the upper part of the town being 4,200 feet approximately. The deposit at American Hill is owned by the Idaho Mining Company. 

About thirty years ago a little work was done here, chiefly in the nature of 

"skim" diggings and ~orne drifting. The present company eight years ago 

removed the gravel down to the bed rock and exposed an old channel of the 

American River running from northeast to southwest. One thousand miner's 

inches of water is used, and an elevator raises the gravel to a series of sluices 

aggregating 500 feet in length and having a grade of 5 inches in 12 feet. Aneroid 

measurements gave the approximate elevation of the bed rock as 4,165 feet, or 

about equal to the lower portion of Elk City, and not much higher than the bed 

of American River a short distance south of the mine. The bed rock consists of 

a soft, coarse gneiss intruded by abundant pegmatitic veins. The gold is fairly 

coarse, much of it being of the size of wheat grains. The slope of the bed 

rock is said to be from 3° to 4° vV.; the banks exposed in the pit, which has an 

area of about 700 by 200 feet, are from 60 to 100 feet high; the material exposed 

is prevailingly of a sandy character. 

The top stratum consists of 10 feet of gravel and clay. This stratum was rich 

and worked in the early days as ''skim" diggings. Below this follow 50 feet of 

sand, clay, and gravel interstratified. The lower portion of the deposit consists of 

20 feet of red gravel, underneath which is found 15 to 20 feet of bluish gravel 

which contains the principal quantity of gold. The gravel is mostly quartzose, 

and the large bowlders on the bed rock often contain native coarse gold. On 
·. 

94 , BITTERROOT AND OLEARW ATER MOUNTAINS, MONT, -IDAHO. 

~he south side of the pit the workings have exposed a decided bluff of bed rock 

30 feet above the general level of the bottom of the channel. Not unlikely this 

represents a .fault since the deposition of the gravel. , 

Tiernan Diggings.-A few miles above American Hill on the river of the same 

name are located some high gravels of considerable interest. The place is close 

to the road from Elk City to Raymond. The gravels are considerably higher 

than those at American Hill and they probably do not belong to the same system , 

of channels. Going east from Elk City a. high ridge . of gneiss is crossed. 

Descending again to American River a distinct bench covered with wash gravel 

is noted at an elevation of 4,300 feet. At the · bridge · the elevation is about 150 

feet less and the exposures consist chiefly of gneiss. 

Tiernan Hill is situated on the east side of the river, a short distance from 

the bridge. The bed rock has an ·elevation of 4,450 feet and the top of the bank 

4,580 feet. On the uneven bed rock lie thus 130 feet of sediments, chiefly consisting of sand and clay with some interstratified gravels. In former years a 

considerable amount of hydraulic work was d'one at. this locality and the amount 

of remaining gravel is probably not large. In elevation, Tiernan Hill corresponds to the high terrace skirting the Elk Creek basin, but' is, if anything, 

somewhat higher than this. It has the appearance as if this . deposit formed a 

part of a larger channel, the central bed of which has been removed by erosion. 

A little work is still done each year. 

Bttjfalo .liill.-The gravel mine of this name is situated on the north side 

of American River about a mile and a half southwest· of Elk City, and near the 

point where Elk Creek empties· into that stream. Something like 180 acres of 

gravel are contained in this isolated area. The larger part of this has already 

been mined by hydraulic operations, though a considerable quantity of poorer 

gravel still remains. Active work was in progress during 1899. The available 

fall is slight, hence there is some difficulty in disposing of the tailings. The 

flume is 2,000 feet long and has a grade of 3 inches in 12 feet, ·wooden riffie 

blocks being used. The size of the flume is 4 by 4 feet. The principal operations have been carried on on the north side of the hill, where several acres of 

bed rock are exposed. In front of this lies a considerable mass of tailings. 

The bed rock is throughout a soft, coarse gneiss of the kind so prevalent 

about Elk City. The configuration of the bed rock shows plainly .that the 

deposit is a part of an old channel of the American River. A high rim lies 

immediately north of that stream and is 150 feet above it. North from this rim 

the bed rock descends until at the principal pit the elevation is about equal to 

that of the bed of the American River. According to aneroid measurements, 

the elevation . is 4,150 feet, or about 50 feet lower than the average elevation of 

Elk City. 
PLACERS OF ELK CITY DISTRICT. 95 

The exposed banks show 40 feet of prevailing sand with some gravel. A 

somewLat coarse gravel rests immediately on the bed rock and consists chiefly of 

cobbles of quartz with some gneiss and also a large amount of black q~artzite; 

the latter is probably derived from an area exposed on Relief Creek a few miles . 

southward. 

The gold is both of a fine and coarse variety, hence the necessity for long 

sluices. It is as usual principally scattered on the bed rock. j 

North of Buffalo Hill, on Buffalo and Blackfoot gulches, the ordinarjr bed 

rock is exposed, although still higher up gravel of the upper. terraces is 

encountered. A very interesting feature is the exposure in the hydraulic pit of 

the mine of a few acres of so-called ''false" bed rock. ' This consists of a beries 

of heavy-bedded clays containing much coaly material, and is evidently a pJrt of 

a sedimentary series resembling lake beds which prior to the accumulatibn of 

the gravels covered a part of this country. On the northwest the clays ~order 

against gneiss, the separating plane b~ing a well-defined perpend-icular faultj line, 

the downthrow being on the southeast side. 

A mile to the southeast of Buffalo Hill is Gold Hill, situated on the lpoint 

between Red River and American River. The elevation of the bed rock or the 

south side of the road is here 4,300 feet; these gravels are thus 150 feet ~igher 

than those of Buffalo Hill. The thickness of the gravel at this point doe~ not 

seem to be considerable. Washing on a small scale is carried on at this lpoint 

each year. 

South of Red River the road from Elk City to Crooked River ascends 

Wheeler Creek, along which shallow diggings are found at intervals at elevations 

from 4,200 to 4,250 feet. The flat bottom of this stream has been ground-sluiced 

all the way up to the divide toward Crooked River, which has an elevation of 

4,900 feet. Much of the . gravel is of a suhangular character. A few well-washed 

quartz pebbles were noted almost up to the divide. 

Crooked River.-The road from Elk City to the head of Crooked River 

descends to the latter by way of Relief Creek. In the flat bottom of this, evidence 

of old placer diggings are found. Quartzite cobbles are very abundant, but no 

great amount · of bench gravels were seen. Crooked River and the gulches 

emptying into it have been worked for several miles above thi:::; point. The 

gravel chiefly consists of the present accumulations' in the creek, togethei· with 

smaller amounts of low bench gravels. The mouth of Crooked River was not 

visited, but it is reported that the Tacoma and Clearwater Mining Company 

was operating a hydraulic mine near this place. 

Little Elk Oreek.-Three miles north of Elk City the Little Elk Mining 

Company was preparing to wash the shallow gravels spread out over the bottom . 

of this creek. A short distance north of this point the actual gneiss bed rock 
96 BIT-r:ERROOT .AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

appears in the creek bottom, but the material on which the gravel rests at this 

mine is what is usually termed "false" bed rock. This consists here of clays and 

micaceous sands with a considerable amount of coaly material. ~ It is exposed at 

two places below the pay gravel and has a dip of 60° E. These beds have very 

much the appearance of being deposited in a broad river or lake and present 

great similarity to the beds of the same kind observed at Buffalo Hill. 

Newsome Creek basin.-About 6 miles due west of Elk City the Moose 

Creek diggings are located on t~e ridge dividing the creek of the same name 

from Newsome. The place was not visited, but from accounts the deposit appears 

to be of the same kind as that exposed at Buffalo Hill. The banks are said to 

_be 160 feet in height, the gold, both coarse and fine, varying from $16 to $19.20 

per ounce. This mine was operated in 1899. 

From Buffalo Hill the road to Har~ste!r, on the qlearwater River, ascends 

over a long ridge of wash gravel. The top of the terrace, which is the same as 

observed on the headwaters of American River, ·has an . elevation of about 4,450 

feet. Scattered wash occurs above this point up to an elevation of 4, 750 feet. 

Above this point the gneiss ris~s in low ridges. The same gravel terrace continues ,into ~4-e .. dr~inage of Newsome ·creek. This stream. has been washed all 

along its course, as have also the benches which accompany it at an elevation of 

30 feet above the water. The bottom is generally flat and filled with tailings to 

a width of 100 or 200 feet. An important gravel terrace appears 300 feet above 

the creek and is well exposed both on the east and west side of Newsome pos.toffice. T4e elevation of the bench is 4,400 feet. These high bench gravels have 

not been generally washed, though placer operations are frequently carried on 

in the small gulches which traverse the terrace and in which a secondary concentration has taken place. 

Along the So_uth Fork of the Clearwater the low bars have been mined for 

many miles downstream; at least as far down as Stuart. High gravels corresponding to those of American River and Newsome Creek were not observed. 

There are, however, occasional small gravel benches 200 feet aboye the river. In 

many cases these have also been washed. , The present production from this kind of 

mining is doubtless very small. 

QV.ARTZ VEINS. 

For many miles west of the mining districts at the head of the Bitterroot 

·River there are no indications at all of mineral deposits until the drainage of the 

Red River is entered, this being a tributary to the . Smith Fork of the Clearwater River. Near the head of Red River; on the Nez _.Perce ·i;tail, ·hetween Ten 

Dollar. and ·Mountain . Meadows, the .first ind!c.ations of quartz veins are found, 

and a . few pr p~~t 'holes "· have" been·''opened' on the ridges,·'wh1ch are covered by a : .. I -· • ) 

·· ';;:.o;•il l,.,, •. J' 

_, .... 
.U. S. GEOLOG

ICAL SURV~V PRO

FESSIONAL PAPER NO. 27 PL XV 
\ 
QUARTZ VEINS OF ELK CITY DISTRICT •. 97 

deep soil, the prevailing rock appearing to be granite. Descending into the · Red 

River, prospects are ag~in found on the ridge north of Ryans Meadows. From 

here on to Elk City, a distance of 10 miles, all creeks show evidence of placer- ! 

mining. operations, and occasional quartz prospects are noted. 

While the gravels near Elk City frequently conta~n quartz bowlders with native · 

gold, indicating the abundant presence of auriferous veins, very few of these 

veins have been actually found and . worked; . prospects are known from several 

places, among others on Red Horse C1·eek, but the developments are in all cases 

slight. The only quartz vein prospected during 1899 in this vicinity appears to 

be the Buster mine, which is located three-fourths of a mile north of Elk City, 

on the east side of Elk Creek. The strike is easterly and westerly, and the dip 

appea;rs to be 65° S. The deposit is a typical quartz vein of moderate width, con ~ 

taining pyrite, zinc; blende, galena and tetrahedrite. · The quartz is coarse and 

shows normal vein structure. Many long, slender crystals are embedded in a 

mass of smaller individuals. The surrounding rock. is gneiss, and the vein cuts 

across the schistosity. An assay of selected ore, without visible gold, gave 3 

ounces of gold and 6t ounces of silver per ton. No ore was being extracted 

during the time of the visit, and the developments are not extensive. Since 1899 

many new locations and generally increased activity in quartz mining are reported. 

The Newsome Creek basin con~ains importa·nt placer diggings, and many prospects have been found in the surrounding hills. None of them, however, have 

been extensively worked. A couple of miles north of Newsome post-office a 

small vein of normal comb quartz was found in gneiss, having a strike of N. 30° E., 

the dip being 20° to the N. This prospect is called the "Lookout" mine. A 

little higher up, in a gulch leading up from the east side ·of Newsome Creek, is 

the Iron Crown Yein. The elevation is here approximately 4, 700 feet. A mill 

has been er:ected, and is shown i~ Pl. XV, B . . Both mine and mill were being 

operated on a moderate scale at the time of visit, and a considerable amount of 

ore was produced every month. The developments were not yery extensive, the 

deposit having the peculiar form of a blanket yein of rusty, decomposed quartz 

from 2 to 6 feet wide and situated at a depth of only a few feet from the 

surface. The gold is free,_ ·which might be expected from the oxidized chatacter 

of the ore. The inclosing rock is the gneiss typical of this section. This mine 

was the only producing quartz mine in the Elk City and Newsome Creek districts 

during 1899. 

Throughout the drainage of Crooked Riyer, · which enters the South Fork 

a short distance above Newsome. Creek, abundant placer diggings occur, but 

strangely enough yery· few quartz yeins of value haYe thus far been encountered. 

Near the head of Crooked . Rive!· several veins have, however, been located. 

5995-N o. 27-04-7 
98 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

The prinCipal producing mine is situated near the head of the river and 

practically on the divide separating this drainage from the Salmon River. 

It is called the Badger mine and a few years ago was the scene of active 

mining operations. A 10-stamp mill was built on the Crooked River about 5 

miles northeast of Buffalo H~mp and a road constructed from there to the mine. 

The vein is said to occur in granite and is a normal quartz vein containing 

a considerable awount of free . gold. 

Another vein, called the "Homestake," is situated on the road to the Badger 

mine, 1,300 feet above the mill and at an elevation of about 6,400 feet. The 

Homestake crops in granite and has a strike of N. 80° W., the dip being 

70° N. The vein appears to be only from 2 to 3 feet wide and is developed 

by two tunnels 100 feet apart. The ore is a white normal quartz containing 

pyrite and a little galena. 

During 1902 the Crooked River ~fining and ~Iilling Company is reported to 

have completed a 20-stamp mill at Oro Grande, on the Crooked R1ver; 12 miles 

in a southerly direction from Elk City and three-fourths of a mile below the old 

Badger town and the forks of Crooked River. The deposit which has been 

developed during 1902 is said to be a very wide mineralized belt of low-grade 

f1:ee-milling ore, striking north and south. The mining and milling expenses 

are claimed to be less than 50 cents per ton. The same company owns the 

Orion and the Regnier quartz veins in the same district. New discoveries of 

veins are also reported 3 miles below Oro Grande and north of Deadwood 

Mountain and Relief Creek. 

In 1901 the following companies have reported production of gold and silver 

from the Elk City district: Gold Hill Placer Company, Little Elk Mining Company, 

Tiernan placers, Relief Creek pbcers, American Hill placers. 

DIXIE DISTRICT. 

A mmmg camp which is of small extent, but which has maintained a certain · 

production for many years, is located at Dixie, on the headwaters of Crooked 

Creek, which drains into Salmon River almost due south of the point where the 

larger stream of the same name enters the Clearwater River. The locality was not 

visited. A wagon road extends t<? it from Elk City, following up Red River to 

near Ryans Meadow_, and continuing thence southward. The placers of Dixie 

camp consist partly of the gravels in the creek beds and to some extent of higher 

benches. Cinnabar is said to have been found in the gravels, with the gold. 

Numerous smaller gold-quartz veins are reported to exist near the camp, and have 

been worked at intervals on a small scale. During 1899 considerable prospecting 

was in . progress in the country between Dixie and the Badger mine, about 8 

miles farther west, and · promising veinS" are reported to have been uncovered. 
QUARTZ VEINS OF BUFFALO HUMP DISTRICT. 99 

BUFFALO HUMP DISTRICT. 

The divide between the Salmon and the South Fork of the Clearwater, in the 

vicinity of Dixie, is a broad, flat ridge rarely rising to elevations of 7,000 feet. 

About 10 miles west of this vicinity it rises to a prominent bare peak, attaining a 

height of 8,800 feet above the sea, which is commonly referred to as Buffalo 

' 

0 2 Scale 3 4 ~miles 

FIG. 8.-Sketch map of the Buffalo Hump mining region. 

i 

Hump. Quartz veins of some importance were discovered at this vicinity m 1898. 

The Robbins mining district was organized to cover these locations, and in 1898 

and 1899 active prospecting was progressing about that camp. The principal veins 

are situated on the south side of the peak on a broad plateau sloping gently 

westward and having an elevation of about 8,000 feet. In 1899 the place was only 
100 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

accessible by means of tr~ils, one leadi~g up from Crooked River and another one, 

more frequently used, from Grangeville. The latter route followed the Florence 

road about 20 miles southward to Adams camp, from which place a trail continued 

to Buffalo Hump, leading over high and bare ridges. It is reported that shortly 

after that date a wagon road was constructed, following the last-named ti·ail. 

The general drainage and the location of principal ·. claims is illu_strated on fig. 8, 

reduced from a map by Mr. "T· H. Hill. 

From the · Badger mill located on Crooked River, the trail ascends westward over sloping ridges to a broad divide covered with thick forest. From 

this point it descends into Lake Creek, a long tributary to the Salmon River, 

heading on -the east side of Buffalo Hump. When Lake Creek is reached the 

trail turns up the same, following it over heavy moraines, ascending about 3,000 

feet. The divide at the head ~f Lake Creek has an elevation of nearly 8,000 feet. 

West of it, and at the foot of Buffalo Hump, extends a flat, marshy in places, and 

containing several small lakes or ponds. 

The predominating rock at Buffalo Hump is the ordinary Clearwater granite 

of. light-gray color, and containing both biotite and muscovite. It is on the 

whole very similar to the large areas of the same rock which extend to the 

south of Salmon River in the vicinity of Warren camp. Near Buffalo Hump 

this granite contains a number of irregular patches and smaller areas. of micaceous 

schist, quartzites, and C'Oarse granular marbles, the latter very largely ' converted 

into greenish and brownish hornfels and garnetiferous rocks. The · strike and 

dip of this sedimentary series are extremely variable, but are usually at moderate 

angles of 30° to 40° to the east or north. It is evident that this sedimentary 

series has been intruded by the granite and suffered intense contact metamorphism. 

The schists are penetrated by granitic dikes, running -in all directions. Regarding 

the age of the schists, nothing more definite can be said than that they are 

older than the intruding granite. No other sedimentary areas · are known in 

the vicinity with which they can be even tentatively connected. The granite 

often shows two well-marked systems of joint planes, one having a northeasterly 

. and the other a northwesterly direction. Mr. · Charles L. Whittle, a who has 

published a short but interesting article on the district, states that ''along the 

northeasterly set of joints, and to a less extent along the northwest set, there 

h~ve been 'introduced small quartz veins in great abundance. These veins are 

the oldest in the camp and vary in width from mere films up to several feet, 

the great majority being about 1 inch across. These small veins seldom appear 

mineralized and usually lack permanence, either horizontally or vertically." The 

producing veins form a linked system diverging slightly northward and having 

a Eng. and Min. Jour., vol. 68, 1899, pp. 215, 216. 
· QUARTZ VEINS OF BUFFALO HUMP DISTRICT. 101 

a strike of a few degrees east of north, the dip being generally very steep 

toward the east. The first vein discovered was called the "Big Buffalo." This 

claim is situated on the high plateau already referred to. A 10 by 12 foot 

shaft was sunk to a depth of 72 feet in 1899 and the drifts and cros~cuts 

amounted to . 100 feet. The . dump covered a large part of the outcrop, in 

which the vein was stated to have a width of 40 feet. In a cut just north 

of the shaft about 12 feet of vein quartz were exposed. The ore is a normal, 

milky-white quartz containing scattered masses of pyrite, galena, copper pyrite 

and tetrahedrite. An assay of some of the material from the dump gave the 

high result of nearly 8 ounces of gold arid t ounces of silver per ton. It is 

stated that the Big Buffalo vein can be traced southward through three claims 

a,nd is then lost along the line of the east and west valley of Sheep Creek, 

which drains the high plateau in a westerly direction and finally turns southward 

toward the canyon of the Salmon River. 

A few claims south of the Big Bu:ffa,lo is the Fortune vein. This was 

found to have a strike of N. 10° E. and a steep easterly dip. Two feet of 

quart~ showed between . well-defined walls and contuined scattered crystals of 

pyrite. 

A short distance east of the Big Buffalo another prominent vein appears 

and is continuous for a distunce of 1 mile. Near the north end of this is the 

Monte Cristo claim, which in 1899 was developed by several small tunnels. The 

vein appears between granite walls. This i~ continued southward by the St. 

Louis and other claims, showing again a well-defined quartz vein from 3 to 6 

feet wide. The normal vein quartz contains small grains of pyrite, chalcopyrite, 

galena, and zinc blende. An assay of a sample taken from a prospect hole 10 

feet deep on the St. Louis gave 3.4 ounces of gold and 9.2 ounces of silver 

per ton. Still farther south on what appears to be the same vein is locuted 

the J urn bo. On this claim the deposit has been opened by two tunnels, the 

lower one 300 feet in length. The vein appears of fair size and of a fairly 

uniform thickness for several feet. Here a,g·ain the quartz contains a little iron 

pyrite, tetrabedrite, and chalcopyrite. 

On the eastern side of the camp, at the head of Lake Creek, a great number 

of prospects were located, the most important of which were called the Vesuvius, 

Crackerjack, and Wii;lslow. On all of these active work was in progress and fair 

ore was exposed. Owing to the glaciated ch~racter of the country, there is but 

little decomposed vein matter with free gold. Ordinarily shallow prospect holes 

. will reach fresh sulphides. It is stated that the quartz is free milling, although 

it seems probable that the larger part of the values are contained in the · 

sulphurets. 
102 BITTERROOT AND CLEARWATER MOUN1'.AINS, MONT.-IDAHO. 

A number of placer claims have been located in the vicinity, but owing to 

the extensive glaciation it is probable that most of these will be disappointing in 

yield. 

According to late information from Mr. V. C. Heikes, of the division of 

mining and mineral resources of the United States Geological Survey, the following properties were producing at Buffalo Hump in 1902: The Jumbo has been 

working 4 stamps during the year, and unverified reports placed the yield. at 

$5,000 per month. On the Crackerjack a 5-stamp mill was running in September, 

and during that month treated about 400 tons of ore. In addition to concentrates 

and tailings the clean up from the plates for the month is given as $4,000. 

On the Wise Boy a mill had been erected and was preparing to ~tart on 

October 1. This claim is believed to contain ore of excellent quality. 

The Buffalo Hump syndicate has been working 25 men, and the 10-stamp mill 

on the Big Buffalo has been operated steadily for the last ten months. Bullion 

has been shipped regularly. 

In the article quoted above, Mr. Whittle expresses himself as follows: 

'• I have been greatly disappointed to note the scarcity of free gold in the 

oxidized portions of the veins, and the sudden and universal thinning out of the 

. prominent veins, their unequal pockety mineralization, and the strong tendency of 

the veins to pass from well-defined walls into a ramifying mass of small stringers 

within a short distance has filled me with apprehensions as to the future of the camp." 

Judgment of the real character of the veins would, however, best be deferred 

until the ore bodies shall have been thoroughly exploited. The result of the last 

two years' work shows that to · some extent Mr. Whittle's predictions had a 

foundation. At the same time it is evident that some shoots of value have been 

encountered and that the camp will continue, for a long time, as· a producer, 

though not on as .large a scale as was predicted during the first boo:qi.. 

PIERCE DISTRICT. 

PLACERS, 

The Pierce district was discovered in 1860, and for the first few years after that 

date a large production was maintained~ Soon; however, most of the mining 

population was attracted to richer. camps elsewhere and the production declined 

greatly. For the last ten years it has p'robably rarely exceeded $20,000 or $30,000 

per annum. As in so many other cases, the total production is impossible to 

obtain. ·Probably the production was considerably less than at Elk City, which, 

in turn, was eclipsed gy Florence, Warren, and the Idaho Basin. · A guess may be 

hazarded that the total output of Pierce is in the vicinity of $5,000,000. A certain 

amount of placer mining is still done every year, and at intervals some of the 
ORE DEPOSITS OF PIERiCE DISTRICT. 103 

numerous quartz veins are also operated. Pierce is situated near the head of Oro 

Fino Creek, which empties into the main Cle rwater River 25 miles farther west. 

The elevation of the camp is in the vicinity of 3,000 feet. From th~ monotonous 

lava plateau extending about Weippe a wagon road leads to Pierce, a distance of 

about 12 miles. After a few miles of eontinu d Columbia River lava, low hills of 

granite or imperfectly gneissoid rock rise, and lover the same rocks the road finally 

descends to Oro Fino Creek. Pierce appears to be located at the contact of an 

extensive area of gneiss and mica-schist, which continues toward the northwest 

across the Mascot Hills to the North Fork of the Clearwater. South of the contact 

granitic and dioritic rocks prevail. Near the contact the schists are penetrated by 

granitic dikes. Below Pierce, Oro Fino Creek runs in a narrow canyon, which 

widens and splits up into two branches close to the settlement. The gravels worked 

are partly the low benches along the creek, partly abo high terraces extending to 

a height of 500 feet above the stream. Canal Gulch extends northward from 

Pierce for several miles, heading at the divide toward the North Fork of the 

Clearwater. It has been extensively worked, and at least in one place a half-mile 

north of town a high gravel bench is still mined. At this place there appear to be 

two levels of terraces, one 100 feet above the creek, while the bed rock of the other 

one is 200 feet above the same level. 

The bed rock is a coarse diorite. The banks are 50 feet high and the gravel 

contains. a great abundance of quartz pebbles. 

Above Pierce, Oro Fino Creek has been I worked for several miles. On the 

road to Rhodes Gulch well-washed gravel extends to a height of 500 feet above I 

the town. Rhodes Gulch, coming down from the north and joining the main Oro 

Fino Creek a few miles above the town, is alro reported to have been very rich, 

which is also confirmed by the extensive dumps of washed gravel covering its 

bottom. East of this point is French Creek Mountain, and a road leads across to 

the quartz prospects which have been found ~here. 

Altogether Oro Fino Creek has been washbd for gold for a distance of 12 miles 

above and 10 miles below Pierce. The gold js usually fine as to size, but of low 

grade as to value, being, at most, worth $17 per ounce, some of it running as 

low as $15. 

A few miles below Oro Fino, not far rom the tri butarv called Poorman 

Creek, the American placer mine was in opJration in 1899, w~shing the gravels 

of the creek bottom. The creek at this point flows over a basaltic bed rock. 

QUARTZ VEI:ks. 

As may be expected a number of quartz l veins have been found and located 

near Pierce. None of them has, however, thps far reached the standing o:f large 

mines. As so often happens in districts ~ this kind they are worked inter-
104 BITTERROOT AND CLEARWATER MOUNTAINS, MONT.-IDAHO. 

mittently and on a small ·scale. Ten miles northeast of Pierce on French Creek, 

tributary to the North Fork of the Clearwater, are two quartz veins half a mile 

apart, and called :the Golden West and . Klondike. Among the important veins 

north of Pierce is mentioned the Sweet mine, which ·from 1894 to 18~6 is reported 

to have produced $40,000. The :Mascot vein is situated 15 miles northwest of 

Pierce, and was operated during 1899. The equipment consists of two steam stamps. 

The veins in the vicinity of ~ierce are reported to have a southwesterly dip of 

about 45°. Below the shallow zo.ne of oxidation the ore is apt to turn base, as 

indeed is suggested by the low grade of the placer gold. 

Prof. I. C. Russen,a who visited the Mascot Hills to the west of Pierce, 

says that the rocks there '"contain numerous small ga·sh veins, but do not reveal 

the presence of any true lode:::; or fissure veins~" 

In 1901 the following properties reported production of gold and silver: 

Vi-Vi placers. 

Last Show placers. 

Woodchuck pla~ers. 

Mdnahassett placers .. 

Boggs Gulch placers .. 

Missouri Rose pla~:ers. 

For 1902 the following report is available: 

May Creek placers. 

Wild Rose quartz. 

. Boise quartz. 

Fisher quartz . . 

Venus quartz. 

The \Vild Rose, owned by Dunn and Wilkinson, Pierce~ Idaho, has been operating a 3-stamp mill in 1901 and 1902, and made a g-ood clean qp. Developments 

amount to 460 feet. The Santiago group, owned by Wilsey & Co., of Pierce, 

has operated a 2-stamp mill the entire season. The Mascot Mining and Milling 

Company, of Pierce, has operated its 10-stamp mill part of the season. The 

Ozark Company, owned by Gaffney and Pond, of Pierce, also has a mill which 

has been producing· during .the season. The Dewey is operated by Ellis & Co., 

who are making arrangements for the erection of a 5-stamp mill. The French 

Creek Mining and Development Company w:ere erecting a new. mill .and expected 

to run it during the winter of 1902-3. 

The -'placer property owned by the American Placer Mining Company, on 

Oro Fino Creek, was in operation the first part of the year, but' closed dm.vn in 

July on account of low water. . This company is installing an elevator plant with 

7 mileR of ditch and flume, and own about 10 miles of placer ground below 

Pierce. Two placer-mining companies are preparing: to work French Creek by 

means of bed-rock flumes. An elevator was being operated during the summer 

of 1~02 on Gold Creek, 20 miles northwest. of Pierce. 

From these reports it will be seen that a great number of quartz prospects 

are actively developed near Pierce. The aggregate production of the Pierce 

a Water-Sup. and Irr. Paper No. 54, U.S. Geol. Survey, 1901, p. 128. 
PLACERS OF MUSSELSHELL AND LOLO CREEKS. 105 

mining distri?t now probably exceeds that of Elk City. The output of the camp 

in 1902 is estimated to be $30,000 from placers and about the same amount from 

quartz veins. These data have been obtained from Dr. D. T. Day, of the division 

of mining and mineral resources of the United States Geological Survey, through 

Mr. V. C. Heikes, field assistant. 

MUSSELSHELL AND LOLO CREEKS. 

Lolo Creek heads near Rocky Ridge between the Lochsa and the North Fork, 

and after a tortuous course empties into the main Clearwater at Greers Ferry, a 

few miles above the mouth of Oro Fino Creek. In its upper course it is joined 

by Musselshel~ Creek, which heads in th~ same vicinity. The latter creek has 

been mined all the way, although no extraordinary richness is reported. Lolo 

Creek has been washed for gold in places, but ordinarily contains too many 

bowlders. The gold, like that of Pierce, is fine in size but of low grade, varying 

in value from $17 to $15 per ounce. . A num her of quartz veins are reported 

from the head of these two creeks, and the district may be conside!'ed as the 

southeasterly extension of the g9ld-bearing area of Pierce and the Mascot Hills. 

A prospect called the Pioneer was worked in 1899 and is situated on the low 

ridges between Musselshell and Lolo creeks, 10 miles east of Weippe. The vein 

strikes N. 70° E. and dips 85° S. 

DEPOSITS BETWEEN CLEARWATER AND SNAKE RIVERS. 

In the plateau country extending between Clearwater and Snake rivers the 

Columbia River lava covers nearly the whole area, though bed rock is occasionally exposed in the deep cuts of the canyons or in points protruding through 

the lava. No placer mines of importance have been worked in this area. The 

bottom gravels and bars of Salmon River and of Snake River contain gold, 

however, and these have been worked to some extent. Along Salmon River, 

especially where the gold is less fine than along the Snake, placer operations 

have been carried on in different places during the last few years. The aggregate 

yield is, however, small. 

Near Harpster and 11£ount Idaho.-Many small quartz veins have been located 

and partly developed along the South Fork of the Clearwater near Harpster. 

None of them have, however, proved rich. The rock inclosing them consists of 

black slate, diorite, and amphibolite. Some miles above Harpster, along the same 

river and only a few miles east of Mount Idaho, a few veins have been 

discovered and were prospected in 18.99. These veins form a silicified and 

mineralized streak in greenstone-schists almost at the river level and on the 

west side of the stream. The strike is ' northeasterly and the dip 60° SE. The 

main tunnel shows principally an altered greenstone containing much pyrite. 
106 BITTERROOT AND CLEARWATER MOUNTAINS, · MONT.-IDAHO. 

There are occasional bunches of quartz containing pyrite and chalcopyrite and 

inclosed in greenstone-schists. Good assays and free gold are reported to have 

been obtained from the Dewey, which was the main prospect worked at the time 

of visit. The developments chiefly consisted of . a 50-foot tunnel. 

Since 1899 a considerable amount of work has been done on these prospects 

and a great deal of ore has been shipped. The prospects near the river have 

been united as the Dewey Consolidated Mining and Smelting Company, and up to 

the present time the development work (tunnels, shafts, raises, and winzes) 

aggregates 3,000 feet. Nearly 200 tons of rich ore were shipped to smelters 

during 1900, yielding net $13,000, according to treasurer's report. Mr. Otto 

Abeling has made a report on the property in 1900 from which it appears 

that there are four parallel veins, striking N. 28° E. and dipping 75° . On 

the two outside veins, the Waverly and the West veins, but little work has 

been done, while the principal developments have been effected on t~e Dewey 

and the St. Patrick. The width of the veins is from 23 to 40 feet. The whole 

distance between the east wall of the Dewey and the west wall of St. Patrick is 

said to be 180 feet, within which distance all assays show some value. As 

stated above, the rock is a roughly schi:::;tose greenstone and the veins are about 

parallel to the . schistosity. The ore consjsts of silicified and pyritic greenstone 

containing streaks and veinlets of quartz. The immedjate outcrops of this rock 

were rather poor, showing little copper and but few dollars in gold. Tunnels 

driven on both veim~ soon struck a number of streaks of shipping ore very rieh 

in gold and greater bodies of lower-grade material, . both classes containing 

chalcopyrite in varying but not large amounts. Very little of the gold is free. 

On the Dewey vein more copper ores were found than on the St. Patrick. A 

small shoot of massive pyritic ore 3 feet wide yielded 3.4 per cent copper and 

$5 in gold. In another place a sample across 4 feet yielded 3.1 per cent copper, 

12.7 ounces silver, and 4.38 ounces gold. according to Mr. Abeling, who also 

estimates the ore jn sight as 34,650 tons with a value of $361,200. 

Higher up on the hill, west of the Dewey, is the similar Evergreen property 

from which considerable shipments of smelting ore were reported in 1901. 

In general character these deposits differ from the ordinary type of gold 

quartz veins common in this part of the country. They show a certain 

similarity to the Bully Hill deposits of Shasta County, Cal., and in both cases 

a certain amount o.f seeondary concentration has probably been active. 

Cottonwood Buttes.-The area of old rocks which protrude as low hills above 

the general surface of the Columbia River lava, a few miles north of Cottonwood 

on the Camas Prairie, contain several veins of quartz which .have been prospected 

on a small scale. The veins strike north and south and are nearly vertical; the 
DEPOSITS BETWEEN CLEARWATER AND SNAKE RIVERS. 107 

width is reported to be 4 feet, and the valuable metals contained are stated to 

be silver, gold, and copper. A shaft 115 feet deep has been sunk on the Eckert 

and Smith vein. As to the actual value of the veins very Jittle is known. 

The lower Olearwater.-Few deposits of importance have been discovered on 

the lower Clearwater River. The only exception, as· far ·as I am aware, consists 

in a few yeins reported to contain gold which have been discovered on Bedrock 

Creek, approximately 15 miles below Oro Fino and 25 miles above Lewiston. 

Quartz veins are reported to occur here in calcareous quartzite cropping below 

the level of the lava plateau three-fourths of a mile above the mouth of the 

creek. 

Canyons of Snake and Salmon rivers.- In the deep trenches of these two 

rivers south of Lewiston the bed-rock formations below the lava, when exposed, 

generally consist of highly disturbed and sedimentary rocks accompanied by 

greenstones of various kind. Neither of the canyons were visited during the 

present examination. On Salmon River prospects are reported to occur in these 

rocks near White Bird. 

Along Snake River several veins containing copper in prom!sing quantity 

have lately been discovered near the mouth of the Salmon Canyon. From reports 

they are often connected with greenstones of dioritic character. A vein known 

as the Mary K is reported ? miles below the mouth of Salmon River, near the 

point where Cottonwood Creek empties into Snake River. At the junction of 

the Imnaha River, entering the Snake a few miles above the mouth of Salmon 

River, important discoveries are reported in the rocks which here underlie the 

thick flows of the Columbia River lava. In this bed-rock series, which extends 

for several miles up above the junction on both rivers, occur a series of deposits 

which, from several concurrent reports, must be considered as fissure veins; they 

contain a rather peculiar combination of chalcopyrite and massive steel-gray 

hematite. The amount of ore is reported ar-; considerable, although the grade is 

stated to be low. If this hematite is a primary mineral, as would appear 

probable from the specimens shown me, it is not likely that the composition of 

the ore will undergo great change in depth. The veins are reported to extend 

over from the Imnaha to the Snake, having a general strike of northeast and 

southwest. Besides copper, the ore contains a small amount of gold and silver". 

There are several gravel benches in the lower course of the Salmon above 

Freedom which have been mined. A short distance below Freedom operations on 

the low bars were contemplated at tbe time of my visit in 1897. At the mouth of 

John Day Creek hydra':llic mining has been done on a bar 100 feet above the river, 

the bed rock being probably 50 feet above the same level. Three-fourths of a mile 

above the mouth of John Day C.reek on the east side of the river is a high bar, the 
108 BITTERROOT .AND CLEARWATER MOUNTAINS, MONT.-ID.AHO. 

slate bed rock being 80 feet above l"iver level and the top of the sandy gravel 300 

feet above the same. This bar was hydraulicked in 1897 by the Victor :Mining 

Company, of Spokane. The pay is concentrated in a thin layer of cemented gravel 

on the bed rock. 

A big gravel bar 200 feet high is situated higher up on the west side opposite 

Carver's ranch. The limestone bed rock is only a few feet above the river and on 

it rests cemented gravel, containing very coarse gold of local origin. This deposit 

has been mined by drifting along the bed rock. Another large bar with much sand 

lies at a · bend of the river a little north of Fiddle Creek. Still another high bar 

on which some placer mining bas been done is. situated on the south side of the 

river a few miles above the great bend at Salmon Point. Above this point there 

are only smaller low bars but the sands of these contain fine gold everywhere. 

COEUR D'ALENE MOUN'TAINS. 

What little is known about .this subject, really outside of the limits of this 

reconnaissance, is given below. For notes on the geology see page 81. 

GOLD DEPOSITS. 

The· Coeur d'Alene Mountains are not rich in known gold deposits. Placer 

mines of moderate richness have been ~orked in the Nloose Creek diggings on a 

branch of the North Fork of the Clearwater, a short distance west of the ~fontanaIdaho line. Minor deposits have also been worked at the head of the Middle Fork 

of St. Josephs River and on the Montana side near the head of Cedar Creek 

halfway between Mullan Pass and Nlissoula. 

The most important deposits, placers as well as quartz veiris, are situated at 

:Murray and Delta on the North Fork of the Coeur d'Alene Rivei·, 15 miles, north of 

the l.ead-mining district. 

LEAD-SILVER VEINS. 

To this cla:ss belong the celebrated deposits near Wardner, Wallace, and Mullan 

on the · Coeur d'Alene River, a which are estimated to have produced about 

$60,000,000 of lead and silver since their discovery fifteen years ago. The lowest 

profitable percentage of lead in the mined ore is said to be about 6 per cent. The 

ores are subjected to careful concentration in large dressing works. 

The ·deposits are clearly defined .fissure veins cutting fine-grained greenish 

quartzites and quartzitic slates of doubtful (though probably pre-Cambrian) age. 

The principal ores are galena and zincblende, . but there is also much finely distributed pyrite. Chalcopyrite is ordinarily absent. · These are practically the only 

metallic minerals, and recur in all the deposits. The principal· gangue mineral is 

a For a brief description of these mines, including technical features, see J. R Finlay, Trans. Am. Inst. Min. Eng., 

February and May, 1902. 
ORES OF COEUR D'ALENE MOUNTAINS. 109 

siderite, accompanied by minor quantities of quartz and barite. Fluorite i's absent. 

The fissures along which the ore bodies appear are well defined, and sometimes 

continuous for one or more miles. The ore bodies do not show much clearly defined 

crustification or other evidence of having been deposited in open space. The 

siderite appears always as an undoubted product of replacement, while many 

veinlets of quartz have in part resulted from the filling of open small fissures. 

Evidences of gradual transitions from ore to country rock are ·abundant, and are 

especially prominent in the mines carrying low-grade ore, as, for instance, in the 

Helena and Frisco. In the exposures underground, as well as in the specimens and 

thin sections, the evidence of replacement is complete and positive. 

The greenish-gray fine-grained quartzite which constitutes the prevailing 

country rock contains no sulphides when fresh. It is composed of small, -rounded, 

or subangular quartz grains, Closely packed-often, indeed, jointing closely, as in a 

normal quartzite. Usually, however, a little sericite, in bunches of small fibers, is 

present as cementing material between the grains. There are few other minerals, 

exept a little feldspar in clastic grains, small prisms of tourmaline, and some grains 

of calcite. Near the veins minute specks of siderite, zincblende, pyrite, and galena 

appear in this quartzite; and these scattered grains gradually merge into bodies of 

merchantable ore. The thin sections show how the rock near the veins is filled with 

small grains of branching and irregular form, which consist of siderite, developed 

by attack first upon the groundmass and then upon the grains of clastic quartz. 

Accompanying the siderite are small grains of zincblende, cubes of pyrite and 

irregularly wiry masses of galena. All these sulphides appear not only in or near 

the siderite, but also in the cementing sericite, and in the apparently perfectly fresh 

quartz grains. 

At a more advanced stage these areas of siderite extend until they join, and 

thus completely replace the rock. In the resulting ore lie scattered many small 

quartz grains, representing remnants of the clastic constituents of the quartzite. 

Occasionally larger masses of zincblende appear to form directly in the quartzite by 

metasomatic replacement of the quartz. The sericite in the quartz then disappears, 

though once in a while small foils of it may be detected. During the transition 

stage, seams and narrow veinlets in the altering rock are filled with sericite, apparently segregated there, when driven out from the main mass. In other specimens 

from the Helena and Frisco mine, the replacing siderite has a strong tendency to 

idiom orphic development. Imperfect rhombohedral forms are often seen, sometimes 

cutting straight across the clastic grains. Certain specimens from the Bunker Hill 

and Sullivan mine show quartzose grayish masses of irregular outline, and apparently 

~erging gradually into the normal greenish quartzite. These quartzose masses 

consist of very irregular interlocking grains of quartz, not in the least. similar to the 
110 BITTERROOT AND CLEARWATER MOUNTAINS, MON'r.-IDAHO. I 

quartz usually deposited by processes of filling, but having every appearance of 

resulting from the silicification of the quartzite. This silicified portion contains 

irregular grains of pyrite, galena, and brown zincblende, with a very little siderite. 

The process, as outlined, is remarkable, as involving a metasomatic replacement of quartz by siderite, pyrite, galena, and zincblende, and is the only clearly 

defined occurrence of this kind of which I am aware. 

Coming frorri the west the first deposits are found near the town of Wardner. 

The Bunker Hill lode is here the principal source of production of the Wardner 

district, estimated by Mr. J. R. Finlay to be $17,500,000. This remarkable vein 

system is continuous for 2 or 3 miles; its principal feature is a well-defined fault 

plane contained in quartzite and striking N. 42° W., the dip being 38° SW. The 

ore forms irregular masses above this fault plane or "foot wall. ? The mines are 

worked by tunnels, a deepest level being recently reached by a long 8 by 9 foot 

tunnel from near the Coeur d'Alene River, striking the veins 700 feet below the 

previously lowest tunnel level on the Bunker Hill and Sullivan mines. The croppings along the foot wall is indicated by a heavy iron cap stoped 50 feet wide at the 

surface. The ore is mainly galena, with a little pyrite and blende; the concentrates 

carry about 25 ounces of silver. There is practically no arsenic, antimony, or 

gold. Some galena appeared in the croppings, but also much cerussite in beautiful 

bunches and this secondary mineral co~tinues in places as far as 200 feet below the 

surface. 

Although the foot wall is so clearly defined by a fault plane, accompanied 

by a few inches of clayey gouge, the hanging wall of the ore bodies is extremely 

ill defined and in many places the mineralization simply fades out gradually . 

. Some of the ore shoots lie on the foot wall, but others reach out as much as 

200 feet horizontally from this plane. Some of the masses of galena, instead of 

strictly following the course of the foot wall, may locally follow a stratification 

plane and then jump back in offsets so as to preserve the general parallelism 

with the wall. The thickness of the ore bodies is as great as 90 feet; within 

the pay shoots the galena occurs irregularly; there are some massive bodies as 

much as 10 feet thick, which may change their outlines rapidly and irregularly 

and which are sometimes separated by horizontal joint planes from the barren 

quartzite. Most commonly, in the poorer ores, the galena occurs as small and 

very irr~gular seams associated with some quartz and siderite. The greatest 

ore body in the Bunker Hill and Sullivan vein had a maximum thickness of 90 

feet, was several hundred feet long, and extended across a vertical distance of 

170 feet. Its .ore averaged 25 per cent lead. The ore stopped against a local 

hanging wall which lower down joined the principal foot wall. 

Near Gem and Burke, 10 miles farther up the river and near a granite boss 

which here is intruded into the steeply dipping quartzites and clay slates, is 
LIGNITE. 111 

another important vein system, generally called the "'Canyon Creek lodes." The 

production of this system, which include such important mines as the HelenaFrisco, Tiger-Poorman, Mammoth Standard, Morning, You Like, and others, is 

estimated as $42,500,000 (J. R. Finlay). One system of vein strikes from Ninemile Creek across to Gem in an east-southeast direction, and thence across toward 

Mullan. Two parallel systems are found 2 and 4 miles north of Gem. The veins 

of the "Canyon Creek lodes" are simpler in structure than the Wardner deposits, 

but like those are typical replacement veins along shear zones of greater or 

smaller width. 

The Helena-Frisco, a representative mine, produces about 600 tons of ore 

per day, which is concentrated in proportions of 9 to 1, yielding 50 to 70 tons of 

concentrates. The mine is opened by a shaft 1,800 feet deep. The country rock 

is a fine-grained greenish-gray quartzite. The vein which cuts the quartzite in 

strike and dip has a course of N. 80° W., and a variable southwest dip averaging 

70° , and gradually straightening on lower levels. The ore averages 10 to 12 feet 

in width, and is taken O).lt uniformly. The foot wall is very poorly defined; the 

hanging wall is also often indistinct, though usually roughly indicated. Sometimes every indication of geometrical walls is absent. The rock is hard and 

compact, even within the walls. Within the wid~h of 12 feet are irregular 

streaks of fine-grained steely galena and blende, occasionally a couple of feet 

thick. Pyrite, and in places chalcopyrite, are sparingly represented. The gangue 

is finely divided siderite and a little quartz, the latter in narrow and irregular 

seams. The vein is clearly the result of replacement of quartzite by galena, 

zinc blende, and siderite, along tight fault planes. The vein system of which the 

Helena-Frisco forms a part continues· for 6 miles and is faulted at several places 

by later fissures striking north-northeast. 

The ~1orning and You Like are situated on the eastern end of this vein 

system, high up on the hill above Mullan. A tunnel 9,000 feet long and 900 

feet below the working tunnel used in 1899 is projected to tap the vein from 

the mill level. The ore shoots, which are said to be strong, are 600 to 700 feet 

in length and 10 to 40 feef in width. The present capacity of this group is 700 

tons of ore per twenty-four hours. 

LIGNITE. 

Coal of a lignitic character. has been found in two widely distant parts of 

the area under examination. In neither case are the developments extensive 

enough to assure their commercial importance. At the head of the South Fork 

of Bitterroot River lignite has been found on Coal Creek, a small tributary 

from the west which enters the South Fork 10 miles above the mouth of the 

West or Nez Perce Fork. The deposit is connected with rhyolite, and appears, 
112 BITTERROOT AND CLEARWATEE MOUNTAINS, M:ONT.-IDAHO. 

in fact, · interbedded together with clays and sands in the upper part of the 

rhyolitic. flows. Mr. J. B. Lei berg a states, that the deposit ·occupies an area of 

about 500 acres, and that two seams have been discovered, the upper one with a 

thickness of 12 feet, while the extent of the lower· is unkown. Coal Creek was 

visited by Mr. G. W. Stose, who reports that the l'hyolite exposed in the bottom 

of the canyon continues practically all the way up to an elevation of 1,000 feet 

above the main stream. Two tunnels, 50 feet apart and at slightly different 

levels, the upper one boarded up, are the only developments. The coal seam was 

only partly exposed; 2t feet of coal were seen, with a 3-inch seam of clay in the 

middle. The dip of the strata seems to be 22°. The roof of the coal consists of 

a clay full of vegetable matter, such as fern-like leaves, grasses, etc. Above this 

clay follows a hard and compact rhyolite tuff. The extent of the coal lands is 

problematic, and I am unable to say whether Mr. Leiberg's estimate is correct. 

At .any rate, it is clear that the extent of the territory underlain by coal is small, 

and the well-],{nown uncertainty of thickness and quality in other fields similar to 

this make predictions of doubtful value. A sample of the coal was analyzed by 

Dr. W. F. Hillebrand, with the following result: 

Analysis of coal from near head of South Fork of the Bitterroot River. 

I. II. 

Moisture at 105° _____ .. ___ . _______ . ___ . __ . · .... _____ . _________________ . _. __ _ 7.21 7.21 

Volatile combustibles _____ .... ___ .. _ ..... _ ... _ .. .. . ___ ....... _ ...... _. __ ... _ 56.09 41.84 

Fixed carbon __ .... _ ............. _ . _ ........ __ ... _ .... - -....... -.......... - 27.09 37.61 

Ash _____ ...... _ .. _ ........ __ .... _ . __ .... _ ..... __ -. _ ... __ . _ ... - ........ -.. . 9.61 13.34 

100.00 100.00 

The :first column represents the composition as usually determined, the ash 

being found ·in the same portion as the volatile combustibles and :fixed carbon. 

But the coal sparks enormously, and much ash and :fixed carbon are ejected with 

the volatile combustibles. 

The second column gives the true ash contents and the corrected volatile 

combustibles and :fixed carbon, calculated on the assumption that the ratio of :fixed 

carbon to ash in the ejected matter is the same as that in the coke of I. The 

coke is thoroughly sandy. The ash is pale .buff colored. 

· The coal is black in color, and crumbles easily on exposure to the air. The 

analysis shows it to be a lignite of very fair quality, approaching a bituminous 

coal in compo.sition. · From its association with the rhyolite, the conclusion is 

strong that it is probably of Miocene age. A little lignite is reported to have 

a ~ineteenth Ann. Rept. U. S. Geol. Survey, pt. 5, 1898, p. 265. 
MINERAL SPRINGS. 113 

been found in the upper area of rhyolite, 10 miles higher up on the South Fork, 

where a similar sur~ession of rhyolitic flows and tuffs is exposed. 

The only other known occurrence is that on the west side of the Clearwater 

Mountains in the canyon of the Clearwater River. This coal, which occurs in a 

series of sedimentary beds interstratified with the Columbia River lava, has been 

described by Prof.· I. C. Russell. a · Professor Russell states that three seams of 

lignite from 2 to 20 inches in thickness and separated by a few feet of sandstone 

have been found half mile below Oro Fino on the south side of Clearwater River and 

at an elevation of about 200 feet above the same. The exposed beds are believed to 

be part of a landslide, and the true position of the beds is suggested to be 500 feet 

hig·her. Lignite is reported to occur at several localities on Oro Fino Creek (all of 

it probably belonging to approximately the same bed) within a distance of several 

miles in the middle portion of its course. In sec. 12, T. 36 N., R. 4 W. an exposure 

of this kind was examined by Professor Russell, who found 20 inches of lignite 

embedded in sandstone and clay. In another place near this exposure a shaft has 

exposed 27 inches of lignite. Here again landslides are t>elieved to have occurred, 

and the true position should be looked for at an elevation of between 400 a~d 

600 feet above the creek. The lignite-bearing rocks no doubt underlie a wide 

extent of the adjacent plateaus. 

Similar exposures are also reported from several places in Little Canyon to the 

south of Oro Fino and on the west side of the river. At the place which was 

examined by Professor Russell no lignite but only carbonaceous shales were observed. 

MINERAL SPRINGS. 

A limited number of generally hot mineral springs are scattered over the area 

examined without special regularity and without showing any connection with lines 

of structure or volcanic flows. Beginning on the north, hot spring·s are found at 

the head of Lolo Fork and about 6 miles north of Lolo Pass. These springs, which 

yield a weak mineral water of high temperature and are of sufficient volume to 

supply a bathing establishment, break through granite not far from the contact 

with the sedimentary series. Going over to the Clearwater side, hot springs of 

similar nature are found at Jerry Johnson's on the Lochsa Fork at an elevation 

of 3,300 feet. They issue at different places a short distance below\¥" arm Springs 

Creek and on the north side of the river. No hot springs are known to exist along 

the foot of the Bitterroot Range, but in the eastern foothills, · about 12 miles southeast 

of Hamilton, hot waters issue at the place known as Weeping Child Hot Springs. 

No hot springs are known on the South Fork of the Bitterroot River, but a cold 

soda spring occurs on a branch of the West or Nez Perce Fork of the Bitterroot 

a Water-Sup. and Irr. Paper No. 54, U. S. Geol. Survey, 1901, p. 122. 

5995-No. 27-04-8 
114 BITTERROOT AND CLEARWATER MOUNTAINS~ MON'r.-IDAHO. 

River 6 or 7 miles above its mouth. · The rock is here a pegmatitic gra~ite. In the 

Salmon River drainage hot springs issue on Horse Creek at an elevation of about 

6,000 feet. ·The water, which has a temperature of 110° F., has no taste or odor. 

Another and somewhat hotter spring issues half a mile below the upper place. 

Farther west in the Clearwater drainage a hot spring is stated to occur on the heaG.-

waters of the Red River, a branch of the South Fork. 

It is a somewhat peculiar fact that no hot waters are known from the large area 

o~cupied by the Colu.mbia River lava between the Clearwater and the Snake River. 

SUMMARY. 

The region described is bordered on the south by the Salmon River and on the 

north by the North Fork of the Clearwater. The fertile Bitterroot Valley is at the 

eastern foot of the imposing Bitterroot Range, which attains an elevation of 11,000 

feet, and westward merges into the great d!ssected high plateau of the Clearwater 

Mountains, which at their western edge descend rather abruptly to the lower 

plateaus of Camas and Cold Spring prairies, forming part of the · great Columbia 

Riyer lava plateau. This plateau has a general elevation of 2,500 to 3,000 feet, and 

is built up of horizontal lava flows. From great glacial cirques in the western 

slopes of the Bitterroot Range the Salmon River and the several forks of the 

Clearwater River find their way westward in canyons from 3,000 to 5,000 feet.deep. 

The canyon of the Salmon especially is remarka?le for its great length and depth. 

In the lower plateau country these rivers flow in more sharply incised but less deep 

canyons, which continue to their junction with the master stream, the Snake River. 

The area is a wild and very sparsely populated mountain region, heavily timbered 

except on the highest ridges, which usually show clear evidence of glacial action. 

The geology is comparatively simple. The main Bitterroot Range and the 

larger part <;>f the Clearwater Mountains consist of a granite, or, defining it more 

correctly, of a quartz-monzonite mass-the northward continuation of the great 

batholith of the same rock which occupies so large an area in south-central Idaho. 

In the latter region this intrusive mass is of post-Carboniferous and probably 

late Mesozoic age, and there is no reason to believe that the granite of the Clearwater and the Bitterroot is of different age. 

Along the whole eastern slope of the Bitterroot Mountains this granite is 

made schistose by pressure and forms a zone a few miles in width and 60 miles 

long, following the front of the range. This schistose zone is probably due to a 

great fa~lt which, like the schistosity, dips about 18° E. Otherwise the granite 

is generally massive and but little altered. Several smaller areas of a much older 

gneiss (pre-Cambrian n occur in the Clearwater Mountains, the largest appearing 

near Elk City. The granite is intrusive in this gneiss. Along Lolo Fork, at the 

northern end of the Bitterroot Mountains, and near the head of the Bitterroot 

River are areas of probably Cambrian or pre-Cambrian quartzites and slates, into 
SUMMAR~. 115 

which the granite is also intrusive. Finally, along the western foot of ~he Clearwater Mountains, near Harpster and Mount Idaho, occur slates, limestones, and 

greenstones, which clearly form the northeasterly extension of the similar sedimentary series of the Seven Devils and the lower Salmon River. This series is 

believed to be of early Mesozoic age and the granite of the Clearwater Mountains 

is intrusive in it. 

The geological history of this region probably begins with the deposition of preCambrian sediments on a basement of gneiss. Much later, in early Mesozoic time, 

sediments, accompanied by basic lavas, were laid down on the western side of the 

area described. Granitic intrusions followed or accompanied a great uplift of these 

sediments, and an active erosion reduced the surface to moderate relief. All this 

is believed to have been accomplished before the beginning of the Cenozoic era. 

A second uplift raised this reduced topography to the present level of the great 

Clearwater Plateau, which probably extended far into Montana. On the west this 

plateau is probably separated from the Columbia River Valley by a dislocation, 

while the Bitterroot Range was differentiated by the remarkable flat fault, 60 miles 

long, which now forms its eastern slope. The deep canyons of the Clearwater and 

the Salmon were excavated before the eruption of the Columbia River basalt. The 

movement along the great Bitterroot fault plane has apparently continued ·until a 

recent date. The vertical movement along the Bitterroot fault is from 4,000 to 

6,000 feet, and the horizontal component at least 2 miles in length. The fault 

appears to be a normal one. A twofold movement has probably taken place, by 

which the foot wall has been raised and at the same time the hanging wall depressed. · 

The Bitterroot Valley represents the result of the down throw, the Bitterroot Range 

the result of the upward movement. This dislocation, remarkable in many ways, 

probably is the most important structural feature . discussed in this report. 

During Miocene times, finally, followed the great outflow of basaltic lavas at 

the foot of the Clearwater Mountains. These swiftly succeeding flows formed the 

plateau of Columbia River lava, their outbursts damming the old canyons. and 

causing many changes of river courses, especially along the lower Salmon and 

Clearwater rivers. The whole course of the Snake River below "r eiser, Idaho, 

has been changed by their eruption. Slow movements have taken place since 

the Miocene, during which time the main body of the Columbia River basalt~ 

were erupted. Besides local warping, such as shown in the Craig Mountains and 

the Uniontown Plateau, near Lewiston, Idaho, it is believed that a general subsidence of a large part of the lava-covered area has taken place. Other parts, 

however, as, for instance, . the high plateau near the Seven Devils, through w hi~h 

Snake River has cut its deep canyons, have probably been raised, the canyon 

cutting keeping pace with the uplift. 

The latest event of geological interest is the glaciation. During early 

Quaternary times a continuous ice sheet covered the whole of the Bitterroot 
,. 

116 BITTERROOT AND CLEARW .ATER MOUNTAINS, MONT. -IDAHO. 

Range for a distance of 60 miles from north to south. Isolated high parts of the 

Clearwater Mountains were likewise centers of local glaciation. The lo"':er limit 

of the glaciated areas is an elevation of 7, 000 feet, though ice tongues . on both 

sides of the mountains reached down to elevation of 4,000 feet. 

The valuable minerals contained in this. area are chiefly confined to the western 

slope of the Clearwater Mountains. The gold deposits are the most important, 

and occur as fissure veins and gravels. At the foot of the Bitterroot Mountains, 

about 12 miles north of Hamilton, Mont., is the remarkable Curlew mine, where 

a body of galena was found on a fissure having limestone and quartzite as its 

foot wall and the gravels of the Bitterroot Valley as hanging wall. On the upper 

South Fork of Bitterroot River prospects of copper, silver, and silver-lead ores 

have been worked. Hughes Creek, in the same vicinity, contains gold-bearing 

gravels which have been worked for many years. 

Elk City, fou.nded in 1862, is one of the centers of the gold-mining industry on 

the west slope. Gold to the value of several million dollars was extracted here 

from late Tertiary bench gravels, and placer mining is still prosecuted on a small 

scale. Quartz vein& have also been recently opened in this old mining di~trict. 

The well-defined quartz veins of Buffalo Hump, discovered in 1897, are actively 

worked, though not as yet on a very large scale. These deposits occur in granitic 

rocks, accompanied by contact metamorphic slates. 

Florence, located 40 miles southwest of Elk City, is another of the old placer 

camps, discovered about 1861. The gravels were \rery rich, and the camp has 

yielded gold to tbe value of many million dollars. At present a few placers and 

quartz mines are worked there also. The bed rock is granite. 

Pierce, on Oro Fino Creek, about 50 miles north-northwest of Elk City, also 

a well-known placer camp, was founded in 1861, and its gravels have been continuously worked since then. The present yield from these placers is probably 

about $30,000. per annum. The gravels occur as creek alluvium and as benches 

up to 500 feet above the present drainage level. Quartz veins have -also beenfound near Pierce, and many of them are being worked on a small scale. The 

veins occur in gneisses and schists. 

The total prdduction of this gold-bearing region, extending at the western foot 

of the Clearwater Mountains, from the North Fork of the Clearwater to Salmon 

River, is at the present time probably about $160,000 per annum. 

Coal of fair quality has been found on the upper South Fork of the BitteiToot 

Valley, and the beds are here associated with rhyolite. The developments have not 

as yet shown the extent of this occurrence. 

Lignite ~f fair quality also occurs on Oro Fino Creek below Pierce, but the beds 

are probably not thick enough to allow profitable working. 
INDEX. 

Page. 

A. 

Alluvial lands near Hamilton and Grantsdale . ..... 29 

Alta post-office, rocks exposed at............... ..... 88 

American Development and Mining Company, 

mines of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 

American Hill, rocks at . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93-94 

American Hill placer mine, description of . . . . . . . . . . 93-94 

rocks of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 

view of .. _-...... , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 

workat.......................................... 104 

American River, placers of................... . . . . . . . 91 

terrace on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92-93 

Analyses, basalt..................................... 75 

coal.............................................. 112 

granitic rocks...... .... ............ .. ............ 18 

lignite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 

Area described, divisions of, by General Land Office. 13 

drainage of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 

early history and explorations of.. . ............. 9-10 

economic geology of............................. 82-114 

erosion in. See Erosion. 

extentof.... ........... ... .......... .... ..... .... 11 

forest reserve in . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

geographic position of .......................... . 

geologic history of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26-28 

geology of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-82 

gold production of................ . .............. 116 

maps and literature of. ........... ... ........... 10-12,14 

profiles of........................................ 16 

topography of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-15 

B. 

Badger mill, rocks at................................ 65 

Badger mine, location and description of . . . . . . . . . . . 98 

Bald Mountain, glaciation ou ............ ........... 67 

Bare Cone, rocks of.................................. 56 

Barnard, E. C., work of.............................. 10 

Basalt, age of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24, 75 

analysis of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 

eruption of, place of............................. 80 

occurrence and character of. ............. 24-25,27,74-75 

See also Tertiary lavas. 

Bass Creek, galena veins on......................... 86 

Bear Creek, rocks on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 

Beaver Creek, rocks along........................... 57 

Becker, G. F., cited on schistosity and jointing...... 50 

Bedrock Creek, rocks exposed on. . . . . . . . . . . . . . . . . . . . 71 

veins on......................................... 107 

Benches. See Gravels; Terraces. 

Big Buffalo vein, description of .................... . 

work on . .. .. ....... ....... ........... -~ ........ . 

Big Canyon, rocks exposed on ...................... . 

Big Creek, gneiss on, ...... ............ . .. . ......... . 

gravels of ............................... ........ . 

Page. 

101 

102 

71 

43 

52 

rocks on and near . .. . . . . . .. . . . .. . . . . . . . . .. . . . . . . 37, 42 

Bilk Mountain, rocks of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 

Bitterroot Forest Reserve, establishment of . . . . . . . . . 10 

Bitterroot Mountains, basic magmatic segregations in 19 

Bitterroot Range, definition of . . . . . . . . . . . . . . . . . . . . . . 13 

description of. .................................. 33,38-55 

drainage of...................................... 40 

elevation of...................................... 13,114 

fault in ....... ............ .... .. ............ ..... 26 

faulting in. See Faulting. 

geologic history of............................... 51 

geology of ................................. 41-55,114-115 

glaciation in . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . 28, 51 

gneiss of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-21 

granite in.................................... . ... 17'-18 

maps of······· ·············-- ~---············· 12,14 

morainesin...................................... 25,:28 

north end of, description of ........ . ... :. ; . . . . . . 33- 31$ 

mineral deposits of. . ........................ 86-87 

profile across... . ................................. 16 

south end of, geology of . . . . . . . . . . . . . . . . . . . . . . . . . 46 

view of............................ . .......... 40, 88 

structure and physiography of. . . . . . . . . . . . . . . . . . . 47-51 

topography of................................... . 38-41 

trails in............ . ..... ...................... .. 41 

views in ................................ ..... 40, 42, 44 , 52 

Bitterroot River, coal deposits of ....... -.............. 113 

course and character of... . . . . . . . . . . . . . . . . . . . . . . . 15 

mineral deposits on.............................. 116 

See also South Fork and West Fork of Bitterroot. 

Bitterroot Valley, coal in.... ........... ............. 82 

description of.................................... 114 

glacial gravels on................................ 26 

granite in........................................ 22 

Quaternary rocks in ................ ".. . . . . . . . . . . 29- 30 

rhyolite in................................... . ... 23 

sedimentary rocks of............................ 16 

settlement and cultivation of................ . ... 10,29 

topography of............................. . .. .. .. 28-29 

Blodgett Canyon, appearance of. . . . . . . . . . . . . . . . . . . . . 40 

Blodgett Creek, morainal gravels of. ... . . . . . . . . . . . . . 53 

Blue Joint Creek, gravel of.......................... 58 

rhyolite on................... . ............... . ... 23,57 

rocks along.-................. . ................. .. 56-57 

117 
118 INDEX. 

Bluenose Mountain, height of .....•......••......... 

Boulder Creek, rocks on .................•........... 

Browne, J. Ross, mention of ........................ . 

Page. 

55 

56 

11 

Buffalo Hill mine, description of .....•...... _ .... _.. 94-95 

rocks at.......................................... 65,66 

Buffalo Hump, glaciation on .................. _ .. _.. 68 

rocks at ...... _ ....................... _........... 64,66 

veins of .............. _ . . _.. . . . . . . . . . . . . . . . . . . . . . . 116 

Imffalo Hump district, location, history, and description of ............................... .. 83,99-102 

mapof............ . .............................. 99 

mines of . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83, 116 

production in.... . ............................... 102 

roads and trails to............................... 99-100 

Buffalo Hump syndicate, work of . . . . . . . . . . . . . . . . . . . 102 

Bunker Hill lode, description of. . . . . . . . . . . . . . . . . . . . . 110 

production of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 

Burke, lodes near .................................... 110-111 

rocksat .......................................... 81-82 

Buster mine, location and description of ... . _ ...... _ 97 

c. 

Camas Prairie, elevation of. ........................ _ 77 

Canal Gulch, work along ................ _ ..... ___ ... 103 

Canyon Creek lodes, description and production of. 110-111 

Canyons, descriptions of. ... . ... _ ...... _ .. ___ ....... 14, 61-63 

See also under names of creeks and rivers. 

Carlton Creek, gravels of............................ 52 

mineral deposits on.............................. 86 

Carlton Creek Canyon, fall of. ...... ._................ 49 

gneiss in . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 

Carlton Creek contact, description of................ 36-37 

"Carver's ranch, gravel near. .. .......... .. ........... 108 

Case knife Mountain, rocks of .................... .".. 65-66 

Castle Butte, glaciation on . . . . . . . . . . . . . . . . . . . . . . . . . . 67 

Castle Rock. See Crown Peak... . ......... .......... 23 

Cedar forest in Clearwater Mountains, view of...... 64 

Cedar Mountain, rocks of.,.......................... 81 

Chaffin Creek, moraines of ..................... _ .. _. 53-54 

rocks near ... __ ............................ _..... 42 

Chickerman vein, ore of . .. ..................... _.... 86 

Cinnabar, occurrence of. ......................... ,.. 98 

Clearwater Canyon, description of .. _ ... _ .. _........ 61-62 

dioritic modifications on. . . . . . . . . . . . . . . . . . . . . . . . . 20 

history of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77-78 

rocks in ............................... :. . . . . . . . . . 76 

sedimentary rocks in............................ 16 

Clearwater drainage, coal in . . . . . . . . . . . . . . . . . . . . . . . . 82 

Clearwater Mountains, basalt in, origin of . . . . . . . . . . 27 

definition of..................................... 13 

description and topography of. .............. 13, 14, 59-63 

geology of ................................. 63-68,114-115 

granite in........................................ 17 

glaciation in..................................... 28,67 

mineral deposits of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 

profile across..................................... 16 

topography of ........... : ......................... 59-63 

Clearwater River, coal dewsits of................... 113 

description of. .................................. 15, 61-62 

granite on....................................... 17 

gold deposits of lower. . . . . . . . . . . . . . . . . . . . . . . . . . . 107 

origin and character of.................. . ....... 114 

placers of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 

rocks exposed on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 

See also South Fork and North Fork of Clearwater. 

Coeur d'Alene Mountains, definition of . . . . . . . . . . . . . 13 

elevation of..... . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . 13 

Page. 

Coeur d'Alene Mountains, geology of................ 81-82 

gold deposits of ...... ~ ................... ! . . . . . . . 108 

lead-silver veins, occurrence and description of. 108-109 

rocks of. ...... . .. :. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108-109 

Coal, analysis of..................................... 112 

occurrence and character of..................... 82, 116 

See also Ligqite. 

Coal Creek, lignites on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 

rhyolite on...................................... 57 

Columbia lava plateau, profiles across............... 16 

Columbia River basalt, plateau of................... 24 

Columbia River lava, occurrence and character 

of ................................... 63,74-75,105 

plateau of........................................ 24 

Columbia River plateau, description of .. . . . . . . . . . . . 24 

Como, rocks near .. : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31, 32 

section near . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 

Como Lake, moraine at ............................. " 54 

schistosity of gneiss near . . . . . . . . . . . . . . . . . . . . . . . . 45 

Como Peak, view of................................. 44 

Contact along Lolo Fork . . . . . . . • . . . . . . . . . . . . . . . . . . . . 36 

at Carlton Creek................................. 36-37 

of gneiss and granite............................ 22 

of quartzite and granite......................... 31-32 

Contact, Idaho, rocks near . ......................... 71 

Copper, occurrence of . . . . . . . . . . . . . . . . . . . 82-83, 86-87, 106, 107 

Copper Queen mine, ore of . . . . . . . . . . . . . . . . . . . . . . . . . . 89 

Cornan, Thomas, acknowledgment to • . . . • . . . • • . . • • 87 

Cornucopia, dikes near.............................. 80 

Cottonwood, deep gravels in bore hole at........... 76 

Cottonwood Buttes, granite in . . . . . . . . . . . . . . . . . . . . . . 17 

origin of .............. . ........................ , . 69, 71 

rocks of. .................... ~. . . . . . . . . . . . . . . . . . . . 71 

sedimentary rocks near.......................... 16 

Cottonwood Buttes district, veins of. ................ 106-107 

Crackerjack mine, work on . . . . . . . . . . . . . . . . . . . . . . . . . 101 

production of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 

Crags, The, elevation of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 

glaciationon ................................ .". ... 67 

rocks of ......................................... 44, 63-64 

Craig Mountain, elevation of........................ 77 

height of. . ....................................... 69 

Crooked River, granite on........................... 20 

placers of...................................... .. !:11, 95 

rocks along . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 

terrace on.... .. ............................... ... 93 

veins of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97-98 

Crooked River Mining and Development Company, 

property of............................... 98 

Crown Peak, rhyolite on . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 23 

rocks on ............ ·. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56-57 

Curlew mine, description of. ...................... 86-87,116 

fault in . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 

ore of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 

production of.................................... 84,87 

rocks of ......................................... 49,86-87 

sedimentary rocks near.......................... 42 

terraces near . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 

D. 

Darby, terrace near.................................. 29 

Day, D. T., cited on Pierce district................... 105 

Denver, Idaho, bore holes at........................ 72 

Dewey Consolidated and Mining Company, mines 

of, description of . . . . . . . . . . . . . . . . . . . . . . . . 106 

Dewey mine, developments in..... . . . . . . . . . . . . . . . . . . 104 

rocks exposed in . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . 74 
INDEX. 119 

Page. 

Diablo Peak, elevation of . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 

Dikes, occurrence of. ................ 20, 2::>, 32, 56, 57, 65-66, 80 

Didrite, analysis of---------------------------------- 19 

Diorite-porphyry, occurrence of ................. -.. - 72 

Dixie district, location and description of........... 98 

Drainage of area discussed. See Bitterroot River; 

Bitterroot Range; Clearwater River. 

E. 

Eagle Creek Range, dikes on. __ ............. ----.--- 80 

Eastern foothills, dikes in ....... ~ ............. _._,_... 20 

geology of . __ ....... __ . . .......... __ . . . . . . . . . . . . . 31-33 

granj te in. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 

section of . _ ......... .. ... _ . . . . . . . . . . . . . . . . . . . . . . . 33 

topography of ___ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30-31 

El Capitan, height of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 

Elk City, auriferous terraces at, origin of............ 27 

gneiss at ................. -.--........ . ............ 20,22 

mines of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 116 

production of.................................... 84 

rocks at ....................... _........ . . . . . . . . . 63,65 

Elk City district, description of . . . . . . . . . . . . . . . . . . . . . 91-98 

gold fields of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83-84, 91-98, 116 

production of .......... -.-................ 84-85, 91, 98, 116 

veins of ..... . ....................... ". __ ......... 97 

Elk Creek, placers of . _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 

gravels of. . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . 92-93 

Epeirogenic movements in area, occurrence and discussion of: ....................... 25, 48, 71-80, 115 

Erosion, extent of .. , . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 26, 27 

F. 

Faults, occurrence and character of................. 26-28, 

47-51,76,87,114-115 

Fiddle Creek, placers near . . . . . . . . . . . . . . . . . . . . . . . . . . 108 

Finlay, J. R., cited on Coeur d'Alene mines......... 108 

cited on production of Bunker Hill lode.... . ... 110 

Florence, gneiss near... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 

gravel terrace near . ...................... _. . . . . . 30 

mines of ........................... -............. 83, 116 

production of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 

rhyolite at....................................... 23 

rocks at. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 

Folds, occurrence and c'haracter of . . . . . . . . . . . . . . . . . 27, 77 

Forest Reserve, Bitterroot, establishment of ... _ . . . . 9-10 

Fortune vein, character of . . . . . . . . . . . . . . . . . . . . . . . . . . 101 

Fossils at Seven Devils ......................... ~ . . . . 16, 73 

in sediments interbedded with basalt, examination of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 

Freedom, placers near.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 

French Creek, work at .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 

French Creek Mining and Development Company, 

mill of . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . 1C4 

G. 

Galena, occurrence of ................. 83,86-87,89,91-96,108 

Gannett, S. S., work of . . . . . . . . .. . . . . . . . . . .. . . .. . . . .. . 10 

Gem, Idaho, lodes near .............................. 110-111 

Geologic history, discussion .of ..... _ .............. 26-28,115 

Gibbonsville, rocks at and near . . . . . . . . . . . . . . . . . . . . . 57,90 

sedimentary rocks at ......... _ .............. _. _ _ 16 

Gibbonsville mining district, location and description of . . . . . . . . . . . . . . . . . . . .. . . . . . .. . . . . . . . 90 

Glacial amphitheater, view of....................... 46 

Glacial deposits in Bitterroot Range. . . . . . . . . . 25-26, 28, 52-55 

in Clearwater Mountains ............. . ... 25-26, 28, 67-68 

See also Quaternary formations. 

Page. 

Glacial gravels in Bitterroot valleys................. 26 

Glacial lakes, view of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • 68 

Glaciation, extent and character of .............. 28,115-116 

in Bitterroot Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51-55 

in Clearwater Mountains........................ 67 

Gneiss, cliffs of, view of.............................. 40 

occurrence and character of.. 20:-23,37,42-47,64-66,70-74 

of St. Marys Peak, age of . . . . . . . . . . . . . . . . . . . . . . . . 37 

photomicrographs of .......... :. . . . . . . . . . . . . . . . . 20 

transformations in ............ ________ .. -----.... 21-22 

Gold, occurrence of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82-108 

Gold Hill mines, mention of......................... 95 

Gold ore, occurrence and character of............... 82-85, 

90,96-102,103-108,116 

Goode, R. U., cited on divisions of area discussed... 13 

Grande Ronde River, limestone on.................. 72 

rock!! at mouth of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 

Granite, age of....................................... 2J 

dikes in .......... . ...... -------- .. _______ ........ 20,32 

occurrence and character of..................... 17-20, 

32, 38,42-47,56,63-64,114 

Granite Creek, rocks near .. . . . . . . . . . . . . . . . . . . . . . .. . . 36, 38 

Granite Peak, view of------------------------------- 64 

Granite-porphyry, dikes of. _______ . ___ --------. ____ . 23 

Granitic rocks, analyses of........................... 18 

composition of................................... 19 

Granodiorite, analysis of . . . . . . . . . . . . . . . . . . . . . . . . . . .. 19 

Grantsdale, alluvial lands near .............. ____ . ... 29 

terraces near............................. . ....... 30 

Grave Creek, rocks of. ____ ...... _________ .. . ......... 38 

Grave Peak, elevation of ............... _________ .... 59 

glaciation on .................... __ ........... __ 67 

rocks of.......................................... 63 

Gr&.vel in boring at Cottonwood .. __ .. __ ........ __ ... 76 

Gravel terrace of Bitterroot River .............. :.... 54 

Gravels of Lolo Fork .... ~............. ............. 38 

of South Fork of Bitterroot ......... __ ........... 58 

Tertiary, occurrence of ............. ____ ......... 67 

H. 

Hamilton, alluvial lands near ........... , ..... __ .... 29 

veins near . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 

Harpster, gold mines near. ............ -.-- ........... 105-106 

rocks at and near ............................ 16, 64, 70, 74 

sedimentary rocks near.......................... 16 

terrace at........................................ 96 

Heald mining district, rocks of. .. __ ............ _____ 73 

Heikes, V. C., cited on Buffalo Hump district._ .. _.. 102 

mention of. . . ................ ------.............. 105 

Helena-Frisco mine, description of................. . 111 

Hematite, occurrence of. ... ------------ ....... ____ .. 107 

Hillebrand, W. F., analysis by---------------------- 112 

Hinckley's ranch, rocks exposed at . . . . . . . . . . . . . . . . . 74 

Homestake vein, location of................... . ..... 98 

Horse Creek, gneiss of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 

mine:ral springs on ........................ ·...... 114 

ore deposits of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 

prospecting on.. . . . . . . . . .. .. . . . . . . .. . . . . . . .. . . . . . 90 

rocks on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63, 64, 66 

Hot Springs, contact near . . . . . . . . . . . . . . .. .. . . . . . .. . . 36 

rocks near . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35, 38 

Hughes Creek, claims on.---- ....... : ........ ___ .... 88-89 

gold of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 

gravel of..---.-----.-----.----------- ...... ------ 58,88 

mi!leral deposits of . . . . . . . . .. .. .. . . . . . .. . . . . . . . . . 88-89 

mining operations on ...................... __ .___ 89 
120 INDEX. 

Page. 

Hughes Creek, plact;rs of............................ 83,116 

rocks exposed on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 

rocks in basin of................................. 56-57 

Huntington, Oreg., rocks near . . . . . . . . . . . . . . . . . ... . . 73 

sedimentary rocks near .. ... . .................. 16 

I. 

Idaho, central, map of. ... .... ...................... . 

central plateau of. .. ..... ............ .. . . ....... . 

map of, by General Land Office . . ...... ... ..... . 

Idaho County, mines of. ....................... . .... . 

production of precious metals in .. :: . ..... ... .. . 

Idaho Mining Company, property of ............ .. . . 

Imnaha River, copper at junction of Snake and ... . 

Indian reservation. See Nez Perce Reservation. 

Iron Crown mine, description of ......... . ......... . 

, Iron Crown quartz mill, view of. ................ ... . 

J. 

John Day Creek, placers on · .. .... ........... ... .... . 

Johnson, H. R., aid by ...... ..................... ... . 

discovery by .................................... . 

Johnson Creek, gold of ............................. . 

Jointing. See Schistosity. 

Jumbo mine, work on .................. : ..... ...... . 

production of ................................... . 

K. 

Kamiaok Butte, character of ................ . 

Kamiah Prairie, elevation of ....................... . 

Keuterville, rocks near ............................. . 

Knowlton, F. H., cited on age of basalt ........... .. 

L. 

10 

48 

10 

85 

85 

93 

107 

97 

96 

107-108 

11 

'74 

89 

101 

102 

81 

77 

72 

24 

Landslides in· Clearwater Canyon . . . . . . . . . . . . . . . . . . . 76 

Lava, Columbfa River, occurrence and depth of.... 81 

Lava flow, elevation of.............................. 77 

time of........................................... 115 

Lava plateau, epeirogenic movements of. .... 25,27-28,77-80 

faulting in. See Faulting. 

geology of. .. _.... .. .. . .. .. . . .. .. .. .. .. . .. . . .. . .. . 70-80 

structure and physiography of................... 76 

topography of.................................... 68-70 

La vas, origin of. .... : .. :. .. .. . .. .. .. .. . .. .. .. . . . .. . .. 25 

Tertiary, occurrence and description of......... 23-25, 

. . . 57-58, 74-75 

Lead, occurrence of ............................. 82-83, 86-87 

Lei berg, J. B., cited on Bitterroot Valley............ 29 

cited on lignite occurrence . . . . . . . . . . . . . . . . . . . . . . 112 

quoted on ru-ggedness of western slope of Bitterroot Range............................... 41 

Lewis and Clarke, exploration by................... 9 

Lewiston, elevatii:m of............. . . . . . . . . . . . . . . . . . . 79 

folds near. . . . . . . . . .. .. . . . .. .. . .. . . .. .. . .. . . . .. . .. 27 

rocks near ·. .. . .. .. . .. . . . .. .. .. . . .. . . . .. .. .. . .. . . . 72-77 

Lewiston plateau, elevation of . . . . . . . . . . . . . . . . . . . . . . 69, 77 

view of ...................................... .'... 76 

Lick Creek, rhyolite on ....... ~...... .. .. . .. .. .. .. .. . 24 

Lignite, analysis of.:................................ 112 

occurrence and character of. .................... 111-113 

See also Coal. 

Limestones of lava plateau.......................... 71,74 

Lindgren, W., cited on gold belt of Blue Mountains. 73 

' cited on origin of lavas.......................... 25 

Lippincott, J. B., 'cited on Bilk Mountain........... 64 

Lippincott, J. B., map by ........................ .- ... . 

photograph by .................................... . 

Little Canyon, lignite in ............................. . 

Little Canyon Creek, rocks in ...................... . 

Little Elk Creek, placers of. . ....................... . 

Pft,ge. 

10 

10,60 

113 

76 

95--96 

terrace on ... .. ............. , . . . .. . . . . . . . . . . . . .. .. 93 

Little Salmon Meadows, rocks near ............. , . . . 20,64 

Lochsa Fork, canyon of .. . .. .. .. . . .. .. . . . .. .. .. .. . . . 62 

mineral springs on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 

rocks along...................................... 65 

Lochsa-Selway divide, location and description of.. 59 

Lolo contact, description of .. .. .. .. .. .. .. .. . .. .. .. .. 36 

Lolo Creek, gold washings of. . . . . . . . . . . . . . . . . . . . . . . . 105 

mineral deposits at .. .. . .. . .. .. .. .. .. . .. . .. .. .. .. 83 

Lolo Fork, geology along............................ 34-38 

topography along................................ 33-34 

mineral deposits of.............................. 86 

mineral springs on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 

sedimentary rocks on............................ 16 

Lolo Pass, height of................. . ................ 40 

rocks of ....... : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 

Lolo Peak, height of........................ .. .. .. .. 33 

rocks near ................... ... c. . . • • . . • . . . . . . . . 42 

Lolo post-office, rocks exposed near...... . . . . . . . . . . . . 34 

Lolo Ridge, rocks of .. .. .. .. . . .. .. . .. .. . .. . .. .. .. .. .. 44, 63 

Lolo series, occurrence of . . . . . . . . . . . . . . . . . . . . . . . 22, 34-35, 37 

Lolo trail, use and character of...................... 9, 34 

Lookout mine, location of........................... 97 

Lost Horse Creek, gap on............................. 40 

moraines of. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. . .. .. . 53-54 

rocks exposed on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44-45 

trail up.......................................... 41 

Lost Horse Pass, rocks at .. .. .. .. . .. .. .. .. . .. .. .. . .. . 21, 64 

M. 

Mascot Milling and Mining Company's mill, work of. 104 

Mascot vein, location and working of............... 104 

Merriam, J. C., cited on age of basalt................ 24 

Merrill, G. P., analysis by................. . ........... 75 

Metalliferous areas, location of.. . ................... 82 

Mesozoic rocks, occurrence of........... .. .. . . . . . .. . 16 

Middle Fork of .Clearwater, canyon of............... 62 

rocks along . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 

Mill Creek, gneiss on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 

graniteon........................................ 18 

gradeof .... : ..................................... 49,50 

rocks exposed on .. .. . .. .. .. .. . .. . . .. .. . . . . .. . .. . 43-44 

Mill Creek Canyon, gravels of....................... 52-53 

view of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40, 42 

Mineral deposits, occurrence and character of. ... 82-114,116 

Mineral Hill, mineral deposits and mines of......... 89-90 

Mineral Hill district, rocks of........................ 66 

Mineral Point, mineral deposits and mines of....... 89 

rocks at.......................................... 56-57 

:Mineral Point Meadows, rocks of.................... 57 

Mineral Springs, occurrence and character of ....... 113-114 

Mining districts. of Clearwater, map showing locations Qf ............................. ~--·· 92 

Miocene epoch, basalt of............................ 24 

rhyolite of . . . . . . . . . .. . . . .. . . . . . . . . . . . . . . . . . . . . . . . 24 

Mission Creek, occurrence. of limestone at . . . . . . . . . . 71 

Missoula River, rocks a~ong.. .. . . .. .. . .. .. .. . . . .. .. .. 82 

_Moose Creeks diggings, location and description of.. 91-96 

Monitor mine, working of . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 

Monte Cristo mine, description of.................... 101 
INDEX. 121 

Page 

Moraines, occurrence and character of ......... .".... . 25, 

28, 44-45,46,49, 52-54 

Mormon Creek, mineral deposits on ................ . 

Mormon Gulch, rocks on ............ . ............ : .. . 

86 

35 

Morning mine, description of........................ 111 

Mount Idaho gold mines near .......... .. ........... 105-'106 

rocks ne~r . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70, 73, 79 

Mountain House, rocks near ........................ . 

Mullan, rocks at ......................... ············ 

Mullan district, production of ...................... · 

Mullan Pass, rocks at and near .................... ·· 

~rurray, gold at ............................ ·········· 

Musselshell Creek, gold washings of ............... . 

mineral deposits on ......................... · · · · 

rocks on ....... . ............. ................... . 

N. 

Neve fields of Bitterroot Mountains, extent o~ ..... . 

Newsome, rocks at ................................. . 

Newsome Creek, placers of ...... . .................. . 

veins of ............... . ......................... . 

Nez Perce Fork. See West Fork. 

Nez Perce Indian Reservation , opening of ......... . 

Nez Perce Pass, height of. .......................... . 

65 

81-82 

108 

81,82 

82 

105 

83 

65 

55 

65 

91,96 

83,97 

10 

40 

rocks near .............. ... ......... -...... -. . . . . 42 

Nez Perce trail, rocks on . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 

North Fork of Clearwater, rocks on .. . ..... ... -... - 17, 23,71 

North Fork-Lochsa divide, location and description 

of .. . -- ........ -- ....... -........ ·····.... 59 

o. 

Ores, character of ..... · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 8

8

3-4-8

8

! 

history and production of....................... v 

geologic relations of............................. 85 

Oro Fino, gold fields of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84, 103 

metamorphL~ at................................ 23 

rocks exposed at ........................ .. 17, 23,70-71,76 

Oro Fino Creek, lignite on........................... 113 

mineral deposits on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83-84 

workon ........ . ........................ ........ 103 

Orographic dislocations of lava plateau........ . .... 25 

Orton, Molloy & Co. , work of........................ 89 

Overwhich Creek, rhyolite 011....................... 23 

Owl Creek, mineral deposits of...................... 90 

Ozark Company, developments of. . ................. 104 

P. 

Paleozoic era, sedimentary rocks of . . . . . . . . . . . . . . . . . 16 

Pierce, gneiss at . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 

gravelsat ........................... : ... .. ....... 67 

mines of .. . -.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83-84, 116 

rocks at and near ......................... 17,63-65,70,76 

Pierc bull'tact , dioritic modifications near.......... 20 

Pierc :district, location; history, and description of. 102-105 

Pine forest in Bitterroot Mountains, view of . . . . . . . . 46 

Placers, gold, occurrence of. 83-85,88-89,91-96,97,102-103,108 

of Elk City district . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91-96 

Plateau of cflntral Idaho, description of... . ......... 48 

Pleasant View prospects, silver of................... 87 

Pliocene epoch, rhyolite of.......................... 24 

Potlatch Creek, rocks on . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 

Precious metals in area discussed, history and production of ............................. 84-85, 116 

Pullman, rocks near....... . . . . . . . . . . . . . . . . . . . . . . . . . . 81 

Page. 

Q. 

Quartz veins in Coeur d'Alene Mountains ........... 108-109 

Quartz veins, gold bearing, occurrence of. 96-97, 101, 103-104 · 

Quartz-monzonite, analyses of.................. ..... 19 

occurrence of. .............................. 18-19,38, 114 " . 

Quartzite, occurrence of.. . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 

Quartzitic schists, occurrence of. ......... :.......... 16, 35 

Quaternary formations, Ol~currence and character 

of .............. ................. .. 25-26, 29, 38, 58 

R. 

Raymond, R. W., mention of... . .............. ...... 11 

Red Horse Creek, placers of..... . ........ .. . . ....... 91-92 

Red River, mineral springs on . . . . . . . . . . . . . . . . . . . . . . 114 

placer mines of.................... . ........ .. .. . 91 

veins of . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96-97 

Relief Creek, rocks on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 

Rhodes Gulch, richness of..... . . . . . . . . . . . . . . . . . . . . . . 103 

Rhodes Peak, glaciation on . . . . . . . . . . . . . . . . . . . . . . . . . 67 

rock of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 

silver vein on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 

Rhyolite, occurrence and character of .... 23-24,32-33,57-58 

See also Tertiary lavas. 

Rhyolite associated with coal, occurrence of. ....... 112-113 

Ridges of Clearwater Mountains . . . . . . . . . . . . . . . . . . . . 59-61 

Roaring Lion Creek, morainal gravels of. . . . . . . . . . . . 53 

terraces of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 

Robbins mining district, organization of............ 99 

Rock Creek, moraines of . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53-54 

rocks exposed on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 

Rocky Canyon, rocks of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 

Rocky Ridge, glt;tciation on.......................... 67 

Rumbo Creek, rocks on ..... . ,..... . ................. 56 

Russell, ·r. C., cited on basalt ............. '.......... 75 

cited on Columbia River lava . . .. . . . . . . . . . . . . . . . 74 

cited on epeirogenic movements................ 79-80 

cited on lava plateau .............. .. ...... ..... 68,79-80 

cited on Lewiston Plateau and Craig Mountain. 77 

cited on lignite .. :............................... 113 

cited on limestones of la·m plateau . . . . . . . . . . . . . 71 

cited on rocks of North Fork . .. .. . . .. .. .. . . .. .. . 71 

cited on Salmon Canyon rocks . . . . . . . . . . . . . . . . . . 72 

cited on Small's ranch boring . . . . .. .. .. . . . . • .. .. 76 

cited on Snake River exposures................. 72-73 

cited on "steptoes" . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 70 

cited on volcanic dust........ ... ................ 76 

quoted on Mascot Hill mines.. ... ............... 104 

quoted on Snake Canyon. . . . . . .. . . . . . . . . .. .. .. .. 63 

quoted on Uniontown Plateau . . . . . . . . . . . . . . . . .. 76 

Ryans Meadows, rocks n ear....... . ................. 64-65 

s. 

St. Marys Peak, gneiss of . . . . . . . . . . . . . . . . . . . . . . . . .. . . 22, 37 

St. Regis de Borgia River, rocks along . . . . . . . . . . . . . . 82 

Salmon Mountain, glaciation on "................... 67 

gneissof ......................................... 20,22 

rocks at and near ................... .......... .. 63, 64, 65 

Salmon Peak, elevation of........................... 60 

Salmon Point, placers near............. . ... .. ....... 108 

Salmon River, Col-umbia river lava on.............. 62 

description of. .............. .. . . ,................ 62 

gold on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105, 107 

origin and character of.......................... 114 

rocks exposed on ........ . , ............... 16, 62, 70, 72,73 
122 INDEX. 

Page . . 

Salmon River Canyon, description of . . . . . . . . . . . . . . . 14, 62 

glacial gravels in... . ............................ 28 

history of ............... . ......... : . . . . . . . . . . . . . . 78 

vie'v of............... . .......................... 68 

Salmon River divide, elevation of........ . ..... . .... 55 

location and description of...................... 59 

Salmon River divide trail, description of............ 60 

·Salmon River Mountains, location of. ........... ·.·.. 13 

view of .................•.............. _,_ . . . . . . . . 60, 69 

Salmon-Snake plateau, height of basalt on.......... 79 

Santiago mines, operation of . . . . . . . . . . . . . . . . . . . . . . . . 104 

Sawtooth Creek, morainal gravels of... . . . . . . . . . . . . . 53 

Sawtooth .Gulch, rocks in............................ 42 

Schistosity and jointing, discussion of . . . . . . . . . . . .. . 50,114 

Searle, A. B., map by................................ 10 

Sear's ranch, glacial deposits at............ . ........ 52-53 

Section near Como...... . ..... . ... . ................. 33 

Sedimentary rocks, occurrence of . . . . . . . . . . . . . . . . . . . 15-

17, 31,34-35,42,56-57,66,70-74,115 

Selway Fork, drainage of..... . . . . . . . . . . . . . . . . . . . . . . 62 

rock~ along.......... . .. .. . . ..... . ......... . ..... 65 

Seven Devils, fossils at . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16, 73 

rocks at. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16, 73 

Sherman Peak, rocks of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63, 65 

Silver, occurrence of. . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . 82-83, 87 

Skalkaho Creek, rocks along . . . . . . . . . . . . . . . . . . . . . . . . 31 

Slate Creek, mineral deposits of . . . . . . . . . . . . . . . . . . . . . 88 

mi::tes at....................... . ..... . .... . ...... 88 

rhyolite on............................... . ....... 57 

veins of...... . ................................... 88 

Small's ranch, boring on . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 

Snake River, copper at junction of Imnaha River 

and................... . ...... ............ 107 

description of ................................... ·. 62-63 

gold on ................ ·...... . . . . . . . . . . . . . . . . . . . . 105, 107 

limestone· of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 

sedimentary rocks near junction of Salmon 

River and.................. . . . . . . . . . . . . . . 16 

Snake River Canyon, description of.. . .............. 63 

glacial gravels in................ . ............... 28 

history of ............ -.--......................... 78-79 

rocks exposed in................................. 70-71 

view of.......................................... 70 

South Fork of Bitterroot River, canyon of........... 62 

dike!! along . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20, 23 

geology of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56-59 

granite-porphyry on ......... ."................... 23 

gravels of .................. : . . . . . . . . . . . . . . . . . . . . . 58 

mineral deposits of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88-90 

Sedimentary rocks on............................ 56-57 

terraces of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 

topography of................. . .................. 55-56 

South Fork of Clearwater River, auriferous terraces 

on...................... . ................ 27 

map of. ......................... :................ 92 

sedimentary rocks on......... . ... . .............. 16 

sediments on . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .. 74 

washings on ............................ ····.····· 96 

Spark's ranch, rocks near . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 

Steptoe Butte, character of.......................... 81 

Step toes, definition of............................. ... 70 

Stose, G. W., aid by.................................. 11 

cited on rock exposures . . . . . . . . . . . . . . . . . . . . . . . . . 66 

cited on rocks of Coal Creek..................... 57 

investigation by. . ..... .......................... 112 

photographs by ............................ .'..... 53 

Page. 

Stose, G. W., work of ............................... 45,46,56 

Stuart, rocks at . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 

Subsidence in Bitterroot Range . . . . .. . ... .. . . .. . . . . . 48-49 

Sweet mine, production of ....... .. ................ : 104 

Symons, T. W., work of....... . . . ......... . .......... 10 

T. 

Tekoa Spur, rocks of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 

Terraces, occurrence of ........... _,_ . . . . 27·, 29-30, 33)58, 93, 96 

Tertiary gravels, occurrence of...................... 67 

Tertiary lavas (see Lavas, Tertiary) ......... ,....... 23 

Tertiary rocks, occurrence of. . . . . . . . . . . . . . . . . . . . . . . . 57 

Tertiary period, erosion in.. . ........................ 27 

events of...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27-28 

Tiernan diggings, description of..................... \14 

Tincup Canyon, gneiss in . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 

Tincup Creek, moraines of........ . .... . . . . . . . . . . . . . . 53-54 

rocks near ................. : .. ·. . . . . . . . . . . . . . . . . . . 42 

Tiptop mine, rocks exposed at....................... 88 

Trails. (See Lolo trail; Bitterroot Range trails; Nez 

Perce trail; Lost Horse Creek trail; 

Salmon River divide trail.) 

Trapper Creek, mineral deposits of.................. 88 

moraines of.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 

rocks exposed on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 

section on ................................ .'...... 46 

Trapper Peak, gneiss zone of, view of........... . . . .. 46 

height of. ......... ·............................... 39 

Triassic period, sedimentary rocks of...... . .... . .... 16 

Twin Lakes, granite near............................ 21 

moraine at................ . .... .................. 54 

schistosity near.................................. 45 

u. 

Unio shells, occurrence of . . . . . . . . . . . . . . . . . . . . . . . . . . . 57-58 

Uniontown Plateau, elevation of................ .... 70,77 

location and height of . . . . . . . . . . . . . . . . . . . . . . . . . . 81 

Uplift, hypothesis of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 

in area discussed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 

of lava plateau . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27-28 

v. 

Van Rise, C. R., cited on schistosity and jointing.... 50 

Victor, rocks near. . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . 31 

Volcanic dust, occurrence of..................... . ... 76 

Volcanic rocks, occurrence of........ . . . . . . . . . . . . . . . . 57 

w. 

Wallace district, production of . . . . . . . . . . . . . . . . . . . . . . 108 

Walton Lake, view of. ................... :........... 68 

Ward Peak, heights near..................... . ...... 39 

Wardner, rocks at .. , ......... . ....................... 81 

Wardner district, mines of .. . ........................ 108,110 

Warren, gold mines and production of . . . . . . . . . . . . . . 85 

rocks at.......................................... 64 

Weed, W. H., cited on Gibbonsville district......... 57,90 

cited on rocks of West Fork... . .................. 58 

Weeping Child Creek, rocks along.................. 31-32 

sedimentary rocks on. , ......................... . 

Weeping Child Hot Springs, location of...... . ...... 118 

West Fork of Bitterroot, gravel on................... 58 

mineral spring on ................................ 113-114 

rocks along ..................................... 46-47,56 

terraces on. . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . 58 

Westerman's ranch, rocks near ......... · ........ : ... . 35, 
INDEX. 123 

Westerman's ranch, veins near .. __ ---- ___ ---- ------- White Bird Creek, rocks near. ___ __________ _________ _ 

Whittle, Charles L., quoted on Buffalo Hump disPage. 

86 

72 

trict _ . _____________ . _____ . ____ . _ _ _ _ _ _ _ _ _ _ 100, 102 

Wild Rose mine, developments ou. __ . ____ . ____ . _ _ _ _ _ 104 

Wise Boy mine, work on . . -- --_ . . ·--- __ . __ .. --- __ . --- 102 

Wood Placer Company, work of.. _____ ---··-----____ 89 

Woodmans Creek, copper on_-- ---.----------------- 86 

gold prospects on .... ____ .. _ .... _ ..•. _ ... _ ... -- -- 86 

Woodmans Creek, rocks n.ear ... ---------------------

Woods Creek, deposits of_ .. --_--- .. ---.--------- .. --

Y. 

Page. 

35 

89 

You Like mine, description oL. ---------- ------· -·-- 111 

z. 

Zinc blende, occurrence of_--- ___ . __ ---- __ .--.------ 108-109 

0 
PUBLICATIONS OF UNITED STATES GEOLOGICAL SURVEY. 

[Professional Paper No. 27.] 

The serial publications of the United States Geological Survey consist of (1) Annual Reports, 

(2) Monographs, (3) Professional Papers, (4) Bulletins, (5) Mineral Resources, (6) 'Vater-Supply 

and Irrigation Papers, (7) Topographic Atlas of the United States-folios .and separate sheets 

thereof, (8) Geologic Atlas of the United States-folios thereof. The classes numbered 2, 7, and 8 

are sold at cost of public~tion; the others are distributed free. A circular giving complete lists may 

be had on application. 

The Professional Papers, Bulletins, and Water-Supply Papers treat of a variety of subjects, and 

the total number issued is large. 'rhey have therefore been classified into the following series: A, 

Economic geology; B, Descriptive geology; C, Systematic geology and paleontology; D, Petrography 

and mineralogy; E, Chemistry and physics; F, Geography; G, Miscellaneous; H, Forestry; I, Irrigation; J, Water storage; K, Pumping water; L, Quality of water; M, General hydrographic investigations; N, Water power; 0, Underground waters; P, Hydrographic progress reports. This paper 

is the thirty-fifth in Series A and the thirty-ninth in Series B, the complete lists of which follow, 

(PP=Professional Paper, B=Bulletin, 'VS= Water-Supply Paper.) 

SERIES A, ECONOMIC GEOLOGY. 

B 21. Lignites of Great Sioux Reservation: Report on region between Grand and Moreau rivers, Dakota, by Bailey Willis. 

1885. 16 pp., 5 pls. (Out of stock. ) 

B 46. Nature and origin of deposits of phosphate of lime, by R. A. F. Penrose, jr., with introduction by N. S. Shaler. 1888. 

143 pp. (Out of stock.) 

B 65. Stratigraphy of the bituminous coal field of Pennsylvania, Ohio, and West Virginia, by I. C. White. 1891. 212 pp., 

11 pls. (Out of stock.) 

B 111. Geology of Big Stone Gap coal field of Virginia and Kentucky, by M. R. Campbell. 1893. 106 pp., 6 pls. 

B 132. The disseminated lead ores of southeastern Missouri, by Arthur Winslow. ·1896. 31 pp. 

B 138. Artesian-well prospects in Atlantic Coastal Plain region, by N. H. Darton. 1896. 228 pp., 19 pls. (Out of stock.) 

B 139. Geology of Castle Mountain mining district, Montana, by W. H. Weed and L. V. Pirsson. 1896. 164 pp., 17 pls. 

B 143. Bibliography of clays and the ceramic arts, by J. C. Branner. 1896. 114 pp. 

B 164. Reconnaissance on the Rio Grande coal fields of Texas, by T. ''' . Vaughan, including a report on igneous rocks from 

the San Carlos coal field, by E. C. E. Lord. 1900. 100 pp., 11 pls. 

B 178. El Paso tin deposits, by W. H. Weed. 1901. 15 pp., 1 pl. 

B 180. Occurrence and distribution of corundum in United States, by J. H . Pratt. 1901. 98 pp., 14 pls. (Out of stock.) 

B 182. A report on the economic geology of the Silverton quadrangle, Colorado, by F. L. Ransome. 1901. 266 pp., 16 pls. 

(Out of stock.) 

B 184. Oil and gas fields of the western interior and northern Texas Coal Measures and of the Upper Cretaceous and Tertiary of the western Gulf coast, by G. I. Adams. 1901. 64 pp., 10 pls. (Out of stock.) 

B 193. The geological relations and distribution of platinum and associated metals, by J. F . Kemp. 1902. 95 pp., 6 pls. 

(Out of stock.) 

B 198. The Berea grit oil sand in the Cadiz quadrangle, Ohio, by W. T. Griswold. 1902. 43 pp., 1 pl. 

PP 1. Preliminary report on the Ketchikan mining district, Alaska , with an introductory sketch of the geology of southeastern Alaska, by Alfred Hulse Brooks. 1902. 120 pp., 2 pls. 

B 200. Reconnaissance of the borax deposits of Death Valley and Mohave Desert, by M. R. Campbell. 1902. 23 pp., 1 pl. 

(Out of stock.) 

B 202. Tests for gold and silver in shales from western Kansas, by Waldemar Lindgren. 1902. 21 pp. 

PP 2. Reconnaissance of the northwestern portion of Seward Peninsula, Alaska, by A. J. Collier. 1902. 70 pp., 11 pls. 

PP 10. Reconnaissance from Fort Hamlin to Kotzebue Sound, Alaska, by way of Dall, Kanuti, Allen, and Kowak rivers, 

by W. C. Mendenhall. 1902. 68 pp., 10 pls. 

PP 11. Clays of the Untted Btates east of the Mississippi River, by Heinrich Ri.es. 1903. 298 pp., 9 pls. 

PP 12. Geology of the Globe copper district, Arizona, by F. L. Ransome. 1903. 168 pp., 27 pls. 

B 212. Oil fields of the Texas-Louisiana Gulf Coastal Plain, by C. vV. Hayes and William Kennedy. 1903. 174 pp., 11 pls. 

B 213. Contributions to economic geology, 1902. S. F. Emmons, C. W. Hayes, geologists incharge. 1903. 449 pp. 

PP 15. The mineral resources of the Mount Wrangell district, Alaska, by W. C. Mendenhall and F. C. Schrader. 1903. 

71 pp., 10 pls. 

B 218. Coal r esources of the Yukon, Alaska, by Arthur J. Collier. 1903. 71 pp. , 6 pls. 

B 219. The ore deposits of Tonopah, Nevada (preliminary report), by J. E. Spurr. 1903. 31 pp., 1 pl. 

PP 20. A reconnaissance in northern Alaska in1901, by F. C. Schrader. 1904. 139 pp., 16 pls. 

PP 21. The geology and ore deposits of the Bisbee quadrangle, Arizona, by F. L. Ransome. 1904. 168 pp., 29 pls. 

B 223. Gypsum deposits in the United States, by G. I. Adams and others. 1904. 129 pp., 21 pls. 

PP 24. Zinc and lead deposits of northern Arka nsas, by G. I. Adams, assisted by A. H. Purdue and E . F. Burchard, with a 

section on the determination and correlation of formations, by E. 0. Ulrich. 1904. 118 pp., 27 pls. 
II PUBLICATIONS OF UNITED STATES GEOLOGICAL SURVEY. 

PP 25. The copper deposits of the Encampment district, Wyoming, by A. C. Spencer. 1904. 107 pp., 2 pls . 

.B 225. Contributions to economic geology, 1903, by S. F. Emmons and C. W. Hayes, geologists in charge. 1904. 527 pp., 1 pl. 

PP 26. Economic resources of the northern Black Hills, by J.D. Irving, with contributions by S. F. Emmons and T. A. 

Jaggar, jr. 1904. 222 pp., 20 pls. 

PP 27. A geological reconnaissance a~::ross the Bitterroot Range and Clearwater Mountains in Montana and Idaho, by 

Waldemar Lindgren. 1904. 122 pp., 15 pis. 

SERIES B, DESCRIPTIVE GEOLOGY. 

B 23. Observations on the junction between the Eastern sandstone and the Keweenaw series on Keweenaw Point, Lake 

Superior, by R. D. Irving and·T. C. Chamberlin. 1885. 124 pp., 17 pis. (Out of stock.) 

B 33. Notes on geology of northern California, by J. S. Diller. 1886. 23 pp. (Out of stock.) 

B 39. The upper beaches and deltas of Glacial Lake Agassiz, by Warren Upham. 1887. 84 pp-., 1 pl. (Out of stock.) 

B 40. Changes in river courses in Washington Territory due to glaciatidn, by Bailey Willis. 1887. 10 pp., 4 pis. (Out oi 

stock.) 

B 45. The present condition of knowledge of the geology of Texas, by R. T. Hill. 1887. 94 pp. (Out ofstock.) 

B 53. The geology of Nantucket, by N. S. Shaler. 1889. 55 pp., 10 pis, (Out of stock.) 

B 57. A geological reconnaissance in southwestern Kansas, by Robert Hay. 1890. 49 pp., 2 pls. 

B 58. The glacial boundary in western Pennsylvania, Ohio, Kentucky, Indiana, and Illinois, by G. F. Wright, with introduction by T. C. Chamberlin. 1890. 112 pp., 8 pls. (Out of stock;) 

B 67. The relations of the traps of the Newark system in the New Jersey region, by N.H. Darton. 1890. 82 pp. (Out of 

· stock.) 

B 104. Glaciation of the Yellowstone Valley north of the Park, by W. H. Weed. 1893. 41 pp., 4 pls. 

B 108. A geological reconnaissance in central Washington, by I. C. Russell. 1893. 108 pp., 12 pis. (Out of stock.) 

B 119. A geological reconnaissance in northwest Wyoming, by G. H. Eldridge. 1894. 72 pp., 4 pls. 

B 137. 'rhe geology of the Fort Riley Military Reservation and vicinity, Kansas, by Robert Hay. 1896. 35 pp., 8 pis. 

B 144. The moraines of the Missouri Coteau and their attendant deposits, by J . . E. Todd. 1896. 71 pp., 21 pls. 

B 158. The moraines of southeastern South Dakota and their attendant deposits, by J. E. Todd. 1899. 171 pp., 27 pl>i. 

B 159. The geology of eastern Berkshire County, Massachusetts, by B. K. Emerson. 1899. 139 pp., 9 pls. 

B 165. Contributions to the geology of Maine, by H. S. Williams and H. E. Gregory. 1900. 212 pp., 14 pis. . 

WS 70. Geology and water resources of the Patrick and Goshen Hole quadrangles in eastern Wyoming and western 

Nebraska, by G. I. Adams. ·1902. 50 pp., 11 pls. 

B 199. Geology and water resources of the Snake River Plains of Idaho, by I. C. Russell. 1902. 192 pp., 25 pls. 

PP 1. Preliminary report on the Ketchikan mining district, Alaska, with an introductory sketch of the geology of southeastern Alaska, by A. H. Brooks. 1902. 120 pp., 2 pls. 

PP 2. Reconnaissance of the northwestern portion of Seward Peninsula, Alaska, by A. J. Collier. 1902. 70 pp., 11 pis . 

. PP 3. Geology and petrography of Crater Lake National Park, by i S. Diller and H. B. Patton. 1902. 167 pp., 19 pls. 

PP 10. Reconnaissance from Fort Hamlin to Kotzebue Sound, Alaska, by way of Dall, Kanuti, Allen, and Kowak rivers, 

by W. C. Mendenhall. 1902. 68 pp., 10 pis. • 

PP 11. Clays of the United States eas~ of the Mississippi River, by Heinrich Ries. 1903. 298 pp., 9 pls. 

PP 12. Geology of the Globe copper district, Arizona, by F. L. Ransome~ 1903. 168 pp. , 27 pls. 

PP 13. Drainage modifications in southeastern Ohio and adjacent parts of We&t Virginia and Kentucky, by W. G. Tight. 

19!)3. 111 pp., 17 pls. · 

B 208. Descriptive geology of Nevada south of the fortieth parallel and adjacent portions of California, by J. E. Spurr. 

1903. 229 pp., 8 pls. , 

B 209. Geology of Ascutney Mountain, Vermont, by R. A. Daly. 1903. 122 pp., 7 pis. 

WS 78. Preliminary report on artesian basins in southwestern Idaho and southeastern Oregon, by I. C. Rus!!ell. 1903. 

51 pp., 2 pls. 

PP 15. Mineral resources of the Mount Wrangell district, Alaska, by W. C. Mendenhall and F. C. Schrader. 1903. 71 pp., 

10 pls. 

PP 17. Preliminary report on the geology and water resources of Nebraska west of the one hundred and third meridian, 

by N.H. Darton. 1903. 69 pp., 43 pls. 

B 217. Notes on the geology of southwestern Idaho and southeastern Oregon, by I. C. Russell. 1903. 83 pp., 18 pls. 

B 219. The ore deposits of Tonopa h, Nevada (preliminary r eport), by J. E. Spurr. 1903. 31 pp., 1 pl. 

PP 20. A reconnaissance in northern Alaska in 1901, by F. C. Schrader. 1904. 139 pp., 16 pis. 

PP 21. The geology and ore d~posits of the Bisbee quadrangle, Arizona, by F. L. Ransome. 1904. 168 pp., 29 pls. 

WS 90. Geology and water resources of part of the lower James River Valley, South Dakota, by J. E. Todd and C. M. Hall. 

· 1904. 47 pp., 23 pls. 

PP 25. The copper deposits of the Encampment district, Wyoming, by A. C. Spencer. 1904. 107 pp., 2 pls. 

PP 26. Economic resources of the northern Black Hills, by J.D. Irving, with contributions by S. F. Emmons and T. A. 

Jaggar, jr. 1904. 222 pp., 20 pls. 

PP 27. A geological reconnaissance across the Bitterroot Range and Clearwater Mountains in Montana and Idaho, by 

Waldemar Lindgren. 1904. 122 pp., 15 pls. 

Correspondence should be addressed to 

THE DIRECTOR, 

JUNE, 1904. 

UNITED STATES GEOLOGICAL SURVEY, 

wASHINGTON, D. c. 
I 

LIBRARY CATALOGUE SLIPS. 

[Mount each slip upon a separate card, placing the subject at the top of the 

second slip. The name of the series should not be repeated on the series 

card, but additional numbers should be added as received, to the first 

entry.] 

Lindgren, Waldemar. 

. . . A geological reconnaissance across the Bitter-

~ root Range and· Clearwater Mountains in Montana and 

..... 

~ Idaho, by Waldemar Lindgren. Washington, Gov't 

print. off., 1904. 

122, nip. illus., 15 pl. (incl. maps) 29-! x 23cm. (U.S. Geological survey. 

Professional paper no. 27. ) 

Subject series: A, Economic geology, 35; B, Descriptive geology, 39. 

"Maps and literature": p. 10-11. 

Lindgren, Waldemar. 

1· . . . A geological reconnaissance across the Eitteras root Range and Clearwater Mountains in Montana and 

:E' 

: Idaho, by Waldemar Lindgren. Washington, Gov't 

"' Q;) 

print. off., 1904. 

122,nip. illus., 15pl. (incl. maps) 29tx23cm. (U.S.Geologicalsurvey. 

Professional paper no. 27.) 

Subject series: A, ,Economic geology, 35; B, Descriptive geology, 39. 

"Maps and literature": p. 10-11. 

U. S. Geological survey. 

Professional papers. 

i 

oo no. 27. Lindgren, Waldemar. A geological reconnaissance across the Bitterroot Range and Clearwater Mountains in Montana and Idaho. 1904. 

U. S. Dept. of the Interio],". 

see also 

U. S. ·. Geological survey. 

III 

I