Mineral Resources of the Battle Creek, 

Yatahoney Creek, and Juniper Creek 

Wilderness Study Areas, Owyhee 

County, Idaho

U.S. GEOLOGICAL SURVEY BULLETIN 1719-B

Chapter B

Mineral Resources of the Battle Creek, 

Yatahoney Creek, and Juniper Creek 

Wilderness Study Areas,

Owyhee County, Idaho

By CAROLYN A. GOELDNER, MICHAEL C. SAWLAN,

and HARLEY D. KING 

U.S. Geological Survey

RICHARD A. WINTERS, ANDREW M. LESZCYKOWSKI, 

and DONALD E. GRAHAM

U.S. Bureau of Mines

U.S. GEOLOGICAL SURVEY BULLETIN 1719-B

MINERAL RESOURCES OF WILDERNESS STUDY AREAS 

OWYHEE RIVER REGION, IDAHO AND NEVADA
DEPARTMENT OF THE INTERIOR 

DONALD PAUL MODEL, Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1986

For sale by the

Books and Open-File Reports Section

U.S. Geological Survey

Federal Center, Box 25425

Denver, CO 80225

Library of Congress Cataloging-in-Publication Data

Mineral resources of the Battle Creek, Yatahoney Creek, 

and Juniper Creek Wilderness Study Areas, Owyhee 

County, Idaho.

U.S. Geological Survey Bulletin 1719-B

Bibliography: p. 7

Supt. of Docs, no.: I 19.3:1719-6

1. Mines and mineral resources Idaho Battle Creek

Wilderness. 2. Mines and mineral resources Idaho 

Yatahoney Creek Wilderness. 3. Mines and mineral

resources Idaho Juniper Creek Wilderness. 4.

Geology Idaho Battle Creek Wilderness. 5. Geology 

Idaho Yatahoney Creek Wilderness. 6. Geology Idaho 

Juniper Creek Wilderness. 7. Battle Creek Wilderness

(Idaho). 8. Yatahoney Creek Wilderness (Idaho). 9. Juniper

Creek Wilderness (Idaho). I. Goeldner, Carolyn A. II.

Series.

QE75.B9 No. 1719-B 557.3 s 86-600349

[TN24.I2] [553'.09796'211
STUDIES RELATED TO WILDERNESS

Bureau of Land Management Wilderness Study Area

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

1976) requires the U.S. Geological Survey and the U.S. Bureau of Mines to conduct 

mineral surveys on certain areas to determine the mineral values, if any, that may be 

present. Results must be made available to the public and be submitted to the President 

and the Congress. This report presents the results of a mineral survey of the Battle 

Creek Wilderness Study Area (ID-016-49E), Yatahoney Creek Wilderness Study Area (ID016-49D), and Juniper Creek Wilderness Study Area (ID-016-52), Owyhee County, Idaho.

CONTENTS

Summary Bl

Abstract 1

Character and setting 1

Mineral resource potential of the Battle Creek Wilderness Study Area 3

Mineral resource potential of the Yatahoney Creek Wilderness Study Area 3

Mineral resource potential of the Juniper Creek Wilderness Study Area 3 

Introduction 3

Area description 3

Previous and present investigations 3

Appraisal of indentified resources 3 

Assessment of mineral resource potential 6

Geology 6

Geochemical studies 6

Geophysical studies 7 

Conclusions 7 

References cited 7 

Appendix 1. Definition of levels of mineral resource potential and certainty of assessment 9

FIGURES

1. Index map showing the locations of the Battle Creek, Yatahoney Creek, and Juniper Creek Wilderness 

Study Areas, Owyhee County, Idaho B2

2. Map showing geology and mineral resource potential of the Battle Creek, Yatahoney Creek, and Juniper 

Creek Wilderness Study Areas, Owyhee County. Idaho 4

3. Major elements of mineral resource potential/certainty classification 9

MINERAL RESOURCES OF WILDERNESS STUDY AREAS: 

OWYHEE RIVER REGION, IDAHO AND NEVADA

Mineral Resources of the Battle Creek, 

Yatahoney Creek, and Juniper Creek

Wilderness Study Areas, 

Owyhee County, Idaho

By Carolyn A. Goeldner, Michael G. Sawlan, and Harley D. King 

U.S. Geological Survey

Richard A. Winters, Andrew M. Leszcykowski, and Donald E. Graham 

U.S. Bureau of Mines

SUMMARY 

Abstract

The parts of the three wilderness study areas 

included in this report and for which mineral surveys 

were requested, Battle Creek (ID-016-49E), Yatahoney 

Creek (ID-016-49D), and Juniper Creek (ID-016-52), 

encompass 31,880 acres, 9,550 acres, and 12,350 acres, 

respectively, in southwestern Idaho. In this report, the 

areas studied are referred to as "the wilderness study 

areas," or simply "the study areas." Field work for this 

report was carried out by the U.S. Bureau of Mines and 

U.S. Geological Survey in 1984 and 1985. The three 

study areas contain no known mines, claims, or 

prospects. They are covered by natural gas leases or 

lease applications, but no exploration has occurred. 

On the basis of geologic studies, geochemical and 

geophysical evidence, and mineral surveys, these 

wilderness study areas are defined as having low 

mineral resource potential for gold, silver, lead, tin, 

and diatomite. In this report, any references to the 

Battle Creek, Yatahoney Creek, and Juniper Creek 

Wilderness Study Areas refer only to those parts of the 

wilderness study areas for which the Bureau of Land 

Management requested mineral surveys.

Character and Setting

The Battle Creek, Yatahoney Creek, and Juniper 

Creek Wilderness Study Areas lie along the Owyhee 

River and its tributaries in extreme southwestern 

Idaho (fig. 1). All three study areas are located in the 

Owyhee Plateau subprovince of the Columbia 

Intermontane geologic province, informally known as 

the Owyhee volcanic field (Pansze, 1975). Elevation 

ranges from 4,609 ft on the Owyhee River near Wiley 

Ranch in the Yatahoney Creek Wilderness Study Area 

to 5,651 ft in the northern part of the Battle Creek 

Wilderness Study Area. Plateau topography 

characterizes the intercanyon areas, although, within 

the study areas, relief is as much as 500 ft along the 

Owyhee River and Battle Creek.

The stratigraphy of the three areas comprises 

horizontal, laterally extensive Miocene (about 14 to 10 

million years before present, or Ma) rhyolitic rocks 

locally overlain by Miocene sedimentary rocks and 

Miocene and (or) Pliocene(5 to 2 Ma) basalt (fig. 2) (see 

Geologic Time Chart, last page of report). In the 

Battle Creek Wilderness Study Area, sedimentary 

rocks and basalt occur mostly southeast of Battle 

Creek. Northwest-trending en echelon normal faults 

with vertical displacements of 20-100 ft occur 

primarily southeast of Battle Creek (fig. 2).

Bl
1 16°45'

' , to Grandview, ID

I

to Jordan Valley, OR BATTLE CREEK WILDERNESS 

STUDY AREA (ID-016-49E)

YATAHONEY CREEK WILDERNESS 

STUDY AREA (ID-016-49D)

JUNIPER CREEK WILDERNESS 

STUDY AREA (ID-016-52)

Juniper Basin 

Reservoir

IDAHO 

NEVADA

Figure 1. Index map showing the locations of the Battle Creek, Yatahoney Creek, and Juniper Creek Wilderness 

Study Areas, Owyhee County, Idaho.

B2
Mineral Resource Potential of the Battle Creek 

Wilderness Study Area

The Battle Creek Wilderness Study Area has no 

known mines, claims, or prospects. Placer samples 

collected by the U.S. Bureau of Mines contained 

detectable levels of gold, but not in concentrations 

sufficient to indicate a mineral resource; the source of 

the gold is thought to be 20 mi north of the study area 

(Winters, 1985). About 50 percent of the area is 

covered by oil and gas leases or lease applications, but 

no exploration has occurred. The area has a low 

resource potential for gold, silver, and tin and an 

unknown resource potential for oil and gas.

Mineral Resource Potential of the Yatahoney Creek 

Wilderness Study Area

The Yatahoney Creek Wilderness Study Area 

contains no known mines, claims, or prospects. Just 

south of the study area, near the gas pipeline crossing, 

there is a small outcrop of diatomaceous earth 

(Leszcykowski, 1986), but the projected size of the 

occurrence does not indicate an undiscovered 

resource. The southern part and the northeast corner 

of the study area is covered by oil and gas leases or 

lease applications, but no exploration has occurred. 

The study area has a low resource potential for lead, 

tin, and diatomite and an unknown resource potential 

for oil and gas.

Mineral Resource Potential of the Juniper Creek 

Wilderness Study Area

The Juniper Creek Wilderness Study Area 

contains no known mines, claims, or prospects. It is 

entirely covered by oil and gas leases or lease 

applications, but no exploration has occurred (Graham, 

1985). The study area has a low mineral resource 

potential for lead, tin, and diatomite and an unknown 

mineral resource potential for oil and gas.

INTRODUCTION 

Area Description

The Battle Creek (ID-016-49E), Yatahoney Creek 

(ID-016-49D), and Juniper Creek (ID-016-52) 

Wilderness Study Areas as a whole include 54,180 acres 

located along the Owyhee River and its tributaries in 

extreme southwestern Idaho. The Battle Creek and 

Yatahoney Creek Wilderness Study Areas are 

contiguous, but a narrow gas-pipeline corridor 

separates the Juniper Creek and Yatahoney Creek 

Wilderness Study Areas. The study areas are 

characterized by flat plateaus, except along the 

stream courses where the waters have incised nearly 

vertical canyons as deep as 500 ft.

Access to the Battle Creek Wilderness Study 

Area is by graded dirt roads and unimproved roads 

suitable only for four-wheel-drive vehicles. The 

Yatahoney Creek Wilderness Study Area is contiguous 

with the southern boundary of the Battle Creek

Wilderness Study Area, and a jeep trail marks the 

common boundary of the two study areas. The Juniper 

Creek Wilderness Study Area lies about one mile south 

of the Yatahoney Creek Wilderness Study Area and is 

bounded on the east by the Duck Valley Indian 

Reservation and on the south by an unimproved road. 

Principal access to the Juniper Creek Wilderness Study 

Area is by gravel roads from Owyhee, Nevada to 

Juniper Basin Reservoir, and then by jeep trail to the 

wilderness study area boundary.

Previous and Present Investigations

Previous work related to the wilderness study 

areas includes mostly large-scale regional studies. 

Ekren and others (1981) published a l:250,000-scale 

geologic map of a portion of Owyhee County. Ekren 

and others (1982) described the volcanic stratigraphy 

of western Owyhee County, and Bonnischen and 

Breckenridge (1982) reported on the general geology of 

southwestern Idaho. Another study by Ekren and 

others (1984) dealt with the origin of the rhyolite of 

the Owyhee plateau.

Mineral resources in the area were evaluated in a 

report on the geology and energy and mineral 

resources by Mathews and Blackburn (1983). Reports 

on the uranium potential of the Owyhee plateau region 

were prepared for the Department of Energy during 

their National Uranium Resource Evaluation program, 

which includes reports by Geodata International Inc. 

(1980), Bendix Field Engineering Corp. (1982), and 

Union Carbide Corp. (1982). In 1976, geologists from 

the U.S. Bureau of Mines studied areas along the 

Owyhee River for mineral resources (R. W. Morris, 

1976, U.S. Bureau of Mines unpub. report, Spokane, 

Wash.).

In 1985, geologists from the U.S. Bureau of Mines 

published open-file reports in conjunction with this 

report on the mineral resources of the Yatahoney 

Creek (Leszcykowski, 1986), Battle Creek (Winters, 

1985), and Juniper Creek Wilderness Study Areas 

(Graham, 1985). The U.S. Geological Survey conducted 

field investigations in the three wilderness study areas 

during 1984 and 1985. The work included field 

checking of existing geologic maps, new mapping 

where necessary, and geochemical sampling.

Appraisal of Identified Resources

By Richard A. Winters, Andrew M. 

Leszcykowski, and Donald E. Graham 

U. S.Bureau of Mines

No mining or commercial mineral exploration has 

occurred in any of the wilderness study areas. In the 

Battle Creek Wilderness Study Area, 6 of 12 placer 

samples contained subeconomic but detectable 

concentrations of gold (Winters, 1985). Each sample 

had a gold value of less than $0.02/yd (price of gold 

calculated at $400.00/troy ounce), whereas $0.10- 

0.15/yd is considered anomalous, and $8-10/yd is 

marginally economic. The source of the gold is 

assumed to be about 20 mi north of the wilderness 

study area (Winters, 1985), where the headwaters of

B3
BATTLE CREEK WILDERNESS 

STUDY AREA (ID-016-49E)

\ L/D Pb, 

Sn. diatomit

YATAHONEY CREEK

WILDERNESS STUDY

AREA (ID-016-49D)

L/D Pb, Sn, diatomite

Tb JUNIPER CREEK WILDERNESS 

 STUDY AREA (ID-016-52)

Figure 2. Map showing geology and mineral resource potential of the Battle Creek, 

Yatahoney Creek and Juniper Creek Wilderness Study Areas, Owyhee County. Idaho.

B4
EXPLANATION

AREA WITH LOW MINERAL RESOURCE POTENTIAL-Au, Ag, Pb, Sn, and diatomite. 

Applies to entire wilderness study area. See appendix 1 and figure 3 for definition 

of mineral resource potential and certainty of assessment

COMMODITIES

Au Gold 

Ag Silver 

Pb Lead 

Sn Tin 

Diatomite

CORRELATION OF MAP UNITS

Tb

Ts

Tlj

^Trb~~

Tju

Pliocene and 

(or) Miocene

- Miocene

-TERTIARY

DESCRIPTION OF MAP UNITS

Tb BASALT (PLIOCENE AND (OR) MIOCENE)

Ts SEDIMENTARY ROCKS (MIOCENE)

Tlj LITTLE JACKS RHYOLITE (MIOCENE)

Trb RHYOLITE OF THE BADLANDS (MIOCENE)

Tju RHYOLITE OF UPPER JUNIPER MOUNTAIN (MIOCENE)

MAP SYMBOLS

- CONTACT 

_J _ _ _ NORMAL FAULT-Bar and ball on downthrown side; dashed where approximately located

Figure 2- Continued.

B5
Battle Creek drain several old mining areas in 

Cretaceous granitic rocks, dioritic to rhyolitic dikes, 

and the Eocene Challis Volcanics (dated at 44.7±0.8 

Ma; Armstrong, 1980) at a location about 30 mi north 

of the wilderness study area. There is a small 

localized outcrop of diatomaceous earth just south of 

the Yatahoney Creek Wilderness Study Area. The 

nearest major diatomite deposit is 14 mi to the north 

(Powers, 1947).

ASSESSMENT OF MINERAL RESOURCE POTENTIAL

By Carolyn A. Goeldner, Michael G. Sawlan, 

and Harley D. King 

U.S. Geological Survey

Geology

The Battle Creek, Yatahoney Creek, and Juniper 

Creek Wilderness Study Areas are underlain by 

laterally extensive, flat-lying Miocene rhyolite 

rheoignimbrites. These are locally overlain by 

fluviolacustrine sedimentary rocks. Upper Miocene 

and (or) Pliocene basalts cap the sequence and form 

the plateaus southeast of Battle Creek.

In the Owyhee Mountains region 25-30 mi north 

of the study areas, the basement rocks consist of 

Paleozoic metamorphic rocks, Mesozoic intrusive 

rocks, and Cenozoic volcanic rocks, particularly the 

lower Miocene rhyolite of Silver City, which contains 

vein gold and silver (Ekren and others, 1982). The 

depth to the pre-Cenozoic basement rocks in the study 

areas is conjectural. The upper Cenozoic rocks are 

inferred to be at least 1,000 to 1,500 ft thick and 

perhaps as much as several thousand feet thick in the 

vicinity of the study areas (Malde and Powers, 1962).

The rhyolitic rocks in the wilderness study areas 

are rheoignimbrites; the flows were emplaced as ash 

flows and continued to flow after collapse of the dense 

ash cloud. Ekren and others (1984) named these rocks 

"tuff" on the basis of the inferred emplacement 

mechanism. However, in most localities, the rhyolite 

formed flow-banded devitrified lava. Vitroclastic 

textures are recognizable in parts of some outcrops, 

most commonly at the tops and bottoms of flow units, 

but these textures have been largely destroyed by 

annealing and shear deformation of glass shards during 

flow. Sigmoidal flow foliations, folds, and diapir 

structures are common in the lavalike parts of the 

flows. The amplitudes of these folded, distorted 

structures ranges from a few inches to more than 300 

ft. Thus, these rocks are more properly classified as 

rhyolite than as tuff. The names of the rhyolitic units 

used in this report have been modified from those used 

by Ekren and others (1984).

Three rhyolitic units were distinguished in the 

wilderness study areas. The oldest unit, the rhyolite of 

upper Juniper Mountain (=upper lobes of Juniper 

Mountain of Ekren and others, 1984), has an 

approximate age of 12-13 Ma (Neill, 1975; Armstrong, 

1980) and is present along the western margin of the 

Yatahoney Creek Wilderness Study Area. This rhyolite 

is overlain by the rhyolite of The Badlands (=tuff of 

The Badlands of Ekren and others, 1984), which crops

out at one location along the Owyhee River in the 

northwest corner of the Juniper Creek Wilderness 

Study Area. This rhyolite is, in turn, overlain by the 

Little Jacks Rhyolite (=Little Jacks Tuff of Ekren and 

others, 1984), which is the most laterally extensive 

rhyolite in the area and is dated at 9-10 Ma (Neill, 

1975; Armstrong, 1980). The Little Jacks Rhyolite is a 

dense flow-foliated rhyolite that forms the steep 

canyon walls of Battle Creek. It attains a maximum 

thickness of 500-600 ft within the study areas and 

more than 1,000 ft at the type locality in Little Jacks 

Creek Canyon (Ekren and others, 1984), about 30 mi 

northeast of the Battle Creek Wilderness Study Area. 

The name "Little Jacks Tuff" is herein changed to 

"Little Jacks Rhyolite" in order to more accurately 

reflect its lithologic character.

The rhyolitic units may comprise a single cooling 

unit (rhyolite of The Badlands) or multiple cooling 

units (rhyolite of upper Juniper Mountain and Little 

Jacks Rhyolite). The rhyolite contains 10-25 percent 

phenocrysts, mainly of plagioclase and (or) sanidine. 

Quartz phenocrysts are abundant in the rhyolite of 

upper Juniper Mountain but are absent or rare in the 

Little Jacks Rhyolite. Ferro-pigeonite is ubiquitous 

but relatively sparse; Accessory phases consist of 

zircon and allanite(?).

Upper Miocene sedimentary rocks are exposed 

along the Owyhee River and Juniper Creek in the 

Yatahoney Creek and Juniper Creek Wilderness Study 

Areas (fig. 2). They consist of poorly lithified 

mudstone, sandstone, and pebble and cobble 

conglomerate. Rhyolite clasts are the most common, 

and fine-grained diatomaceous or tuffaceous 

sedimentary-rock pebbles are locally present. 

Deposition occurred in a fluviolacustrine environment, 

most likely within shallow grabens. These Miocene 

sedimentary rocks are usually overlain by basalt, 

although sedimentary rocks and basalt are locally 

intercalated.

Upper Miocene and (or) Pliocene basalt caps the 

stratigraphic sequence and is present south of Battle 

Creek and along either side of the Owyhee River (fig. 

2). It includes 1 to 4 flows of intergranular to 

subophitic, sparsely and finely porphyritic olivinephyric or olivine and plagioclase-phyric lava. 

Chromian spinel is commonly included in these olivine 

phenocrysts. Individual flows are thin (10-40 ft), and 

their composite thickness is typically less than 100 ft; 

they erupted locally from low-profile shield volcanoes.

In the Battle Creek Wilderness Study Area, 

north-to-northwest-trending en echelon normal faults 

exhibit 20-100 ft vertical displacements of the 

Tertiary strata. Shallow grabens formed among the 

basalt mesas as a result of offset of the capping 

basalt.

Geochemical Studies

The reconnaissance geochemical study was based 

on analysis and evaluation of stream sediments and the 

nonmagnetic fraction of heavy-mineral concentrates 

from stream sediments. The stream-sediment and 

concentrate samples contain material derived from 

major rock units of the drainage basin. Sampled 

drainage basins range in area from less than one to

B6
about 3 square miles.

All 90 stream-sediment (SS) samples and 47 

heavy-mineral-concentrate (HMC) samples were 

analyzed for 31 elements by a semiquantitative 

emission-spectrographic method. Stream-sediment 

samples were analyzed by the method described by 

Myers and others (1961) and HMC samples by the 

method of Grimes and Marranzino (1968). Heavymineral concentrate samples were also analyzed for 

selected elements by atomic-absorption spectroscopy 

and inductively coupled argon plasma-atomic emission 

spectroscopy. These analyses identify drainages with 

anomalously high concentrations of metallic and 

metal-related elements. Anomalous concentrations 

were determined by inspection of histograms and by 

noting enrichment relative to crustal abundances of 

these elements.

In the Battle Creek Wilderness Study Area, 4 of 

17 HMC samples had slightly elevated concentrations 

of tin and lead. Some HMC samples from the 

Yatahoney Creek Wilderness Study Area (5 of 18 

samples) and the Juniper Creek Wilderness Study Area 

(7 of 19 samples) exhibited weakly anomalous 

concentrations of tin and lead. These anomalies are 

not considered to be significant. Small lead anomalies 

in HMC samples occur in areas near roads and are 

probably due to culturally introduced material, such as 

lead shot. Heavy-mineral concentrate samples with 

anomalous tin concentrations are widely scattered 

throughout the study areas and the Owyhee Plateau in 

general (H. D. King, unpub. data). They are often 

located next to samples with no anomalous 

concentrations, are not clustered along specific 

drainage basins, and are not associated with any 

specific rock unit. Therefore, these weakly anomalous 

concentrations are regarded as insignificant.

Geophysical Studies

The Bouguer gravity-anomaly map of extreme 

southwestern Idaho and southeastern Oregon is 

characterized by a gravity plateau with values 

between -150 and -175 milligals over a predominantly 

rhyolitic terrane (Kulik, written commun., 1986). The 

wilderness study areas lie in the middle of this gravity 

plateau and possess values between -165 and -170 

milligals.

Aeromagnetic data for the wilderness study 

areas were obtained from the Aeromagnetic Map of 

Idaho (U.S. Geological Survey, 1978). Flight lines run 

east-west at 5-mile spacing and 12,500 ft barometric 

elevation. These data show only a minor magnetic 

gradient within the wilderness study areas, with values 

from 1,000 to 1,100 gammas, and provide no 

significant constraints on mineral resource potential.

CONCLUSIONS

Geologic, geochemical, and geophysical studies 

indicate that the likelihood of the occurrence of any 

mineral resources in the wilderness study areas is 

extremely remote. Therefore, the Battle Creek 

Wilderness Study Area is assigned a low mineral 

resource potential for gold, silver, and tin with a

certainty level of D. The Yatahoney Creek Wilderness 

Study Area is assigned a low mineral resource 

potential for lead, tin, and diatomite with a certainty 

level of D, and the Juniper Creek Wilderness Study 

Area is assigned a low mineral resource potential for 

lead, tin, and diatomite with a certainty level of D. 

All three wilderness study areas have an unknown 

mineral resource potential for oil and gas.

REFERENCES CITED

Armstrong, R.L., 1980, K-Ar dating of Snake River 

(Idaho) volcanic rocks new results: Isochron 

West, no. 27, p. 5-10.

Bendix Field Engineering Corp., 1982, National 

Uranium Resource Evaluation (NURE), Jordan 

Valley quadrangle, Idaho and Oregon (contract 

DE-AC07-76GJ101664): U.S. Geological Survey 

Open-File Report PGJ/F-132(82), 33 p.

Bonnischen, Bill, and Breckenridge, R.M., eds., 1982, 

Cenozoic geology of Idaho: Idaho Bureau of 

Mines and Geology Bulletin 26, 725 p.

Ekren E.B., Mclntyre, D.H., and Bennett, E.H., 1984, 

High-temperature, large-volume, lavalike ashflow tuffs without calderas in southwestern 

Idaho: U.S. Geological Survey Professional Paper 

1272, 7 6 p.

Ekren, E.B., Mclntyre, D.H., Bennett, E.H., and Malde, 

H.E., 1981, Geologic map of Owyhee County, 

Idaho, west of longitude 116° W.: U.S. 

Geological Survey Miscellaneous Investigations 

Map 1-1256, scale 1:250,000, 2 sheets.

Ekren, E.B., Mclntyre, D.H., Bennett, E.H., and 

Marvin, R.F., 1982, Cenozoic stratigraphy of 

western Owyhee County, Idaho, in Bonnischen, 

Bill and Breckenridge, R.M., eds., Cenozoic 

geology of Idaho: Idaho Bureau of Mines and 

Geology Bulletin 26, p. 215-235.

Geodata International, Inc., 1980, Aerial radiometric 

and magnetic survey, Jordan Valley, National 

topographic map, Oregon and Idaho (subcontract 

79-7336-S): U.S. Geological Survey Open-File 

Report GJBX-95(80), 192 p.

Graham, D.E., 1985, Mineral Resources of the Juniper 

Creek Wilderness Study Area, Owyhee County, 

Idaho: U.S. Bureau of Mines Open-File Report 

MLA 73-85, 9 p.

Grimes, D.J., and Marranzino, A.P., 1968, Directcurrent arc and alternating-current spark 

emission spectrographic field methods for the 

semiquantitative analysis of geologic materials: 

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

Leszcykowski, A.M., 1986, Mineral resources of the 

Yatahoney Creek Wilderness Study Area, Owyhee 

County, Idaho: U.S. Bureau of Mines Open-File 

Report MLA 11-86, 9 p.

Malde, H.E., and Powers, H.A., 1962, Upper Cenozoic 

stratigraphy of the western Snake River Plain, 

Idaho: Geological Society of America Bulletin, 

v. 73, no. 10, p. 1197-1220.

Mathews, G.W., and Blackburn, W.H., 1983, 

Assessment of geology, energy, and mineral 

(GEM) resources, Owyhee River GEM Resources 

Area (ID-010-11), Owyhee County, Idaho:

B7
prepared under U.S. Bureau of Land Management 

contract: YA-553-LT2-1042, TERRA DATA, 

Lakewood, Colorado, 37 p.

Myers, A. T., Haven, R. G., and Dunton, P. J., 1961, A 

spectrochemical method for the semiquantitative 

analysis of rocks, minerals, and ores: U.S. 

Geological Survey Bulletin 1084-1, p. 207-229.

Neill, W.M., 1975, Geology of the southeastern Owyhee 

Mountains and environs, Owyhee County, Idaho: 

Stanford, Calif., Stanford University, unpub. M.S. 

thesis, 59 p.

Pansze, A.J., 1975, Geology and ore deposits of the 

Silver City-DeLamar-Flint region, Owyhee 

County, Idaho: Idaho Bureau of Mines and 

Geology Pamphlet 161, 79 p.

Powers, H.A., 1947, Diatomite deposits of

southwestern Idaho: Idaho Bureau of Mines and 

Geology Mineral Resources Report 4, 27 p.

Union Carbide Corp., 1982, Hydrogeochemical and 

stream sediment reconnaissance basic data for 

Adel, Jordan Valley, and Twin Falls quadrangles, 

Oregon and Idaho (contract W-7405 eng 26): U.S. 

Geological Survey Open-File Report GJBX170(82), 70 p.

U.S. Geological Survey, 1978, Aeromagnetic map of 

Idaho: U.S. Geological Survey Geophysical 

Investigations Map GP-919, scale 1:500,000, 1 

sheet.

Winters, R.A., 1985, Mineral resources of the Battle 

Creek Wilderness Study Area (BLM No. ID-16- 

49E), Owyhee County, Idaho: U.S. Bureau of 

Mines Open-File Report-MLA 48-85, 10 p.

B8
APPENDIX 1. Definition of levels of mineral resource 

potential and certainty of assessment

Mineral resource potential is defined as the 

likelihood of the presence of mineral resources in a 

defined area; it is not a measure of the amount of 

resources or their profitability.

Mineral resources are concentrations of naturally 

occurring solid, liquid, or gaseous materials in such 

form and amount that economic extraction of a commodity from the concentration is currently or potentially feasible.

Low mineral resource potential is assigned to 

areas where geologic, geochemical, and geophysical 

characteristics indicate a geologic environment where 

the existence of resources is unlikely. This level of 

potential embraces areas of dispersed mineralized rock 

as well as areas having few or no indications of 

mineralization. Assignment of low potential requires 

specific positive knowledge; it is not used as a catchall 

for areas where adequate data are lacking.

Moderate mineral resource potential is assigned 

to areas where geologic, geochemical, and geophysical 

characteristics indicate a geologic environment 

favorable for resource occurrence, where interpretations of data indicate a reasonable chance for resource 

accumulation, and where an application of genetic and 

(or) occurrence models indicates favorable ground.

High mineral resource potential is assigned to 

areas where geologic, geochemical, and geophysical 

characteristics indicate a geologic environment 

favorable for resources, where interpretations of data 

indicate a high likelihood for resource accumulation, 

where data support occurrence and (or) genetic models 

indicating presence of resources, and where evidence 

indicates that mineral concentration has taken place. 

Assignment of high resource potential requires positive 

knowledge that resource-forming processes have been 

active in at least part of the area; it does not require 

that occurrences or deposits be identified.

Unknown mineral resource potential is assigned 

to areas where the level of knowledge is so inadequate 

that classification of the area as high, moderate, or

low would be misleading. The phrase "no mineral 

resource potential" applies only to a specific resource 

type in a well-defined area. This phrase is not used if 

there is the slightest possibility of resource 

occurrence; it is not appropriate as the summary 

rating for any area.

Expression of the certainty of the mineral 

resource assessment incorporates a consideration of (1) 

the adequacy of the geologic, geochemical, geophysical, and resource data base available at the time of 

the assessment, (2) the adequacy of the occurrence or 

the genetic model used as the basis for a specific 

evaluation, and (3) an evaluation of the likelihood that 

the expected mineral endowment of the area is, or 

could be, economically extractable.

Levels of certainty of assessment are denoted by 

letters, A-D (fig. 3).

A. The available data are not adequate to 

determine the level of mineral resource potential. 

Level A is used with an assignment of unknown mineral 

resource potential.

B. The available data are adequate to suggest 

the geologic environment and the level of mineral 

resource potential, but either evidence is insufficient 

to establish precisely the likelihood of resource occurrence, or occurrence and (or) genetic models are not 

known well enough for predictive resource assessment.

C. The available data give a good indication of 

the geologic environment and the level of mineral 

resource potential, but additional evidence is needed 

to establish precisely the likelihood of resource occurrence, the activity of resource-forming processes, or 

available occurrence and (or) genetic models are 

minimal for predictive applications.

D. The available data clearly define the geologic 

environment and the level of mineral resource 

potential, and indicate the activity of resourceforming processes. Key evidence to interpret the 

presence or absence of specified types of resources is 

available, and occurrence and (or) genetic models are 

adequate for predictive resource assessment.

U/A

UNKNOWN 

POTENTIAL

H/B

HIGH POTENTIAL

M/B

MODERATE POTENTIAL

L/B

LOW POTENTIAL

H/C

HIGH POTENTIAL

M/C

MODERATE POTENTIAL

L/C

LOW POTENTIAL

H/D

HIGH POTENTIAL

M/D

MODERATE POTENTIAL

L/D

LOW POTENTIAL

N/D

ND POTENTIAL

B C

LEVEL OF CERTAINTY

Figure 3. Major elements of mineral resource potential/certainty classification.

B9
GEOLOGIC TIME CHART 

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

EON

Phanerozoic

Proterozoic

Archean 

pre-Arc

ERA

Cenozoic

Mesozoic

Paleozoic

Late Proterozoic

Middle Proterozoic

Early Proterozoic

Late Archean

Middle Archean

Early Archean 

:hean 2

PERIOD

Quaternary

Neogene 

Subperiod

Tertiary 

Paleogene 

Subperiod

Cretaceous

Jurassic

Triassic

Permian

Pennsylvanian 

Carboniferous

Periods 

Mississippian

Devonian

Silurian

Ordovician

Cambrian

 -(3800?)- -

EPOCH

Holocene

Pleistocene

Pliocene

Miocene

Oligocene

Eocene

Paleocene

Late 

Early

Late 

Middle 

Early

Late 

Middle 

Early

Late 

Early

Late 

Middle 

Early

Late 

Early

Late 

Middle 

Early

Late 

Middle 

Early

Late 

Middle 

Early

Late 

Middle 

Early

 _

AGE ESTIMATES 

OF BOUNDARIES 

(in Ma)

- 0.010 

- 1.7

- 24

OO

CO

- 96 

_ no

one

- 290

oou

- 410

- 500

\j/ \j 

- 900

- 1600

1 CAft

O\J\J\J

- 3400 

 dRRn 

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

informal time term without specific rank.

BIO GPO 785-048/48012