Mineral Resources of the Devils Garden 

Lava Bed, Squaw Ridge Lava Bed, and Four 

Craters Lava Bed Wilderness Study Areas, 

Lake County, Oregon

U.S. GEOLOGICAL SURVEY BULLETIN 1738-A

Chapter A

Mineral Resources of the Devil's Garden Lava Bed, 

Squaw Ridge Lava Bed, and Four Craters Lava Bed 

Wilderness Study Areas, Lake County, Oregon

By WILLIAM J. KEITH, HARLEY D. KING, and 

MARK E. GETTINGS 

U.S. Geological Survey

FREDRICKL JOHNSON 

U.S. Bureau of Mines

U.S. GEOLOGICAL SURVEY BULLETIN 1 738

MINERAL RESOURCES OF WILDERNESS STUDY AREAS: 

SOUTH-CENTRAL OREGON
DEPARTMENT OF THE INTERIOR 

DONALD PAUL MODEL, Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1988

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 Devil's Garden Lava Bed, Squaw 

Ridge Lava Bed, and Four Craters Lava Bed Wilderness 

Study Areas, Lake County, Oregon.

(U.S. Geological Survey bulletin ; 1738-A)

Supt. of Docs. no. : I 19.3:1738-A

Bibliography: p.

1. Mines and mineral resources Oregon Devil's 

Garden Lava Bed Wilderness. 2. Mines and mineral 

resources Oregon Squaw Ridge Lava Bed Wilderness. 

3. Mines and mineral resources Oregon Four Craters 

Lava Bed Wilderness. 4. Devil's Garden Lava Bed 

Wilderness. (Or.) 5. Squaw Ridge Lava Bed Wilderness 

(Or.) 6. Four Craters Lava Bed Wilderness (Or.) 

I. Keith, William J., 1933- . II. Series. 

QE75.B9 no. 1738-A 557.3 s 88-600094 

[TN24.07] [553'.09795'93]
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 of 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 parts of the Devil's Garden 

Lava Bed, Squaw Ridge Lava Bed, and Four Craters Lava Bed Wilderness Study Areas (OR-001-002, OR-001- 

003, OR-001-022 respectively), Lake County, Oregon.

CONTENTS

Summary Al

Abstract 1

Character and setting 1 

Identified resources 1 

Mineral resource potential 2

Devil's Garden Lava Bed Wilderness Study Area 2 

Squaw Ridge Lava Bed Wilderness Study Area 3 

Four Craters Lava Bed Wilderness Study Area 3 

Introduction 3

Area description 3 

Previous and present investigations 3 

Appraisal of identified resources 5

Mines and prospects, mining claims, and leases 5 

Reserves and identified resources 5 

Assessment of mineral resource potential 7 

Geology 7 

Geochemistry 7 

Geophysics 7 

Mineral and energy resources 8

Devil's Garden Lava Bed Wilderness Study Area 8 

Squaw Ridge Lava Bed Wilderness Study Area 9 

Four Craters Lava Bed Wilderness Study Area 9 

References cited 9 

Appendixes

Definition of levels of mineral resource potential and certainty of assessment 12 

Resource/reserve classification 13 

Geologic time chart 14

FIGURES

1. Index map showing location of the Devil's Garden Lava Bed, Squaw Ridge Lava Bed, 

and Four Craters Lava Bed Wilderness Study Areas, Lake County, Oregon A2

2. Map showing mineral resource potential and generalized geology of the Devil's Garden 

Lava Bed Wilderness Study Area, Lake County, Oregon 4

3. Map showing mineral resource potential and generalized geology of the Squaw Ridge 

Lava Bed and Four Craters Lava Bed Wilderness Study Areas, Lake County, Oregon 6

Contents V

MINERAL RESOURCES OF WILDERNESS STUDY AREAS: 

SOUTH-CENTRAL OREGON

Mineral Resources of the Devil's Garden Lava Bed, 

Squaw Ridge Lava Bed, and Four Craters Lava Bed 

Wilderness Study Areas, Lake County, Oregon

By William J. Keith, Harley D. King, and Mark E. Gettings 

U.S. Geological Survey

Fredrick L. Johnson 

U.S. Bureau of Mines

SUMMARY

Abstract

The Devil's Garden Lava Bed (OR-001-002), Squaw 

Ridge Lava Bed (OR-001-003), and Four Craters Lava Bed 

(OR-001-022) Wilderness Study Areas are located in the 

southwestern part of the High Lava Plains physiographic 

province, northwestern Lake County, Oregon. At the request 

of the U.S. Bureau of Land Management, 28,160 acres of the 

29,680-acre Devil's Garden Lava Bed, 21,040 acres of the 

28,660-acre Squaw Ridge Lava Bed, and 9,100 acres of the 

12,600-acre Four Craters Lava Bed Wilderness Study Areas 

were studied. In this report, the areas investigated are 

referred to as "the wilderness study areas," or simply "the 

study areas." Geologic, geochemical, geophysical, and 

mineral surveys were conducted by the U.S. Geological 

Survey and the U.S. Bureau of Mines in 1986 to assess the 

mineral resources (known) and mineral resource potential 

(undiscovered) of the study areas. No resources were 

identified in the study areas, but the results of these surveys 

indicate an area of low potential for perlite resources in the 

Devil's Garden Lava Bed Wilderness Study Area. The Devil's 

Garden Lava Bed and the north half of the Squaw Ridge Lava 

Bed Wilderness Study Areas also have low potential for slablava (building stone) resources. All three study areas have low 

potential for low-temperature (less than 194 °F) geothermal 

resources and for oil and gas resources.

Character and Setting

The study areas are located in the southwestern part of 

the High Lava Plains physiographic province, northwest

Lake County, Oregon. They are north to northwest of 

Christmas Valley and east of Fort Rock (fig. 1). Relief is 

moderate; elevations range from 4,325 ft at the edge of 

Four Craters Lava Bed to a high of 5,612 ft in the center 

of the Squaw Ridge Lava Bed. The basaltic lava flows 

underlying the study areas are of Pleistocene or Holocene 

age (see appendixes for geologic time chart), these in turn 

overlie Pliocene and (or) Pleistocene lava flows and cinder 

cones.

Identified Resources

There are no metallic or nonmetallic reserves or 

identified resources in the three study areas. There are a 

few small, scattered occurrences of good quality slab lava 

in the Devil's Garden Lava Bed and Squaw Ridge Lava 

Bed Wilderness Study Areas, but most of the accessible 

material has been removed. Slab lava in the Four Craters 

study area is generally of poor quality. Cinder and natural 

aggregate also occur in all three study areas, but sites are 

far from prospective markets.

Mining claim records show that there are no active 

mining claims in or adjacent to the three study areas and 

that past mining activity has been minimal. Several claims 

for borax were located at the turn of the century just outside 

the Four Craters Lava Bed Wilderness Study Area; four 

uranium claims were staked during the mid-1950's in 

Devil's Garden Lava Bed Wilderness Study Area; and six 

building stone claims were staked in the early 1970's in the 

Squaw Ridge Lava Bed Wilderness Study Area.

Mineral Resources of the Devil's Garden Lava Bed, Squaw Ridge Lava Bed, and Four Craters Lava Bed Wilderness Study Areas, Oregon A1
Mineral Resource Potential Devil's Garden Lava Bed Wilderness Study Area

A small area in the southern part of the Devil's Garden 

Lava Bed Wilderness Study Area has low potential for 

perlite resources, and the Devil's Garden Lava Bed and the 

north half of the Squaw Ridge Lava Bed Wilderness Study 

Areas have low potential for slab lava. All three study 

areas have low potential for low-temperature (less than 194 

°F) geothermal resources and oil and gas resources.

A small area containing low-quality perlite occurs near 

the southern part of Devil's Garden Lava Bed Wilderness 

Study Area. More recent lava beds may cover part or most 

of the deposit. The area, which lies near the base of Cougar 

Mountain, is considered to have low potential for perlite 

resources (fig. 2) of commercial quality, although 

development is unlikely due to the lava cap.

121° 00' 120° 30'

43° 45'

43° 30'

43° 15'

Pine Mountain

A

Newberry Crater

China Hat

A

APPROXIMATE BOUNDARY

OF

DEVIL'S GARDEN LAVA BED

WILDERNESS STUDY AREA

(OR-001-002)

Flat Top

Fort Rock

A

 Fort Rock

Frederick Butte

APPROXIMATE BOUNDARY

OF

SQUAW RIDGE LAVA BED

WILDERNESS STUDY AREA

(OR-001-003)

Wart Peak

A

APPROXIMATE BOUNDARY*

OF

FOUR CRATERS LAVA BED 

WILDERNESS STUDY AREA

Christmas Valley

AREA OF AAAP

Figure 1. Index map showing location of the Devil's Garden Lava Bed, Squaw Ridge Lava Bed, and Four Craters 

Lava Bed Wilderness Study Areas, Lake County, Oregon.

A2 Mineral Resources of Wilderness Study Areas South-Central Oregon
The study area also has low potential for slab-lava 

resources, but development is also unlikely due to low 

quality, poor access, and an abundance of higher quality 

rock from other areas.

Holocene volcanism has occurred in the study area, 

and the area also has relatively high heat flow, suggesting 

low potential for low-temperature (less than 194 °F) 

geothermal resources.

This study area also has low potential for oil and gas 

resources. Source beds may underlie or interbed with the 

older lava flows in this area and could contain oil and gas.

Squaw Ridge Lava Bed Wilderness Study Area

The north half of the Squaw Ridge Lava Bed 

Wilderness Study Area has low potential for slab-lava 

resources. However, these resources will probably not be 

developed due to low quality, poor access, and an 

abundance of higher quality rock from other areas.

Holocene volcanism has occurred in the Squaw Ridge 

Lava Bed Wilderness Study Area (fig. 3), and the area also 

shows relatively high heat flow suggesting low potential for 

low-temperature (less than 194 °F) geothermal energy 

resources.

This study area also has low potential for oil and gas 

resources. Source beds may underlie or interbed with the 

older lava flows in this area and could contain oil and gas.

Four Craters Lava Bed Wilderness Study Area

Holocene volcanism has occurred in the Four Craters 

Lava Bed Wilderness Study Area (fig. 3), and the area also 

shows relatively high heat flow suggesting low potential for 

low-temperature (less than 194 °F) geolhermal energy 

resources.

This study area also has low potential for oil and gas 

resources. Source beds may underlie or interbed with the 

older lava flows in this area and could contain oil and gas.

INTRODUCTION

This mineral survey was requested by the U.S. Bureau 

of Land Management and is a joint effort by the U.S. 

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

introduction to the wilderness review process, mineral 

survey methods, and agency responsibilities was provided 

by Beikman and others, (1983). The U.S. Bureau of Mines 

evaluates identified resources at individual mines and 

known mineralized areas by collecting data on current and 

past mining activities and through field examination of 

mines, prospects, claims, and mineralized areas. Identified 

resources are classified according to the system described

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

(1980). Studies by the U.S. Geological Survey are 

designed to provide a reasonable scientific basis for 

assessing the potential for undiscovered mineral resources 

by determining geologic units and structures, possible 

environments of mineral deposition, presence of 

geochemical and geophysical anomalies, and applicable 

ore-deposit models. Mineral assessment methodology and 

terminology as they apply to these surveys were discussed 

by Goudarzi (1984). See the appendixes for definitions of 

levels of mineral resource potential and certainty of 

assessment, and for the resource/reserve classification.

Area Description

At the request of the U.S. Bureau of Land 

Management, 28,160 acres of the 29,680-acre Devil's 

Garden Lava Bed, 21,040 acres of the 28,660-acre Squaw 

Ridge Lava bed, and 9,100 acres of the 12,600-acre Four 

Craters Lava Bed Wilderness Study Areas in northwest 

Lake County, Oregon (fig. 1), were studied. These study 

areas lie approximately 50 mi southeast of Bend, Oregon 

and are part of the High Lava Plains physiographic 

province. In this report, the areas studied are referred to as 

"the wilderness study areas," or simply "the study areas." 

The study areas are underlain by sparsely vegetated, 

basaltic lava flows that have flowed over and around older 

surface features. The study areas are accessible on all sides 

by unmaintained jeep trails. The interiors are accessible 

only by helicopter or on foot except for the Devil's Garden 

Lava Bed Wilderness Study Area which has several jeep 

trails scattered throughout the north half of the area. 

Elevations range from 4,325 ft at the east edge of the Four 

Craters Lava Bed Wilderness Study Area to 5,612 ft on top 

of Lava Mountain in the central part of the Squaw Ridge 

Lava Bed Wilderness Study Area.

Previous and Present Investigations

A geologic map of the study areas, prepared by the 

U.S. Geological Survey in 1986 (figs. 2 and 3), provided a 

base for the interpretation of geochemical, geophysical, 

remote sensing, and mining claim data. The geologic map 

is adapted from the reconnaissance geologic map of the 

east half of the Crescent quadrangle, Lake, Deschutes, and 

Crook Counties, Oregon, by Walker and others (1967). 

Studies by Engineers International, Inc. (1980), MacLeod 

and others (1976), and Wilson and Emmons (1985) also 

provided geologic data for this report.

Geochemical data were obtained from analyses of 

rock-chip samples collected by the U.S. Geological Survey 

(unpub. data, 1986) and rock-chip, soil, and streamMineral Resources of the Devil's Garden Lava Bed, Squaw Ridge Lava Bed, and Four Craters Lava Bed Wilderness Study Areas, Oregon A3
sediment samples collected by the U.S. Bureau of Land 

Management (Durga Rimal, unpub. data, 1983).

Geophysical data consist of two aeromagnetic surveys 

that, when combined, cover all three study areas (U.S. 

Geological Survey, 1972, 1984), and a third study of

radiometric and aeromagnetic data for the National 

Uranium Resources Evaluation (High Life HelicoptersQEB, 1981).

The U.S. Bureau of Mines reviewed all available 

information on geology, mining, and exploration in the

APPROXIMATE BOUNDARY

OF

DEVIL'S GARDEN LAVA BED 

WILDERNESS STUDY AREA 

(OR-001-002)

L/CGeo[ll 

(entire study area)

L/B O,G [2] 

(entire study area)

imile

Figure 2. Map showing resource potential and generalized geology of the Devil's Garden Lava Bed Wilderness 

Study Area, Lake County, Oregon.

A4 Mineral Resources of Wilderness Study Areas South-Central Oregon
area, including county mining claim records, prior to field 

work. The field investigation, conducted during the spring 

of 1986, included driving all roads in and near the study 

areas and making numerous foot traverses. All areas 

described by Engineers International, Inc. (1980) as having 

"high"potential for slab lava were investigated to determine 

quality and tonnage.

Geo 

O.G 

SI 

per

Qb

QTo

EXPLANATION

Area with low mineral resource potential-- 

See appendixes for definition of 

levels of mineral and energy 

resource potential (L) and certainty 

of assessment (B,C)

Commodities

Geothermal 

Oil and gas 

Slab lava 

Perlite

[ ] Type of deposit or occurrence

Geothermal water 

Source beds and (or) traps 

Silicic glass 

Surficial deposits

Geologic map units

Basalt (Holocene or Pleistocene)- 

Pahoehoe and aa type basalt flows, 

agglutinates, and cinder cones

Older lava flows (Pleistocene and (or) 

Pliocene)--Older basalt, andesite, 

dacite, and rhyolite flows and 

domes. Locally includes tuffaceous 

sediments and basin-fill material

Contact 

Cinder cone

Figure 2. Continued.

APPRAISAL OF IDENTIFIED RESOURCES

By Fredrick L. Johnson 

U.S. Bureau of Mines

Mines and Prospects, Mining Claims, and Leases

A search of Lake County and Bureau of Land 

Management mining records revealed that no active claims 

and only a few historical claims were located in the study 

areas. Four claims were located for uranium during the 

mid-1950's in the Devil's Garden Lava Bed Wilderness 

Study Area. Six claims, located during the early 1970's in 

the west-central part of the Squaw Ridge Lava Bed 

Wilderness Study Area, were probably for slab-lava 

building stone. Apparently no claims were ever located in 

the Four Craters Lava Bed Wilderness Study Area, but 

several claims for borax were located at the turn of the 

century just southeast of the area.

The only working in the study areas was a small pit at 

the base of a cinder cone near the northwest boundary of 

Four Craters Lava Bed Wilderness Study Area. Just a few 

cubic yards of cinder had been removed.

At the time of the study, the nearest mining activity 

was about 2 mi southwest of Christmas Valley (fig. 1) 

where diatomite was being mined and processed.

Reserves and Identified Resources

There are no mineral reserves or identified resources in 

the three areas studied. However, slab lava, used as 

building stone, is present. Some slab lava in the Devil's 

Garden Lava Bed and Squaw Ridge Lava Bed Wilderness 

Study Areas is of good quality, but occurrences are widely 

scattered and access poor. At those areas most accessible, 

most usable material has been removed. The Four Craters 

Lava Bed Wilderness Study Area, principally underlain by 

aa lava (lava flows typified by a rough, jagged, spinose, 

clinkery surface), also contains some slab lava, but the 

material is of poor quality.

In the Bend area, the nearest town of any size, demand 

for slab lava has dropped significantly since 1980; the local 

market is currently being met by sources in southeastern 

Idaho. Wholesale prices (1986) for 3- to 4-in.-thick and 2- 

in.-thick slab lava were $45 and $60 per ton, respectively 

(Willamette Greystone Co., oral commun., 1986). 

Transportation costs, relatively low unit prices, difficult 

access, and the scattered, sparse distribution of the slab lava 

make commercial production of this stone unlikely in the 

foreseeable future.

Cinder and sand and gravel occurrences in the study 

areas might be suitable for some construction purposes. 

However, transportation costs to potential markets, a major

Mineral Resources of the Devil's Garden Lava Bed, Squaw Ridge Lava Bed, and Four Craters Lava Bed Wilderness Study Areas, Oregon AS
part of total production costs for these high bulk-low unit 

value commodities, would far exceed the value. Similar 

material, abundant elsewhere in central Oregon, is closer to 

major markets in the region.

Additional information on U.S. Bureau of Mines work 

in these study areas is available from the Western Field 

Operations Center, E. 360 Third Avenue, Spokane, WA 

99202 and in Johnson (1987).

120°4S T

L/C SI [3] 

(excluding QTo)

APPROXIMATE BOUNDARY

OF

SQUAW RIDGE LAVA BED

WILDERNESS STUDY AREA

(OR-001-003)

\

L/C Geo [ 1 ] (entire study area) 

L/B O,G [2] (entire study area)

APPROXIMATE BOUNDARY

OF

FOUR CRATERS LAVA BED 

WILDERNESS STUDY AREA 

(OR-001-022)

EXPLANATION

I Area with low resource potential-See appendixes for 

1 ' definition of levels of mineral and energy resource 

potential (L) and certainty of assessment (B,C)

Commodities

Geo Geothermal

O,G Oil and Gas

SI Slab lava

[ ] Type of deposit or occurrence

1 Geothermal water

2 Source beds and (or) traps

3 Surficial deposits

Geologic map units

Qb Basalt (Holocene or Pleistocene)-Pahoehoe and aa 

type basalt flows, agglutinates, and cinder cones

QTo Older lava flows (Pleistocene and (or) Pliocene)-

Older basalt, andesite, dacite, and rhyolite flows 

and domes. Locally includes tuffaceous 

sediments and basin-fill material

 Contact

 Fault and (or) tension fracture

-<>- Cinder cone

L/C Geo [1] 

(entire study area)

L/B O.G [2] 

(entire study area)

1 mile

Figure 3. Map showing mineral resource potential and generalized geology of the Squaw Ridge Lava Bed and 

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

A6 Mineral Resources of Wilderness Study Areas South-Central Oregon
ASSESSMENT OF MINERAL RESOURCE 

POTENTIAL

fiy William J. Keith, Harley D. King, and Mark E. Gettings 

U.S. Geological Survey

Geology

Devil's Garden Lava Bed, Squaw Ridge Lava Bed, and 

Four Craters Lava Bed Wilderness Study Areas are all 

underlain by Pleistocene or Holocene basalt flows that 

overlie older (Pliocene to Pleistocene) basaltic to more 

silicic lavas and palagonitized basaltic ejecta. The younger 

basalts range from predominantly pahoehoe type in the 

Devil's Garden area to predominantly aa type in the Four 

Craters area. The young basalt in the Squaw Ridge area 

consists largely of aa type with a lesser amount of 

pahoehoe scattered throughout The surface of the Devil's 

Garden area contains many textbook-type examples of 

pahoehoe-related features such as tumuli, collapse features, 

and spatter cones. On the northeast edge of the Devils' 

Garden area, one large lava tube has been found that is over 

1,500 ft long and, in places, over 40 ft high (Engineers 

International, Inc. 1980, p. 86). Features in the Squaw 

Ridge and Four Craters areas are more typical of aa lavas. 

These consist of cinder cones and pressure ridges of 

clinkery blocks. The older lavas include basalt, andesite, 

dacite, and rhyolite flows as well as dacitic to rhyolitic 

domes and plugs. The young basalts flowed around older 

features such as older cinder cones and domes of silicic 

lava. One of the silicic domes (Cougar Mountain) on the 

south border of the Devil's Garden Lava Bed Wilderness 

Study Area (fig. 2) has a potassium-argon age of 4.31 ± 

0.34 Ma (MacLeod, Walker, and McKee, 1976, p. 468). 

Outcrops of impure perlite here probably owe their origin 

to the hydration of rhyolitic glass by ground water or freshwater lakes that formerly covered this area.

Structure in the area consists of high-angle faults and 

tension fractures which trend in a generally northwest 

direction. Some of the tension fractures are over 30 ft deep 

and have vertical walls.

Geochemistry

The reconnaissance geochemical study of the Devil's 

Garden Lava Bed, Squaw Ridge Lava Bed, and the Four 

Craters Lava Bed Wilderness Study Areas included the 

collection, analysis, and evaluation of 36 rock samples 

collected from 36 sites in the three study areas. The 

distribution of the sample sites is as follows: Devil's 

Garden Lava Bed Wilderness Study area, 19 samples; 

Squaw Ridge Lava Bed Wilderness Study Area, 8 samples; 

Four Craters Lava Bed Wilderness Study Area, 9 samples. 

The sampling was done partly in conjunction with geologic 

mapping.

Rock samples were used as the only sample medium in 

this reconnaissance geochemical study. Representative 

rock samples were taken from outcrops of each rock unit 

present in the three study areas. Rock that appeared altered 

or mineralized was looked for but not found. Lack of 

appropriate streams in the study areas prevented the use of 

stream sediments or heavy-mineral concentrates. The few 

streams present drain areas chiefly underlain by eolian 

deposits, hence sediment associated with them is unlikely 

to reflect bedrock mineralization. Water from wells is a 

possible sample medium, since a number of wells are 

located peripheral to the study areas; however most of the 

wells are abandoned or inactive, and water samples were 

rarely available or are of questionable quality.

The rock samples were crushed and pulverized to a 

grain size of less than 0.007 in. prior to analysis. The 

samples were analyzed semiquantitatively for 31 elements 

using direct-current arc emission spectrography (Grimes 

and Marranzino, 1968). The samples were also analyzed 

by inductively coupled argon plasma-atomic emission 

spectroscopy for antimony, arsenic, bismuth, cadmium, and 

zinc and by atomic absorption for gold and mercury 

(methods described in Crock and others, 1987). Analytical 

data are from M.S. Erickson and others (written commun., 

1987).

A value of 70 parts per million (ppm) lead was found 

in one sample of a rhyolitic flow taken from the north slope 

of one of the domes in the Devil's Garden Lava Bed 

Wilderness Study Area. The value is slightly anomalous 

relative to an average crustal abundance of 20 ppm for 

felsic igneous rocks (Levinson, 1980). No other elements 

were found in anomalous concentration in this sample. 

Therefore, this anomalous concentration of lead is believed 

to be nonsignificant and does not reflect mineralized rock.

Three samples of flow basalts from the Devil's Garden 

Lava Bed Wilderness Study Area and one from the Four 

Craters Lava Bed Wilderness Study Area contained slightly 

anomalous values for antimony (3-5 ppm), compared to 

average crustal abundance values of about 1 ppm or less in 

basalts (Onishi, 1969; Levinson, 1980). The samples are 

from widely separated sites. The low values and absence 

of other indications of antimony deposits in the areas 

suggest that the values represent background values for the 

basalt flows.

No other elements were found in anomalous 

concentrations in samples from any of the three study areas.

Geophysics

An aeromagnetic survey of the Devil's Garden Lava 

Bed, Squaw Ridge Lava Bed, and Four Craters Lava Bed 

Wilderness Study Areas was flown and compiled in 1972 

(U.S. Geological Survey, 1972). Total field magnetic data 

were collected in analog form along flightlines in an eastMineral Resources of the Devil's Garden Lava Bed, Squaw Ridge Lava Bed, and Four Craters Lava Bed Wilderness Study Areas, Oregon A7
west direction spaced at approximately 2-mi intervals at a 

constant barometric altitude of 9,000 ft. Corrections were 

applied to the data to compensate for diurnal variations of 

the Earth's magnetic field. A regional field of 8 nanotesla 

(nT) per mile in the direction of N. 30° E. was subtracted 

to yield a residual magnetic anomaly dataset. An 

aeromagnetic map of the study areas was prepared at a 

contour interval of 50 nT from the digitized analog data for 

comparison with geologic and topographic maps. North of 

lat 43°30', aeromagnetic data are available from another 

survey (U.S. Geological Survey, 1984) flown along eastwest lines spaced approximately 3 mi apart at a constant 

barometric elevation of 7,500 ft. The southernmost 

flightline of the survey crosses the northern part of Devil's 

Garden Lava Bed Wilderness Study Area, and the contour 

map in the report (U.S. Geological Survey, 1984) was used 

to examine the continuation of regional magnetic anomalies 

north of lat 43°30'.

Airborne radiometric and magnetic data are also 

available for the Crescent quadrangle from the National 

Uranium Resource Evaluation study (High Life 

Helicopters-QEB, 1981). Survey lines for this survey were 

oriented east-west and spaced 6 mi apart at a terrain 

clearance of approximately 400 ft. Three flight lines from 

this study cross the study areas. The radiometric profiles 

did not detect any significant anomalies, and no new 

information was gained from the magnetic data because of 

the wide line spacing. The radiometric profiles show that 

the Tertiary and Quaternary mafic volcanic rocks have a 

systematically higher gamma-ray emission than the late 

Quaternary basalt flows, and thus the two rock units are 

distinguished by the data although neither are anomalous.

The magnetic intensities within and near Devil's 

Garden Lava Bed Wilderness Study Area have a total range 

of about 250 nT and form a northwest-trending trough-like 

magnetic minimum. The anomaly is smooth, does not 

exhibit any suggestion of shallow magnetization contrasts, 

and is interpreted as reflecting variations of magnetization 

and depth to magnetic basement. This does not, however, 

give any indication of the physical thickness of the lava 

flows.

A regional magnetic maximum in the form of a 

northwest-trending ridge about 3.7 mi wide borders the 

Devil's Garden Lava Bed Wilderness Study Area to the 

north and extends southeast through the Squaw Ridge Lava 

Bed Wilderness Study Area. Within the Squaw Ridge Lava 

Bed Wilderness Study Area, the magnetic field consists of 

a positive anomaly of about 300 nT amplitude of which 

approximately 200 nT is closely correlated with the 

topographic expression of Lava Mountain (fig. 1), and the 

remaining portion of the anomaly is the regional northwest 

trending ridge. The magnetic data within and near the 

Squaw Ridge Lava Bed Wilderness Study Area do not 

contain any anomalies which are not attributable to 

topographic effects or regional structural blocks delineated

by the mapped fault patterns. A left-lateral offset of 1.2 to 

1.9 mi of the magnetic anomaly ridge suggests strike-slip 

faulting in a northeast-trending area located approximately 

along the northwest boundary of the Devil's Garden Lava 

Bed Wilderness Study Area.

The magnetic field within and near the Four Craters 

Lava Bed Wilderness Study Area consists of a smooth 

magnetic field gradient, increasing to the southeast. The 

field increases about 250 nT across the study area, and the 

gradient suggests that a northeast trending boundary 

marking an increase in average magnetization to the 

southeast, occurs near the northwest boundary of the study 

area. Northwest of this boundary the contours of magnetic 

intensity are sub-parallel to the mapped faults and form a 

gradient that increases to the southwest. No other magnetic 

anomalies were observed in the study area.

D.L. Sawatzky mapped the orientations of linear 

features for southeastern Oregon from Landsat 

multispectral scanner images at a scale of 1:800,000 and 

plotted them on a l:l,000,000-scale map. Images of the 

area between long. 120°-121° W. and lat. 43°-44° N. 

(including the study areas) do not reveal any linear features. 

This is probably due to the young volcanic cover (D.L. 

Sawatzky, written commun., 1987).

Mineral and Energy Resources

Except for perlite and slab lava, the potential for 

mineral and energy resources is the same in all three study 

areas. The resource potential is discussed separately below 

to facilitate planning and decision making on each area 

independently.

Devil's Garden Lava Bed Wilderness Study Area

The Devil's Garden Lava Bed Wilderness Study Area 

has low potential (certainty level B) for perlite resources in 

the area under the basalt flows near Cougar Mountain (fig. 

2). Impure perlite occurs in numerous small areas near the 

base on the south side of Cougar Mountain. A small (20 

ft2) exposure located at the base of the north side of Cougar 

Mountain contains granular perlite similar to that described 

at the Tucker Hill perlite deposit in southern Lake County, 

Oregon (Wilson and Emmons, 1985). These occurrences 

support the conclusion that the perlite might extend under 

the basalt. Therefore, the area of low resource potential for 

perlite (fig. 2) includes part of the covering basalt near 

Cougar Mountain. Although other areas of silicic rock are 

present in and near the study area, they show no indication 

of perlite formation and are therefore not included in the 

area having low resource potential for perlite. The perlite 

is likely to be relatively impure. Development of presently 

undiscovered perlite resources is not anticipated due to the

A8 Mineral Resources of Wilderness Study Areas South-Central Oregon
poor quality of the materials, the need to strip off the 

volcanic cover, the distance from markets, and the 

abundance of better quality perlite from other sources.

The resource potential for slab lava (building stone) is 

low (certainty level C) in the study area. The bulk of the 

slab lava is probably of low quality, the access to the 

material is poor to nonexistent, and there is an abundance 

of high-quality material from other areas. It is therefore 

doubtful that slab lava from this area will be developed in 

the forseeable future.

The study area has low potential (certainty level C) for 

low-temperature (less than 194 °F) geothermal resources. 

No thermal springs are known to exist in the study area, 

and no areas of hydrothermal alteration were found. 

However, the study area has undergone Holocene 

volcanism and has relatively high heat flow. Potential for 

geothermal resources is also somewhat enhanced by the 

presence of three igenous-related geothermal systems 

(Newberry Crater, Wart Peak Caldera, and Frederick Butte 

areas, Smith and Shaw, 1979) within a 50-mi radius of the 

study area.

The study area also has low potential (certainty level 

B) for oil and gas resources. There are no known surface 

occurrences of oil or gas in the study area, nor are there any 

indications in any of the water wells. However, source 

beds of older basin material may underlie or be interbedded 

with the volcanic rocks at depth (Fouch, 1983). The 

maturation level for oil may have been exceeded in the 

older basin fill of the study area (Fouch, 1983). In that 

case, oil would not have been preserved. However, since 

the thermal history has not been established, the study area 

has low resource potential for oil as well as gas.

Squaw Ridge Lava Bed Wilderness Study Area

The north half of the Squaw Ridge Lava Bed 

Wilderness Study Area has low potential (certainty level C) 

for slab lava (building stone). The bulk of the slab lava is 

probably of low quality, the access to the material is poor 

to nonexistent, and there is an abundance of high-quality 

material from other areas. This makes it doubtful that slab 

lava from this area will be developed in the forseeable 

future.

The study also has low potential (certainty level C) for 

low-temperature (less than 194 °F) geothermal resources. 

No thermal springs are known to exist in the study area, 

and no areas of hydrothermal alteration were found. 

However, the study area has undergone Holocene 

volcanism and has relatively high heat flow. Potential for 

geothermal resources is also somewhat enhanced by the 

presence of three igenous-related geothermal systems 

(Newberry Crater, Wart Peak Caldera, and Frederick Butte 

areas, Smith and Shaw, 1979) within a 50-mi radius of the 

study area.

The study area has low potential (certainty level B) for 

oil and gas resources. There are no known surface 

occurrences of oil or gas in the study area, nor are there any 

indications in any of the water wells. However, source 

beds of older basin material may underlie or be interbedded 

with the volcanic rocks at depth (Fouch, 1983). The 

maturation level for oil may have been exceeded in the 

older basin fill of the study area (Fouch, 1983). In that 

case, oil would not have been preserved. However, since 

the thermal history has not been established, the study area 

has low resource potential for oil as well as gas.

Four Craters Lava Bed Wilderness Study Area

The Four Craters Lava Bed Wilderness Study Area has 

low potential (certainty level C) for low-temperature (less 

than 194 °F) geothermal resources. No thermal springs are 

known to exist in the study area, and no areas of 

hydrothermal alteration were found. However, the study 

area has undergone Holocene volcanism and has relatively 

high heat flow. Potential for geothermal resources is also 

somewhat enhanced by the presence of three igenousrelated geothermal systems (Newberry Crater, Wart Peak 

Caldera, and Frederick Butte areas, Smith and Shaw, 1979) 

within a 50-mi radius of the study area.

The study area also has low potential (certainty level 

B) for oil and gas resources. There are no known surface 

occurrences of oil or gas in the study area, nor are there any 

indications in any of the water wells. However, source 

beds of older basin material may underlie or be interbedded 

with the volcanic rocks at depth (Fouch, 1983). The 

maturation level for oil may have been exceeded in the 

older basin fill of the study area (Fouch, 1983). In that 

case, oil would not have been preserved. However, since 

the thermal history has not been established, the study area 

has low resource potential for oil as well as gas.

REFERENCES CITED

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

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

Survey and the Bureau of Mines of Bureau of Land 

Management Wilderness Study Areas: U.S. Geological 

Survey Circular 901, 28 p.

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

Analytical methods for the analysis of stream sediments and 

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

Open-File Report 87-84, 35 p.

Engineers International, Inc., 1980, Geological investigations and 

mineral inventory of Devil's Garden, Four Craters, and 

Squaw Ridge in Lake County, Oregon: Report prepared for 

the U.S. Bureau of Land Management, contract no. OR-910- 

CT9-16, 135 p.

Mineral Resources of the Devil's Garden Lava Bed, Squaw Ridge Lava Bed, and Four Craters Lava Bed Wilderness Study Areas, Oregon A9
Fouch, T.D., 1983, Petroleum potential of wilderness lands in 

Oregon, in Miller, B.M., ed., Petroleum potential of 

wilderness lands in the western United States: U.S. 

Geological Survey Circular 902, p. J1-J5.

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

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

Report 84-787, 51 p.

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

alternating-current spark emission spectrographic field 

methods for the semiquantitative analysis of geologic 

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

High Life Helicopters-QEB, 1981, Airborne gamma-ray 

spectrometer and magnetometer survey, Crescent quadrangle 

(Oregon), final report: U.S. Department of Energy Grand 

Junction Office [Report] GJBX 240-81, v. 2, scale 1:500,000.

Johnson, F.L., 1987, Mineral resources of the Devil's Garden 

Lava Bed, Squaw Ridge Lava Bed, and Four Craters Lava 

Bed study areas, Lake County OR: U.S. Bureau of Mines 

Open-File Report MLA 37-87, 10 p.

Levinson, A.A., 1980, Introduction to exploration geochemistry, 

second edition, the 1980 supplement: Ltd. Wilmette, 111., 

Applied Publishing.

MacLeod, N.S., Walker, G.W., and McKee, E.H., 1976, 

Geothermal significance of the eastward increase in age of 

late Cenezoic rhyolitic domes in southeastern Oregon: 

United Nations Symposium on Development and Use of

Geothermal Resources, v. 1. 

Onishi, H., 1969, Antimony in Wedepohl, K.H., ed., Handbook of

geochemistry, vol. HI: Berlin, Heidelberg, New York,

Springer-Verlag, p. 51 B-M, O. 

Smith, R.L., and Shaw, H.R., 1979, Igneous-related geothermal

systems, in Muffler, L.J.P., ed., Assessment of geothermal

resources of the United States-1978: U.S. Geological Survey

Circular 790, 163p. 

Walker, G.W., Peterson, N.V., and Greene, R.C., 1967,

Reconnaissance geologic map of the east half of the Crescent

quadrangle, Lake, Deschutes, and Crook Counties, Oregon:

U.S. Geological Survey Miscellaneous Investigations Map I493, scale 1:250,000. 

Wilson, J.L., and Emmons, D.L., 1985, Tucker Hill perlite

deposit, Lake County Oregon: Mining Engineering, vol. 37,

no. 11, p. 1301-1308. 

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

Principles of a resource/reserve classification for minerals:

U.S. Geological Survey Circular 831, 5 p. 

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

Falls and part of the Crescent 1° x 2° quadrangles, Oregon:

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

U.S. Geological Survey, 1984, Aeromagnetic map of east-central

Oregon: U.S. Geological Survey Open-File Report 84-512,

scale 1:250,000.

A10 Mineral Resources of Wilderness Study Areas South-Central Oregon
APPENDIXES
DEFINITION OF LEVELS OF MINERAL RESOURCE POTENTIAL 

AND CERTAINTY OF ASSESSMENT

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

characteristics define a geologic environment in which the existence of resources is permissive. This 

broad category embraces areas with dispersed but insignificantly mineralized rock as well as areas with 

few or no indications of having been mineralized.

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

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

of data indicate reasonable likelihood of resource accumulation, and (or) where an application of 

mineral-deposit models indicates favorable ground for the specified type(s) of deposits.

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

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

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

models indicating presence of resources, and where evidence indicates that mineral concentration has 

taken place. Assignment of high resource potential to an area requires some positive knowledge that 

mineral-forming processes have been active in at least part of the area.

UNKNOWN mineral resource potential is assigned to areas where information is inadequate to assign low, 

moderate, or high levels of resource potential.

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

Levels of Certainty

O

0.

LU 

L) 

QC 

D 

O 

(/) 

ui

QC

LU 

>

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

NO POTENTIAL

A. 

B. 

C. 

D.

B C 

LEVEL OF CERTAINTY

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

Available information suggests the level of mineral resource potential. 

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

Available information clearly defines the level of mineral resource potential.

Abstracted with minor modifications from:

Taylor, R. B., and Steven, T. A., 1983, Definition of mineral resource potential: Economic Geology,

v. 78, no. 6, p. 1268-1270. 

Taylor, R. B., Stoneman, R. J., and Marsh, S. P., 1984, An assessment of the mineral resource potential

of the San Isabel National Forest, south-central Colorado: U.S. Geological Survey Bulletin 1638, p.

40-42. 

Goudam, G. H., compiler, 1984, Guide to preparation of mineral survey reports on public lands: U.S.

Geological Survey Open-File Report 84-0787, p. 7, 8.

A12 Mineral Resources of Wilderness Study Areas South-Central Oregon
RESOURCE/RESERVE CLASSIFICATION

Demonstrated

Measured Indicated

Inferred Probability Range

Hypothetical Speculative

SUBECONOMIC

Reserves Inferred 

Reserves

Marginal 

Reserves

Inferred 

Marginal 

Reserves

Demonstrated

Subeconomic

Resources

Inferred

Subeconomic

Resources

Major elements of mineral resource classification, excluding reserve base and inferred reserve base. Modified from U.S. Bureau of Mines 

and U.S. Geological Survey, 1980, Principles of a resource/reserve classification for minerals: U.S. Geological Survey Circular 831, p. 5.

Mineral Resources of the Devil's Garden Lava Bed, Squaw Ridge Lava Bed, and Four Craters Lava Bed Wilderness Study Areas, Oregon A13
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

Tertiary

Neogene 

Subperiod

Paleogene 

Subperiod

Cretaceous

Jurassic

Triassic

Permian

Carboniferous 

Periods

Pennsylvanian

Mississippian

Devonian

Silurian

Ordovician

Cambrian

 -(3800?)- -

EPOCH

Holocene

Pleistocene

Pliocene

Miocene

Oligocene

Eocene

Pateocene

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

- R

O A

 OQ

*J*J

cc

- 96 

_ 100

one

£S1\J

^\j\j

_ /^oon

- ouu ^fin

- 410 

- &v^ *too 

- 500

9/U

DUU

- 1600

_ ocnn

- 3000

OHUU

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

Informal time term without specific rank.

A14 Mineral Resources of Wilderness Study Areas South-central Oregon

GPO 585-045/78049