Geologic and Hydrologic 

Characterization and Evaluation 

of the Basin and Range Province 

Relative to the Disposal 

of High-level Radioactive Waste 

Part II Geologic and Hydrologic Characterization 

I 

I -----i--- -----1----~ 

\ 

~ _ ... -.,..~v--~/ I 

GEOLOGICAL SURVEY CIRCULAR 904-B 

This is Part II of a series of reports being prepared 

by the U.S. Geological Survey in consultation with 

States in the Basin and Range Province. 

I 

I 

\ 
BASIN AND RANGE 

PROVINCE WORKING GROUP 

U.S. Geologil:al Survey Members 

Chairman of the Province Working Group: 

M.S. Bedinger 

Hydrologist 

Water Resources Division 

Denver, CO 

Member: 

K.A. Sargent 

Geologist 

Geologic Division 

Denver, CO 

State Memb rs and Alternates 

ARIZONA 

Member: 

Larry D. Fellows 

Assistant Director and State Geologist 

Arizona Bureau of Geology and Mineral 

Technology 

Tucson, AZ 

Alternate: 

H. Wesley Peirce 

Principal Geologist 

Arizona Bureau of Geology and Mineral 

Technology 

Tucson, AZ 

CALIFORNIA 

Member: 

Robert Streitz 

Geologist 

California Division of Mines and Geology 

Sacramento, CA 

IDAHO 

Member: 

Frank Sherman 

Chief, Ground-Water Section 

Idaho Department of Water Resources 

Boise, ID 

Alternate: 

Darrel Clapp 

Chief, Technical Services Bureau 

Idaho Department of Water Resources 

Boise, ID 

NEVADA 

Member: 

John Schilling 

State Geologist 

Nevada Bureau of Mines and Geology 

University of Nevada, Reno 

Reno, NV 

Alternate: 

Susan L. Tingley 

Deputy to the State Geologist 

Nevada Bureau of Mines and Geology 

University of Nevada, Reno 

Reno, NV 

NEW MEXICO 

Member: 

Emery Arnold 

State Geologist 

New Mexico Mining and Minerals Division 

Santa Fe, NM 

Succeeded in July, 1982 by: 

James Hill 

Chief, Bureau of Geology 

New Mexico Mining and Minerals Division 

Santa Fe, NM 

Alternate: 

Frank Kottlowski 

Director 

New Mexico Bureau of Mines and Mineral Resources 

Socorro, NM 

TEXAS 

Member: 

Christopher Henry 

Geologist 

Texas Bureau of Economic Geology 

University of Texas at Austin 

Austin, TX 

Alternate: 

Douglas Ratcliff 

Associate Director 

Texas Bureau of Economic Geology 

University of Texas at Austin 

Austin, TX 

UTAH 

Member: 

Genevieve Atwood 

State Geologist 

Utah Geological and Mineral Survey 

Salt Lake City, UT 

Alternate: 

Don R. Mabey 

Senior Geologist, Applied Geology 

Utah Geological and Mineral Survey 

Salt Lake City, UT 
Geologic and Hydrologic 

Characterization and Evaluation 

of the Basin and Range Province 

Relative to the Disposal 

of High-level Radioactive Waste 

Part II Geologic and Hydrologic Characterization 

By K. A. Sargent and M. S. Bedinger 

ij I I :\ \__, ____ j l 

I' 

I ~ l ~ ,,_,i t I I 

I 

I 

I 

I 

I 

I 

-----+--------r----· I I \ I I 

I \ ~~ .... v-, .. ..r-... .., I 

' \ \ 

I 

\~ __ (' 

GEOLOGICAL SURVEY CIRCULAR 904-8 · 

This is Part II of a series of reports being prepared 

by the U.S. Geological Survey in consultation with 

States in the Basin and Range Province. 
United States Department of the Interior 

WILLIAM P. CLARK, Secretary 

Geological Survey 

Dallas L. Peck, Director 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1985 

Free on appli~tion to the Branch of Distribution, Eastern Region, U.S. Geological Survey, 604 South Pickett Street, Alexandria, VA 22304 
CONTENTS 

Summary ................................. . 

Introduction ............................... . 

Sources and compilation of information .......... . 

Acknowledgments .......................... . 

Climate and surface hydrologic features .......... . 

Distribution of selected rock types .............. . 

Fine-grained detrital rocks and their metamorphic 

equivalents ........................... . 

Granitic rocks .......................... . 

Page 

1 

1 

3 

4 

4 

6 

8 

8 

Tuffaceous rocks ......................... 10 

Mafic extrusive rocks . . . . . . . . . . . . . . . . . . . . . 11 

Evaporites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 

Page 

Distribution of selected rock types-Continued 

Other rock types . . . . . . . . . . . . . . . . . . . . . . . . . 11 

Unsaturated media. . . . . . . . . . . . . . . . . . . . . 12 

Tectonic factors .............................. 14 

Seismicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 

Quaternary faults ........................ 15 

Late Cenozoic volcanic activity .............. 16 

Quaternary vertical crustal movement . . . . . . . . 18 

Heat flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 

Ground-water hydrology. . . . . . . . . . . . . . . . . . . . . . . 20 

Ground-water quality . . . . . . . . . . . . . . . . . . . . . . . . . 22 

Pleistocene hydrologic features . . . . . . . . . . . . . . . . . . 28 

References cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 

ILLUSTRATIONS 

Page 

FIGURE 1. Map of western conterminous United States showing location of the Basin and Range 

Province as defined for this study and geographic features . . . . . . . . . . . . . . . . . . . . . . . . . . 2 

2-22. Maps showing: 

2. Mean annual precipitation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

3. Mean annual free-water surface evaporation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

4. Mean annual runoff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

5. Outcrop areas of fine-grained detrital rocks and their metamorphic equivalents. . . . . . . . . . . . . . . 8 

6. Outcrop areas of granitic rocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 

7. Outcrop areas of tuffaceous rocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

8. Outcrop areas of mafic extrusive rocks of pre-Quaternary age ............................ 12 

9. Major surface and subsurface occurrences of Tertiary and older salt and anhydrite . . . . . . . . . . . . 13 

10. Areas of unsaturated thickness greater than 150 meters (500 feet) ......................... 14 

11. Earthquake epicenters ........................................................... 15 

12. Strain release from earthquakes ................................................... 16 

13. Quaternary faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 

14. Areas of outcrop of volcanic rocks of late Cenozoic age. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 

15. Rates of vertical crustal movement ................................................. 19 

16. Heat flow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 

17. Areas of outcrop of bedrock and basin fill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 

18. Diagrammatic sections showing lines of equal hydraulic head and flow lines . . . . . . . . . . . . . . . . . 23 

19. Subprovinces and ground-water units ............................................... 24 

20. Ground-water quality types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 

21. Dissolved-solids concentration in ground-water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 

22. Pleistocene lakes and marshes ..................................................... 28 

III 
Metric unit 

square kilometer (km2) 

meter(m) 

kilometer ( km) 

millimeter ( mm) 

X 

X 

X 

X 

CONVERSION FACTORS 

Conversion factor 

0.386 

3.281 

0.621 

0.039 

IV 

English unit 

square mile (mi2) 

foot (ft) 

mile (mi) 

inch (in.) 
Geologic and Hydrologic Characterization and 

Evaluation of the Basin and Range Province 

Relative to the Disposal of High-Level Radioactive Waste 

PART II 

GEOLOGIC AND HYDROLOGIC CHARACTERIZATION 

by 

K. A. Sargent and M.S. Bedinger 

SUMMARY 

The geology and hydrology of the Basin and Range Province 

of the western conterminous United States are characterized 

in a series of data sets depicted in maps compiled for evaluation 

of prospective areas for further study of geohydrologic 

environments for isolation of high-level radioactive waste. 

The data sets include: ( 1) Average precipitation and evaporation; 

( 2) surface distribution of selected rock types; ( 3) tectonic 

conditions; and ( 4) surface- and ground -water hydrology and 

Pleistocene lakes and marshes. 

Rocks mapped for consideration as potential host media 

for the isolation of high-level radioactive waste are widespread 

and include argillaceous rocks, granitic rocks, tuffaceous 

rocks, mafic extrusive rocks, evaporites, and laharic breccias. 

The unsaturated zone, where probably as thick as 150 meters 

( 500 feet), was mapped for consideration as an environment 

for isolation of high-level waste. Unsaturated rocks of various 

lithologic types are widespread in the Province. 

Tectonic stability in the Quaternary Period is considered 

the key to assessing the probability of future tectonism 

with regard to high-level radioactive waste disposal. Tectonic 

conditions are characterized on the basis of the seismic 

record, heat-flow measurements, the occurrence of Quaternary 

faults, vertical crustal movement, and volcanic features. 

Tectonic activity, as indicated by seismicity, is greatest in 

areas bordering the western margin of the Province in Nevada 

and southern California, the eastern margin of the Province 

bordering the Wasatch Mountains in Utah and in parts of 

the Rio Grande valley. Late Cenozoic volcanic activity is 

widespread, being greatest bordering the Sierra Nevada in 

California and Oregon, and bordering the Wasatch Mountains 

in southern Utah and Idaho. 

The arid to semiarid climate of the Province results in few 

perennial streams and lakes. A large part of the surface 

drainage is interior and the many closed basins commonly 

are occupied by playas or dry lake beds. The Province is 

divided into ground-water flow units defined on the basis of 

ground-water divides, ground-water flow lines, and surface 

streams that receive ground-water discharge. 

1 

Ground water contains less than 500 milligrams per liter 

of dissolved solids throughout most of the Province. Ground 

water is more mineralized in areas underlain by evaporitic 

rocks, overlain by playas, and near saline lakes. Ground 

water is of the calcium, magnesium, or sodium bicarbonate 

type in the areas where dissolved-solids concentrations are 

less than 500 milligrams per liter, and of the calcium, magnesium, 

or sodium sulfate or chloride type where dissolved-solids 

concentrations are greater than 500 milligrams per liter. 

Geologic and hydrologic evidence is found for about 100 

lakes and marshes that existed during the Pleistocene Epoch. 

The possibility of a recurrence of pluvial conditions, such as 

existed in the Pleistocene, is of concern in repository siting 

because of possible changes in hydrologic conditions. The 

Pleistocene lakes and marshes provide clues to the hydrology 

during pluvial climates. 

INTRODUCTION 

This second part of a three-part report describes 

the information compiled to characterize the geology 

and hydrology of the Basin and Range Province 

(fig. 1). The boundary of the Basin and Range 

Province, as used for this study, closely follows the 

physiographic province defined by Fenneman ( 1928 ). 

The boundary, as used here, follows the natural 

ground-water flow-unit boundaries that define most 

of the study area. Part I is the introduction to the 

study and a discussion of the guidelines that will be 

used in evaluation (Bedinger, Sargent, and Reed, 

1983 ). Part III is the evaluation of the Province 

(Bedinger, Sargent, and Brady, 1983). Factors selected 

for characterization in Part II are those that are 

considered to be significant in identification of suitable 

environments for waste isolation for which 
/2QO 

soo-r- 1/5° 

+ -·- I T 

I -1> 

I 

"'WAS ) 

<> ' .. \ o MONTANA 

'--· 

I 

45"+ ' ) r ) '--'\ + " 

~ I ., + I I 

IDAHO \ 

•Boise 

.Helena 

C' 0~~ (}ts1 

~~~~ I 

I 

f- ·- ·- ·-·-- -·+·-; 

WYOMING 

.-·-·-·-,--·- ~- - ·-

0 100 200 300 400 500 600 700 800 KILOMETERS 

0 100 200 300 400 500 MILES 

Base mop from 

U.S. Geolog i col Survey 

FIGURE 1.-Location of the Basin and Range Province as defined for this study (shaded) and geographic features. 

approximately comparable data are available for 

the entire Province. The scope of data sets compiled 

for Province characterization is thus limited by the 

extent of information available. Factors selected 

for characterization included: ( 1) Surface distribution 

2 

of selected rock types including fine-grained detrital 

rocks and their metamorphic equivalents, granitic 

rocks, tuffaceous rocks, mafic extrusive rocks, and 

evaporites; ( 2) unsaturated media; ( 3) tectonic conditions 

including seismicity, Quaternary faults, late Cenozoic 
volcanic activity, Quarternary vertical crustal movement, and heat flow; (4) ground-water hydrology; 

(5) ground-water quality; and (6) Pleistocene hydrologic features. Areal gravity and magnetic data 

were used to provide supplementary information. 

SOURCES AND COMPILATION 

OF INFORMATION 

Sources of geologic and hydrologic information 

compiled for characterization include published reports, 

information in files of the U.S. Geological Survey, 

the U.S. Geological Survey WATSTORE computer 

file of ground-water information and ground-water 

chemical analyses, and data in files of other Federal 

and State agencies. 

The following table shows information covered 

in previously published reports of the U.S. Geological Survey. These reports have been used in the 

characterization of the Basin and Range Province. 

Information Geographic Area Author(s) 

Outcrop of ........ Eastern Nevada ......... Simpson, Weir, 

argillaceous and Woodward, 

rocks. 1979. 

Seismic maps . 

Quaternary . 

faults .. 

Quaternary 

volcanic 

rocks. 

. Basin and Range ........ Algermissen and 

Province. others, 1983; 

Askew and 

Algermissen, 1983. 

. Basin and Range . . ... Nakata, 

Province. . ........... Wentworth, 

and Machette, 

1982. 

. Arizona and New Mexico ... Luedke and Smith, 1978a. 

Colorado, Utah, and 

southwestern Wyoming .. Luedke and Smith, 1978b. 

California and Nevada ... Luedke and Smith, 1981. 

Oregon and Washington. Luedke and Smith, 1982. 

Quaternary ....... Basin and Range . . Gable and 

vertical Province, Hatton, 1980. 

crustal .conterminous United 

movement. States. 

Heat flow ........ Basin and Range . . Sass and others, 

Province. 1976. 

Geothermal ....... United States ........... Muffler, L.J.P., 

resources editor, 1979. 

Published reports of State and other Federal 

agencies were used also. These include the list of 

thermal springs of the United States compiled by 

Berry, Grim and Ikelman (1980). 

The rock outcrop maps and information on lithology, 

thickness and age were compiled by the following 

members of the U.S. Geological Survey, Lakewood, 

Colorado: Kenneth A. Sargent, Jane J. Dickson, 

William D. Johnson, Judith S. Gassaway, David A. 

Lopez, and F. Allan Hills. Rock outcrop maps for 

3 

Texas were compiled by Christopher D. Henry and 

Gail L. Fisher of the Texas Bureau of Economic 

Geology. Laharic breccias and volcanic rocks of 

New Mexico were compiled under the direction of 

John Hawley of the New Mexico Bureau of Mines 

and Mineral Resources. 

Thomas G. Hildenbrand, U.S. Geological Survey, 

Lakewood, Colorado, compiled areal geophysical 

information on gravity and magnetics data. 

Most of the information on hydrology and quality 

of ground water was compiled by hydrologists in 

the following offices of the U.S. Geological Survey: 

Thomas Anderson of the Tucson, Arizona, District 

Office directed compilation of data for Arizona; 

Richard Ireland in the Sacramento, California, District 

Office compiled information for northern California; 

Richard Moyle and Lynda Woolfenden of the Laguna 

Nigel, California, office compiled information for 

southern California; Joseph Gates, James Stark, 

and James Mason of the Salt Lake City, Utah, 

District Office compiled information for Utah and 

Idaho; James Harrill, James Thomas, and Allan 

Welch of the Carson City, Nevada, office compiled 

information for Nevada; Donald Hart of the 

Albuquerque, New Mexico, District Office compiled 

information for New Mexico; Joseph Gonthier and 

William McFarland of the Portland, Oregon, District 

Office compiled information for Oregon; Bruce Timothy 

Brady of the Lakewood, Colorado, office and John 

Mikels and Donald White of the El Paso, Texas, 

office compiled information for Texas. 

Information on depths to ground water in the 

Province were examined by William Langer, U.S. 

Geological Survey, Lakewood, Colorado, who, with 

the assistance of Deborah Mulvihill, U.S. Geological 

Survey, Lakewood, Colorado, outlined areas within 

which the depth to water is probably 150 meters 

( 500 feet) or greater. . 

Information on the chemical quality of ground 

water was synthesized and mapped by Thomas 

Thompson of the U.S. Geological Survey, Lakewood, 

Colorado, with the assistance of Richard Chappel 

and Janet N uter, graduate students of the Colorado 

School of Mines. Thomas Thompson provided the 

classification of water-quality types used in this 

report and the description of areal distribution of 

water-quality type and dissolved-solids concentrations of ground water. 

Thomas Williams, graduate student, Colorado· 

State University, and U.S. Geological Survey, Lakewood, 

Colorado, compiled information on Pleistocene lakes 

and marshes. 
ACKNOWLEDGMENTS 

The State members and alternates of the Province 

Working Group were the principal consultants and 

reviewers during the planning, compilation, and 

preparation for release of the geologic and hydrologic 

information used to characterize the Province. 

The following individuals also are acknowledged 

for their assistance during various phases of the 

preparation, compilation, and review of this report: 

Harry D. Goode, who serves as ground-water consultant 

to the Utah Geological and Mineral Survey, Salt 

Lake City, Utah; John Hawley and William Stone 

of the New Mexico Bureau of Mines and Mineral 

Resources; Robert B. Scarborough and Stephen J. 

Reynolds of the Arizona Bureau of Geology and 

Mineral Technology; Joe Tingley of the Nevada 

Bureau of Mines and Geology; Charles Jennings of 

the California Division of Mines and Geology; and 

Donald Hull, John Beaulieu, and John Bela of the 

Oregon Department of Geology and Mineral Industries. 

CLIMATE AND SURFACE 

HYDROLOGIC FEATURES 

The climate in the Basin and Range Province is 

arid to semiarid. Seasonal weather patterns are 

caused by annual variations in the magnitude and 

movements of air masses from the Pacific Ocean, 

Gulf of Mexico, and the polar continental region. 

Prolonged periods of extremely cold weather are 

rare, primarily because of the mountains north of 

the Province and the moderating effect of maritime 

air masses from the Pacific. 

The mean annual precipitation is about 28 centimeters 

( 11 inches) (fig. 2 ). The great variability in the areal 

distribution of precipitation is directly related to 

the pattern of topographic relief between the ranges 

and the intervening basins. Precipitation ranges 

from less than 10 centimeters ( 4 inches) in the 

basins to as much as 30 to 40 centimeters ( 12 to 16 

inches) at higher elevations. The predominant source 

of moisture during the winter is storms that originate 

in the north Pacific and move from west to east 

across the Basin and Range. The Coast Ranges and 

the Sierra Nevada, to the west of the Basin and 

Range Province, cause precipitation in the mountains 

as the moist air masses rise. Descending from the 

Sierras into the lower elevations of the Basin and 

Range, the winds are warmed and compressed and 

as the storms move eastward across the Province, 

precipitation occurs mostly at higher elevations. 

4 

Continental polar air masses periodically move 

southward into the Province from the north, bringing 

cold, dry air. Precipitation occurs when cold air 

from the north encounters warm, moist air from the 

Gulf of Mexico, south Pacific Ocean region, and 

Gulf of California. 

In the summer, the prevalent Pacific high-pressure 

area drifts northward and Pacific air masses generally 

are deflected over the continent north of the Province. 

Consequently, the Province receives relatively little 

summer precipitation from northern Pacific air masses. 

In the middle and late summer, storms originating 

in the Gulf of Mexico, and occasional storms laden 

with warm, moist air from the southern Pacific 

region and Gulf of California, move into the southern 

and southwestern part of the Province. 

The potential evaporation greatly exceeds the 

annual precipitation. The mean annual free-water 

surface evaporation ranges from 89 to 254 centimeters 

(35 inches to 100 inches) (fig. 3). 

Low precipitation and high water loss by evaporation 

and transpiration results in little annual runoff 

(fig. 4) and few perennial streams and lakes. Mean 

annual runoff from the Basin and Range Province 

generally is less than 0.5 centimeter (0.2 inch). A 

few perennial streams within the arid and semiarid 

parts of the Basin and Range Province originate at 

the higher elevations in the highlands and ranges 

within the Province or the bounding ranges, such 

as the highlands bordering the Colorado Plateau in 

Arizona and New Mexico, the Sierra Nevada of 

California, and the Wasatch Range of Utah. Two 

perennial streams, the Colorado River and the Rio 

Grande, originate outside the Province and flow 

through the Province. Surface drainage basins include 

closed basins with interior drainage and basins 

with surface drainage to the sea. Closed basins 

comprise about 80 percent of the surface area of the 

Province, most ranging in size from a few tens to 

several hundred square kilometers. A few large 

closed basins in the Great Basin region of Utah, 

Nevada, and California, the Great Salt Lake basin, 

the Death Valley basin, and the Humboldt River 

basin, have areas of thousands of square kilometers. 

Perennial streams in these and a few other basins 

terminate in perennial lakes. Streams in most of 

the closed basins only convey water from occasional 

storms to usually dry lakes or playas where water 

evaporates or infiltrates to the subsurface. Beneath 

many of the dry lakes, the ground-water level remains 

below the land surface because of evaporation through 

the soil and transpiration by plants. 
120° 

0 100 200 300 400 500 KILOMETERS ' I f 1 I I I t' 

0 100 200 300 MILES 

FIGURE 2.-Mean annual precipitation. IntervallO centimeters. Modified from U.S. Department of Commerce, 

1968. 

In contrast, beneath some of the dry lakes of 

closed basins, the depth to ground-water is greater 

than the effects of surface and plant evapotranspiration, 

indicating that storm water that infiltrates the soil 

to the water table becomes part of the ground-water 

flow system and is discharged in other basins. 

The water deficiency of the Province, measured 

by the excess of potential evapotranspiration compared 

to precipitation, is a significant characteristic with 

respect to isolation of radioactive wastes. As a 

consequence of the climate, ground-water recharge 

is low. Recharge probably is variable in time occurring 

during infrequent times of water excess. The areal 

5 

distribution of recharge is affected by the permeability 

of outcropping rocks, areas where excess water 

may be concentrated during brief periods of runoff, 

and the areas of greater precipitation at higher 

elevations. As a direct result of slow recharge rates, 

the unsaturated zone is very thick in some areas 

and the moisture content and rate of movement in 

the unsaturated zone are very small. These 

characteristics enhance the unsaturated zone's capability 

to isolate radioactive wastes from the accessible 

environment. 

Because of the long duration of toxicity of high-level 

radioactive wastes, the future climate also is of 
0 100 200 300 400 500 KILOMETERS 

I ' I ' ' r ' t' 

0 100 200 300 MILES 

FIGURE 3.-Mean annual free-water surface evaporation. Interval is 25 centimeters. Modified from U.S. 

Department of Commerce, 1982. 

concern in evaluating the Province relative to the 

isolation of the wastes. Among the evidence that 

wetter climates existed at times in the past few 

tens of millenia are the vestiges of nearly 100 abandoned 

lake shorelines in the Province. These shorelines 

are as much as several hundred feet higher than 

present lake levels or the dry lake beds that now 

occupy the basins. Evidence from Pleistocene lakes 

(see the section on "Pleistocene hydrologic features") 

can assist in estimating the magnitude of hydrologic 

6 

changes that could result from possible future climatic 

change. 

DISTRIBUTION OF SELECTED ROCK TYPES 

Several rock types have been considered as potential 

host media for high level radioactive-waste repositories. 

Among those that have been studied are the following 

generic types: shale, granite, tuff, basalt, and salt. 

Other rock types, generally of less widespread occurrence, 
120° 

0 100 200 300 400 500 KILOMETERS I I I I I I I ,, 

0 100 200 300 MILES 

FIGURE 4.-Mean annual runoff. Interval in centimeters is variable. Modified from Busby, 1965. 

in the Province have been mapped where, by their 

physical properties and occurrence, they have potential 

as host media. In addition, the unsaturated zone, in 

which several rock types may be suitable, has been 

the subject of investigation as a distinct repository 

host medium. 

In compiling information about the occurrence 

of the selected rock types, the surface distribution, 

thickness (where appropriate), lithology, age, and 

major published references were compiled. Additional 

data on the subsurface occurrence, depth, and thickness 

were compiled for evaporites. The surface outcrop 

7 

provides an initial perspective of the Province-wide 

distribution of the rock types and reflects, in part, 

the relative subsurface abundance of rock types 

from area to area. Each rock type is not a uniformly 

suitable host medium throughout its occurrence; 

indeed, some rock types appear to have unsuitable 

characteristics for prospective host rocks in much 

of the Province. The rock-type maps also provide 

useful supplementary information for other phases 

of the study. For example, the map of evaporite 

distribution is useful in mapping the distribution 

of chemical types and dissolved-solids concentration 
12QO 

40" 

0 

I 

100 200 300 400 500 KILOMETERS 

0 100 200 300 MILES 

FIGURE 5.-Outcrop areas (shaded) of fine-grained detrital rocks and their metamorphic equivalents. Only 

areas where thicknesses are about 150 meters (500 feet) or more are shown. 

of ground water; the maps of shales are useful 

because these rocks impede ground-water flow and 

commonly have significant sorptive capacities for 

radionuclides. 

FINE-GRAINED DETRITAL ROCKS AND 

THEIR METAMORPHIC EQUIVALENTS 

Outcrop areas of shale, siltstone, claystone, mudstone, 

and their metamorphic equivalents, argillite, slate 

and schist, were compiled where the aggregate thickness 

is approximately 150 meters (500ft) or more (fig. 

5). This thickness is considered ample as a host 

8 

rock for a mined repository. More detailed maps 

being prepared will include data about lithology, 

facies changes, and thickness where the information 

is available. Argillaceous rocks generally have little 

permeability and impede movement of ground water. 

They commonly have sorptive properties that could 

significantly retard radionuclide transport. 

GRANITIC ROCKS 

Outcrops of granite, granodiorite, and other mediumto coarse-grained crystalline plutonic rocks were 

compiled (fig. 6). These rocks commonly extend to 
120• 

35° 

•• j : ·j) -

... ,r 

[. ·.i .). 

! 

! 

j • .;. 

i. ' I r-·-·· 

.! !I-.-~) ,.~ ::J 

0 100 200 300 400 500 KILOMETERS 

0 100 200 300 MILES 

FIGURE 6.-0utcrop areas (shaded) of granitic rocks. 

depths of several hundred meters or more and probably 

are'/present at depths as great as 1,000 meters 

( 3,300 feet), the nominal maximum depth of interest 

for a mined repository. Exceptions to this generalization 

are laccolithic and other shallow bodies, such as 

locally occur in New Mexico, Texas, Utah, and 

other parts of the Basin and Range Province. Shallow 

intrusive rocks need to be distinguished from the 

larger deep-seated plutonic bodies. 

The intercrystalline permeability of granitic rocks 

is very low. The permeability and porosity primarily 

are determined by density and size of openings of 

fractures. Fracture density in 10 test wells drilled 

9 

in three areas of the United States, 7 to depths of 

200 to 250 meters ( 660 to 820 feet) and 3 to depths 

of about 1 kilometer ( 3,300 feet) was found to decrease 

only slightly with depth (Seeburger and Zoback, 

1982 ). They present no information, however, related 

to changes in permeability with depth. In crystalline 

rocks at damsites in the Front Range of Colorado 

at depths from a few to 100 meters ( 330 feet), Snow 

( 1968a) found that the density of hydraulically significant 

fractures and porosity decreased with depth. Snow 

showed that the logarithm of permeability decreases 

linearly with the logarithms of depth and concluded 

that the decrease of permeability with depth was 
0 

I 

100 200 300 400 500 KILOMETERS 

0 tOO 200 300 MILES 

FIGURE 7.-Outcrop areas (shaded) of tuffaceous rocks. 

more a result of decrease in fracture openings than 

decrease in fracture density (Snow, 1968b ). 

Measurements of permeability with depth in crystalline 

rocks in Canada (Davison, Keys, and Paillet, 1982) 

show no uniform decrease in permeability with depth, 

although the lesser permeability values generally 

were found in the deeper parts of the sections. 

Although increased overburden pressure with depth 

tends to decrease the fracture openings, zones of 

significant permeability are found at depths as 

great as a few thousand meters (Keys and Sullivan, 

1979; W. S. Keys, U.S. Geological Survey, oral 

commun., 1983 ). 

10 

TUFFACEOUS ROCKS 

Tuffaceous rocks in the Province include welded 

and partly welded ash-flow tuff, ash-fall tuff and 

zeolitic-bedded tuff. Compilations being prepared 

include principally densely welded ash-flow tuffs 

(fig. 7), but because of the nature of the available 

data, the compilations also may include partly welded 

tuff and other associated tuffaceous rocks. Welded 

and zeolitic tuffs generally are permeable, and effective 

porosity is controlled by fractures; in friable bedded 

ash-fall tuff, the effective porosity and permeability 

are controlled by interstices (Thordarson, 1965). 
Mapping of ash-flow tuffs has evolved during the 

past 2 decades from delineating lithologic units 

such as rhyolites and dacites, commonly identified 

as lavas, to the mapping of genetic cooling units 

which may (or may not) contain non-welded, partly 

welded, densely welded to vitrophyric tuffs, and 

vapor-phase zone rocks in a single mapped unit. 

Because of the evolving knowledge of ash-flow tuffs, 

it is difficult for a compiler to know how much, or 

even if, densely welded tuff exists in some mapped 

areas. To further complicate the task of compiling a 

map of these rocks, it has been demonstrated that 

in some areas of sharp relief, the continuity of 

cooling zones is interrupted over topographic highs. 

In the vicinity of most calderas, however, the existence 

of thick sections of moderately to densely welded 

tuffs is most likely. Thicknesses of intracaldera 

tuffs are known to attain one to two thousand 

meters, and similar thicknesses hav~ been mapped 

in paleotopographic lows in the vicinity of extrusive 

centers. Because of these spatial relationships, calderas 

and the associated ash-flow tuffs are being compiled 

where information permits. 

MAFIC EXTRUSIVE ROCKS 

The outcrops of basalt, basaltic andesite, and 

other mafic extrusive rocks of pre-Quaternary age 

have been mapped where they are 100 meters (330 

feet) or greater in thickness. Areas where mafic 

extrusive rocks are younger than about two million 

years generally are not considered prospective because 

of the possibility of renewed volcanism. Data compiled 

on mafic extrusive rocks for this study include 

thickness where available. Because thicknesses may 

change markedly within short distances, mappers 

of such rocks are not likely to record thicknesses at 

numerous locations; thus, thicknesses in many mapped 

areas were estimated from topographic maps. The 

occurrence of known mafic extrusive rocks with a 

thickness of about 100 meters (330 feet) or more is 

shown in figure 8. These rocks generally are heterogeneous and permeable by virtue of the presence of 

joints, fractures, bedding- and foliation-plane openings, 

and sedimentary interbeds. Although relatively 

impermeable beds are common in these rocks, the 

heterogeneity of basalt sequences and the common 

occurrence of abundant fractures mitigate against 

their suitability as potential host rocks in the saturated 

zone. The significant permeability and heterogeneity, 

however, are not adverse characteristics for host 

media in the unsaturated zone. Basalt is a potential 

11 

host medium where the thickness of the unsaturated 

wne is sufficient to construct a repository. Fortuitously, 

the distribution and thickness of basalt are best 

known at and near the surface where basalt is best 

suited as a host rock in the unsaturated wne. Predictions 

of the occurrence of mafic extrusive rocks at a 

depth of 300 to 900 meters ( 1,000 to 3,000 feet) for a 

potential repository are tenuous based on surface 

exposures. Only where very thick sections of mafic 

extrusives occur or where sections are known to be 

down faulted is it likely to find mafic extrusive 

rocks at the desired repository depth. 

EVAPORITES 

The surface and subsurface occurrence, thickness, 

and inferred extent of Thrtiary and older salt and 

anhydrite throughout the Basin and Range Province 

are shown in figure 9. Evaporites are both candidate 

repository rocks and potential barriers to movement 

of radionuclides. Bedded evaporites commonly contain 

interbedded fine silt and clay, which may be sorptive 

media for radionuclides, but which also contain 

significant moisture. 

Data were collected on occurrences reported to 

be 100 meters (330 feet) or more thick. Because of 

the relative mobility and structural instability of 

evaporites, due largely to their ability to move 

plastically under lithostatic load, it commonly is 

difficult to determine if an evaporitic body is bedded, 

has thickened or thinned from its original bedded 

thickness, or if the body has begun to move from its 

original position to a position of isostatic adjustment. 

Because the thick evaporite units are encountered 

in few wells, the extent of the units has not been 

defined. Sections of halite greater than 100 meters 

(330 feet) have been penetrated by wells in Utah 

and Arizona. 

OTHER ROCK TYPES 

Locally certain rock types occur that have potential 

as host rocks; such rocks include laharic and mudflow 

breccias which occur in parts of New Mexico, Oregon, 

Idaho, Ariwna, and Nevada. Laharic breccia occurrences 

have been compiled for New Mexico and Idaho 

where they are known to occur as thick homogeneous 

units. They are believed to contain a significant 

percentage of finely comminuted clastic particles 

that give the rock coherence and should enhance 

sorptive properties. In addition, data on shallow 

intrusive bodies such as rhyolite and dacite domes 
120° 

0 100 200 300 400 500 Kl LO METERS 

0 100 200 300 MILES 

FIGURE 8.-0utcrop areas (shaded) of mafic extrusive rocks of pre-Quaternary age. 

have been compiled for Texas and California. These 

units would have properties similar to some densely 

welded tuffs and may be suitable as host rocks in 

the unsaturated zone. 

UNSATURATED MEDIA 

The concept of the unsaturated zone of arid regions 

as an alternate environment for isolation of high-level 

radioactive waste was first advanced by Winograd 

in 1974. The concept was further examined at a site 

in southern Nevada by Winograd ( 1981 ). The 

unsaturated zone is much more than just another 

12 

host rock type; it is a different hydrologic environment. 

The geohydrologic implications of the nature of the 

unsaturated environment in exploration, characterization 

and design of the repository and waste package are 

considered by Roseboom (1983). 

The depth to the water table is the thickness of 

the unsaturated zone, except where perched ground 

water occurs. In basin fill and other relatively uniformly 

porous and permeable material, the water table is a 

continuous gently varying surface, and depth to 

water can be predicted with reasonable confidence 

between widely spaced data points. In the bedrock 

areas, the water table may be an irregular surface 
EXPLANATION 

X AVAWATZ OUTCROP AND NAME 

DRILL HOLE AND NUMBER.•-See 1 ist below 

'...} 

t) GILA LOW 

APPROXIMATE BOUNDARY OF SUBSURFACE EVAPORITE BODY 

APPROXIMATE BOUNDARY OF DEPOSITIONAL BASIN AND NAME 

BOUNDARY OF BASIN AND RANGE PROVINCE AS DEFINED FOR THIS STUDY 

DRILL HOLES.--First number is thickness of undifferentiated evaporites, in meters; second 

number is depth to top of zone of undifferent 1 a ted evaporites, in meters; 

numbers in parentheses are thickness and depth in feet. 

1. Gulf Oi 1 Gronning, 1 ,525 m/777. 75 m (5000/2550) 

2. Argonaut #1 C2 

3. Detrital Valley, 183 m/152.5 m (600/500) 

4. Red Lake, 1,525 m/457.5 m (5000/1500) 

5. Date Creek, 213.5 m/457.5 m (700-1500/2700) 

6. Wenden, 88.45 m/271.45 m (290/890) 

7. Picacho, 24.4 m/701.5 m (80/2300) 

8. Pima, 3.05 m/701.5 m (10/2300) 

9. 1 ,281 m/555.92 m (4200/1850) 

10. 590.17 m/768.6 m (1935/2520) 

0 100 200 300 400 500 KILOMETERS 

0 100 200 300 MILES 

FIGURE 9.-Major surface and subsurface occurrences of Tertiary and older salt and anhydrite. 

because of large differences in permeability distribution. 

Ground water occurs in joints or fractures in the 

bedrock, and these may be poorly interconnected. 

Approximate areas where the unsaturated section 

is greater than 150 meters (500 feet) are delineated 

based on depth to water in wells and mine shafts, 

spring locations and flow rates, location of gaining 

reaches of streams, and estimates of geologic and 

hydrologic conditions in the area (fig. 10). These 

areas have potential for being evaluated as prospective 

environments for isolation of high-level radioactive 

waste in the unsaturated zone. 

Depths to water greater than 150 meters (500 

feet) commonly occur in consolidated rock beneath 

mountain ranges. The greatest thickness of the 

unsaturated zone in the Province is in south-central 

Nevada, where the depth to water is as great as 

13 

1,000 meters ( 3,300 feet). Here, the basins are underlain 

at depth by a permeable carbonate-rock aquifer, 

which is a deep ground-water drain in the region. 

Many rock types may be considered as potential 

host media in the unsaturated zone. The suitability 

of rock in the unsaturated zone is more dependent 

on physical properties of the rock and the movement 

of water through the zone than on the lithologic 

type of the rock. In the unsaturated zone, the host 

medium needs to be mineable and sufficiently permeable 

to provide natural drainage. In some rocks drainage 

could be induced or enhanced by construction of 

water-control structures in the repository. The 

unsaturated zone ideally should be subject to little 

or no downward movement of recharge water. Rocks 

that may be unsuitable as a potential host media 

for a repository in the saturated zone, such as basin 
0 100 

I I 

0 

I 

200 

3()0 

I 

300 MILES 

FIGURE 10.-Areas (shaded) of unsaturated thickness greater than 150 meters (500 feet). 

fill, and fractured and permeable basalt and welded 

tuff, are potential host media in the unsaturated 

zone. 

TECTONIC FACTORS 

Tectonic stability in the Quaternary Period is 

considered the key to assessing the probability of 

future tectonic activity with regard to high-level 

radioactive waste disposal. Tectonic conditions in 

the Province are characterized by the seismic record; 

the distribution of Quaternary faults, volcanic feature$, 

and vertical crustal movement; and heat-flow 

measurements. 

14 

SEISMICITY 

The record of seismicity from 1803 to 1977 was 

used to prepare maps showing the distribution (fig. 

11) and magnitude of earthquakes in the province 

(Askew and Algermissen, 1983). In addition, a series 

of maps has been prepared by Algermissen and 

others ( 1983) showing: ( 1) Strain release as contoured 

values of cumulative energy released by the earthquakes 

of record (fig. 12); (2) probabilistic estimates of the 

horizontal velocity in rock, due to earthquake vibrations; 

( 3) probabilistic estimates of horizontal acceleration 

in rock due to earthquakes; and ( 4) seismic-source 

zones of the Province based on the historic seismic 

record and tectonic characteristics. 
.. -. . . 

. ... 

................. 

I 

J 

0 100 200 300 400 500 KILOMETERS 

0 100 200 300 MILES 

FIGURE H.-Earthquake epicenters (dots). Modified from Askew and Algermissen, 1983. 

QUATERNARY FAULTS 

The map of the Basin and Range Province showing 

Quaternary faults, by Nakata, Wentworth, and Machette 

(1982), was used to prepare figure 13. This map 

shows several wnes of relatively concentrated faulting: 

( 1) A north· to northwest-trending zone along the 

western border of the Great Basin in eastern California 

and western Nevada; ( 2) a north-trending zone along 

the eastern border of the Great Basin in Utah and 

northwestern Arizona, adjacent to the Wasatch 

Range; and (3) a north-trending wne in the Rio 

15 

Grande rift area extending from El Paso, Texas, 

northward through Albuquerque, New Mexico. 

Fault movement tends to recur along the preexisting 

faults under the existing stress field. Areas having 

few or no Quaternary faults thus may reflect areas 

with little potential for faulting and with little crustal 

weakness. However, the apparent absence of Quaternary 

faults in some areas may be due to lack of detailed 

study; or Quaternary-fault movement may be masked 

by younger Quaternary deposits. 

Trask ( 1982) discussed the problem of performance 

assessment of mined repositories with respect to 
120° 

D 

D 

EXPLANATION 

Less than 0.1 

Strain release equivalent 

M =4.0 earthquakes s 

0.1 to 10 

10 to 100 

IIIII Greater than 100 

0 100 200 300 400 500 KILOMETERS 

0 100 200 300 MILES 

FIGURE 12.-Strain release from earthquakes. From Algermissen and others, 1983. The equivalency of a given 

earthquake to a M5 =4.0 earthquake is computed as 10 to the exponent (0.75M5 =3.0). Areas of equal strain release 

represent the number of equivalent M 5 =4.0 earthquakes per 823 square kilometers (318 square miles) 

(0.25° latitude by 0.33° longitude). 

fault movement. Trask has suggested an upper 

unit on the rate of recurrence of major movements 

of 8 x 105 events per year on active faults within 

the Basin and Range Province other than those 

near Sierra Nevada and Wasatch fronts. 

LATE CENOZOIC VOLCANIC ACTIVITY 

Recent compilations of late Cenozoic volcanic 

centers encompassing most of the States in the 

Basin and Range Province are now available (Luedke 

16 

and Smith, 1978a, 1978b, 1981, and 1982; and Aldrich 

and Laughlin, 1981 ). The occurrence of late Cenozoic 

flows and eruptive centers indicates areas where 

analysis of volcanic hazards needs to be made in 

regard to repository siting. 

Luedke and Smith ( 1978a) show local areas where 

there has been a distinct migration of the centers of 

volcanism. In general, Quaternary volcanism has 

been most prevalent along the east and west margins 

of the Great Basin and along a north-trending zone 

in the Rio Grande valley. Radiometric dating of 
120° 

:::; (_,' 

'' I.' 

I 

. 1 . I; I 

r 

0 100 200 300 400 500 KILOMETERS 

0 100 200 300 MILES 

FIGURE 13.-Quaternary faults. After Nakata, Wentworth, and Machette, 1982. 

volcanic features may reveal additional trends of 

movement of volcanic loci, such as the eastward 

and northeastward trends that have been documented 

in southern Utah and northeastern and central Arizona. 

A compilation of information from Luedke and 

Smith (1978a, 1978b, 1981, and 1982) showing 

volcanism for the last 5 million years is presented 

in figure 14. 

Crowe and Carr ( 1980) suggest that the southern 

Great Basin can be zoned based on the risk of 

recurrence of basaltic volcanism. Ascending magma 

could intersect a mined repository and subsequently 

erupt at the surface. Crowe and others ( 1983) consider 

17 

various aspects of the magnitude of distruption of 

a repository by basaltic magma in southern Nevada 

and the means and extent of dispersal of radioactive 

waste by surface eruption of the magma. They 

conclude that the part of the repository potentially 

intersected by a basaltic intrusion would be relatively 

small. Surface dispersal of waste by a Stromboliantype eruption would be restricted to a limited area 

admixed with basaltic tephra. Because most of the 

volcanic activity in the Basin and Range Province 

during the past 5 million years has involved basaltic 

magmas, their considerations also are applicable 

elsewhere in the Basin and Range. 
120• 

0 100 200 300 400 500 KILOMETERS 

0 100 200 300 MILES 

FIGURE 14.-Areas of outcrop (shaded) of volcanic rocks of late Cenozoic age. Modified from Luedke 

and Smith, 1978a, 1978b, 1981, and 1982. 

QUATERNARY VERTICAL CRUSTAL MOVEMENT 

Gable and Hatton ( 1980) compiled a series of 

four maps showing the amount of vertical crustal 

movement in the Basin and Range Province since 

the beginning of the Quaternary Period. These maps 

generally are useful in identifying regions of potentially 

rapid rates of uplift where erosion could decrease 

the thickness of cover over a repository. If a prospective 

region is studied further, additional data on subsidence 

or uplift would be appropriate. In addition, certain 

areas of uplift or bulging might indicate the shallow 

18 

invasion by magma or tectonic instability. Rates of 

uplift in the Province shown in figure 15 are based 

on the following data from Gable and Hatton ( 1980): 

( 1) Geology, geomorphology, and radiocarbon dating; 

and ( 2) geodetic leveling. 

HEAT FLOW 

Heat-flow measurements are an attempt to quantify 

the amount of the Earth's heat that is being transferred 

to the atmosphere at a given point. Heat flow is 

determined by measuring the geothermal gradient 
120° 

.._ __ rJ_.s-- I 1~ t 

110° 'r, 

---t-1 :l''v 300 

0 100 200 300 400 500 KILOMETERS 105~ 1 

I I I I I I I II ..... "_; 

0 100 200 300 MILES 

FIGURE 15.-Rates of vertical crustal movement. Solid lines are in meters per 10,000 years based on geology, 

geomorphology, and radiocarbon dates. Solid lines with dots are in millimeters per year based on geodeticleveling data. Modified from Gable and Hatton, 1980. 

(rate of temperature change with depth) in drill 

holes and measuring the thermal conductivity of 

rock samples from the drill hole. The standard 

measurement unit is called the heat flow unit ( HFU ). 

One HFU is equivalent to 1 x 106 calories per 

square centimeter per second. 

A map of heat flow (fig. 16) has been compiled for 

the Basin and Range Province by J. H. Sass (U.S. 

Geological Survey, written commun., 1982) revising 

the map of heat flow for the conterminous United 

States (Sass and others, 1976). The mean value of 

650 point measurements is 2.1 HFU, although the 

points are not evenly distributed. 

Within the Province, areas with greater than 

average heat flow include: ( 1) The Battle Mountain 

19 

high area of northern Nevada and adjacent parts of 

Idaho, Oregon, and Utah, (2) the Salton Trough 

area of southern California, and ( 3) the Rio Grande 

rift area of southern New Mexico. Other areas with 

greater than average heat flow occur along the 

eastern margin of the Province in Utah, along the 

western boundary of the Province in California, 

Nevada, and Oregon, and at localities in eastern 

Nevada and southcentral Arizona. The greater than 

average heat-flow areas of the Salton Trough, Rio 

Grande rift and the eastern and western margins of 

the Province are in tectonically active areas as 

evidenced by Quaternary faulting, seismicity, and 

locally by late Cenozoic volcanic activity. In contrast, 

the Battle Mountain high is relatively quiet tectonically, 
EXPLANATION 

HEAT-FLOW UNITS 

c==J 0.75 to l .5 

fZZZ1 l . 5 to 2. 5 

~ Greater than 2.5 

0 

I 

100 200 300 400 500 KILOMETERS I I I I I I ,, 

0 100 200 300 MILES 

FIGURE 16.-Heat flow. One heat-flow unit is equivalent to 1 x 10·6 calories per square centimeter per second. 

Modified by J. H. Sass (U.S. Geological Survey, ~ritten commun., 1982) from Sass and others (1976). 

but was recently found to have a thin crust ( 23 to 35 

kilometers or 14 to 22 miles thick), at least 20 

kilometers ( 12 miles) thinner than in central Nevada 

(Stauber, 1983). 

Three areas within the Province have heat flow 

that is markedly less than the average for the 

Province. The Eureka low in central Nevada, a part 

of the Mojave Desert in southern California, part 

of the Trans-Pecos region of Texas and New Mexico, 

and a smaller area in south-central Oregon have 

heat-flow values that are less than 1.5 HFU. These 

heat-flow areas may be related to slow transfer of 

20 

heat (low reduced heat flow) or to convective redistribution of heat by ground-water flow. 

GROUND-WATER HYDROLOGY 

Characterization of the ground-water hydrology 

of the Province is based principally on information 

compiled on ground-water-level elevation, depth to 

ground-water below the land surface, flow and 

temperature of springs, ground-water withdrawal, 

perennial surface-water features, chemical quality 

of ground water, and information on the geology of 
0 100 200 300 400 500 KILOMETERS 

I I I I I I I •' 

0 100 200 300 MILES 

FIGURE 17.-Areas of bedrock (shaded) and basin fill (unshaded). 

the Province and hydrologic properties of the rocks. 

The most obvious geologic distinction that has 

hydrologic significance in the Province is the difference 

in properties of the basin-fill deposits and consolidated 

rocks (fig. 17). Basin-fill deposits vary in lithology 

and include evaporites, clays, silts, sands, and gravels. 

The older deposits of the basin date the time of 

formation of the basin and range structures in the 

middle Thrtiary Period; they commonly are more 

consolidated and cemented and less permeable than 

the more recent deposits. Though grain size of 

deposits varies considerably vertically as well as 

laterally because of the varying rates of uplift and 

21 

erosion of the bounding mountain blocks in many 

basins, a consistent change in texture commonly 

occurs from coarse at the margins to fine sediments 

in the central parts of the basins. Evaporites typically 

occur in the central parts of the basins and include 

carbonates and simple to complex salts that may 

be interbedded with silts and clays. The thickness 

of the evaporite and fine-grained sequence in basins 

is as great as 3,000 meters (10,000 feet) (Peirce, 

1981; Smith and others, 1983 ). Although permeability 

of basin-fill deposits varies greatly, basin fill constitutes 

the principal aquifers of the Province, yielding water 

supplies to wells for many uses. 
The consolidated rocks in the Province vary in 

age (Precambrian to Quaternary) and rock types 

(igneous intrusive and extrusive rocks, sedimentary 

carbonate rocks, shale, sandstone, and metamorphic 

schist, gneiss, and phyllite), and commonly have 

relatively little permeability. Permeability in consolidated 

rock commonly is dependent on the presence of 

joints and fractures. Solution along joints and fractures 

has increased the permeability of some carbonate 

rocks. 

Hydraulic head is the single most definitive parameter 

in determining flow within a system and in delineating 

system boundaries. However, the interpretation of 

hydraulic-head distribution needs to recognize the 

three-dimensional aspects of the parameter as affected 

by sources (recharge) and sinks (discharge), fluid-density 

variations, and the permeability of the materials 

comprising the flow system. Interpretation of hydraulic 

head can be aided by the use of generalized models 

of flow showing equipotential and flow lines in 

hypothetical sections (fig. 18). The hypothetical 

sections are drawn through several topographic 

basins and ranges. Recharge occurs in the ranges; 

discharge occurs in the basins. A flow net in a 

system of uniform permeability is depicted in figure 

18A; a flow net in a system with a more permeable 

layer at depth is depicted in figure 18B. 

Conditions that can be identified from these sections 

include: 

1. The vertical component of hydraulic gradient is 

downward beneath areas of recharge; 

2. the vertical component of hydraulic gradient is 

upward beneath areas of discharge; 

3. the vertical component of hydraulic gradient is 

zero in areas of horizontal flow; 

4. ground-water divides on the surface of the zone 

of saturation may or may not extend vertically downward to the base of the flow 

system. The resulting pattern is small, subsidiary flow system at shallow depth, underlain by regional transbasin flow; and 

5. flow at depth, especially in zones of greater permeability (regional flow systems), may extend 

beyond boundaries of shallow, subsidiary 

flow system. Regional flow is less probable 

in areas where less permeable rocks occur 

at depth. 

Although hydraulic head is the most definitive 

parameter in defining flow system, other data were 

used in addition to hydraulic head in defining flow 

systems. These include indirect evidence of recharge 

and discharge of ground water, chemical quality of 

22 

ground water, and data for water-budget components 

of the flow system. 

The Province was divided into ground-water flow 

units based primarily on ground-water level altitude, 

discharge areas, and perennial surface-water features 

(fig. 19 ). The boundaries of ground-water flow units 

were defined on the basis of ground-water divides, 

ground-water flow lines, and surface streams that 

receive ground-water discharge. A ground-water unit 

is defined by the water table in a manner analogous 

to that by which surface-drainage basins are defined 

by the topography. Not all topographic divides are 

coincident with water-table divides; however, where 

water-level data were insufficient to completely define 

the boundaries of the units, ground-water divides 

and the directions of ground-water gradients were 

assumed to be reflected by the surface topography. 

Each ground-water unit receives ground-water recharge 

and contains one or more discharge areas. Because 

ground-water units were defined by water levels in 

relatively shallow wells and other observations of 

surface features, such as the occurrence of springs, 

playas, lakes, and streams, the ground-water units 

reflect relatively shallow flow of ground water beneath 

the water table. The ground-water units do not 

reflect deep, regional flow which may occur beneath 

ground-water units in some areas. Deep, regional 

flow, known or inferred, beneath ground-water unit 

boundaries will be shown in the ground-water unit 

maps for each State that are being prepared. 

Many ground-water studies in the Basin and Range 

Province have provided evidence that ground-water 

flow may occur in deep aquifers between groundwater units. Paleozoic carbonate rocks at depth in 

southern and eastern Nevada and western Utah are 

believed to constitute large regional flow systems. 

The flow system in southern Nevada has been described 

by Winograd and Thordarson ( 1975); the flow system 

in western Utah has been identified by Gates and 

Kruer ( 1981 ). Flow beneath adjacent ground-water 

units also has been inferred by many studies in 

Nevada and Utah based on water-budget calculations. 

Price and Eakin (1974) summarize much of the 

information on interbasin flow of ground water in 

the Great Basin. 

GROUND-WATER QUALITY 

Chemical analyses of ground water were used in 

characterization of the Province to describe the 

spatial distribution of chemical properties of ground 
!'.:) 

Co:~ 

A 

B 

FIGURE lB.-Diagrammatic sections showing lines of equal hydraulic head (solid) and flow lines (solid with arrows). A, hydraulic head and flow lines in an 

isotropic aquifer; B, hydraulic head and flow lines in a two-layered aquifer in which the lower part of the aquifer is 10 times as permeable as upper part 

of the aquifer. 
3so _ 

1 1 LAHONTAN SUBPROVINCE 

08 DEATH VALLEY 

SUBPROVINCE 

07 MOJAVE SUBPROVINCE 

I 

120° 

06 SAL TON TROUGH 

SUBPROVINCE 

115° 

10 BONNEVILLE 

SUBPROVINCE 

09 WHITE RIVER 

SUBPROVINCE 

FIGURE 19 (above and facing page).-Subprovinces and ground-water units. Boundary of the Province is dashed where 

not coincident with a ground-water flow unit boundary. Ground-water units are numbered; the first two digits refer 

to the subprovince; the second two digits are unique for each ground-water unit within the subprovince. Arrows 

indicate the general direction of ground-water flow at the water table; shaded areas outlined by closed dashed 

lines are natural discharge areas; dashed lines are stream reaches that receive ground-water discharge; areas outlined by hachured lines are areas of withdrawal by wells, or, in unit 0104 in Texas, a natural depression in the 

water table (noted by*). 

24 
05 SONORAN DESERT 

SUBPROVINCE 

04 TRANSITION 

SUBPROVINCE 

110° 

water, and as an aid in understanding the chemical 

evolution of the water and the flow systems. 

The water quality in the Basin and Range Province 

is shown in figure 20 as classified by major cations 

and anions and in figure 21 as classified by content 

of dissolved-solid concentration. 

A principal ion (cation or anion) is one which 

exceeds the other ions (cations or anions) by 10 

percent of the total ions expressed in milliequivalents 

per liter. Two or three ions may be principal ions in 

a water in which the milliequivalents per liter of the 

predominant constituents are within 10 percent. 

Waters of Type I, calcium, magnesium, bicarbonate 

waters, commonly have dissolved-solids concentrations 

that are less than 500 mg/L and rarely exceed 1,000 

mg/L. These waters underlie about 30 percent of 

the Province and occur in areas where the geologic 

materials have a greater abundance of calcium and 

magnesium than sodium. Such materials include 

carbonate rocks, mafic and intermediate lava flows, 

extrusive rocks, and silicic intrusive and metamorphic 

rocks that have a significant content of ferromagnesian 

25 

02 RIO GRANDE 

SUBPROVINCE 

I 

105° 

- 35° 

01 TRANS-PECOS 

SUBPROVINCE 

- 30° 

minerals. Hydrologically this type of water occurs 

in the upgradient, recharge parts of the flow systems. 

Waters of Type II are principally sodium bicarbonate 

waters; however, calcium and magnesium may also 

be major cations. The dissolved-solids concentration, 

although as much as 2,000 mg/L, is generally less 

than 1,000 mg/L and commonly less than 500 mg/L. 

Water of Type II underlies about 40 percent of the 

Province and originates from: ( 1) Solution of 

sodium-enriched materials, especially glassy volcanic 

rocks, and also such rocks as granite, syenite, and 

crystalline silicic volcanics; (2) ion exchange, in 

which calcium and magnesium in ground water are 

exchanged for sodium in clays; and (3) increased 

concentration of sodium by precipitation of less 

soluble salts of calcium and magnesium. 

Waters of Type III, sulfate waters, underlie about 

10 percent of the Province. Sulfate waters, commonly 

a calcium sulfate type, originate from solution of 

rocks containing anhydrite and gypsum, as in New 

Mexico east of the Rio Grande and in southern 

Nevada. Sulfate enrichment also may occur by 
D 

• • 

• 

0 100 200 300 400 500 KILOMETERS 

0 100 200 300 MILES 

EXPLANATION 

GROUND-WATER QUALITY TYPES 

Type !---Calcium or magnesium are principal cations; 

bicarbonate is the principal anion. 

Type II--Sodium is a principal cation; bicarbonate 

is the principal anion. 

Type III-Calcium, magnesium, or sodium is a principal 

cation; sulfate is a principal anion; 

chloride is not a principal anion. 

Type IV--Calcium, magnesium, or sodium is a principal 

cation; chloride is a principal anion. 

FIGURE 20.-Groundwater quality types. 

26 
..... 

EXPLANATION 

DISSOLVED-SOLIDS CONCENTRATION, 

IN MILLIGRAMS PER LITER 

c==J Less than 500 

~ili:ilit~i] 500 to 3,000 

1111 Greater than 3,000 

0 100 200 300 400 500 KILOMETERS 

0 100 200 300 MILES 

FIGURE 21.- Dissolved-solids concentration in ground water. 

evaporation. The dissolved-solids concentration of 

these waters generally ranges from 1,500 to 4,000 

mg/L. Water containing significant sulfate occurs 

in some playas where sulfate is concentrated by 

evapotranspiration of ground water. In this environment, 

sodium commonly is increased relative to calcium 

and magnesium by precipitation of the less soluble 

salts of calcium and magnesium. 

Waters of Type IV are chloride waters and underlie 

27 

about 17 percent of the Province. Bicarbonate and 

sulfate also may be present in major concentrations. 

The principal cation commonly is sodium. These 

waters may originate by solution of halite or by 

concentration of the soluble salts by evaporation of 

water and deposition of less soluble salts such as 

calcium and magnesium bicarbonates. Chloride waters 

are common in playas and concentrations of dissolved 

solids range from 1,500 to more than 300,000 mg/L. 
120° 

0 100 200 300 400 500 KILOMETERS 

0 100 200 300 MILES 

FIGURE 22.-Pleistocene lakes (shaded) and marshes (open). 

PLEISTOCENE HYDROLOGIC FEATURES 

Geologic evidence for the existence of approximately 

100 lakes and marshes (fig. 22) indicates that pluvial 

climates existed at times during the Pleistocene 

Epoch. Investigators have presented evidence based 

on orbital variations of the Earth to support the 

theory that climatic conditions similar to those of 

the Pleistocene may recur within the next 10 to 20 

thousand years (Imbrie and Imbrie, 1980 ). A recurrence 

of a pluvial climate would affect the ground-water 

flow system. The climatic change would be accompanied 

28 

by increased recharge, increased ground-water flow, 

regional water-level rises, and adjustments in hydraulic 

gradients to these changes. The most significant 

changes would be the rise in ground-water level at 

the pluvial lakes and in the flow system because of 

the increase in recharge and the shortening of 

ground-water flow paths from the ground-water 

divides to the natural discharge points. ' 

Shorelines of Pleistocene water bodies have been 

identified from geologic evidence. The elevations of 

the Pleistocene lake levels are indicators of the 

elevation of the water table at that time. Few of the 
Pleistocene lake basins are occupied by lakes today. 

However, beneath many of the basins the modern 

water table is within 10 meters ( 30 feet) of the 

surface. The difference between maximum Pleistocene 

lake elevation and the present ground-water level is 

a measure of the possible future change in ground-water 

level at that location during pluvial conditions. 

Several investigators have used data from the Pleistocene 

lake basins to estimate the climate during the time 

of maximum lake elevation (Leopold, 1951; Snyder 

and Langbein, 1962; Mifflin and Wheat, 1979; 

Brakenridge, 1978). Though the analyses differ in 

degree of sophistication and in detail and in estimates 

of magnitudes, the general consensus of the studies 

is that a cooler and wetter climate existed during 

Pleistocene pluvial times. 

REFERENCES CITED 

Aldrich, M. J., and Laughlin, A. W., 1981, Age and location 

of volcanic centers S 3.0 M.Y. old in Arizona, New 

Mexico, and the Trans-Pecos area of West Texas: Los 

Alamos, New Mexico, Los Alamos National Laboratory 

Map LA-8812-MAP, Revised, UC-11, scale 1:1,000,000. 

Algermissen, S. T., Askew, Bonny, Thenhaus, P. C., Perkins, 

D. M., Hanson, S. L., and Bander, B. L., 1983, Seismic 

energy release and hazard estimation in the Basin and 

Range Province: U.S. Geological Survey Open-File 

Report 83-358, 13 p. 

Askew, Bonny, and Algermissen, S. T., 1983, An earthquake catalog for the Basin and Range Province, 1803-

1977: U.S. Geological Survey Open-File Report 83-86, 

21 p. 

Bedinger, M. S., Sargent, K. A., and Brady, B. T., 1983, 

Geologic and hydrologic characterization and evaluation of the Basin and Range Province relative to the 

disposal of high-level radioactive wastes, Part IIIGeologic and hydrologic evaluation: U.S. Geological 

Survey Circular 904-C, 27 p., 1985. 

Bedinger, M. S., Sargent, K. A., and Reed, J. E., 1983, 

Geologic and hydrologic characterization and evaluation of the Basin and Range Province relative to the 

disposal of high-level radioactive wastes, Part IIntroduction and guidelines: U.S. Geological Survey 

Circular 904-A, 16 p., 1984. 

Berry, G. W., Grim, P. J., and Ikelman, J. A., compilers, 

1980, Thermal springs list for the United States: National Oceanic and Atmospheric Administration Key 

to Geophysical Records Documentation no. 12, 59 p. 

Brakenridge, G. R., 1978, Evidence for a cold, dry, fullglacial climate in the American southwest: Quaternary 

Research, v. 9, no. 1, p. 22-40. 

Busby, M. W., 1965, Annual runoff in the conterminous 

United States: U.S. Geological Survey Hydrologic Investigations Atlas HA-212, scale 1:7,500,000. 

Crowe, B. M., and Carr, W. J., 1980, Preliminary assessment of the risk of volcanism at a proposed nuclear 

waste repository in the southern Great Basin: U.S. 

Geological Survey Open-File Report 80-357, 17 p. 

Crowe, Bruce, Self, Stephen, Baniman, David, Amos, Robert, 

29 

and Perry, Frank, 1983, Aspects of potential magmatic 

disruption of a high-level radioactive waste repository 

in southern Nevada: Journal of Geology, v. 91, p. 259-

276. 

Davison, C. C., Keys, W. S., and Paillet, F. L., 1982, Use 

of borehole-geophysical logs and hydrologic tests to 

characterize crystalline rock for nuclear-waste storage, 

Whiteshell nuclear research establishment, Manitoba, 

and Chalk River nuclear laboratory, Ontario, Canada: 

Atomic Energy Canada Limited and U.S. Geological 

Survey, Office of Nuclear Waste Isolation, Battelle 

Memorial Institute, Technical Report, ONWI-418, 

UC-70, 103 p. 

Fenneman, N. M., 1928, Physiographic divisions of the 

United States (3rd ed. ): Association of American Geographers, Annals, v. 18, no. 4, p. 264-353, map. 

Gable, Dolores, and Hatton, Tom, 1980, Vertical crustal 

movements in the conterminous United States over the 

last 10 million years: U.S. Geological Survey Open-File 

Report 80-180, 9 p. 

Gates, J. S., and Kruer, S. A., 1981, Hydrologic reconnaissance of the southern Great Salt Lake Desert and 

summary of the hydrology of west-central Utah: Utah 

Department of Natural Resources Technical Publication 

71, 55 p. 

Imbrie, John, and Imbrie, J. Z., 1980, Modeling the climatic 

response to orbital variations: Science, v. 207, p. 943-

953. 

Keys, W. S., and Sullivan, J. K., 1979, Role of borehole 

geophysics in defining the physical characteristics of 

the Raft River geothermal reservoir, Idaho: Geophysics, 

v. 44, no. 6,p. 1116-1141. 

Leopold, L. B., 1951, Pleistocene climate in New Mexico: 

American Journal of Science, v. 249, no. 2, p. 152-168. 

Luedke, R. G., and Smith, R. L., 1978a, Map showing 

distribution, composition, and age of late Cenozoic 

volcanic centers in Arizona and New Mexico: U.S. 

Geological Survey Miscellaneous Investigations Series 

Map 1-1091-A, scale 1:1,000,000, 2 sheets. 

---1978b, Map showing distribution, composition, and 

age of late Cenozoic volcanic centers in Colorado, 

Utah, and southwestern Wyoming: U.S. Geological 

Survey Miscellaneous Investigations Series Map 

1-1091-B, scale 1:1,000,000. 

---1981, Map showing distribution, composition, and 

age of late Cenozoic volcanic centers in California, 

and Nevada: U.S. Geological Survey Miscellaneous 

Investigations Series Map 1-1091-C, scale 1:1,000,000. 

---1982, Map showing distribution, composition, and 

age of late Cenozoic volcanic centers in Oregon, and 

Washington: U.S. Geological Survey Miscellaneous 

Investigations Series Map 1-1091-D, scale 1:1,000,000. 

Mifflin, M. D., and Wheat, M. M., 1979, Pluvial lakes and 

estimated pluvial climates of Nevada: Nevada Bureau 

of Mines and Geology Bulletin 94, 57 p. 

Muffler, L. J. P., ed., 1979, Assessment of geothermal resources of the United States-1978: U.S. Geological 

Survey Circular 790, 163 p. 

Nakata, J. K., Wentworth, C. M., and Machette, M. N., 

1982, Quaternary fault map of the Basin and Range 

and Rio Grande rift provinces, western United States: 

U.S. Geological Survey Open-File Report 82-579, scale 

1:2,500,000, 2 sheets. 
Peirce, H. W., 1981, Major Arizona salt deposits: Arizona 

Bureau of Geology and Mineral Technology, Fieldnotes, 

v. 11, no. 4, p. 1-4. 

Price, Don, and Eakin, T. E., 1974, Water in the Great 

Basin region, Idaho, Nevada, Utah, and Wyoming: 

U.S. Geological Survey Hydrological Investigations 

Atlas HA-487, scale 1:2,000,000. 

Roseboom, E. H., Jr., 1983, Disposal of high-level nuclear 

waste above the water table in arid regions: U.S. Geological Survey Circular 903, 21 p. 

Sass, J. H., Diment, W. H., Lachenbruch, A. H., Marshall, 

B. V., Monroe, R. J., Moses, T. H., Jr., and Urban, 

T. C., 1976, A new heat-flow contour map of the conterminous United States: U.S. Geological Survey OpenFile Report 76-756, 24 p. 

Seeburger, D. A., and Zoback, M. D., 1982, The distribution 

of natural fractures and joints at depth in crystalline 

rock: Journal of Geophysical Research, v. 87, no. B7, 

p. 5517-5534. 

Simpson, H. E., Weir, J. W., Jr., and Woodward, L. A., 

1979, Inventory of clay-rich bedrock and metamorphic 

derivations in eastern Nevada, excluding the Nevada 

Test Site: U.S. Geological Survey Open-File Report 

79-760, 147 p. 

Smith, G. I., Barczak, V. J., Moulton, G. F., and Liddicoat, 

J. C., 1983, Core KM-3, a surface-to-bedrock record of 

Late Cenozoic sedimentation in Searles Valley, California: U.S. Geological Survey Professional Paper 

1256, 24 p. 

Snow, D. T., 1968a, Hydraulic character of fractured metamorphic rocks of the Front Range and implications 

to the Rocky Mountain Arsenal well: Golden, Colorado, 

Colorado School of Mines Quarterly, v. 63, no. 1, p. 

167-199. 

---1968b, Rock fracture spacings, openings, and porosities: Journal of Soil Mechanics and Foundations Division, Proceedings of the American Society of Civil 

Engineers, v. 94, no. SM1, p. 73-91. 

30 

Snyder, C. T., and Langbein, W. B., 1962, Pleistocene lake 

in Spring Valley, Nevada, and its climatic implications: 

Journal of Geophysical Research, v. 67, no. 6, p. 2385-

2394. 

Stauber, D. A., 1983, Crustal structure of north central 

Nevada from seismic refraction, gravity and surface 

wave data, in The role of heat in the development of 

energy and mineral resources in the northern Basin and 

Range Province: Program with Abstracts, Geothermal 

Resources Council, May 1983, Reno, Nevada, p. 26. 

Thordarson, William, 1965, Perched ground water in zeolitizedbedded tuff, Rainier area and vicinity, Nevada Test 

Site, Nevada: U.S. Geological Survey TEI-862, 90 p. 

Trask, N.J., 1982, Performance assessments for radioactive 

waste repositories-The rate of movement of faults: 

U.S. Geological Survey Open-File Report 82-972, 11 p. 

U.S. Department of Commerce, 1968, Weather atlas of the 

United States: Detroit, Michigan, Gale Research Company, 262 p. 

---1982, Evaporation atlas for the contiguous 48 United 

States: National Oceanic and Atmospheric Administration, Technical Report NWS 33, 26 p. 

Winograd, I. J., 1974, Radioactive waste storage in the 

arid zone: Transactions, American Geophysical Union, 

v. 55, no. 10,p. 884-894. 

---1981, Radioactive waste disposal in thick unsaturated 

zones: Science, v. 212, no. 4502, p. 1457-1464. 

Winograd, I. J., and Doty, G. C., 1980, Paleohydrology of 

the southern Great Basin, with special reference to 

water table fluctuations beneath the Nevada Test Site 

during the Late(?) Pleistocene: U.S. Geological Survey 

Open-File Report 80-569, 91 p. 

Winograd, I. J., and Thordarson, William, 1975, Hydrogeologic and hydrochemical framework, south-central 

Great Basin, Nevada-California, with special reference 

to the Nevada Test Site: U.S. Geological Survey Professional Paper 712-C, 126 p. 

' 

1:r U.S. GOVERNMENT PRINTING OFFICE: 1985--576-049/20,021 REGION NO.8