-10.0

 -7.5

 -5.0

 -2.5

 0.0

 2.5

 5.0

 7.5

 10.0

 12.5

 15.0

 17.5

 20.0

 22.5

 25.0

mGal

F'

F

SPRING

MTNS

FM

GP

LM

BD

G

G'

0 5 10 15 20 25 KILOMETERS

36°15'

36°30'

36°00'

116°00' 115°45' 115°30' 115°15' 115°00'

Figure 7. Basement gravity with 

aeromagnetic contours in red. Aero

contour interval 20 nT. BD, Blue D

Gass Peak; FM, Frenchman Mount

Lone Mountain. Cross sections F–F

are shown in figures 8 and 9 in the 



4.2

3.9

3.6

3.3

3.0

2.7

2.4

2.1

1.8

1.5

1.2

0.9

0.6

0.3

 0.0

KILOMETERS

LAS VEGAS 30' x 60'

QUADRANGLE BORDER

E

E'

PreCz

PreCz

State Line

fault zone

SPRING

MTNS

116°07'30" 116°00' 115°52'30" 115°45' 115°37'30"

36°22'30"

36°15'

36°07'30"

36°00'

35°52'30"

0 5 10 15 20 25 KILOMETERS

Figure 6B. Basin thickness of Pahrump 

Valley (from Blakely and others, 1998). Gray 

areas are non-basin areas. PreCz, Pre-Cenozoic 

rocks; white lines, lineaments and faults from

Hoffard (1991). The absence of faults south of 

36° reflects lack of detailed mapping. Cross 

section E–E' is shown in figure 9 in the 

pamphlet.

D

D'

CC

Tv

PreCz

PreCz

GP

SPRING

MTNS

EG

F

F'

LV-4

115°30' 115°22'30" 115°15' 115°07'30" 115°00'

36°30'

36°22'30"

36°15'

36°07'30"

0 5 10 15 20 25 KILOMETERS

4.2

3.9

3.6

3.3

3.0

2.7

2.4

2.1

1.8

1.5

1.2

0.9

0.6

0.3

 0.0

KILOMETERS

Figure 6A. Basin thickness of Las Vegas Valley. 

Gray areas are non-basin areas. CC, Corn Creek 

Springs; EG, Eglington scarp; GP, Gass Peak. Tv, 

Tertiary volcanic rocks; PreCz, Pre-Cenozoic 

rocks. Solid white lines with black border, 

Quaternary fault scarps from Bell (1981); solid 

black circles, wells that penetrated basement; red 

circles, seismic picks on basement; white circles, 

minimum thickness of Cenozoic deposits from 

wells. Blue line is seismic-reflection profile LV-4. 

Dashed white lines are strands of the LVVSZ 

cutting across the valley, as inferred from the 

gravity data. Cross sections D–D' and F–F' are 

shown in figures 8 and 9 in the pamphlet.

116°00' 115°45' 115°30' 115°15' 115°00'

36°30'

36°15'

36°00'

0 10 20 KILOMETERS

nT

10

9

8

7

6

5

4

3

2

1

0

-1

-2

-3

-4

-5

-6

-7

-8

-9

FM

GP

BD

SPRING

MOUNTAINS

E

E'

D

D'

F

F'

CALIFORNIA NEVADA

Figure 5. Residual aeromagnetic map of the 

Las Vegas 30' × 60' quadrangle, Nevada and 

California. Blue lines enclose areas of preCenozoic rocks; black line with hachures encloses 

area of Tertiary volcanic rocks; black lines are 

faults from Bell (1981) and Hoffard (1991); red 

lines with balls show location of the Las Vegas 

Valley shear zone as inferred from gravity data. 

BD, Blue Diamond; FM, Frenchman Mountain; 

GP, Gass Peak. Cross sections D–D', E–E', and 

F–F' are shown in figures 8 and 9 in the 

pamphlet.

E

E'

F

F'

D

36°22'30"

36°30'

116°00'

36°15'

36°07'30"

116°00'

36°00'

115°52'30" 115°45' 115°37'30" 115°30' 115°22'30" 115°15' 115°07'30" 

115 

115°30' 115°22'30" 115°15' °07'30" 115°52'30" 115°45' 115°37'30"

MAP C. AEROMAGNETIC MAP

By

V.E. Langenheim, R.J. Blakely, W.R. Page, S.C. Lundstrom, G.L. Dixon, and R.C. Jachens

1 012 4 3 56789 10 KILOMETERS

SCALE 1:100 000

1 0 234567 1 8 MILES

E

E'

F

F'

D

MAP B. ISOSTATIC GRAVITY MAP

By

V.E. Langenheim, R.J. Blakely, S.C. Lundstrom, W.R. Page, G.L. Dixon, and R.C. Jachens New gravity station (U.S. Geological Survey, 1980s to 1998;

 Langenheim and others, 1999)

Old gravity station (data from Defense Mapping Agency

 and Kane and others, 1979)

Gravity anomaly contours—Contour interval

 2 mGal. Hachures point toward areas of lower

 gravity. Contours were computer-generated 

 based on a 300-m grid. Although the data 

 have been edited, caution should be exercised 

 when interpreting anomalies controlled by only 

 a single gravity station 

EXPLANATION

Cross section—Cross sections D–D', E–E',

 and F–F' are shown in figures 8 and 9 in

 the pamphlet

[See chapter B in accompanying pamphlet for more information about data acquisition and processing.

See Map A for explanation of geologic base. Names of U.S. Geological Survey 7.5' topographic 

quadrangles are also shown on this map.]

36°22'30"

36°30'

116°00'

36°15'

36°07'30"

116°00'

36°00'

115°52'30" 115°45' 115°37'30" 115°30' 115°22'30" 115°15' 115°07'30" 

115 

115°30' 115°22'30" 115°15' °07'30" 115°52'30" 115°45' 115°37'30"

EXPLANATION

Contours of total magnetic intensity relative to the International Geomagnetic

 Reference Field—Contour interval 20 nT. Hachures point toward areas of lower

 magnetic intensity. Solid red circles indicate possible locations of boundaries between 

 regions of different magnetizations. Circles are scaled to the magnitude of the 

 horizontal gradient. Larger circles indicate larger lateral changes

[See chapter B in accompanying pamphlet for more information about data acquisition and processing.

See Map A for explanation of geologic base. Names of U.S. Geological Survey 7.5' topographic 

quadrangles are also shown on this map.]

Cross section—Cross sections D–D', E–E', and F–F' are shown in figures 8 and 9 in

 the pamphlet

Prepared in cooperation with the

SOUTHERN NEVADA WATER AUTHORITY

U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

SCIENTIFIC INVESTIGATIONS MAP 

Pamphlet accompanie

SHEET 2 

GEOLOGIC AND GEOPHYSICAL MAPS OF THE LAS VEGAS 30' × 60' QUADRANGLE, CLARK AND NYE COUNTIES, NEVADA, AND INYO COUNTY, CALIFORNIA

By

William R. Page,1

 Scott C. Lundstrom,1 Anita G. Harris,1 Victoria E. Langenheim,2 Jeremiah B. Workman,1 Shannon A. Mahan,1

James B. Paces,1 Gary L. Dixon,3 Peter D. Rowley,4 B.C. Burchfiel,5 John W. Bell,6 and Eugene I. Smith7

2005 Pr

1

U.S. Geological Survey, Denver, CO

2

U.S. Geological Survey, Menlo Park, CA

3

Southwest Geology, Inc., Blackfoot, ID

4

Geologic Mapping, Inc., New Harmony, UT

5

Massachussetts Institute of Technology, Cambridge, MA

6

Nevada Bureau of Mines and Geology, Reno, NV

7

University of Nevada, Las Vegas, NV