-12

-10

 -8

 -6

 -4

 -2

 0

 2

 4

 6

 8

 10

 12

 14

 16

 18

 20

 22

 24

 26

Magnetic Field, 

in nanoteslas

Contact between Yager and Coastal terranes from 

Bachman and others (1984)

Coastal Belt Thrust (or contact between Coastal and 

Central Belt terranes) from Bachman and others (1984), 

Wagner and Bortugno (1982), Jayko and others 

(1989), and McLaughlin and others (2000)

Quaternary fault from Jennings and Bryant (2010)

Contact between Yager and Coastal terranes from 

Jayko and others (1989) and McLaughlin and others 

(2000)

Yager terrane conglomerate from McLaughlin and 

others (2000)

Contours of residual, reduced-to-pole 

magnetic field intensity. Contour interval is 2 

nanoteslas. Hachures indicate closed magnetic 

lows. Contours were computer generated 

based on a 200-m grid

Greenstone, basalt, or metavolcanic rock 

from Blake and others (2002), McLaughlin and

others, 2000, Jayko and others (1989), Wagner and 

Bortugno (1982), Kleist (1974), Kramer (1976) and 

Jennings and Strand (1960)

Ultramafic rock or serpentinite from Blake and 

others (2002), Jayko and others (1989), Wagner 

and Bortugno (1982), Kleist (1974), Kramer (1976)

 and Jennings and Strand (1960)

Magnetic susceptibility measurement indicating 

weakly magnetic clastic rock

Magnetic susceptibility measurement indicating 

magnetic clastic rock

Magnetic susceptibility measurement of volcanic V rock

V

V

V

V

V

V

Residual, Reduced-to-pole Aeromagnetic Map of the Northern Coast Ranges, California

King

Range

terrane

124°22'30" 15' 124° 52'30" 45' 37'30" 30' 22'30" 15' 7'30" 123° 122°52'30"

U.S. Department of the Interior

U.S. Geological Survey Scientific Investigations Map 3188

Sheet 2 of 3

Pamphlet accompanies map

1 0 1 2 43 5 6 7 8 9 10 KILOMETERS

SCALE 1:100 000

1 0 1 2 3 4 5 6 7 8 MILES

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not 

imply endorsement by the U.S. Government

This map was printed on an electronic plotter directly from digital files. Dimensional calibration may vary 

between electronic plotters and between X and Y directions on the same plotter, and paper may change 

size due to atmospheric conditions; therefore, scale and proportions may not be true on plots of this map.

For sale by U.S. Geological Survey, Information Services, Box 25286, Federal Center, Denver, CO 80225, 

1–888–ASK–USGS

Digital files available at http://pubs.usgs.gov/sim/3188/

Suggested Citation: Langenheim, V.E., Jachens, R.C., Wentworth, C.M., and McLaughlin, R.J., 2011, 

Aeromagnetic and aeromagnetic-based geologic maps of the Coastal Belt, Franciscan Complex, 

northern California: U.S. Geological Survey Scientific Investigations Map 3188, pamphlet 20 p., 3 sheets, 

various scales, and database, available at http://pubs.usgs.gov/sim/3188/.

Data compiled by Victoria E. Langenheim

GIS database and digital cartography by 

Victoria E. Langenheim

Edited by Theresa Iki; digital cartographic 

production by K. Nimz

Manuscript approved for publication 

October 28, 2011

CALIF.

MAP LOCATION

Aeromagnetic and Aeromagnetic-based Geologic Maps of the 

Coastal Belt, Franciscan Complex, Northern California

By

V.E. Langenheim, R.C. Jachens, C.M. Wentworth, and R.J. McLaughlin

2011

San Andreas Fault

MAACAMA FAULT

BARTLETT SPRINGS FAULT

SAN ANDREAS FAULT

Point

Arena

Shelter

Cove

Ukiah

Willits

Lake

Pillsbury

Clear

Lake

Point

Delgada

Cape

Mendocino

Mendocino

Fort

Bragg

Petrolia

Fortuna

Elk

Boonville

Cloverdale

Healdsburg

Bodega Bay

Covelo

Laytonville

Garberville

east-west 

flightline

artifacts?

northeast-southwest

flightline

artifacts?

PACIFIC OCEAN

Fort Ross

124°22'30" 15' 7'30" 124° 52'30" 45' 37'30" 30' 22'30" 15' 7'30" 123° 122°52'30"

7'30"

38°22'30"

30'

37'30"

45'

52'30"

39°

7'30"

15'

22'30"

30'

37'30"

45'

52'30"

40°

7'30"

15'

22'30"

40°30'

38°22'30"

30'

37'30"

52'30"

39°

7'30"

22'30"

30'

37'30"

45'

52'30"

40°

7'30"

15'

22'30"

40°30'

45'

15'