SOME RESULTS OF MAGNETOMETER SURVEYS 
IN CALIFORNIA! 
EDWARD D. LYNTON? 
Los Angeles, California 
ABSTRACT 
The writer describes magnetic conditions associated with some typical structural 
features in California,—an anticline, a syncline, an outstanding magnetic feature in 
the San Joaquin Valley, a buried fault near Mount Diablo, a part of Ventura County, 
and Kettleman Hills. 
INTRODUCTION 
Magnetometer work was begun in California by the Standard Oil 
Company of California on January 1, 1927. Acknowledgment is here 
made to officials of the company for permission to publish, to H. N. 
Herrick of the Research and Development Department of the company 
for his assistance and criticism in the preparation of this paper, and to 
all members of the geophysical field parties in California. 
General conditions for use of magnetic geophysical methods in 
California are good, as there is marked variation in the magnetic suscep- 
tibility of the sedimentary rocks of economic interest. In the Tertiary 
rocks, the magnetic susceptibility varies from 14 X 10° in the Saugus of 
the Upper Pliocene to 4,120 X 10° in the vivianitic sandstone of the 
McKittrick group of the Pliocene. This variation is sufficient to give 
a definite magnetic contrast at several horizons. ‘‘ Magnetic marker 
beds,” such as this vivianitic sandstone, beds of volcanic tuff and inter- 
bedded basaltic flows, extending thoughout considerable areas, have been 
found, which are sufficiently thick and magnetic to cause anomalies of 
several hundred gammas at surface exposures and recognizable indica- 
tions under deep cover. 
The Cretaceous rocks, especially the Knoxville, on the average, are 
somewhat more uniformly and strongly magnetic than the Tertiary. 
The Jurassic (Franciscan) is much more magnetic than either the Ter- 
tRead before the Association at the San Antonio meeting, March 21, 1931. Man- 
uscript received, February 19, 1931. Published by permission of the Standard Oil 
Company of California. 
Petroleum geologist, Standard Oil Company of California. 
1351 
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