MAGNETOMETER SURVEYS IN CALIFORNIA 1355 
This is probably the best method of showing actual results, and is 
undoubtedly the best when it is desirable to show the regional trend of 
folding. During the last few years all the results of our work have been 
reported in the form of contour maps, as they can be readily extended 
from area to area throughout large expanses of country and placed ona 
regional map with some very interesting results. 
RESULTS OF MAGNETOMETER SURVEYS IN CALIFORNIA 
It would be impossible to publish the results of all the magnetometer 
surveys we have made in California during the last four years; therefore, 
only a few of them are offered here. They are chosen because the results 
are type pictures of known geological conditions, such as the Raven Pass 
anticline and the White Creek svncline, and the others submitted show 
the interpretation of magnetometer surveys as carried from known geo- 
logical features to the unknown. 
The following work on known structures was done to test the ver- 
tical and horizontal magnetometers so as to use the resulting data in 
interpreting future results in areas covered by alluvial deposits. 
RAVEN PASS ANTICLINE 
This anticline trends almost N. 45° W. for a considerable distance, 
but the location chosen for the magnetometer survey was at the junction 
of Sections 29, 30, and 31, T. 26S., R. 18 E. (Fig. 2). 
The oldest beds exposed along the axis are the Cretaceous, with the 
younger Vaqueros and Monterey shale resting unconformably on both 
flanks. The anticline is apparently symmetrical, the dips ranging from 
40° to 50° on both flanks. From surface observations there does not 
seem to be any faulting in the Cretaceous. As previously mentioned, the 
Cretaceous is strongly magnetic and the Miocene shales weakly mag- 
netic. Therefore, an anticline in these contrasting formations should 
give a type picture of the behavior of the vertical intensities and the 
vectors of disturbance. 
Results—Both the vertical intensities and the magnetic vectors of 
disturbance were plotted. The vertical intensity curve rose from an 
intensity of 15 gammas over the Monterey shale on the extreme north- 
east end of the line to 110 gammas at the axis. From the axis south- 
westward, the intensity curve fell to 50 gammas over the Monterey 
shale. A short distance southwest of the axis, the vertical intensity 
curve gave a sharp “kick” to a maximum of 125 gammas, which strongly 
suggested a small fault. As stated before, no fault could be traced on 
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