MAGNETIC VECTOR STUDY OF REGIONAL AND 
LOCAL GEOLOGIC STRUCTURE IN 
PRINCIPAL OIL STATES! 
W. P. JENNY? 
Dallas, Texas 
ABSTRACT 
The local magnetic vectors at the United States Coast and Geodetic Survey stations 
in Louisiana, Texas, Arkansas, Oklahoma, Kansas, Mississippi, Alabama, and Cali- 
fornia have been computed by deducting the normal values of the earth’s magnetic 
field from the absolute measurements, at each station, of the declination and of the 
vertical and horizontal magnetic intensities. 
The local magnetic vectors have been plotted as vector triangles at the respective 
stations on the vector maps of the different states. 
These vectors indicate the intensity and the direction in space of the magnetic 
lines of force, as due to local magnetic anomalies mainly within the first 15,000 feet of 
subsurface. 
As local magnetic anomalies are, with negligible exceptions, the result of geologic. 
features, either of structural or petrographic character, a large amount of regional 
and local geologic information is obtained by a study of these maps. 
The main magnetic anomalies of the different states have been interpreted in 
terms of geology, though no attempt has been made to exhaustively interpret all 
vectors. 
The vector maps show at a glance which areas are of interest for magnetometer 
surveys, what size anomalies may be expected, how far a magnetometer survey Has to 
be extended, or where it is best commezced to cover a certain area. 
As the vectors are of sufficient accuracy, they allow a checking and tying-in of 
scattered magnetometer surveys. 
INTRODUCTION 
Extensive studies of the anomalies of the magnetic vertical in- 
tensity and their correlation with geology were made some years ago 
in Europe,’ in the Mid-Continent and Gulf Coast areas* and in 
California.® 
1 Read in part before the Association at the Oklahoma City meeting, March 25, 
1932. Manuscript received, May 18, 1932. 
2 Geologist and geophysicist, 6241 Richmond Avenue. 
8 A. Nippoldt, ‘Karten der Verteilung des Erdmagnetismus und seiner oertlichen 
vertikalen Stoerungen in Europa,” Arcksv des Evdmagnetismus, Heft 6 (Julius Springer, 
Berlin, 1927). 
4 Magnetometer survey of seven states in the Mid-Continent and Gulf Coast 
peer by L. Spraragen, series of articles published in the Oil and Gas Journal (1928- 
29). 
5 G. B. Somers, “Anomalies of Vertical Intensity Compared with Regional Geology 
for the State of California,”’ Colorado School of Mines Magazine (September, 1929). 
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