8 We 2. JENNY 
The investigations were based on the measurements made by the 
surveys of the respective European states, and by the United States 
Coast and Geodetic Survey.! 
Though by these studies a definite connection between broad 
structural features—such as the West Texas Permian basins, the 
Central Mineral region, the main geological trends in California and 
Europe—and magnetic anomalies of the vertical intensity could be 
definitely established, such studies could only incidentally yield any 
information about the type of structure which is of special interest 
SCHEMATIC CROSS SECTION THROUGH TWO ANTICLINES 
SHOWING MACNETIC LINES OF FORCE AND LOCAL MACNETIC VECTORS 
ROCK OF LESS THAN AVERAGE vv 
MAGNETIC PERMEABILITY 257 4 POSITIVE VECTOR 
T TOTAL LOCAL VECTOR NEGATIVE VECTOR 
ROCK OF MORE THAN AVERACE H HORIZONTAL VECTOR 
MACNETIC PERMEABILITY GOAVERTICADMINECTOR NEUTRAL VECTOR 
MAGNETIC LINES OF FORCE NECATIVE POLE POSITIVE POLE 

FIc. 1 
to the commercial geologist, because the distances between the mag- 
netic stations, ranging from 20 to 50 miles, were far too large. 
It is quite evident that two, three, and more magnetic “highs” and 
“‘lows’”’ may occur between stations placed at such distances and the 
lines of equal magnetic intensity, drawn on the base of such stations, 
as a rule veil, rather than set forth, the local magnetic anomalies 
which are due to small “structures.” 
Study of Figure 1 will make the previous statement clear. This 
cross section through two anticlines separated by a syncline demon- 
strates schematically the paths of the magnetic lines of force and the 
1 “United States Magnetic Tables and Magnetic Charts for 1925 by U. S. Depart- 
ment of Commerce,” U.S. Coast and Geodetic Survey Serial 453. 
336 
