MAGNETIC VECTOR STUDY IN OIL STATES 23 
But, though in central and western Kansas magnetic “‘lows” seem 
actually to correspond in some places with structura] ‘“‘highs,” the 
vector map seems to be in favor of the assumption that in the eastern 
part of the state magnetic “lows” correspond with structural “lows,” 
and magnetic “highs” with structural “‘highs.”’ 
The axis of the Nemaha ridge lies slightly east of Seneca, 5 miles 
west of Alma and Council Grove, slightly west of Cottonwood Falls 
and Eldorado, and between Winfield and Wellington. The ridge 
has a very steep eastern flank but slopes much more gently toward 
the west. Thus, the center of mass of the ridge lies considerably west 
of the structural axis, which would explain a corresponding shift of 
the magnetic axis. 
We think that the axis of the ridge is indicated by the positive vec- 
tors at Seneca, Council Grove, and Winfield-Wellington, and by the 
negative vectors at Alma and Eldorado, both of which point toward 
the west, so that the magnetic lines of force, emerging at Alma and 
Eldorado, may enter the positive ridge a few miles west of the sta- 
tions. 
Drilling has revealed a structural low trend along the east flank of 
the ridge and another extended “‘low,”’ with a west-east axis, between 
Eureka-Emporia and Yates Center-Burlington. The first trend is indi- 
cated magnetically by the negative vectors at Hiawatha, Holton, 
Alma, and Eldorado. In the second trend, it is clear that the negative 
vectors at Eureka, Yates Center, Iola, Burlington, Cottonwood 
Falls, and the positive vector at Emporia may all be assumed to 
emerge from the same magnetic “low.” 
We have pointed out already that in central and western Kansas 
both magnetic “lows” and “‘highs’”’ may correspond with structural 
“highs.” 
The large and irregular vectors should yield considerable informa- 
tion, if the vector map is combined with magnetometer surveys and 
detail geologic maps. 
MISSISSIPPI" 
Many of the magnetic horizontal components of the vectors in the 
northern half of Mississippi have a northeast or a southwest direction, 
which may indicate a general northwest-southeasterly trend of the 
deeper ‘‘structure.”” We might suspect two magnetic high trends: (1) 
Butler-Philadelphia-K osciusko-Greenwood-Rosedale on the south and 
1 The local magnetic vectors are based on the information given in “United States 
Magnetic Tables and Magnetic Charts for 1925,” op. cit. 
351 
