20 W. P. JENNY 
magnetic conditions exist in the region of the nappes of the European 
Alps. 
Arkansas Valley and Ozark Mountain regions.—The magnetically 
positive zones of the Arkansas Valley and Ozark Mountain regions 
are separated by a negative zone extending from Fayetteville tc 
Marshall. 
OKLAHOMA! 
Eastern Oklahoma.—In eastern Oklahoma is to be observed the 
same arrangement of the magnetic anomalies as in western Arkansas; 
that is, the positive vector at Miami is indicative of the Ozark Moun- 
tains, the negative vectors near Westville are indicative of the mag- 
netic “low” between the Ozark uplift and the Arkansas Valley, which 
latter “‘structure’’ is represented by the positive vectors at Sallisaw, 
Muskogee, Stigler, and Poteau. 
The few stations in the general area of the Ouachita Mountains 
seem to confirm the interpretation given for the magnetic anomaly 
in the Ouachita region of Arkansas. 
On the basis of the west-east direction of the horizontal magnetic 
components, it seems possible to follow a positive magnetic trend 
from Nowata to Pryor and a second trend from Bartlesville through 
Tulsa, Sapulpa, and Okemah to Holdenville, along which trends lie 
the main oil ‘‘structures”’ of northern Oklahoma. 
Arbuckle Mountains ——The Arbuckle Mountains are indicated by 
a strong positive vector at Tishomingo. The positive vector at Durant 
might indicate the axis of the Arbuckle Mountains as extending south- 
east and northwest. 
Wichita Mountains —The Wichita Mountains lie along a magnetic 
high trend beginning at Marietta and passing north of Waurika, 
Walters, and Hobart to Sayre. The oil fields of southern Oklahoma 
lie along this line. 
A magnetic high trend is indicated between Sulphur and Okla- 
homa City. 
Another high trend lies east of Rush Springs, Chickasha, and 
Minco. 
Another possible high trend lies between Alva and Carmen, be- 
tween Trail and Taloga, and east of Hammon. 
The southern extension of the Nemaha mountains might be indi- 
cated by the positive vectors at Medford, Pond Creek, and Enid. 
1 The local magnetic vectors are based on the information given in “‘United States 
Magnetic Tables and Magnetic Charts for 1925,’ op. cit. 
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