44 riie American Geologist. July, i«i9 
GEOLOGIC NOTES ON THE WICHITA MOUNTAINS, 
OKLAHOIVIA, AND THE ARBUCKLE HILLS, 
INDIAN TERRITORY,* 
By T. Wavland Valghan. Wasliiiiyton, I). C. 
Containing a Report Upon Igneous Rocks, by Dr. A. C. Spencer. 
The notes here published were accumulated during a re- 
connoissance, made in the fall of 1896, under instructions 
received from Mr. Robert T. Hill. 
The Wichit.\ Mountains. 
Probably there is no other area in the United States of so 
much geologic interest that has been less studied than the 
Wichita mountains. The first explorations were made in con- 
nection with Marcy's Red River expedition. Both Capt. Marcy 
and Dr. G. G. Shumard published general descriptions of the 
mountains in their itinerary, and Prof. Edward Hitchcock 
furnished for the report some notes on the rocks collected. 
The following description f of the mountains may be quoted 
with propriety: 
Thus far about twelve of the Wichita mountains have been exam- 
ined, and have been found to present nearly uniform appearance and 
structure. Composed of fine granite of various degrees of hardness 
and color, they rise abruptly from a smooth and nearly level plain to 
the height of eight or nine hundred feet.. Many of them are isolated 
and of an irregular conical shape, while others are grouped together 
in small clusters, and are more or less rounded. At a distance they 
appeared to be smooth, but upon a nearer approach their surfaces 
were found to be quite rough, and presenting the appearancec of loose 
rocks thrown confusedly together. In many places the granite was 
observed occupying its original position, and was variously traversed 
by joints and master-joints, which, intersecting each other at right an- 
gles, gave to the mass somewhat of a cuboidal structure. Soil rich, and 
from three to four feet thick; sub-soil argillaceous and of a red color. 
Areas of "basalt," "greenstone" and "porphyry" are noted, 
also the occurrence of quartz veins. On page 146 of the report 
Prof. Hitchcock mentions "a great predominance of feldspar, 
and the almost total absence of mica" in the granite. 
Dr. T. B. Comstock made a brief reconnoissance of the 
Wichita mountains in connection with his work on the Texas 
♦Published by permission of the Director of the U. S. Geological 
Survey. 
IMarcy's Exploration of Red River, p. 163, 1854. 
