70 University Geological Survey of Kansas. 
covered. Owing to its solubility as erosion wears away the 
surface in most cases the gypsum would dissolve a little more 
rapidly than erosion would remove the covering, so that it 
would be found beneath the surface covering of soil and other 
refuse matter produced by erosion. 
Medicine Lodge Deposits. 
The gypsum of the Medicine Lodge area is entirely rock gyp- 
sum, is white in color, and in the lower portion of the stratum 
it is very compact. This portion is used at the Medicine Lodge 
mill for the manufacture of terra alba. The upper portion has 
more of the sugary texture, and is used in the manufacture of 
wall plaster. The satin spar which is found throughout the 
Red Beds below the gypsum is in the form of wavy plates, with 
perpendicular needles, and variable in character. Some of it is 
soft, and readily crumbles, while other portions are compact 
and glassy in appearnce. 
EXTENT OF THE AREA. 
This southern gypsum area is the largest in Kansas, and, with 
its continuation in Oklahoma and Texas, forms the largest gyp- 
sui area in the United States. Therock extends from near the 
town of Medicine Lodge westward through Barber and into 
Comanche county, southward into Oklahoma and Texas, and — 
passes under the Tertiary gravels to the north. The trend of 
the outcroppings of the deposit is the characteristic one of the 
state, northeast to southwest. 
The gypsum is first seen six miles southwest of Medicine 
Lodge, in an isolated range of hills three miles long and sepa- 
rated by a narrow valley from a second hill one mile in length. 
The valleys of East and West Cedar creeks, two miles wide, 
separate these hills from the next series, in which the gypsum 
plateau is continuous to the west. Medicine Lodge river cuts 
the gypsum in a valley six or seven miles wide. The northern 
limit of the gypsum cannot be determined, for it is covered 
with Tertiary deposits. Salt Fork and Sandy creeks cut out 
broad valleys to the south, and the streams in the eastern por- 
tion of Comanche county have removed much of the stratum ; 
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