72 University Geological Survey of Kansas. 
depending upon the amount of erosion. Forty feet below the 
gypsum is a green gypseous sandstone 25 feet thick, which 
stands out as a prominent ledge through the hills. The red 
clays and shales below the gypsum contain an interlacing net- 
work of selenite and satin-spar layers of variable thickness. 
This material has been dissolved out of the solid stratum and 
carried downward through the agency of circulating water and 
redeposited. 
At the town of Medicine Lodge is located the gypsum mill 
shown in Plate XXV, operated by Best Brothers, and built in 
1889. The lower story of the mill is constructed of stone, but 
the upper is aframe structure. At the side of the mill isa Krantz 
patent kiln, 8 feet in diameter and 17 feet high, in which 
the rock is calcined again, forming a very hard and durable ce- 
ment known as Keene’s (or Robinson’s) cement. 
Another gypsum mill was built near Sun City, but it has not 
been in operation for a year or more. 
SOLUTION EFFECTS. 
In the western part of Barber and the eastern part of Coman- 
che counties the solvent effects of water on the gypsum are well 
shown, for here are found natural bridges and underground water 
courses. On Cave creek, four miles west of Evansville, is the 
Big Gypsum cave in the Medicine Lodge gypsum. A stream of 
considerable size flows into the west entrance and out of the east 
one, making the cave, in reality, an underground water course. 
The length of the cave is at least 100 feet, with a roof at the east 
entrance 15 feet above the water level, but which soon narrows 
down toa height of 3 feet. The floor is strewn with large slabs 
of white gypsum. At the center is an opening through the roof 
to the sky above. This hole is a few feet in diameter in the cave 
and 30 feet on the surface and is nearly circular. ‘The western 
half of the cave is low and the floor is muddy and covered with 
water so as to be almost impassable. The section near this cave 
shows 30 feet of the Medicine Lodge gypsum separated by 15 
feet of red shale from the Shimer gypsum, which is 15 feet in 
thickness. This is the typical exposure of the Cave Creek forma- 
tion of Cragin. ; 
