236 G. P. GRIMSLEY -GYPSUM DEPOSITS OP KANSAS. 



■ The gypsum is first seen 6 miles southwest of Medicine Lodge in an 

 isolated range o hills 3 miles long and separated by a narrow 'va ley 



eel" 7™f P milei " le " gth - The ValIeyS ° f Ea * ta " d West Cedlr 

 creeks, 2 mi]es wide, separate these hills from the next series, in which 



the gypsum plateau is continuous to the west. Medicine Lodge river 



cute out the gypsum in a valley 6 or 7 miles wide. The northern limit 



nltl ^T/r?^ de j termined > f °'- * « covered with Tertiary de- 

 posit Salt Fork and Sandy creeks cut out broad valleys to the south 

 and the streams in the eastern portion of Comanche county have re- 

 moved much of the stratum; but the gypsum is continuous over the 

 greater portion of western Barber and Comanche counties. The rock 

 usually lies near the 1,800-foot contour line 



In the eastern part of Comanche county, on Cave creek, a second gyp- 

 um layer, US feet thick, is found 15 feet above the Medicine Lodge 

 layer. This layer was called the " Shinier gypsum " by Cragin * and it 

 appears to be a local deposit. g ' 



GEOLOGICAL RELATIONS. 



Looking west from the town of Medicine Lodge one can see inthedis- 

 tonoe a range of eroded hills with sloping sides and level tops. These 

 hills extend in a north-and-south direction and are called the Gypsum 

 hills. The sides are composed of the red clays and shales of the red 



2' t 7 ^V 3 T el ' tain and mUCh dis ' 5uted > but the y Probably 

 mark the transition from Permian to Cretaceous. The cap rock is a 



ledge of solid- gypsum, which has protected to a considerable extent the 

 underlying soft strata. 



The base of file hills is a massive red sandstone, a second red sand- 

 stone is found 125 feet higher, and 100 feet above this comes the ledge of 

 gypsum forming the top of the hills. This gypsum layer varies from 3 

 to 20 teet m thickness, depending upon the amount of erosion The 

 eastern portion of the area shows characteristic shore markings. ' Forty 

 lee below the gypsum is a green gypseous sandstone two and one-half 

 teet thick, which stands out as a prominent ledge through the hills The 

 red cays and shales below the gypsum contain an interlacing network 

 of selemte and satinspar layers of variable thickness. This material has 

 been dissolved out of the solid stratum and carried downward and re- 

 deposited through the agency of circulating water. 



SOLUTION EFFECTS. 



In the western part of Barber and the eastern part of Comanche coun- 

 ties the solvent effects of water on the gypsum are well shown, for here 



: Loc. cit. 



