230 G. P. GRIMSLEY — GYPSUM DEPOSITS OF KANSAS. 



valleys and hills are covered with fertile lime soils, and are dotted with 

 prosperous farms, while numerous small towns are located in the valley 

 of Blue river. 



CENTRAL AREA. 



The central area is located 70 miles southwest of Blue Rapids, and the 

 gypsum deposits lie south of the Smoky Hill river, north of the Rock 

 Island railroad and west of the Atchison, Topeka and Sante Fe railroad. 

 The area is drained by the Smoky Hill river with its north-flowing tribu- 

 taries, and the main watershed is 22 miles south of that stream. The 

 district is a dissected plateau forming a very irregular surface near the 

 divide, while the gradual northward sloping gives a smoother topography 

 near the river. The main industry, the manufacture of rock plaster, 

 centers in the towns of Dillon, Hope, and formerly Gypsum City. 



SOUTHERN AREA. 



The southern area lies 120 miles southwest of Gypsum City. The 

 northern part is drained by the Medicine Lodge river and the southern 

 part by the Nescatunga. The soft red shales and gypsum layers, which 

 form such a characteristic feature of the region, are favorable to rapid 

 erosion, so that the numerous tributary streams have excavated deep 

 canyons, separated by narrow divides or buttes of red clays and shales, 

 with interlacing selenite layers. These are often 150 feet above the bot- 

 tom of the canyons, and they are capped by the massive white gypsum, 

 producing an effect very much like that of the " bad lands " of the north- 

 west. These features are well shown in plate 22, figure 1.* This whole 

 region presents the most rugged topography to be found in the state, and 

 forms scenery of great beauty, especially interesting to the geologists 

 through the lessons in erosion it so clearly depicts. 



Blue Rapids Deposits. 



Three companies are now engaged in plaster manufacture in the north- 

 ern area. The gypsum occurs as a mottled gray rock of saccharoidal 

 texture, breaking with irregular fracture. It is more or less crystalline, 

 showing fibers and plates. The top is covered with a layer of white 

 satinspar needles, which stand normal to the gypsum ledge and vary in 

 length from one-fourth to one and three-fourths inches. The rock is 

 irregularly traversed by blue clay seams, which contain a small amount 

 of carbonate of lime. On exposure to the air for some time or when 



* Made from a photograph taken and kindly loaned by Professor Prosser, of the Kansas Geo- 

 logical Survey. 



