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



Subsequent solution removed a great portion of the gypsum, which was 

 precipitated in the shales below, where it is now seen in the interlacing 

 network of selenite and satinspar. This characteristic feature is absent 

 from the shales above. As in the northern gulf, a salt deposit occurs to 

 the southwest in the Salt Plains district, but no trace of salt is found 

 close to the gypsum. 



Analyses of the Gypsum. 



Through the kindness of Professor Bailey, of Lawrence, Kansas, the 

 following analyses have been furnished. The percentages of carbonate 

 of lime and silica are seen to be very high in the dirt deposits, while the 

 percentage of sulphate of lime is lower than in the gypsum rock. There 

 is also a notable increase in the amount of iron. The dirt is thus more 

 impure than the solid rock — a natural result of its secondary origin : 



Hope Shaft Medicine Lodge j)m on T)irt Longford 

 Rock. Rock. Dirt. 



Si0 2 34 .19 12.13 18.69 



Fe 2 3 16 .10 .99 1.21 



CaS0 4 76.98 77.46 64.63 56.56 



CaC0 3 1.68 1.43 3.57 6.10 



MgC0 3 1.38 .34 .88 .90 



H 2 19.63 20.48 16.80 15.54 



100.17 100.00 99.00 99.00 



Conclusions. 



The gypsum beds of economic importance in Kansas are all Permian 

 in age, ranging from middle Permian or Neosho to the close. They cover 

 a belt approximately 200 miles long, 10 miles in width at the north, 20 

 miles in central Kansas, and 60 miles in the southern part of the state. 

 The deposit is 8 feet thick in northern Kansas, 14 feet in the central area, 

 25 feet in the southern area, and farther south even thicker. It will thus 

 be seen that the deposit increases in width and thickness southward. 

 The northern and central rock gypsum was deposited in the same gulf 

 cut off from the western Permian sea, while the gypseous dirt deposits 

 are secondary and of recent age. The southern deposit was formed in a 

 shallow bay cut off from the Permian sea not far from the close of Per- 

 mian time. Salt appears to have been deposited in these bays, but now 

 it is only found farther out in the old gulf. 



Washburn College, Topeka, Kansas, 

 December 28, 1896. 



