82 University Geological Survey of Kansas. 
water along channels near these places. Where the gypsum ° 
water of the springs in these deposits is evaporated there re- 
mains a crust of gray earthy gypsum resembling very closely 
the gypsum earth. Sand, clay and lime in small amounts occur 
in the deposit mingled with some organic material, as shown in 
the following analyses of rock and earth gypsum, by Professor 
HH Ss) Bailey: 
Gypsum earth 
Gypsum rock at Dillon 
in Hope shaft. Agatite deposit. 
Silicarandsincolublesresidie ene eee 0.34 6.49 
IbRovaL Byayey AYNVATAMIO, OIC oo coo a soconboonecooooevnse 0.16 1.04 
Caleiumisulphaterngas: te we Vee OEE 76.98 65.97 
@aleimmycarbonate gy. pa ee eee ate Te See ear 1.68 6.96 
Maonesiumycarbonaleynaae reer ener erin 130) 0.27 
Wea tO rr si. bee CEN CRC aN a Bieig SAUNA Mn en Ue ae 19.63 18.56 
100.09 99.29 
In all the analyses made the amounts of silica alumina and 
lime carbonate in the earth deposits are higher than in the rock, 
which could be expected in a secondary deposit in a swamp. 
The amount of sulphate of lime is lower, so that the earth de- 
posits are not as pure as the rock strata. The impurity of the 
earth makes it set more slowly, and so makes the material more 
favorably adapted to wall-plaster manufacture. 
The microscopical crystals of gypsum in this earth are angu- 
lar and many of them perfect. No masses of gypsum rock are © 
ever found in the earth, and no fragments of other stone or sand 
in any amount. The material is quite uniform in size and 
chemical composition through the whole deposit. If the ma- 
terial was washed from gypsum rock of higher levels, as some 
have maintained, some fragments of gypsum and other rock 
would certainly be found in some of these deposits. 
SPRING THEORY OF ORIGIN. 
The gypsum earth, then, must have been deposited in these 
places from solution. If from solution in surface streams, con- 
siderable sand and silt would be carried in and the chemical 
composition would vary in different parts of the mass. Further, 
as in nearly all the areas, no gypsum is over the earth, so that 
the streams would have to bring the material from long dis- 
