84 KANSAS ACADEMY OF SCIENCE. 



top of the sand-hills which cover a large part of northern Day county, 

 and differs only in having the cementing material. The fact that the 

 Antelope hills can be seen for a long distance depends more on the 

 height of the broad, gently sloping base than on the height or size 

 of the steeper portion at the top. South and southwest of the buttes 

 there are lower hills, rising with gentle, rounded slopes, and covered 

 with a sandy soil. The whole appearance of the surrounding country 

 seems to indicate that there was a local hardening in a Tertiary sand 

 plain by the deposition of calcium carbonate in it. Later the South 

 Canadian river cut though this plateau, making a bend to the north 

 around the hardened part. Erosion went on rapidly in the loose sand 

 near the river, but was checked by the hardened layer. Finally, the 

 hardened portion was cut into several parts and left only in the tops 

 of a few buttes which it still protects. 



