Geological Papers. 65 



The gravel layers have furnished an excellent channel for 

 a subsurface flow from the mountains of surplus waters, and 

 are the source of the invaluable sheet water of the western 

 part of Kansas and neighboring states. The Staked Plains 

 are underlaid by the same stratum of Tertiary gravel, and 

 thousands of acres are now irrigated with water from wells 

 that penetrate this source of water supply. 



Among the strange mammals which roamed the plains of 

 Kansas were camels, mastodons, three-toed horses, rhinoc- 

 eroses, saber-tooth tigers and wolves, but man had not yet 

 appeared. 



THE AGE OF ICE AND OF MAN. 



By the close of the Tertiary and the opening of the Quater- 

 nary periods the great interior seas were much smaller, and 

 many of them were completely filled with sediment. The 

 forms of life became more nearly what we find in Kansas 

 to-day. Early in the new period the climate became so cold 

 that finally the snow stayed on the ground summer as well as 

 winter, and the great Kansan glacier pushed into the state 

 from the north as far as the Kaw and Big Blue rivers and a 

 little farther. This glacier, as do all others in a plains region, 

 pushed the hills into the valleys, dug deeper into the soft 

 shales than into the hard limestones, and shoved great quanti- 

 ties of northland bowlders and gravel into southern latitudes. 

 The limestone in Nemaha county shows the planing work of 

 glaciers, and the hills south of Topeka are full of quartzite and 

 granite bowlders from Minnesota and South Dakota. 



While the glaciers were still plowing the northern states 

 man made his appearance, whether in Europe first, in Asia, 

 Africa, or America, no one knows ; but of this we are sure, he 

 dominated the world when he made his entrance in it. He 

 soon became intensely interested in flocks and herds, in crops 

 and soils, and in forests and rainfall. Wherever these are 

 directly influenced by the geological development of Kansas, 

 we shall find material for profitable study. Therefore with 

 soils and water supply this paper must close. 



THE SOILS, SUBSOILS AND CROPS. 



As explained in the preceding pages, Kansas owes the clays, 



sands and calcite of her shales, sandstones and limestones, 



respectively, first, to the disintegrating granites and lavas uf 



the Ozarks and Oklahoma mountains ; second, to the floods that 



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