Kansas Diiriuf/ the Ice Age. 45 



The age was not stationary long enough to form a moraine, 

 and the till deposited was very thin. The ice was compara- 

 tively thin. It did not grind the underlying rocks with much 

 pressure. 



In the Aftonian gravels, which were deposited after the 

 retreat of the Nebraskan ice sheet, in Western Iowa, there are 

 found the fossil remains of numerous interesting mammals, 

 including the American mammoth, one or two species of mas- 

 todon and of horses, a large bison, a musk ox, and of other 

 subarctic animals. The remains of some of these have been 

 found in the gravels of Kansas. For example, a mammoth 

 tooth from near Hiawatha ; a bison west of Atchison ; and near 

 Lawrence, but of uncertain age, the skull of a horse, bison and 

 large cat ; but unf ortunatelj^ the exact source of these fossils 

 has not been determined. 



As we speak of the novel state of affairs of the ice age, some 

 are curious to know how thick was the ice, whether it was clear 

 or mixed largely with debris, and how fast it moved. Rational 

 replies can best be given by learning what conditions exist to- 

 day in a closely similar case in southern Greenland, for there 

 the land rises to about two thousand feet above the sea, only 

 a little higher than the region we have been considering. Those 

 who have studied the matter inform us that above a few feet in 

 the lower part of the ice, the ice sheet is spotless ; also that its 

 upper surface rises at the rate of from 45 to 75 feet per mile, 

 but that the rate is greater near the edge than further back. At 

 this rate, when the ice reached beyond Topeka at its maximum 

 extent, at the northeastern corner of Kansas, 75 miles away, it 

 was 3,375 to 5,600 feet thick. 



The velocity of the ice at certain outlet points on the coast 

 of Greenland has been reported from 60 to 100 feet per day. 

 This was pouring into the sea. On the land it would move 

 more slowly. The velocity reported was for midsummer. It is 

 less than one-fourth as much in the wintertime. 



The Recession of the Ice. For some unknown reason, 

 whether diminished altitude or greater heat from the sun, or 

 more carbon dioxide in the air, the climate became warmer. 

 The ice mantle could no longer resist the withering effects of 

 the south wind, and began soon to gradually retreat by shed- 

 ding floods of water. 



As soon as the edge of the ice had withdrawn from the 



