Kansas Duriufi the Ice Age. 43 



The Missouri river was not then in existence. The north- 

 eastern part of the state, including Atchison and Seneca, prob- 

 ably drained northeast into the Platte-Grande river, as has 

 been already suggested. 



The Advance of the Kansan Ice Sheet. From other regions 

 we learn that there was at least one advance of the ice before 

 the Kansan, viz., the Nebraskan ; but we have no evidence that 

 it affected Kansas, except that streams may have deepened 

 their channels somewhat lower than the higher-level chert 

 gravels. After the Nebraskan ice sheet, and the following 

 stage of Aftonian gravels, came the Kansas ice sheet, probably 

 from the Kewatan center by way of the Des Moines valley— 

 that is, from the northeast. 



One of the first effects of this advance was the damming of 

 the Platte-Grande river somewhere near Stanberry, Mo. The 

 result would have been a lake, which filled the valley of the 

 Nemaha and other streams in northeastern Kansas. The 

 water rose until it found a way over the divide southward. 

 This condition probably caused the bowldery stratum near 

 Weston, Mo., inaugurating the course of the present Missouri. 

 The bowlder-filled channel west of Bethel may have been part 

 of a similar stream which was not permanently followed. 



Later the ice advanced, causing the water to rise until higher 

 cols were reached and occupied by small streams such as de- 

 posited gravels near Seneca, Sabetha, Hiawatha, and other 

 points. The larger tributaries of the Kansas and Big Blue, 

 augmented with more water but not at first with correspond- 

 ing amounts of debris, eroded down to the level of the lower 

 chert gravel ; in them the higher gravels were rearranged at 

 lower levels, and in the later stages, if not in the earlier, north- 

 ern erratics were intermixed. 



The larger streams at that time flowed about 75 to 100 feet 

 higher than at present. 



The Ma.riminn Extent of Kansan Ice. When the ice reached 

 its maximum extent, as has already been mentioned, it filled 

 the trough of the Kansas river from Wamego to Lecompton 

 and pushed on until its edge lay upon the divide south — a few 

 miles north of the limit of the drift as already given. 



Kaw lake filled and overflowed through its outlet into Mill 

 creek, and across the next divide to Mission Creek, where, at 

 Dover, a small stream broke over into the valley of the Waka- 



