218 Kansas Academy of Science. 



more rapid filling of the channel of the other with drift — had cut 

 lower than the Wakarusa a few miles south. The seepage from the 

 latter, down the dip and in the direction of main joints, conspired 

 to the final result. A branch from Deer creek finally captured the 

 Wakarusa west of Clinton and diverted it northward past Belvoir 

 along the course it has since followed. This may have been about 

 the time the ice began to recede, but it cannot be stated with defi- 

 niteness. 



SINCE THE DEPARTURE OF THE ICE SHEET. 



The Wakarusa was at its greatest development when the ice was 

 at its prime. When warmer days forced the ice to recede, very soon 

 the waters which had been forced over the divide south began again 

 to follow the larger valley of the Kansas, as they had done before. 

 This left the Wakarusa again to its own resources alone, to rainfall 

 only. Erosion, therefore, was much slower. The level of its mouth, 

 however, was still lowered by the cutting down of the Kansas val- 

 ley. This for some time — i. e., until the ice had receded perhaps 

 to the mouth of the Platte river in Nebraska, at least until it had 

 reached the Nemaha — must have been the main channel of the 

 master stream of the western plains as well as of the west edge of 

 the ice sheet. To this influence we ascribe the main part of the 

 erosion of the lower hundred feet of the Kansas and of the Missouri 

 below their junction. 



As the "base level" of the Wakarusa was lowered, in this way, 

 that stream cut out also its lower hundred feet, and at the same 

 time shifted southward. This accounts for the general absence of 

 northern drift south of the stream, even at low levels. Any erratics 

 which may once have rested there have been undermined, rolled 

 into the stream and buried or carried away. 



This finishes our main story, but there is an appendix which may 

 appropriately be added. As the Wakarusa was lowered with the 

 Kansas, so were its other tributaries, including the Shunganunga. 

 As that was lowered, erosion was very active east of Burnett's 

 mound around the head of the Pauline branch, or "valley train." 

 The shales were rapidly cut down, while the bouldery contents of 

 the old channel resisted. Ere long a valley appeared on either side 

 of the old channel, and each rapidly cut back southward, assisted 

 by numerous springs in the shales. At length the eastern one cut 

 considerably deeper, and then began seepage through the coarse 

 gravel of the channel from the western channel to the eastern, with 

 the result that a tributary of the latter tapped the western one and 

 stole its headwaters. This interesting case of "piracy" may be 

 seen two or three miles northwest of Pauline. 



