History of Kaw Lake. 191 



the terrace along Mill creek; moreover, it is there also 

 sprinkled with northern bowlders. 



6. No Distinct Trace of Glacial Action. 



Another fact of significance is that no distinct trace of glacial 

 action has yet been found in the basin of Kaw Lake. No stri- 

 ated ledges and no unmistakable till has been discovered. This 

 may be explained by the supposition that deep deposit had 

 formed before the ice sheet reached this locality. The under- 

 lying rocks were well covered. The absence of till would be 

 accounted for by the same conditions. The ice would rest on 

 lacustrine beds, but had little molding effect because of flota- 

 tion by the waters of the lake. 



ACCEPTED CONCLUSIONS. 



These are the most significant facts. How may we account 

 for them and weave the interpretation into a consistent his- 

 tory ? 



1. The Age and Deposition of the Chert Gravels. 



As has already been hinted, the chert has every appearance 

 of having been deposited in a river, and its derivation from 

 the abundant cherty limestones of the Permian which cap the 

 higher points about Manhattan and westward is quite obvious. 

 It was evidently deposited before glaciers had come near 

 enough to bring their contribution of northern material, for 

 no northern erratic has yet been found intermingled with the 

 gravel, when in its original position. Further east, near St. 

 Marys and Topeka, where they have been rearranged at lower 

 levels, there has been an intermingling. Still' further east, 

 northeast of Lawrence, where they are again found at an 

 altitude of 125 to 150 feet above the Kansas, they are again 

 distinctly separate. Their deposition must have been before 

 the Kansas flowed through south of Manhattan, and before 

 that channel and the one from Rock creek had been deepened 

 as has been noted about St. George. This is attested by the old 

 channel north of Manhattan, which shows the chert gravel, 

 and on a level corresponding to that near Wam.ego. It seems, 

 therefore, that the chert gravels may be as old as the Pliocene. 

 It has been hoped that fossils might appear which might de- 

 cide their age, but such have not yet been found. 



