192 Kansas Academy of Science. 



2. The Age and Caiise of the Buried Channels West and North of 



St. George. 



The result of the last season's investigation has been the 

 assurance that the channels north and west of St. George 

 were eroded earlier than had been formerly thought. The 

 former view had been that the somewhat lower surface west 

 of St. George was really a terrace formed after the recession 

 of the Kansan ice sheet, but it is now evident that the deep 

 erosion preceded the damming of the Kansas by the ice. 

 Stratified deposits are found to be continuous from the level 

 of St. George up to the level of the divide separating from 

 Rock creek. Moreover, northern bowlders are found to the 

 bottom of the series as exposed near St. George, and well 

 drillers report striking them down to a corresponding depth. 

 This shows that before the lake was filled the Kansas river had 

 cut down the bottom of its channel to within 20 or 30 feet of 

 the present surface of that stream, or within 60 to 80 feet of 

 the bottom of the alluvium in the trough of the present stream. 

 From this it may reasonably be inferred that the drainage 

 level had been Ipwered 70 or 80 feet from the time of the chert 

 gravels, or about half way from the latter to the present level. 



Of course this new view will require a rearrangement of 

 conclusions all along the line. If the general drainage level 

 had been lowered at St. George there must have been a corre- 

 sponding lowering at Topeka, Lawrence and Kansas City. 

 The erosion underneath the terrace at Cameron's bluff and 

 Lawrence would have been before the maximum advance of 

 the Kansan ice, not after it. And the occurrence of bowlder 

 clay low down at Kansas City, Kan., is easily explained, which 

 in the earlier view had been quite a puzzle. 



The channel north of Manhattan was not cut down because 

 the Kansas had broken through eastward, south of that place. 

 The chert gravel was also left intact at other points because of 

 the lateral shifting of the streams as they cut down. 



\Vhat could have been the cause of the general drainage 

 after it had remained so long at the chert-gravel level ? 



It could have hardly have been due to a differential elevation 

 of the region, for there seems to be close parallelism between 

 the older and later drainage levels, or slopes. Possibly there 

 has been a general elevation. In fact, it is quite probable that 

 there has been considerable elevation since the ice retreated, 



