THE LOESS AND THE LANSING MAN. 335 



In the papers cited it is assumed: 



1. That there "were widely extended depressions of our 

 vast glacial area," — and that in these depressions loess was 

 deposited in water, and by subsequent elevation was brought 

 to the present level. 



2. That the streams flowed in ice-walled channels, and the 

 swollen rivers were uplifted on them to bights of 150 to 250 

 feet above their present beds, and that the floods of these riv- 

 ers deposited loess in successive layers. 



3. That the valleys were filled with loess and subsequently 

 eroded, so that the loess now represents only a remnant which 

 remained after extensive erosion. 



4. That the loess was deposited wholly (or at least in 

 greater part) during the Iowan stage of glaciation. 



5. Since the evidence of seolian origin cannot be wholly 

 set aside, it is assumed that there is an "upland loess" of seol- 

 ian origin, but that a "valley loess" owes its origin to fluvia- 

 tile agencies. 



6. Professor Winchell, (1. c.) especially maintains that there 

 is no satisfactory distinction between the loess and the drift. 



The first of these assumptions has been made repeatedly 

 simply to meet an emergency. There is no direct evidence 

 that such movements have taken place in more recent time. 

 There is evidence in other parts of the world that slight move- 

 ments do take place, but nothing has thus far been produced 

 in the area under discussion, other than the assumption which 

 is essential to a theory of the formation of the loess. Such 

 depression would result in the formation of large bodies of 

 water. Where are the shore-lines or other evidences of the 

 existence of such bodies of water? 



The second assumption is based on McGee's explanation of 

 the formation of the river-valleys along the highest ridges, 

 which, while applying to the underlying drift cannot be ex- 

 tended to the loess. The ice-walled channels would call for 



