32 



THE POPULAR SCIENCE MONTHLY. 



The geologic evidence of the environment of the celt-users of 

 the Delaware River is complete and intelligible : the continuity of 

 the deposits proves that the Trenton gravels were laid down while 

 the northern part of the country was occupied by ice, and while 



the terminal moraine was forming ; their structure and composi- 

 tion prove that they were laid down in shallow floe-bearing 

 waters ; their distribution indicates unmistakably the geography 



