652 



THE ICE AGE IN NORTH AMERICA 



stone knobs formed by the outcropping of the subcarbonif- 

 erous strata, which here dip to the west. The unglaciated 

 area is, therefore, considerably higher than that which adjoins 

 it on the east, and is much cut up into gorges along the 

 drainage lines, and must have furnished a favorite retreat, 

 both for man and animals, during the maximum extension of 

 the ice. 



Mr. Cresson, having been called into this locality on busi- 

 ness, and finding that it was near the glacial boundary as I 

 had recently traced it, was led to turn aside for an hour or 

 two to examine a bank of modified drift. While digging 

 with his hunter's knife under a bowlder of about one hun- 

 dred pounds weight to see if it showed signs of glaciation, he, 

 to his surprise encountered a well-wrought palaeolithic flint 

 implement. Fortunately, a long experience in exploring the 

 gravel-beds in France where pakeoliths occur (and, indeed 

 from experience in exploring while a youth a shelter-cave 

 which we will hereafter describe, on the banks of the Dela- 

 ware) had prepared him fully to appreciate the discovery ; 



™M 



Fig. 176.— Section of glacial gravel at Medora, Indiana, in which Mr. Cresson found the 

 palseolith figured in the text. A. is a deoosit of soil three feet in depth ; B, modified 

 drift eight feet in depth : D. is prohahly till ; L, L, layers of alluvium ; C, the bowl- 

 der, under which the implement was found at X. 



and he remained a day or two until he had thoroughly in- 

 vestigated the surroundings and made further search for im- 

 plements. Such search, however, was not rewarded with suc- 

 cess, since all that he found later were from the surface, and 

 of a neolithic type. According to Mr. Cresson, this palseo- 



