GLACIAL MAN IN THE TRENTON GRAVELS. 



25 



forming correct opinions upon the subject, held pretty much 

 the same views of Dr. Abbott's finds. 



To make the above criticism entirely clear, a few words of 

 explanation of talus phenomena may be added. As a river cuts 

 its channel deeper and deeper into deposits of gravel a section 

 is gradually exposed, but the gravels break down readily under 



mm7M, 



Fig. 4. A freshly formed gravel bluff. 



^//////////m^^m^A 



Fig. 5. Early stage of talus formation. 



y//////////Mmm^m, 



Fig. 6. An ancient talus. 



atmospheric influences and the exposed face does not retain a 

 high angle. The upper part crumbles and descends toward the 

 base, there to rest against the slope or to be carried away by the 

 stream. A supposititious case will be convenient for illustration. 

 A gravel terrace twenty feet in height is encroached upon by the 



