REPRESENTATIVES OF PRE-WISCONSIN TILL 329 



the overriding of deposits laid down during a temporary retreat 

 or local recession of the ice of the same general invasion. 



10. The post-glacial weathering is in general confined to a 

 slight oxidation of the till, the wearing of the pebbles, bowlders, 

 and glaciated ledges being usually limited to a slight superficial 

 decay or a mere discoloration of the surface. 



11. There are numerous exposures showing rock disintegra- 

 tion of a type intermediate between the high decay characteristic 

 of the pre-Pleistocene weathering and the slight weathering of 

 post-glacial times. This disintegration is believed to have taken 

 place largely in interglacial times. 



Myron L. Fuller. 

 U. S. Geological Survey, 

 Washington, D. C. 



