THE DATE OF THE GLACIAL PERIOD. 



593 



material containing coarse gravel and a good deal of fine 

 sand. Above this to the top seems again to be true till, 



Fig. 151.— Section of till near Germantown. Ohio, overlying thick bed of peat. The man 

 in the picture stands upon a shelf of peat from which the till has been eroded by the 

 stream. The dark spot at the right hand of the picture, just above the water, is an 

 exposure of the peat. The thickness of the till is ninety-five feet. The partial strat- 

 ification spoken of in the text can be seen about the middle of the picture. The fur- 

 rows up and down had been made by recent rains. (United States Geological Sur- 

 vey.) (Wright.) 



with, however, an occasional pocket of sand or thin stratum 

 of stratified material. But. both up and down the stream 

 from this point the till merges into gravel-beds partially ce- 



