Science, Geology and Physics 



carried on similar observations north of Lake Superior, 1 and 1898 

 Prof. H. L. Fairchild in New York. The deserted beaches pencCT 

 show but little terrestrial oscillation about the western end of 

 lake Erie, but it increases towards the northeast and amounts 

 from four to seven feet per mile. 



With the surveys of the deserted beaches, new questions arose 

 concerning the history of the lakes and of Niagara River, which 

 forms an inseparable chapter. At the same time, opposing 

 hypotheses presented themselves. 



None of the beaches have been fully surveyed. They occur 

 at various altitudes from near the greatest elevation of the land 

 down to the levels of the lakes, and they have not always been 

 separated from other Pleistocene deposits. While there are ques- 

 tions as to the higher forms, those from lower levels have undoubt- 

 edly been accumulated about extensive bodies of water — the 

 character of which is the subject of disagreement. The writer 

 has regarded them as accumulations at sea-level, and other 

 observers as margins of glacial lakes, irrespective of their eleva- 

 tion. The theoretical aspect is not one likely to be settled 

 speedily. Those who advocate the glacial character of the lakes 

 have sought to terminate the beaches against morainic deposits 

 to the northeast, but their ice dams have been frequently thrown 

 along lines beyond which the beaches have subsequently been 

 traced. Thus Prof. Claypole made ice dams in Ontario where 

 open water, bounded by beaches, was afterwards found to 

 prevail. At Adams Centre, Prof. Gilbert drew an ice dam 

 for the Ontario basin, beyond which, however, the writer found 

 that the old shore line extended, and this was later confirmed 

 by Prof. Gilbert. Mr. Leverett made an ice dam at Cleveland, 

 beyond which the writer has been informed by two observers that 

 the beach extends, and Prof. Gilbert and Mr. Leverett described 

 another glacial dam near Crittenden, N. Y., beyond which the 



1 Sketch of the coastal topography of north side of Lake Superior. 

 20th Rep't of Geol. Surv. Minnesota, 1891, pp. 181-289. 

 2 Rept. of meeting A. A. A. S., Science, Sept., 1895, 222. 



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