l66 . NEW YORK STATE MUSEUM 



physiography of the Hudson and Champlain valleys with special 

 reference to changes in altitude and drainage since glacial times. 

 All three men found evidence that bodies of water had occupied 

 this region just subsequent to the disappearance of the continental 

 ice sheet, and that the level of these bodies had not remained con- 

 stant during the whole time of their duration. 



The epochs of the several bodies of water which have occupied 

 this region in the time since the retreat of the ice from the Brooklyn- 

 Perth Amboy moraine were designated by Peet (1904, p. 661) as 

 follows : 



1 Hudson-Champlain 



2 Higher glacial Lake Champlain 



3 St Lawrence-Champlain 



4 Marine Qiamplain 



5 Present Lake Champlain 



All three believed the earlier and higher bodies of water to have 

 been glacial lakes, and that the latest and lowest of the ancient 

 water levels was marine. 



G. K. Gilbert in 1896 made observations at the northern end of 

 the Champlain valley in the vicinity of Covey hill. His unpub- 

 lished notes were available to Woodworth (1905, p. 67). 



Between 1900 and 1903 Prof. J. B. Woodworth of Harvard Uni- 

 versity, as a member of the New York State Geological Survey, 

 studied this region and attempted to solve the problems of its 

 glaciation and subsequent alterations. His conclusions were that, 

 pari passu with the retreat of the ice sheet in the Hudson-Champlain 

 valleys, a glacial lake occupied the uncovered portion of the region ; 

 and that when the ice finally left the northern end of the valley the 

 ocean came in by way of the St Lawrence valley converting the 

 Champlain valley into an estuary. At different times these waters 

 stood at different levels, and these stands are marked by clearly 

 defined shore line phenomena. Professor Woodworth has corre- 

 lated these isolated shore line phenomena along continuous lines, 

 and thus has been able to trace the outlines of the ancient lakes at 

 each stage of their existence. 



More recently (1910-12) Prof. H. L. Fairchild of the University 

 of Rochester has revisited the region in the service of the State to 

 continue the researches of Professor Woodworth. His conclusions 

 are stated in a preliminary report in the Annual Report of the State 

 Geologist for 1912 (Fairchild 1913). He believes that all the 

 ancient shore lines are due to marine waters rather than to waters 



