1 8 NEW YORK STATE MUSEUM 



that marine organisms entered the Champlain valley the div'de, 

 near Fort Ann had possibly been lifted out of the sea-level waters. 

 If Covey hill had been raised 215 feet then perhaps Fort Ann might 

 have been raised the 300 feet necessary- to make it dry land and 

 break the connection of the two valleys. However, even if a narrow 

 sea-level strait yet existed between Whitehall and Fort Edward, and 

 salt-water organisms were swept by tmusual storms southward nto 

 the Hudson section, they undoubtedly found a freshened condition 

 of the Hudson water that was unsuited to their propagation. And 

 af .er the Fort Ann strait was abolished the southward sweep of river 

 waters certainl}^ forever prohibited sea life from passing far up the 

 Hudson estuar}-. 



The altitude relation of the Upper Hudson valley to the Cham- 

 plain waters is an interesting problem. The topography of the 

 river channel in the district show-n by the map does not indicate 

 the flow of a stream much if any larger than the present Hudson. 

 But if the detrital filling of the valley had been lifted above sea level 

 while the Champlain glacial waters were yet forced southward a 

 river much larger than the St La\\Tence would have swept the 

 valley. It would, therefore, appear that the waning Labradorian 

 glacier had given the Champlain waters an eastward connection to 

 the sea before the Fort Edward-Cohoes section of the valley was 

 exposed to river work. 



