GLACIAL AND FOST-GLACIAL HISTORY 



629 



streams extended their courses across the newly exposed lake-floor 

 from near Whitehall to the new water-level, which was, perhaps, 

 somewhere near Putnam Station. The main stream of these united 

 streams is referred to as the Poultney-Mettawee River (see Fig. 

 25, B). As the "marine" water body gradually withdrew, this stream 

 extended its course to the new levels, and finally at the close of Marine 

 Champlain time, on the inauguration of present Lake Champlain, 

 it had its mouth some five miles northeast of Port Henry (Fig. 25, 

 C, e) where, apparently, it built out a delta which is now about 23-51 



Fig. 25. — Changes in the Poultney-Mettawee River System. 



A, the system dissevered in Hudson-Champlain time; B, the united and extended courses ol the 

 Poultney and Mettawee Rivers and their tributaries at the beginning of " Marine " Champlain time; C, the 

 same at the close of " Marine " Champlain time or on the inauguration of present Lake Champlain; D, the 

 Poultney-Mettawee system dissevered by the tipping of the water of Lake Champlain into the southern 

 end of its basin caused by differential northern uplift; £, Port Henry; F, Benson Landing and Putnam 

 Station; G, Poultney River; H, Mettawee River. 



feet above sea-level or 50-78 feet below lake-level (Fig. 20, p. 467). 

 During "Marine" Champlain time this stream cut out the channel in 

 the clay plain described above (pp. 466-68) fromWhitehall to Benson 

 Landing and northward to beyond Port Henry. Deposits made 

 by the stream at successive positions of its advancing terminus, 

 other than the submerged delta, have not been recognized, but they 

 are in large part beneath the waters of the lake. The earlier deposits, 

 however, should be found at low levels north of Benson Landing. 



INAUGURATION OF PRESENT LAKE CHAMPLAIN. 



The emergence from the sea of the barrier which makes present 

 Lake Champlain, closed Marine Champlain history and inaugurated 



