GLACIAL AND POST-GLACIAL HISTORY 631 



of this work, while north-heading tributaries have been given the 

 advantage. It is beheved that on some of the streams this record 

 can be read from the topographic maps. 



HISTORY IN HUDSON VALLEY IN HIGHER GLACIAL LAKE CHAMPLAIN 



TIME AND LATER. 



The history of the Hudson Valley has been left at the point where 

 the southern uphft brought a barrier south of Fort Edward into 

 effective position and inaugurated Higher Glacial Lake Champlain 

 (see Fig. 23). How long the Hudson water body survived is not 

 known. It is not known, indeed, that its history overlaps to any 

 extent the history of Higher Glacial Lake Champlain. The uplift 

 which produced the latter may have been the final cause for the 

 disappearance of the former. If the Hudson water body survived 

 long after the inauguration of Higher Glacial Lake Champlain, 

 then deposits made by the outlet stream from that lake would be 

 expected at the point where it debouched into the Hudson water 

 body. They may be present, but the region where they would be 

 expected has not been studied enough to determine this point. Some 

 stages in the lowering of the Hudson water body are represented 

 by the low-level deltas mentioned at South Bethlehem, on the Hoosick 

 River, on the Batten Kill, on the Hudson River, and possibly on 

 other streams. It is a question whether any of these fall within Higher 

 Glacial Lake Champlain time. Possibly the 280-300-foot Hudson 

 River delta between Glens Falls and Fort Edward does. If neither 

 this nor the Oniskethau low-level delta at South Bethlehem falls 

 within that time, then certainly the Hudson water body had been 

 reduced to a very shallow representative of its former extent, for the 

 latter delta is only 20-40 feet higher than the lowest part of the floor 

 opposite this place. 



Whatever may have been the history soon after the inauguration 

 of Higher Glacial Lake Champlain, it is certain that long before the 

 close of that history the Hudson water body had disappeared, and 

 that the outlet stream of Higher Glacial Lake Champlain, the greater 

 part of which flowed through the present Hudson River valley (see 

 Fig. 23), had taken its course across the old floor of the Hud- 

 son water body, that the streams which had debouched into -4:he 



