636 CHARLES EMERSON PEET 



The emergence of the barrier assumed in this correlation requires 

 a fall of the Hudson- Champlain water-level of 120 to 160 feet, while 

 the ice was retiring from the neighborhood of the barrier south of 

 Fort Edward to Street Road and Crown Point. If the Hudson- 

 Champlain water body was an arm of the sea, this fall of water-level 

 was due to uplift. The time necessary to produce this uplift was 

 sufficient to permit the making of at least one secondary delta near 

 Glens Falls on the Hudson — the 340-foot delta, and perhaps a sec- 

 ond — the 280-300-foot delta east of the latter (see Fig. 18, p. 455). 

 It is possible, however, that the 280-300-foot delta was made in the 

 Higher Glacial Lake Champlain water body. It is a question whether 

 this length of time was not more than that required for the ice 

 to retreat to Street Road and Crown Point, and to make any deposits 

 that are known between the deposits in the vicinity of Glens Falls 

 and these points. If the time for the ice to retreat from its position 

 near Glens Falls to Street Road is indicated by the time necessary to 

 make the two secondary deltas of the Hudson River, it would seem 

 that the ice retreat was excessively slow. If, on the other hand, the 

 rate of retreat was similar to that in the lower Hudson, it would seem 

 that the rate of uplift was excessive. There are, however, some indi- 

 cations that the history between the making of the glacial deposits in 

 the vicinity of Glens Falls and those at Street Road and Crown Point 

 was somewhat complicated, and, if so, there may have been time for 

 the uplift mentioned during this history. If the Hudson-Champlain 

 water body was a lake, the fall of the water-level which preceded the 

 emergence of the barrier south of Fort Edward was in part due to the 

 cutting of the Brooklyn Narrows outlet. The full amount of the 

 cutting of this outlet, so far as known, is only 122 feet. If this be 

 distributed among the sixteen or more halting-places between Brook- 

 lyn and Street Road, it would produce but a few feet of fall during 

 the time of the retreat of the ice from the barrier south of Fort Edward 

 to Street Road and Crown Point. Even if allowance be made for 

 the increase in rate of cutting of the Narrows outlet on the accession 

 of the waters of Lake Iroquois through the Rome outlet, the lowering 

 of the water-level from this cause, while the ice was retreating from 

 the barrier south of Fort Edward to Street Road, can have been 

 only a small part of the total change in water-level produced by the 



