GLACIAL AND POST-GLACIAL HISTORY 635 



about 200-220 feet at Street Road and Crown Point. This great range 

 extends north of the latter point, but not so far north as the Bouquet 

 River. From this river northward the range is from 75 to 100 feet, 

 apparently increasing from south to north. The question arises at 

 once: What is the explanation of the greater range of wave- wrought 

 features at Street Road and Crown Point ? Were they produced 

 wholly in Higher Glacial Lake Champlain, or are part of them due 

 to wave-action in the preceding Hudson-Champlain water body 

 before the inauguration of Higher Glacial Lake Champlain? The 

 decision of these questions depends on the correlation of the terraces 

 in the Champlain Valley and the water-levels represented in the 

 Hudson Valley. Since terraces have not been found in the narrow 

 east and west passages which would connect the levels in the Hudson 

 and Champlain regions, the possible correlation of the terraces in 

 these regions must be covered by a series of assumptions which shall 

 include the range of probable fact. 



First assumption. — If the making of the gravel plateaus at Street 

 Road and Crown Point be correlated with the emergence of the 

 barrier at the south of the Fort Edward outlet, then the wave-wrought 

 terraces of the upper series all fall within the history of Higher Glacial 

 Lake Champlain and the greater range here might be due to the 

 cutting down of the outlet and consequent fall of water-level, before 

 the ice had retired far enough north to permit the making of these 

 terraces in the northern Champlain valley. If this be the true 

 explanation, it would require a total cutting of the Fort Edward 

 outlet of 200-220 feet, during Higher Glacial Lake Champlain 

 history, which is greater by 60-80 feet than any possible barrier 

 which the present topography will permit. The second hypothesis 

 to account for the greater range of wave- wrought terraces in southern 

 Champlain, on the assumption that they were all made in the Higher 

 Glacial Lake Champlain water body, is that during the history 

 of this water body there were not only the conditions mentioned in 

 hypothesis i, but there was also a warping upward of this particular 

 portion of the basin, in excess of the up-warping at the outlet, so 

 as to produce the extra spread of terraces. On the most favorable 

 assumption as to the original height of the barrier south of Fort 

 Edward, this would require no less than 60-80 feet of up-warping 

 at Street Road and Crown Point in excess of that at the outlet. 



