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GEOLOGY: H. L. FAIRCHILD 
water levels, while the initial or summit features are commonly weak and 
unobtrusive; or the latter lie so far inland and are so detached as to be unrecog- 
nized in their genesis and relationship, being commonly referred to glacial 
origin. However, the summit or initial level at any point is the critical and 
essential element in the problem. 
Several years of study in the Hudson-Champlain, Ontario and Connecticut 
valleys has determined the position of the uplifted and tilted marine level. 
In the Hudson-Champlain Valley the ancient estuary features rise from zero 
south of New York City to 740 feet on the north boundary of New York, and 
to over 800 feet on the north line of Vermont. Comparison of these features 
with similar phenomena in the Connecticut Valley gives the direction of the iso- 
bases (lines of equal uplift) as 20 degrees north of west by south of east; or 20 
degrees east of north for the direction of steepest tilting. This figure is in close 
agreement with the determinations of Coleman, Goldthwait, Spencer and Taylor 
for the later deformation of the glacial lake shore lines in the Great Lakes area. 
