ANCIENT WATER LEVELS OF CHAMPLAIN-HUDSON VALLEYS 223 



Chapter 11 



COMPARISONS AND CONCLUSIONS 



In the foregoing eliaptel's the local history of the retreat of the 

 ice through the Hudson and Champlain valleys has been presented 

 in its general outlines, with its accompaniment of proglacial lakes 

 of ever increasing length, finally giving way to the invasion of the 

 sea over the Champlain district. It remains to compare certain 

 phases of this history with reference to related data before pro- 

 ceeding to the drawing of such conclusions as appear tenable. 



COMPARISON OF THE WATER LEVELS OF THE CHAMPLAIN AND HUDSON 



VALLEYS 



The difference in the aspect of the surface deposits of the 

 Champlain and lower Hudson districts is so great when viewed 

 in the light of a critical diagnosis of glacial and marine pheno- 

 mena that I am sure one coming from the easily recognized 

 shore line and sea bottom phenomena of the Champlain valley 

 to the mouth of the Hudson would find no equivalent indica- 

 tion of submergence in that district other than that which now 

 appears to be in progress. All of the evidence in the lower 

 Hudson appears to me permissive of a much higher stand of the 

 land thereabouts during and since the retreat of the Wiscon- 

 sin ice sheet began. But one serious point of difference which 

 has been much discussed by Dr Merrill and myself concerns 

 -certain fine silty sands which occasion the tops of bluffs near 

 the Hudson river, ranging in altitude up to 200 feet at least. It 

 Iiasi seemed possible that some of this material may have been 

 laid down over the district during a time of late submergence. 

 In such places as I have examined the deposits or where they 

 were examined in company with Dr Merrill, they seemed to me 

 to be involved in the ice-laid drift in such a manner as to 

 indicate their contemporaneity with the melting of the ice 

 sheet in the southern Hudson valley and I have, rightly or 

 wrongly, considered the evidence of the proglacial deltas and 

 terraces with their ice contact borders and their exemption from 

 overlying clays and marks of erosion by standing water as 

 weighing more strongly in favor of the nonsubmergence of this 



