﻿[8 NEW YORK STATE MUSEUM 



A recent Canadian survey has marked altitudes about the region 

 of Covey hill and westward beyond Franklin, which helps to give 

 precise figures for the height of the marine waters. The highest 

 well-developed bar about Covey hill is 523 feet, which is 65 feet 

 over the former aneroid figures. 



The physical character of shoreline phenomena is alone conclusive 

 argument for the marine origin. Going east from Covey Hill post 

 office, eighteen good bars are noted in the descent of 130 feet, the 

 widest interval being 12 feet. Such uniformity in strength and 

 spacing could not be produced in the fall of glacial lake waters, but 

 it is to be expected in the lifting of the land out of sea-level waters. 



The remarkable series of close-set bars were followed westward 

 about Covey hill promontory into New York, having a slow fall in 

 summit altitude. This altitude of the unquestioned marine shore 

 lines along the international boundary brings them into the same 

 plane as the Gilbert gulf beaches in Jefferson and St Lawrence 

 counties and removes any doubt as to the sea-level origin of the latter. 

 The rise of the marine plane from Lafargeville to Franklin, Ont., 

 is a little under 1 foot to the mile. 



Professor Chadwick has directed attention to the several heavy 

 delta sand plains lying in height between the Iroquois and the 

 marine levels. These seem to indicate a stand of water too long" to 

 represent merely a pause in the rapid down-draining of Iroquois 

 water across the steep face of Covey hill. They suggest some 

 undiscovered complexity in the glacial lake history which requires 

 further study. 



In the Mohawk-FIudson region Professor Brigham has directed 

 his observations to the southern limit of the Mohawk glacial lobe 

 and to its relation to the Hudson valley lobe. The designation, 

 Mohawk lobe, is of somewhat indefinite application, because the 

 lobe was a part of the waning ice sheet and there is no boundary 

 so marked by topographic features, glacial or otherwise, as to 

 create a sharply definable stage deserving this name. Certain 

 features, nevertheless, point to a reasonable differentiation of a 

 glacier within the Mohawk valley and overlapping to some distance 

 upon the headwaters region of the Susquehanna. 



( ' )n the south the place of bifurcation between the Hudson and 

 Mohawk lobes may be confidently placed at the northern end of the 

 bolder development of the Helderberg escarpment, in the Berne 

 quadrangle west and southwest of Altamont. This was inferred 

 from an inspection of the contours of the map and is abun- 



