20 NEW YORK STATE MUSEUM 



ravine locally known as the " Gulf " in the resistant Potsdam sand- 

 stone, and the seaward escape of the Ontario basin waters was 

 shifted from the Mohawk-Hudson to the Champlain-St Lawrence. 

 These waters, with level inferior to the Iroquois and with different 

 outlet, require a distinctive name and it is proposed to call them 

 Hypo-Iroquois. 



With only a little further recession of the front of the ice sheet 

 on the end or nose of Covey hill the Hypo-Iroquois waters found 

 yet lower escape between the ice and the snorth- facing land slope, 

 and the outflow carved the slope into a series of irregular benches 

 or terraces. When the waters were lowered between three and four 

 hundred feet below the intake of the Covey gulf the level of the 

 ocean was reached and the waters in the Ontario basin blended with 

 the sea. 



The gravel bars of the Iroquois shore have been traced to a point 

 midway between Watertown and Carthage, but eastward and north- 

 eastward from here the shoreline is weak and very irregular, 

 passing far up the valleys of the present north-flowing streams. 

 The deltas built at the mouths of these rivers in the Iroquois waters 

 are proofs of the relation of streams to the high-level lake, and they 

 have interesting characters. Excepting the Potsdam quadrangle the 

 long stretch of the Iroquois shore from Carthage to Covey hill is 

 unmapped by the topographic survey and its close study is not at 

 present advisable. 



(3) Gilbert gulf. The marine beaches on the north slope of 

 Covey hill are remarkable for their strength, number and composi- 

 tion. The upper ones are strong, close set ridges of sandstone 

 boulders. Aneroid measure makes the highest continuous bar about 

 460 feet A. T. This is 10 feet higher than the figures previously 

 given for the upper reach of the marine waters by Gilbert and 

 Woodworth. It is particularly desirable to determine the precise 

 altitudes for the several Covey hill features and the State should 

 place benches along the International boundary. 



Passing down the hill slope from the marine summit bar it is 

 found that 20 distinct bars occur in a descent of only 140 feet, the 

 greatest interval (aneroid measure) being 12 feet. This multiplica- 

 tion of the wave-built ridges agrees with the theoretical expectation, 

 since the vertical spacing was produced by the very slow, and prob- 

 ably uniform, uplifting of the land out of the sea, giving oppor- 

 tunity and time for bar construction at all interior levels. 



Professor Woodworth has traced the marine shore westward 

 some distance and Professor Fairchild has located the upper limit 



