260 H. L. Fairchild — Glacial Lakes in Central JVeiv York. 



This large channel, excavated in Hamilton shales by the 

 Warren overflow, leads southeast four miles, opening into the 

 Otisco Y alley two miles south of Marcellus village. The local 

 name is the " Gulf," which, for want of a better name is 

 retained. The waters were again impounded in the Otisco 

 yalley, where the debris derived from the excavation of the 

 Gulf was piled in a delta, with terraces from 860 down to 800 

 feet elevation. The Otisco waters (Marcellus Lake) escaped 

 by another great rock channel, Cedarvale channel (named after 

 a hamlet in the gorge) that heads at Marcellus village and leads 

 southeast to the Onondaga yalley at South Onondaga. 



These great channels, with others farther east (see page 251), 

 show the final result of some centuries of erosion. Their 

 initiation was probably not in the present geographic sequence, 

 and the primitive conditions of elevation, etc., are uncertain. 

 The Skaneateles and Tully sheets of the New York State topo- 

 graphic map will, when published, show the Gulf and Cedar- 

 vale channels and deltas with clearness.* Dr. Gilbert was the 

 first to study these channels and to point out their relationship 

 to those lying further east.f 



Hyper-Iroquois Waters. 



Lake Dana (" Geneva" beach). — At the time of Warren 

 extinction the Ontario basin was still largely occupied by the 

 glacier. Certainly most of the eastern part of the basin north 

 of the locality now under discussion was filled with the ice. 

 Considerable time was required for the front of this ice-body 

 to recede so far as to permit an expanse of Ontario waters in 

 the region under discussion, with immediate outlet at Rome — 

 that is to say, for the westward expansion of Lake Iroquois. 

 During this interval the glacial waters fell about 500 feet, from 

 the Warren plane to the Iroquois. This subsidence was not a 

 steady or continuous lowering, but per saltum, — a series of 

 comparatively sudden falls, as progressively lower outlets were 

 opened, with intervals of steady level, or very slow falling, as 

 each outlet remained effective. 



During one of these phases of repose it is believed that the 

 beach was formed which has been traced along the west side of 

 the Seneca Yalley and described in a former paper as the 

 " Geneva " beach. ;{; It is also believed that the level of the 

 beach correlates with the Cedarvale outlet at Marcellus. This 

 is the only waterlevel between the Warren and Iroquois planes 



* To the U. S. Geological Survey the writer is indebted for advance copies of 

 the maps in manuscript which have facilitated this study. 



f Old Tracks of Erian Drainage in Western New York, by G-. K. Gilbert. Bull. 

 Geol. Soc. Amer., vol. viii, p. 285. 



X Bull. Geol. Soc. Amer., vol. viii, p. 281 ; vol. x, p. 44. 



