rl2 



NEW YORK STATE MUSEUM 



angle, the point of the reentrant being at Salamanca. On the 

 west side of this angle the ice front had to recede only some 

 30 miles to allow the waters of Lake Warren to creep in from 

 the westward. The entire drama of the glacial waters in this 

 region occurred in that narrow belt. But north of the angle 

 the ice had to retreat some 60 miles in order to let the Warren 

 waters into the Genesee embayment. And to allow the same 

 waters to escape eastward to the Mohawk, the ice had to 

 uncover a breadth of land from the eastern side of the reentrant 

 to Rome or Utica of about 150 miles. Across this broad tract 

 of dissected plateau the ice removal was the recession of the 

 continental glacier. In the basins of Erie and Ontario, on the con- 

 trary, vast lobes of the continental glacier were left as com- 

 paratively stagnant masses, to spread and steadily push against 

 the bordering high ground for many centuries. Accretion, by 

 local snowfall, doubtless prolonged their life. 



In consequence of the relation of the land topography to the 

 position and movement of the glacier masses, the drainage at 

 the west was westward and at the east was eastward. The 

 westward drainage slowly backed up, or extended eastward, 

 while the eastward drainage extended westward. In other 

 words, with the contraction of the Erie ice lobe, the land and 

 glacial drainage in the Erie basin found escape westward to 

 Lake Warren, and ultimately to the Chicago outlet and the 

 Mississippi river, such drainage extending itself eastward as 

 the ice receded, while the eastern waters found their outlet to 

 the ocean by the Mohawk. These opposing movements met in 

 the Syracuse region. This was the critical point, because here 

 the ice lingered the longest at the Warren level. The latter 

 fact is explained by the topography. Oneida and Onondaga 

 lakes lie in a broad depression of the Ontario lowland which 

 is abruptly bordered on the south by the northern edge of the 

 Alleghany plateau and the Ontario ice mass rested long on this 

 low ground, pressing against the steep north-facing slope. 



Lake Warren had successfully crept past the glacier front 

 from the Pennsylvania border of the State and had captured 

 all the drainage on the north of the divide, sending it to the 

 Mississippi, till finally it reached the Onondaga valley. Then it 

 overreached itself, or, as it were, fell into ambush and defeat, 

 for, when the ice south and southeast of Syracuse backed away 

 a little more from the high ground, the Warren waters fell over 

 and were captured by Mohawk drainage. Lake Warren there 

 and then found its extinction. The slow eastward discharge 

 of the vast body of the W T arren water produced the great rock 

 channels across the high ridges, which lead into the Onondaga 



