GLACIAL WATERS IN CENTRAL NEW YORK 55 



The areas of the lake waters are indicated in only a general way, 

 it being impossible in such small maps to show minor features. A 

 special difficulty in mapping the ancient shore lines is due to the 

 land warping. The northward uptilting of the Ontario basin was 

 probably in progress during the time of the waning of the ice sheet 

 and has continued down to the present. This progressive uplift 

 makes it impossible to closely assign the proportionate deformation 

 for the individual lakes. The slant of the Newberry plane is esti- 

 mated at about 2 feet per mile on the average, and the lake areas 

 are here mapped on that basis; the Newberry plane rising from 

 about 900 feet at Horseheads (the channel bottom) to about 1000 

 feet toward the Batavia parallel. 



The matter of the glacial water levels is further complicated by 

 some east and west deformation. We have as yet no clear measure 

 of the warping in that direction previous to Iroquois time, though 

 the Warren beaches indicate that it was not large. The long west 

 to east stretch of the south shore of Iroquois and its mature char- 

 acter give us a fair measure of the post-Iroquois deformation. 

 Altitudes on the Iroquois shore are as follows: Hamilton, Ont., 362 

 feet above tide; Lewiston, 383; Lockport, 402; Gaines, 430; Sodus, 

 456; Rome, 460. From Hamilton to Sodus is about 138 miles, 

 with equal latitude, and the rise of the water plane is c.68 feet per 

 mile, or something over 8 inches. From Sodus to Rome, in direc- 

 tion only slightly south of east, and the distance about 82 miles, 

 the deformation is practically nothing. It is apparent that since 

 Lake Iroquois was drained away the Sodus- Rome district has been 

 lifted about 100 feet more than the west end of the basin. 



To restore the geographic conditions that existed during the ice 

 retreat we must depress the Rome end of the basin about 100 

 feet. This fact, coupled with the low channels in the Syracuse dis- 

 trict prove that in pre-Iroquois time there was free drainage to the 

 Mohawk valley, as shown in stage 5 [pi. 38]. The col at Rome is 

 partly due to differential uplift and partly to delta filling by the 

 upper Mohawk river in the glacial waters held in the Mohawk 

 valley. 



The altitude figures given in the descriptive legends on the maps 

 refer to the present altitudes. 



SUMMARY OF THE GLACIAL DRAINAGE HISTORY 



1 All the glacial waters of the Lake Erie basin down to and 

 including Lake Warren escaped westward to the Mississippi. 



