GLACIAL WATERS IN CENTRAL NEW YORK 



19 



If the reader will assemble in order plates 3 and 4 with the 

 intervening Weedsport sheet, not here included, he will see that 

 the Fairport-Lyons channel is continued east as a series of low 

 passages which probably carried post-Warren flow, although 

 their great breadth, their depth beneath the drumlins and their 

 burial in silts indicate that they were not wholly excavated by 

 the last ice border drainage. 



In connection with the study of the water flow in its relation to 

 the ice barrier it must be understood that the general down-slope 

 of the land surface at the time of the glacier recession was as much 

 greater than today by whatever amount the surface has been 

 differentially lifted to the northward in postglacial time. The 

 total amount of postglacial deformation is not closely determined 

 in this region but the Newberry plane has been tilted between 2 

 and 3 feet to the mile. 



The Pinnacle Hills moraine at the south edge of the city of 

 Rochester with its northwestward continuation to Brockport, 

 Holly and Albion, and its indefinite eastward extension through 

 the townships of. Penfield and Walworth seems to mark the loca- 

 tion of the ice border at a time not far previous to the initiation of 

 the Fairport channel. 



On plates 2 and 3 the fragmentary phenomena of Lakes Warren 

 and Dana are shown. Plate 2 shows the Warren shore line as 

 occurring only south of the glacial channels, probably because 

 there were no hights of land north of the channels up to the 

 Warren plane, about 880 feet. But numerous cliffs and spits of 

 Lake Dana occur at 700 feet, both north and south of the channels. 

 On plate 3 are recorded evidences of both the water planes, but 

 here we fortunately find the Warren phenomena north of the 

 Victor channel, on the Baker Hill kame moraine. The occurrence 

 of wave work by Lakes Warren and Dana north of the channels 

 and at much higher levels seems conclusive proof that the lakes 

 were subsequent in time to the last ice border drainage. 



Another evidence of the later date and imposed character of 

 Lake Warren is found in the nature of its shore-line features. At 

 the Warren level in central New York there are no outwash plains 

 or glacial deltas, which should have formed if these waters had 

 laved the ice front during its recession from the higher ground. 

 The phenomena at the Warren level are interpreted as either wave 

 work or land-stream construction, and the weak planes are mainly 

 erosional. The same conclusions apply .to the Dana phenomena. 



