ICE-SHEET EROSION IN NEW YORK 65 



the Indian quarry the corraded layer shown in the view is removed and 

 the till rests directly on the subjacent, firm, un weathered bed. 



Plate 22, figure 1, is from the Goodrich quarry, near Cottage street, in 

 the city of Auburn, lying in the northward continuation of the Owasco 

 valley. 



Plate 23, figure 1, is from the northside of the Thomas quarry, 1 mile 

 south of Waterloo, in Corniferous limestone. About 2 feet of the base of 

 the mound that looks like till, in the center of the view, is a bed of greatly 

 corraded rock, but with the top of the weathered blocks well glaciated 

 and with perfectly preserved polish. In the left of the view the same 

 bed is shown quite unweathered, while on the west and south sides of 

 the quarry the same bed, in perfect freshness, is buried under higher 

 and weathered layers. 



In the Cayuga valley the proofs of non-erosion by the ice are abundant. 

 At Union Springs the limestone quarries yield the usual good evidence, 

 as do also the gypsum pits. A good example of preglacial weathering- 

 is found in the Portland Cement Company's quarry, in Tully limestone, 

 about 6 miles north of Ithaca, on the east side of the valley. Plate 23, 

 figure 2, shows in the background remnants of a much corroded bed, 

 about 4 feet thick, having the open joints filled with red, residual clay, 

 Striae on the tops of the corraded blocks and elegant glaciation of the 

 firmer bed in the foreground of the view prove the lack of postglacial 

 weathering. The large, open joints and seams in the subjacent beds are 

 also filled with residual clay, so characteristic that the quarrymen 

 recognized the material as different from the till. This quarry is only 

 about 200 feet above Cayuga lake. 



These facts of observation, which can be indefinitely multiplied and 

 easily verified, prove beyond any reasonable doubt the failure of the 

 glacial ice to remove even the superficial, weathered rock, even at low 

 altitudes in the Finger Lakes valleys. It is plainly evident that the ice 

 did not produce the valleys ; it did not even enlarge them ; and it would 

 be unwarranted, in view of our knowledge of the mechanics of glaciers, 

 to claim that the ice trenched below the present lake levels without 

 effective cutting above those levels. 



The most that can be reasonably claimed for the ice-work is that it 

 smoothed off the intervalley ridges and also the valley sides. The val- 

 leys are stream valleys, like valleys everywhere, and only slightly modi- 

 fied by ice action. 



Let us hope that assertions of the glacial origin or deepening of the 

 Finger Lakes valleys (or any other valleys) will cease, and that former 

 statements to that effect will be corrected. 



