GLACIAL EROSION ON KELLEYS ISLAND 



641 



quarters of a mile north is located the deeply grooved limestone that is classic 

 among the better known areas of glaciation ; 3 these grooves (figure 1, plate 

 109) are quite regular in horizontal extension; their original length is not 

 known because of partial obliteration by quarrying. The details of this 

 grooving will be considered later. 



Northward from the area under discussion the limestone at the West quarry 

 also shows plainly the work of ice, but not in the marked degree seen at the 

 North quarry ; the rock is scored and striated and contains some shallow 

 grooves. 



The drift on the island wherever exposed consists almost entirely of clay 

 and of limestone blocks. In several exposures, studied closely, erratics were 

 rare. 



Figure 1. — Kelleys Island, Ohio 



The South quarry is indicated by S ; the North quarry by N ; the recently stripped area 



by X. 



Discussion 



A north-south section of the island through the areas above described shows 

 a striking variation in the intensity of ice erosion. Not only does its intensity 

 vary from place to place, but the change is abrupt. A surface of uneven and 



3 G. K. Gilbert : Surface geology of the Maumee valley. Geological Survey of Ohio, 

 vol. i, 1871, p. 538. 



T. C. Chamberlin : Seventh Annual Report, U. S. Geological Survey, 1885, pp. 211-216. 

 G. P. Wright : Ice age in North America, 1889, pp. 232-238. 



