104 MAN AND THE GLACIAL PERIOD. 



of Lake Erie. Through the interest aroused in them by 

 an excursion of the American Association for the Ad- 

 vancement of Science, while meeting in Cleveland, Ohio, 

 in 1888, the Kelly Island Lime and Transport Company, 

 of which Mr. M. C. Younglove is the president, has been 

 induced to deed to the Western Eeserve Historical So- 

 ciety for preservation a portion of one of the most re- 

 markable of the grooves still remaining. 



The portion of the groove preserved is thirty-three 

 feet across, and the depth of the cut in the rock is seven- 

 teen feet below the line, extending from rim to rim. 

 Originally there was probably here a small depression 

 formed by preglacial water erosion, into which the ice 

 crowded the material, which became its graving-tool, and 

 so the rasping and polishing went on in increasing degree 

 until this enormous furrow is the result. The groove, 

 however, is by no means simple, but presents a series of 

 corrugations merging into each other by beautiful curves. 

 When exposed for a considerable length it will resemble 

 nothing else so much as a collection of prostrate Corin- 

 thian columns lying side by side on a concave surface. 



The direction of these grooves is a little south of west, 

 corresponding to that of the axis of the lake. This is 

 nearly at right angles to the course of the ice-scratches on 

 the summit of the water-shed south of this, between the 

 lake and the Ohio River. The reason for this change of 

 direction can readily be seen by a little attention to the 

 physical geography. The highlands to the south of the 

 lake rise about seven hundred feet above it. When the 

 Ice period was at its climax and overran these highlands, 

 the ice took its natural course at right angles to the termi- 

 nal moraine and flowed southeast according to the direc- 

 tion indicated by the scratches on the summit; but when 

 the supply of ice was not sufficient to overrun the high- 

 lands, the obstruction in front turned the course and the 

 resultant was a motion towards Toledo and the Maumee 



