OF DENISON UNIVERSITY. 23 



they separate considerably, apparently planed out by the ice, and 

 there are drift deposits more than loo feet high through which the 

 creek now cuts its way. These may have been formed by the advanc- 

 ing ice pushing through the valley a little ahead of that on either side 

 which had to ascend the hills ; or they may have been left on its 

 retreat : or it is possible, though scarcely probable, they mark a re- 

 entrant angle of the moraine. It is true there is a wide gap in the 

 heavy deposits in the main stream below here, but it is more reasona- 

 ble to suppose that they have been removed by erosion than to believe 

 the ice-sheet would stop moving in a place so favorable to its progress. 

 At any rate, a lake of considerable depth was at one time held back 

 above them; for at the point A. on the hill-side, 75 feet above the 

 railway, is a finely stratified deposit of sand. This, however, may 

 have settled in the water which rose in front of the ravine (which then 

 extended much farther to the north,) until it broke over the divide. 

 When this happened, such water as went out this ravine became a 

 part of Paint lake until the extension of the ice confined the latter 

 above the point D. But between jB and D there would still result 

 from the melting ice a great quantity of water whose most natural, and 

 indeed only means of escape until new channels were opened miles to 

 the northward, would be toward C along the bed from which Paint 

 creek had been so summarily shut off. This continued until the pres- 

 ent course had been cut to a depth lower than the surface toward the 

 east or west ; and North Fork, being thus debarred from following the 

 old valley in either direction, has ever since flowed directly across it, 

 high above the original bed, as though carried on an aqueduct. 



Note. — Too late to add to above paper, I discovered a glacial 

 outlet in the eastern part of Ross county. A number of ravines from 

 the hills back of Mount Logan and Rocky Knob, united and flowing 

 past Mooresville or Halltown, discharged into the Scioto about four 

 miles below Chillicothe. A smaller ravine skirted the northern slope 

 of Rattlesnake Knob, and entered the river not far below the other. 



With the greatest extent of the glacier, a lake was formed be- 

 tween its front and the hills a short distance west of Adelphi, over 

 what is now known as Maple Swamp. This finally broke over into 

 the first ravine mentioned, making a narrow gorge in the hills; at the 



