220 MAN AND THE GLACIAL PERIOD. 



We have already described* the various temporary lakes 

 and lines of drainage caused by the direct obstruction of 

 the northward outlets to the basin of the Great Lakes. 

 In connection with the map, it will be unnecessary to do 

 anything more here than add a list of such temporary 

 southern outlets from the Erie-Ontario basin. f The first 

 is at . Fort Wayne, Indiana, through a valley connecting 

 the Maumee River basin with that of the Wabash. The 

 channel here is well defined, and the high-level gravel 

 terraces down the Wabash River are a marked characteris- 

 tic of the valley. The elevation of this col above the sea 

 is 740 feet. Similar temporary lines of drainage existed 

 from the St. Mary's River to the Great Miami, at an eleva- 

 tion of 942 feet ; from the Sandusky River to the Scioto, 

 through the Tymochtee Gap, at an elevation of 912 feet ; 

 from Black River to the Killbuck (a tributary of the 

 Muskingum) through the Harrisville Gap, at 911 feet; 

 from the Cuyahoga into the Tuscarawas Valley, through 

 the Akron Gap, at 971 feet ; from Grand River into the 

 Mahoning, through the Orwell Gap, 938 feet ; from Cat- 

 taraugus Creek, N. Y., into the Alleghany Valley through 

 the Dayton Gap, about 1,300 feet ; between Conneaut 

 Creek and Shenango River, at Summit Station, 1,141 feet ; 

 from the Genesee River, N. Y., into the head-waters of the 

 Canisteo, a branch of the Susquehanna, at Portageville, 

 1,314 feet; from Seneca Lake to Chemung River, at 

 Horseheads, 879 feet ; from Cayuga Lake to the valley of 

 Cayuga Creek, at Spencer, 1ST. Y., 1,000 feet ; from Utica, 

 N. Y., into the Chenango Valley at Hamilton, about 900 

 feet. 



Perhaps it would have been best to give this list 

 in the reverse order, which Avould be more nearly chrono- 

 logical, since it is clear that the highest outlets are the 

 oldest. We should then have to mention, after the Fort 



* See pp. 92 seq., 199 seq. f See also accompanying map. 



