QUATERNAEY AGE. — CHAMPLAIN PERIOD. 553 



new ones. There is an old gorge of Niagara River, commencing at 

 the Whirlpool, which was thus filled. It is probable that, when the 

 •damming by Drift was accomplished, the waters of Lakes Erie and 

 Ontario were on a common level, so that there was no river-flow to 

 prevent the catastrophe ; and that, when the elevation that ended the 

 Cham plain era began, the river first found out that its old channel was 

 gone. The stream, then renewing its flow, began, at the Queenstown 

 heights, the present cut through the rocks to the Whirlpool (p. 590). 



Dr. Newberry has stated that the Ohio River formerly had a more southern channel 

 around the Falls, near Louisville, and lost it, in a similar way, in the Champlairi period; 

 that formerly Lake Huron discharged into Lake Erie by a more easterly channel than 

 the present one, and was forced in this era to take the route over the rocks. The chan- 

 nel of discharge, from Lake Michigan to the Mississippi, which F. H. Bradley has 

 -pointed out as having been made or used in the Glacial period, he shows was filled up 

 in the Champlain, and then the more western channel, from Chicago along the Des 

 Plaines to the Illinois, became the outlet, and continued to be so until the elevation 

 ■opening the Recent period. 



. 2. Circumstances attending the Diluvian depositions. The Final 

 Flood from the melting of the Glacier. — That the melting of the 

 glacier should have ended in a great flood is evident from the common 

 observation that, in cold latitudes, floods terminate ordinary snowy 

 winters. 



The subsidence of northern lands brought on the conditions of a 

 warmer climate ; and, as the melting went slowly forward, this amelio- 

 ration must have finally become very decided. Consequently, there 

 was melting, not merely along the southern edge of the glacier, but 

 over its wide surface ; and, when the thickness of the ice was at last 

 reduced to a few hundreds of feet, and it had become rotten through- 

 out, the melting must have gone forward with greatly augmented 

 Tapidity ; and a flood, filling rivers and lakes to an unwonted height, 

 must inevitably have followed. 



The fact that such a flood, vast beyond conception, was the final 

 -event in the history of the glacier, is manifest in the peculiar stratifi- 

 cation of the flood-made deposits, and in the spread of the stratified 

 Drift southward along the Mississippi valley to the Gulf, as first made 

 known by Hilgard. Only under the rapid contribution of immense 

 amounts of sand and gravel, and of water from so unlimited a source, 

 •could such deposits have been accumulated. 



The Mississippi waters, from the mouth of the Ohio to the Gulf (550 miles), have at 

 high water a pitch of about six inches to the mile; the level at high water adds, at the 

 Ohio, fifty feet to the height. If the supply of waters were sufficient to increase the 

 ■slope to eleven inches per mile, the height of water would be great enough to deposit all 

 the loess at its present level. But the land was certainly depressed, in the latitude of the 

 Ohio, at least fifty feet below the present level; and, in that case, with less than nine 

 inches to the mile, the existing Champlain depositions could have been made. Much 

 greater changes of level actually took place in the vicinity of the Gulf, according to 

 Hilgard (Am. J. Sci., II. xlviii. 331, and III. ii. 398.) 



