296 Tertiary. 



whole formation consists of the disintegrated rocks of the immediate 

 locality, or those at no great distance north. The grooves and 

 scratches upon the rocks between Niagara and Hamilton, have a 

 north and south direction. 



In 1847, W. E. Logan* found on the north shore of Lake Superior, 

 about three miles below the Petits Ecrits, six terraces, in addition to 

 the summit, which, presenting a level surface throughout the whole 

 length, may be considered a seventh. Blocking up the extremit}^ of a 

 deep cone from the rock on one side to that on the other, the accumu- 

 lation is a barrier to an extensive flat and marshy surface, that spreads 

 out in a valley behind, down to the level of which there is a rapid slope 

 from the summit of the drift, at a distance of about 1,000 j-ards from 

 the margin of the lake. The height of the ancient beaches as measured 

 by a pocket spirit-level is as follows: 



Above the Lake. Above the Sea. 

 Feet. Feet. 



1st Beach 30 627 



2d " 40 637 



3d " 90 687 



4th " 224 821 



5th " 259 856 



6th " 267 864 



7th " or summit 331 928 



The 3d and 4th beaches are the most decidedly marked, the steps, 

 rising behind them, sloping up at an angle of nearly 30°, 



Alexander Murrayf described the drift on the Kamanitiquia river, 

 which flows into Lake Superior, near Fort William, as consisting be- 

 tween McKay's mountain and the Grand Falls, where the principal 

 display was found, of a light bufl^-colored cla}', covered over by strati- 

 fied yellow ferruginous sand, both together attaining a thickness of 

 60 feet above the level of the water. Banks of sand were found on 

 Dog river, at a much higher level than the deposit further down. 



In 1848, John L. Leconte;*; described, from a Post-pliocene deposit 

 in a crevice in northern Illinois, Platygonus compressus and Anomo- 

 don snyderi. 



Mr. Charles Whittlesey§ designated the different l)eds of the drift 

 in Ohio and the West as follows : 



* Geo. Sur. of Canada. 



-h Ibid. 



X Am. Jour. Sci. and Arts, 2d ser., vol. v. 



<S Ibid. 



