74 NEW YORK STATE MUSEUM 



recession of the right hand portion of the falls. In the course of a 

 comparatively short time the channel became so deep on the right, 

 and the falls receded so fast on that side, that all the water was 

 drawn off from the larger portion of the river bed on the left, which 

 today remains as a triangular platform comparable to Wintergreen 

 flat, with steep sides, and several hundred feet wide, at its down- 

 stream end. The river now flows in a channel, in places less than 

 10 feet wide, and lOO feet below the level of the platform which 

 was its bed less than loo years ago. The present lower fall, having 

 mostly receded beyond the upstream end of the platform, again 

 extends across the entire bed of the river. The water in the river 

 has not, as far as known, changed in average volume, though above 

 and below the narrow part the gorge is many times as wide. All 

 the water which passes in a thin sheet over a broad fall above the 

 -narrow gorge is forced to pass through this contracted portion, and 

 presents a rushing current, though the bed is deeper here than 

 where the gorge is broader. The time required for the recession 

 of the fall over the space of the 2000 feet of narrow gorge, must 

 have been much shorter than that required for the recession through 

 a similar length in the broader portion of the gorge, for the con- 

 centration of the waters here enabled it to do much more effective 

 work. 



Judging by analogy, we may assume that the narrow channel op- 

 posite Foster's flats was cut by a stream of the full power of the 

 present Niagara, but whose main mass of waters was carried over 

 the right side of the fall on account of the bend in the stream above. 

 The present Horseshoe falls is cutting a much narrower gorge than 

 that to the north of it, owing to its peculiar position at the angle 

 of a second great bend. (Fig. 19) From the fact that the cutting 

 was most profound on the eastern or right bank of the river at 

 Foster's flats, this bank has received the precipitous character which 

 it has retained to the present day. 



An interesting fact bearing on the interpretation of the history 

 of Foster's flats, is the occurrence in the sands among the huge 

 boulders near the foot of the ancient falls, of shells of the small 

 fresh-water gastropod, Pomatiopsis lapidaria Say,^ 



'^See chapter 5. 



