444: Spencer — Another Episode in the History of Niagara. 



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long to 1)0 an important 

 feature, although remnants of 

 terraces corresponding to its 

 height are traceable at Foster's 

 flats, at the mouth of the 

 whirlpool, and perhaps a few 

 hundred feet above this point, 

 near the foot of the Whirlpool 

 Rapids upon the eastern side. 

 This epoch of maximum 

 volume and descent appears to 

 have been of short duration, as 

 the deep channel above Fos- 

 ter's flats is only 3,200 feet in 

 length, and is limited by the 

 barrier at the outlet of the 

 whirlpool (fig. 2), which is a 

 later remnant of a river 

 floor similar to that of the flats 

 below. The same hard Medina 

 ledges are exposed as far as 

 the foot of the Whirlpool 

 Rapids. The deeper cauldron 

 of the whirlpool behind its 

 contracted outlet occurs only as 

 an incident in the excavation of 

 the gorge, for, in part, it was 

 the site of a short fragment of 

 an ancient buried channel, and 

 it is not a record of the chang- 

 ing episodes of the modern 

 Niagara. The occurrence of 

 the rocky ledge, at the mouth 

 of the whirlpool, indicated 

 that the maximum descent 

 of the river was reduced 

 when the Falls reached this 

 point. The dissection of this 

 ledge by a channel, only 

 400 feet in width and 50 

 feet in depth, is the work 

 of the modern restoration of 

 the lowest cataract, which 

 was interrupted as will be ex- 

 plained later. 



