448 Spencer — Another Episode in the History of Niagara. 



the lake. The succession of plains can he traced for a long 

 distance down the St. Lawrence, so that one may conclude that 

 there has been comparatively little warping or unequal deforma- 

 tion of the region, since the river began to deepen its channel. 

 Thus it would seem that the dissected barrier had a height 

 between 100 and 140 feet, and that the subsequent uplift of 

 the region has been only about 25 feet more than at the mouth 

 of the Niagara gorge. Thus the features of Lake Ontario con- 

 firm the hypothesis of the recent rising of the waters in the 

 Niagara gorge, which has been adopted to interpret one of the 

 important episodes in the history of Niagara Ttiver. 



Explanation of the Narrows of the Gorge at the Whirlpool Rapids. 



The most important feature in the history of the river that 

 has remained unexplained is the narrowing of the canon along 

 the section of the Whirlpool Rapids. Mr. F. B. Taylor* has 

 accounted for both the narrowness and the shallowness of the 

 section somewhat as follows. He says that one of the princi- 

 pal hypotheses for explaining the section of the gorge at the 

 Whirlpool Rapids is that " the whole gorge, excepting always 

 the whirlpool basin, has been made by the modern or post- 

 glacial river Niagara, and that the magnitude of the gorge in 

 the different sections is due to the variation of volume." He 

 says that this seems to be the simpler of the hypotheses and 

 proceeds a priori to support his' proposition by a lengthy 

 brochure entitled " Origin of the Gorge of the Whirlpool 

 Rapids at Niagara." According to his supposition, the waters 

 of the Huron basin, hitherto retained by an ice dam to the 

 northeast, were now withdrawn from the Niagara discharge 

 while the falls were passing the whirlpool section, thus reduc- 

 ing its volume to one-ninth the present amount. Here it 

 should be noted that by actual measurement, the drainage is 

 between \ and \ (at different periods of the season of measure- 

 ment). Until there is a more perfect determination, these are 

 the only figures that we have to go by. Not only has he 

 reduced the discharge of the Niagara to half as great as indi- 

 cated by ascertained data, but he neglects to take into account 

 the evidence of the buried channel at this point, which in part 

 still remains intact upon the sides of the chasm, and which the 

 modern river has taken possession of. Such a depression 

 is only characteristic of this section of the Whirlpool Rapids, 

 for just at its foot the rocky walls are higher than those along 

 the mid section. Mr. Taylor assumes that the preglacial gorge 

 of the whirlpool ended abruptly, in an amphitheater, like 

 modern canons, and not by transition slopes (which everywhere 

 mark the features of the preglacial erosion) from the buried 



*Bull. Geol. Soc. Am., vol. xix. pp. 59-84, 1898. 



