CHARACTERS OF THE OLDER SECTIONS OF THE NIAGARA GORGE 703 



calls the "Erie Stage," meaning by that that the river carried only the dis- 

 charge of Lake Erie throughout this whole time. But his interpretation ignores 

 entirely two well established stages of the lake history. 



There are characters .in the Niagara gorge which appear to correlate per- 

 fectly with the three lake stages mentioned above. Ignoring the older basin 

 of the Whirlpool and beginning at the upper side of the Eddy Basin (lower end 

 of the gorge of .the Whirlpool rapids), the gorge from there to its mouth is 

 divisible into three sections on the basis of characters indicating variations of 

 volume. The newest of these sections extends from the upper side of the Eddy 

 Basin to the bend of the river just below Niagara University and is known as 

 the Lower Great gorge, for its cross-section corresponds to that of the Upper 

 Great gorge now being made, and its place among the other sections corre- 

 sponds precisely to the Port Huron stage of Lake Algonquin, when Niagara 

 had the full discharge of the four upper lakes. 



The remainder of the gorge to its mouth comprises the two earlier sections 

 and must, therefore, include the gorge correlative of the Kirkfield stage, which 

 endured a relatively long time and during which Niagara carried only the 

 discharge of Lake Erie. But this section can not be supposed to extend all the 

 way to the mouth of the gorge, for beginning at that point there must be a 

 section extending at least a short distance southward, which is the correlative 

 of Niagara's first flow, when the volume of the river was divided between five 

 points of discharge over the escarpment. The line of division between this first 

 or earliest section and the succeeding longer section which corresponds to the 

 Kirkfield stage is not so clear as might be desired, for the whole gorge below 

 the university has been subjected to important modifying conditions, which 

 have obscured very considerably the characters originally given to that part 

 when it was made. Among these modifying conditions are: (1) changes of 

 level of both lakes Iroquois and Ontario ; (2) thinner beds of the capping 

 Lockport limestone; (3) greater thickness of shale in the gorge wall, and (4) 

 longer time of weathering. 



It is believed, however, that the division point between the first or oldest 

 two sections is indicated with considerable clearness at a point about 2,000 feet 

 south of the mouth of the gorge. North of this point the alinement of the 

 cliffs is somewhat irregular and the average top width is approximately 1,400 

 feet. South of the division point the cliffs are remarkably straight and parallel 

 as far as the bend just below the university, and the average top width is close 

 to 1,300 feet. Only at one place, about opposite Smeaton ravine, does this part 

 of the gorge bend out of a straight line. For about 2,000 feet above its mouth, 

 therefore, the gorge appears to be the correlative of Early Lake Algonquin and 

 the period of first and divided flow of the river. The remaining portion south- 

 ward to the university is the correlative of the Kirkfield stage of Lake Algon- 

 quin, when Niagara carried only the discharge of Lake Erie. This section of 

 the gorge was therefore narrow, like the gorge of the Whirlpool Rapids, when 

 it was first made, though its top width is now nearly twice as great. The his- 

 tory found for this second section agrees in the main with Spencer's interpre- 

 tation, but the other two sections do not, for they both require large volume 

 for the river. 



The paper is devoted mainly to a discussion of the history and modifying 

 conditions which have affected these older parts of the gorge and made so 

 diflicult their correlation with the lake history. 



