and the Geology of the Surrounding Country. 131 



Lewiston. From the nature of the bed cf the river for fifteen 

 miles below Lake Erie, it may be doubted whether this rapid 

 descent along the whole distance would be continued ; for 

 the stream, having no heavy blocks of rock to remove, would 

 keep its channel clear with a far less declivity ; and should 

 this prove the case here, we might still have a fall of a few 

 feet, at the outlet of Lake Erie, over the limestone succeeding 

 the saliferous group. 



Whether such a fall would occur at the outlet of Lake Erie, 

 depends on the solution of the problem regarding the acquired 

 declivity in the bed of the river below Lake Erie. Which- 

 ever way it may occur it will make no material difference in 

 the great result, which will be either a continuous rapid 

 stream from Lake Erie to Lewiston, or a rapid stream with a 

 fall at the outlet of Erie. If present causes continue to ope- 

 rate as now, such will be the consummation, the finale, of 

 the grand cataract of Niagara. 



It is unnecessary here to follow on this recession gradually 

 from the outlet of Lake Erie to the final drainage of a great 

 portion of its waters. The views which have been enter- 

 tained of the sudden drainage of this or any of the upper 

 lakes, and a deluging of the country on the north and east, 

 are no longer considered as tenable by any one, and even 

 if Lake Erie could be drained suddenly, it would cause no 

 deluge of any importance. If the whole lake were at once 

 placed upon Lake Ontario, it would only elevate its surface 

 by about one hundred and fifty feet, so that its extent would 

 scarcely exceed the limits of the ancient lake ridge, and the 

 outlet would still be the valley of the St. Lawrence. 



In calculating the future recession of Niagara falls, there 

 are many disturbing influences to be considered. At the 

 present time, by means of the Erie and Welland canals, large 

 quantities of water, which formerly flowed over the fall, are 

 returned to Lake Ontario by other than the natural channels. 

 The Illinois canal, at the southern extremity of Lake Michigan, 

 will drain a large amount of water in that direction, which 

 will find its way to the ocean through the Mississippi river 

 and Gulf of Mexico. Extensive improvements have been 



