Niagara Falls 



1908 cleft has been sawed by the force of the water, from a structure 

 Hu,bert whose features were continuous, as is manifest by the similarity 



of the exposed strata on the two sides of the stream. To be 

 convinced of the fact that the Falls are gradually receding, it is 

 only necessary to observe them closely for a few years. The 

 breaking away of an immense mass of rock previously described 

 is one of the recent events in the history of the river. This 

 establishes the fact that the Gorge is growing longer from its 

 northern end through the agency of the waterfall. 



These facts show us the river working at a monstrous task. 

 Its work is only partly done. Two questions come to us almost 

 immediately: When this work is done what will it do? and, 

 What did it do before its present work begun? The waters of 

 Lake Erie could never have flowed to Lake Ontario without 

 wearing away at the Gorge we now see. The birth of the river 

 and the cutting of the canyon were simultaneous. Of this much 

 we are assured. 



A superficial study of a map of North America will show at 

 once a great difference in the northern and the southern sections. 

 From the region of the Great Lakes northward the district is 

 one continuation of lakes, ponds, swamps and rivers with many 

 rapids. South of the Ohio there are few lakes, and the rivers 

 flow on with almost unbroken courses. Here is a region much 

 older than that to the north; and its waters have had ages more 

 in which to mould down elevations and fill up depressions. The 

 cause of this difference in the characteristics of the streams of the 

 North and those of the South is to be explained by the great Ice 

 Age. As far as we now know there may have been little differ- 

 ence in relief forms between the two sections before the encroach- 

 ment of the ice. During the glacial epoch the whole northern 

 part of the continent was covered with a thick ice sheet, which 

 was continually renewed at the north, and as continually drifted 

 slowly in a general southerly direction. As this heavy ice cap 

 passed over the surface, it acted somewhat like a river in its 

 erosive power, only working much greater changes. It not only 



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