Science, Geology and Physics 



the general level of the land be so changed that the Falls will 1908 

 never recede to the lake? The last and most important of all is: u eM 

 How long has it taken the Falls to grind out the Gorge thus far? 

 This latter question, viewed in its relation to the first one, forms 

 the basis of the present chapter. The great work of the Cataract 

 is going on before our very eyes. The history of this great river is 

 working itself out at the height of its glory, in an age when all 

 can behold. It is the more interesting since it is the only example 

 of the kind known. One can easily look back to the time when 

 the water flowed along the top of the plateau to Lewiston and 

 the Falls were situated at that point. This date, of course, wit- 

 nessed the birth of Niagara, for, wherever the waters flowed 

 before, they could not have taken this course before the Falls 

 began their work. The day that witnessed the beginning of the 

 one witnessed also the birth of the other. Likewise one cannot 

 help looking forward to the day when Niagara shall have accom- 

 plished its work, when its waters shall have completely ground 

 the plateau in two, and so drained Lake Erie to its bottom. 



What did the waters of the lakes do before the Niagara 

 began its history? How long has it been at its present work? 

 These are the questions interesting to every one; and by far 

 more interesting to one who is making a study of the formative 

 forces now contributing, and which have contributed to bring 

 about the present characteristics of surface structure. A few 

 important facts exist, and these now are beyond doubt, upon 

 which rest the inferences concerning the age of the Falls. In 

 ancient times the waters of Lake Erie did not find an outlet 

 through Niagara River, so there was no channel ready made for 

 the river when it began its present course. Even after the begin- 

 ning of the river the upper lakes, Huron, Michigan and Superior, 

 did not discharge their waters through Niagara. Until com- 

 paratively recent times only the waters from Lake Erie discharged 

 through this channel and therefore for many ages only a small 

 fraction of the present volume could possibly have been at work 

 on the Falls. 



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