19 



to Port Huron brought the Nipissing great lakes to an 

 end and inaugurated the present lakes. Thus, the present 

 volume of Niagara river includes the entire discharge 

 from the four lakes above, and this arrangement of over- 

 flow has continued ever since the last change of outlet. 



INFLUENCE OF THIS SUCCESSION ON THE VOLUME OF 

 NIAGARA RIVER. 



The main facts of the lake history stated in the fore- 

 going outline are all firmly established by observations, 

 and the order of the lake stages, with their changes of 

 outlet and the effects of these changes upon the volume 

 of Niagara falls, are fixed beyond peradventure. The 

 variations of volume are fixed primarily by the facts 

 of the lake history, without any reference whatever to 

 the characters displayed in the Niagara gorge. These 

 facts are, therefore, the key to Niagara history and are 

 far more weighty and reliable than any of the characters 

 seen in the gorge ; for no matter what characters are found 

 there, it is- certain, nevertheless, that the volume of Niagara 

 river and the falls have varied as indicated by the lake 

 stages and in the order named. With these facts in hand, 

 the problem of correlation is relatively simple : can definite 

 correlatives of lake stages be recognized in the gorge, 

 and can five such correlative units, corresponding in 

 character and order of occurrence to the five lake stages 

 mentioned, be recognized? 



The investigations of Dr. G. K. Gilbert and the 

 writer of this text indicate that the correlation of gorge 

 characters with the lake stages mentioned above is com- 

 plete. The variations of volume of Niagara as deduced 

 from the history of the great lakes may be represented 

 graphically as in the accompanying diagram (p. 16). 



Dr. J. W. Spencer also has contributed many valuable 

 facts to the discussion of these subjects and was a pioneer 

 in the study of the Great Lakes region. He named Lake 

 Algonquin and, although its beach was already known 

 in several places, its continuity and the rate and direction 

 of its deformation in Ontario were first determined by 

 him. He also named Lake Iroquois and made the first 

 extended survey of its shore in Ontario. His views, 

 differing from the views here expressed, sometimes with 

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