academy of sciences] NIAGARA RIVER 159 



ing example be found of the interaction of many factors in the explanation of a great natural 

 feature of the earth's surface than in the evolution of Niagara Falls? Where can the signifi- 

 cance of the surface forms and the importance of accounting for them be better illustrated than 

 in the narrowing and widening, the shoaling and deepening, of the Niagara gorge ? And yet a 

 still further refinement in the analysis of Niagara's history was made several years later. 



The reader of a convincing explanation sometimes gains the impression that the problem 

 treated is wholly solved. Gilbert's lecture, convincing as it was as far as it went, was so con- 

 trived that it should leave no such impression of finality, for near its end a list of 16 unsolved 

 questions is presented, and it is then remarked: 



The tale of the questions is not exhausted, but no more are needed if only it has been shown that the sub- 

 ject is not in reality simple, as many have assumed, but highly complex. Some of the questions are, indeed, 

 easily answered. It may be possible to show that others are of small moment. . . . But after all paring 

 and pruning what remains of the problem will be no bagatelle. It is not to be solved by a few figures on a 

 slate, nor yet by the writing of many essays. ... It is a problem of nature, and like other natural problems 

 demands the patient gathering of many facts, of facts of many kinds, of categories of facts suggested by the 

 tentative theories of today, and of the new categories of facts to be suggested by new theories. 



It is presumably because Gilbert so fully recognized the complications of the problem 

 that he refrained from — one might say, resisted the temptation of — giving any numerical 

 estimate of the age of the Falls. To a man of smaller caliber the temptation would have been 

 irresistible. 



THE HUMAN ELEMENT 



The last page of the Toronto lecture contains one of its most interesting if not most im- 

 portant announcements. Early man was a witness of early Niagara. 



On a gravelly beach of Lake Iroquois ... he rudely gathered stones to make a hearth, and built a fire; 

 and the next storm breakers, forcing back the beach, buried and thus preserved, to gratify yet to whet our curiosity, 

 hearth, ashes and charred sticks. In these Darwinian days, we cannot deem primeval the man possessed of the 

 Promethean art of fire, and so his presence on the scene- adds zest to the Niagara problem. Whatever the an- 

 tiquity of the great cataract may be found to be, the antiquity of man is greater. 



It is pleasant to know that to Gilbert's keen observation the discovery of this ancient 

 hearth was due. 1 



' The geologic history of a prehistoric hearth. Amer. Anthrop., ii, 1889, 173-176. 



