20 



regard to the meaning of facts, but mainly in the broader 

 interpretations, may be found in his volume on the "Evolu- 

 tion of Niagara Falls" [10]. 



INFLUENCE OF THE ONTARIO BASIN ON NIAGARA FALLS. 



The waters in the Lake Ontario basin have had an 

 important influence on the early history of the falls and 

 in the making of the older parts of the gorge. The history 

 of Lake Iroquois and the succeeding waters of the Lake 

 Ontario basin has not yet been fully worked out. There 

 is a remarkable submerged terrace at the mouth of Niagara 

 river known as Niagara bar, which has been supposed 

 to be a delta of the river formed when the lake stood at a 

 somewhat lower level. It is not certain that it is wholly 

 of the nature of a delta. The shallower part extends 

 about three miles (5 km.) out and six miles (9-6 km.) 

 along shore; the deeper part five miles (8-o km.) out 

 and 15 to 20 miles (24 to 32 km.) along shore. Many 

 soundings on it show "rocky" bottom. It is not known 

 whether these indicate stranded blocks or ledges of bed 

 rock in place. 



The place of this formation in Niagara history is 

 not yet definitely known, but it seems certain that it does 

 not belong to the early time of Lake Iroquois. It seems 

 more probable that such part of the deposit as is true 

 delta corresponds to a recent lower level of Lake Ontario. 

 On the other hand, it may be largely of inter-glacial age. 



Faint remains of what is supposed to be the first 

 or earliest shore of Lake Iroquois have been found north 

 of Lockport and Lewiston, N. Y., at Hamilton, Ontario, 

 and elsewhere, showing that Lake Iroquois first stood 

 at a lower level than the well known Iroquois beach and 

 was afterwards raised to the level of that beach by an uplift 

 of the land in the region of the Iroquois outlet at Rome, 

 N.Y. At Lewiston the level of the lake was raised about 

 50 feet (15 m.) and at its higher level stood 125 feet 

 (38 m.) above the present level of Lake Ontario. The 

 effect of this depth of water backing up into the gorge, 

 was much the same as a reduction in the height of the 

 falls, producing a corresponding decrease in the boring 

 of the cataract as well as a higher level for the caldron 

 bored out at the base of the falls. 



