I02 PROCEEDINGS OF THE CANADIAN INSTITUTE. 



The modern Niagara took possession of the old Tonawanda channel, which had 

 drained a portion of the Niagara tableland in pre-glacial times. Its valley was about 

 one and a half miles wide and ninety feet deep, and crossed the course of the modern 

 river. The rapids above the Falls represent the site of the modern waters, now 

 descending over its side into the ancient Tonawanda channel, which had been filled 

 with drift. This ancient valley is now buried, and continues westward of the whirl- 

 pool to form the St. David's Valley, about which so much has been written. The 

 whirlpool gorge is only a modern enlargement of a small valley starting, in pre- 

 glacial times, from near where the railway bridges are now located, and forming a 

 little tributary of the Tonawanda channel, just mentioned. 



The older geological features and the character of the strata have been known 

 for fifty or sixty years, but the features here mentioned are those directly bearing 

 upon the physics of the river, which were not formerly understood. 



The episodes of the river may be briefly outlined. The first was of long dura- 

 tion, when the descent of the river was about 200 feet, and the volume of water 

 one-fourth of that of the present amount (only the drainage of the Erie basin). 

 Then we have all the waters of the upper lakes flpwing over Niagara, and shortly 

 afterwards the surface of Lake Ontario was lowered to 420 feet below the upper 

 level of the river. Thus, in a general way, we have arrived at the time when the 

 Falls had reached the foot of the whirlpool rapids, by which time the waters of the 

 Ontario basin rose sixty feet or more above their present level. In the meanwhile 

 there were three principal cataracts, the lower gaining upon the upper. But by 

 the time the Falls had retreated to just above where the railway bridges cross the 

 gorge the Ontario waters were again lowered, so that the modern descent of Niagara 

 river is 326 feet. The physics of the short section along the whirlpool rapids is 

 not yet understood; but even in spite of this, with the consequent errors in the 

 theoretical determination, the age of the Falls so far has not been found to greatly 

 differ from the computations made in 1893, which assigned the period between the 

 time when the Niagara was a strait and the present day to be 32,000 years. 



These changing episodes, which appear complex, are after all largely assignable 

 to one cause, namely, the unequal elevation of the earth's crust in the lake region, 

 the amount being greater towards the north-east than in the opposite direction. 

 With the rise of the land, the Huron, Michigan and Superior, collectively named 

 the Algonquin basin, was eventually drained by way of the Nipissing and the Ottawa 

 valleys; and the waters of the Lundy basin, the name for the united Erie and Ontario 

 basins, were lowered so as to leave only an insignificant Lake Erie, and the Iroquois 

 gulf, extending in the Ontario basin to the foot of the escarpment at the mouth of 

 the Niagara river, into which the Falls descended directly at their birth. With the 

 continued rise of the land the waters of the Ontario basin sank, in so far as they 

 affected Niagara, to eighty feet below their present level. The' land, now rising 

 more rapidly towards the north-east than the south-west, tilted the river of the 

 Algonquin basin so as to raise a barrier across the Nipissing outlet (worked out 

 by Mr. F. B. Taylor), which diverted the waters of the upper lakes into the Niagara 

 drainage only some 7,000 or 8,000 years ago. The same kind of movement raised 

 the barriers at the outlets of both Lake Erie and Lake Ontario so as to back their 

 waters towards the heads of the basins; and, in the case of Lake Ontario, its surface 

 rose some sixty feet or more in the lower part of the Niagara gorge. But a portion 

 of the barrier at the outlet of Lake Ontario, being composed of drift, has recently 

 been washed way by the St. Lawrence river so as to reduce the surface of Lake 

 Ontario to its present level. 



The movement is slow. The rise of the land in the Niagara district is about 

 one and a quarter to one and a half feet a century; about the region of Lake 

 Nipissing, nearly two and a half feet, and about the outlet of Ontario, between four 

 and five feet a century. These upward movements were determined from geological 

 observations made at Niagara, and their effect upon the tilted beaches, which had 



