1881.] OKjO [Spencer. 



possibility of Lake Erie flowing down through the Dundas valley (though 

 it suggested itself) did not seem probable, owing to the high lands between 

 the two great lakes. However, in the Canadian Naturalist, 1874, I re- 

 ferred to it as having been produced by a "mighty river." Tiiis was like 

 one of those gratuitous hypotheses that are common, now-a-days, for 

 attributing to a continental ice sheet most of the causes of the present phys- 

 ical features of the continent, which do not readily explain themselves. Sub- 

 sequently, Mr. George J. Hinde refers to it as having been scooped out by a 

 glacier. This assertion will be found in the sequel to be a perfectly un- 

 tenable hypothesis. Certainly, the origin of the valley was obscure, yet it 

 showed that the excavation of a canon of such magnitude required a pro- 

 portionately great agent; and no present stream would account for even a 

 small portion of the excavation. However, in this paper it will be seen that 

 its existence was unquestionably occasioned by the action of a mighty 

 river, as originally suggested. This outlet of Lake Erie also perfectly ac- 

 cords with, and accounts for the preglacial drainage of Pennsylvania, as 

 made known at the close of last year by Mr. Carll, of the Geological Sur- 

 vey of that State. 



II. Topography of the Region about the Western End of Lake 



Ontario. 



Ti^ie Niagara Escarpment. — This range of hills commences its course in 

 Central New York, and extends westward, at no great distance south of Lake 

 Ontario. It enters Canada at Queenston Heights, and thence its trend is 

 to the western end of the lake, where, near Hamilton, it turns northward 

 and extends to Cabot's head and Maintoulin island. Everywhere in Canada, 

 south of Lake Ontario, it has an abrupt fall looking towards the northward ; 

 but at Thorold and other places to the eastward its bow is more broken than 

 at Grimsby, and westward. At Hamilton, the brow of the escarpment varies 

 from 388 to 396 feet above Lake Ontario.* About five miles east of Ham- 

 ilton, the escarpment makes an abrupt bend enclosing a triangular valley, 

 down which Rosseaux creek, and other streams now flow. This valley is 

 about two miles wide at its mouth, and has a length of about the same 

 distance. 



About five miles westward of Hamilton, the Niagara escarpment be- 

 comes covered with the drift deposits of a broken country, or rather ends 

 abruptly in the drift of the region. Above the range, the country gradually 

 rises to the divide between Lake Ontario and the Grand river, or Lake Erie, 

 without any conspicuous features. South-eastward of Hamilton, at a 

 point about five miles from the brow of the escarpment, where the Ham- 



* Prof. Dana places the mean level of Lake Ontario at 233.5 feet above ocean- 

 level; the Canadian Geological Survey, at 232 feet; the New York Central 

 Railroad, at 24J).81: the Geological Survey of Pennsylvania, takes SifS feet as the 

 mean of the results of determining the level of Lake Erie ; tne Wetland canal 

 levels show Lake Erie as being 326.75 feet higher than Lake Ontario; and the 

 Hamilton and North Western Railway a dltterenee of 328 feet, t)oth of these last 

 routes being short lines with direct courses. Therefore the height of Lake 

 Ontario should be about 245 feet above the sea. 



