262 W. UPHAM — GLACIAL LAKES IN CANADA. 



Lake Warren that the country adjoining the eastern end of Lake Erie was 

 at that time depressed more than 200 feet, while the vicinity of Owen Sound 

 and the region north of Lake Superior were respectively about 180 feet and 

 about 300 feet lower than now. The Rome outlet of Lake Iroquois was at 

 first 50 or 100 feet above the sea level, and it was uplifted to about 300 feet 

 above the sea while it continued to be the outlet, and to probably 350 feet, 

 lacking less than 100 feet of its present height, by the time of the extension 

 of the sea to Ogdensburgh and Brockville. 



A similar comparison of the latest beaches of Lake Agassiz with the 

 marine submergence of the country southwest of James's bay, where the 

 land after the withdrawal of the ice-sheet stood 350 to 500 feet below its 

 present height, suggests that the outlet of Lake Agassiz at lakes Traverse 

 and Big Stone was slightly lower in relation to the sea level then than it is 

 now, perhaps by a difference of 25 or 50 feet; but probably this difference 

 was considerably greater, amounting to 100 or 200 feet, when the earliest 

 and highest beaches of that glacial lake were formed. In this connection 

 it may also be remarked that the studies of Chamberlin and Salisbury on 

 the driftless area of Wisconsin indicate a greater depression on the western 

 than on the eastern part of that area in the closing stage of the first Glacial 

 epoch,* just as Chicago had its present height while western Minnesota was 

 somewhat depressed at the time of recession of the later ice-sheet. 



Before leaving the Laurentian lakes, we may glance rapidly over some of 

 the explanations of their ancient elevated shore lines which have been offered 

 by successive writers. Mr. Thomas Roy, a civil engineer of Toronto, in a 

 paper communicated in 1837 by Lyell to the Geological Society of London, 

 regarded the body of water that formed the terraces and beach ridges near 

 Toronto as an immense lake, with surface at one time about 1,000 feet above 

 the sea, held in on all sides by formerly higher barriers of land, f But 

 Lyell during his travels in this country in 1841-42 examined these shore 

 lines with Mr. Roy and pronounced them to be of marine origin. J In 1861 

 Professor E. J. Chapman attributed the deposition of drift in this lake region 

 to a marine submergence exceeding 1,500 feet, but he was unable, like all sub- 

 sequent observers, to find any marine fossils. The beach ridges he referred 

 to a very extensive fresh-water lake formed in a later epoch w^hen the land 

 was uplifted, the lake being supposed to be held in by a greater elevation 

 of the country between the Adirondacks and the Laurentide highlands. § 

 During the same year Mr. Sandford Fleming published a detailed descrip- 

 tion and map of the Davenport ridge and terrace, which are portions of 

 the Iroquois shore line near Toronto, referring them to the action of Lake 



* U. S. Geo!. Survey, Sixth Annual Report, pp. 277, 304. 



t Proceedings Geol. Soc. London, vol. II, pp. 537-8. 



j Travels in North America, vol. II, chapter xx. 



I Canadian Journal, new series, vol. VI, pp. 221-229 and 497-8. 



