1()8 A. p. COLEMAN LAKE IROQUOIS AT TORONTO 



I have found the same two genera in the old lake deposits of Rainy river, 

 said b}^ Upham to have been formed in an arm of lake Agassiz, but by 

 Tyrrell to belong to a later lake. Dr Bell has found fresh water shells in 

 old lake deposits north of lake Superior, and lake Warren (or possibly 

 lake Algonkin) left man}'- species of fresh water shells in its muds and 

 sands near Georgian bay. Professor Chapman, formerly of Toronto Uni- 

 versity, gives a list of 11 species from Angus, south of Georgian bay, and 

 the present writer has collected 19 species from the same region. 



These great sheets of water, then, from Agassiz to Iroquois, were evi- 

 dently fresh. A fragment of marine shell picked up last summer in the 

 Peninsula gravel pit north of lake Superior has been submitted to Dr 

 Dall, of the Smithsonian Institution, who pronounces it that of a recent 

 oyster, but as the transcontinental trains of the Canadian Pacific railway 

 pass along one side of the ballast pit, there seems no doubt that the shell 

 reached its position by human agenc^^ 



All the evidence, then, afforded by fossils sj^eaks of fresh water, and it 

 fails altogether to support the idea that the sea has invaded any part of 

 the Great Lake region in Glacial or post-Glacial times. It is a striking 

 fact, however, that marine deposits occur but a short distance away in 

 the Saint Lawrence valley to the east, the Ottawa valley to the northeast, 

 and on the shores of the rivers flowing into Hudson bay on the north. 

 Sir William Dawson and others note the Leda clays and Saxicava sands, 

 often with numerous subarctic marine shells, all along the Saint Law- 

 rence valley up to 550, or perhaps 600, feet above sealevel. Similar shells 

 and marine fish occur along tbe Ottawa, and the boiies of a whale have 

 been found 420 feet above sealevel in a railway gravel pit near Smiths 

 Falls, between the two rivers.* Dr Bell and Mr Tyrrell report marine 

 terraces with shells not more than 200 miles north ol the Great lakes. 



Warping of the Iroquois Beach 



It is evident that if the sea rose uniforml}^ over the eastern part of 

 Canada and the adjoining states the lake Ontario basin, which now stands 

 247 feet above the sea, would be deeply submerged when marine terraces 

 were being formed at Montreal, 550 i'eet above the present sealevel, so 

 deeply as to rise 130 feet above the Iroquois beach at Toronto. However, 

 the researches of Gilbert and Si)encer prove a very marked differential 

 elevation of the old beach, which is now tilted up at its northeastern end. 



Spencer holds that if we subtract the total elevation of the land since 

 Iroquois times it will leave the beach at the level of tidewater. To test 



*The Canadian Ice Age, 1S93, p. G3 ; also pp. 195- A13. 



