40 Reviews — Dr. Daivson's Canadian Geology. 



TABULAR VIEWS OF GLACIAL DEPOSITS AND THEORIPS; 



INLAND PT.ATlSrS. 



MARGINAL AREAS. 



FLOATING ICE 

 GLACIER THEORIES. THEORIES. 



Terraces. 



Terraces and raised 

 beaches. 



Emergences of Modern Land. 



Travelled boulders 

 and glaciated 

 etones and rocks. 



Stratified sand and 

 gravel. 



(Algoma sand, etc.) 



Sand and gravel, 

 with sea shells and 

 boulders. 

 (Saxicava sand.) 



Shallow Seas and 

 Floating Ice. 



Stratified clay with 

 drift wood, and a 

 few stones and 

 boulders. 

 (Erie clay.) 



Striated rocks. 



Stratified clay, 



with sea shells. 



(Leda clay.) 

 Clay and boulders 



with or without 



sea shells. 



(Boulder-clay.) 

 Striated rocks. 



Deep water with 

 Floating ice. 



Submergence of 

 the land. 



Great continental 

 mantle of ice. 



Much floating ice 

 and local glaciers. 



Submergence of 

 Pliocene land. 



Old channels, indi- 

 cating a higher 

 level of the land. 



Old channels indi- 

 cating previous 

 dry land. 



Erosion by conti- 

 nental glaciers. 



Erosion by atmo- 

 spheric agencies, 

 and accumulation 

 of decomposed 

 rock. 



The Boulder-clay corresponds precisely in character with that of 

 Scotland and Northern Europe ; but land-ice has, in Dr. Dawson's 

 opinion, had nothing to do with its formation. To the period of its 

 deposition he assigns the excavation of the basins of the great 

 American lakes. Of course he rejects utterly the possibility of the 

 mode of this excavation being referred to glaciers. "Its real cause," 

 he says, " was obviously the flowing of cold currents over the 

 American land during its submergence." Further on he asserts that 

 "running water could not have done this [cut out the lake-basins], 

 for it could have no outlet," whereas in the same page (p. 14) he 

 mentions with approval the large collection of facts given by Dr. 

 Newberry in his Eeport on the Geology of Ohio, "which," he 

 admits, "go far to show that were the old channels cleared of drift, 

 and the continent slightly elevated, the great lakes would be drained 

 into each other and into the ocean by the valleys of the Hudson and 

 the Mississippi without any rock cutting." We do not know how 

 Dr. Dawson reconciles the two statements. 



The action of glaciers in Eastern America Dr. Dawson would 

 limit to the most insignificant degree, and he indeed goes so far as to 

 say that in Canada and Nova Scotia he has "seen nothing that could 

 fairly be regai'ded as the work of glaciers." The moraines which less 

 strictly marine glacialists often find in those regions, he regards as 

 " shingle beaches and bars, old coastlines loaded with boulders and 

 ozars " (sic). 



