No. L] DAWSON — POST-PLIOCENE. 23 



Lawrence, and of Arnprior on the Ottawa. Below these points 

 the Valleys of the Ottawa and St. Lawrence present everywhere 

 the deposits above tabulated, in a greater or less degree of com- 

 pleteness. They are connected with the similar deposits of New 

 England, through the valley of Lake Champldin, and across the 

 low lands of Nova Scotia and New Brunswick. 



Whittlesey has described the Western Drift Deposits in tlie 

 Smithsonian Contributions, vol. xv., and according to him the 

 Boulder drift is there the upper member of the series. More 

 recently Prof. Newberry has given a summary of the ficts in his, 

 Report of the Geological Survey of Ohio for 1869. From these 

 sources I condense the following statements, 



The lowest member of the Western drift, corresponding to the 

 Erie clays of the Canadian Report, is very widely distributed and 

 fills up the old hollows of the country, in some cases being two 

 hundred feet or more in thickness. Toward the north these 

 clays contain boulders and stones, but do not constitute a true 

 Boulder-clay. They rest, however, on the glaciated rock sur- 

 faces. They have afforded no fossils except drifted vegetable 

 remains. 



Above these clays are sands of variable thickness. They con- 

 tain beds of gravel, and near the surface teeth of elephants have 

 been found. On the surfiice are scattered boulders and blocks of 

 northern origin, often of great size, and in some cases transported 

 two hundred miles from their original places. 



More recent than all these deposits are the "Lake Ridges" 

 marking a former extension of the great lakes. Dr. Newberry 

 considers the Erie clay to be the deposit of a period of submer- 

 gence following the action of a continental glacier, and he main- 

 tains that the old channels now filled with Erie clay are so deep 

 as to indicate that in the earlier glacier period the land was at 

 least five hundred feet higher than its present level. At the close 

 of this period of submergence the boulder drift was deposited by 

 northern currents and ice, and then the land gradually rose to its 

 present level. 



The facts thus summed up by Dr. Newberry indicate, in pro- 

 ceeding from the older to the newer. 



1 . An elevated continent and the erosion of deep valleys. 



2. Glaciation of th'^, surface. 



o. Filling of the valleys with Erie clay. 



•4. Distribution over the surface, of boulders and Northern drift. 



