514 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 16, 



place a similarity of condition of the North American Continent from 

 latitude 75° down to 45°. 



Elevatory Movements ; and Pleistocene deposits. — Into such 

 questions, however, as the above, or into the discussion of the various 

 hypotheses by which the elevations and depressions of the surface of 

 these vast territories may be accounted for, it is beyond the province 

 of the present paper to enter ; nor, in the present state of our know- 

 ledge, would a summary of this kind admit of the necessary elucida- 

 tion. I sliall merely say, that, adopting the opinion of Sir John Ri- 

 chardson and the geologists of the United States, that " the eastern 

 portion of the continent was first elevated, and that the older rocks 

 on the west were subsequently overlaid by newer deposits," I con- 

 sider that the great mass of the underlying formations surrounding 

 Hudson's Bay are wholly palaeozoic, and that the currents or waves 

 of translation, if such there were, must have had an easterly direction 

 in these latitudes, and gained strength as they rolled towards the 

 Atlantic, when they swept away wholly or partially the fossiliferous 

 deposits that covered the older rocks of Hudson's Bay, Canada, and 

 the eastern parts of the United States ; the former extent of the newer 

 rocks being indicated by the patches which remain. The only recent 

 formations overlying the Silurian rocks, which have been hitherto 

 discovered along the eastern coasts of Arctic America, are patches 

 of pleistocene deposits, with marine shells of existing Arctic species 

 (Mya truncata, Saxicava n'gosa, &c.) ; the whole crowned by an 

 immense profusion of boulders and erratic blocks. The country 

 forming the Hudson's Bay Territories is too flat for the immense 

 erratic formation extending over every part of it to be explained by 

 reference to the motion of glaciers ; and I think it is more probably 

 due to the action of icebergs and floating masses of ice, still so com- 

 mon along these coasts, and which are without doubt performing 

 at the present day precisely a similar oflice, in strewing the bed of 

 the ocean in which they are found with the fragments transported 

 from the adjacent shores *. 



With reference to the character of the pleistocene or drift forma- 

 tion, it may be mentioned that as we ascend the rivers of this region, 

 especially along the basins of Lake Winipeg and its affluents in the 

 prairie districts, the sandy and clayey deposits are found to abound 

 with land and freshwater shells, such as Unio, Helix, Pupa, &c., of 

 species now living on the borders, or in the beds of the rivers and 

 lakes. The eliifs containing those shells are often raised more than 

 100 feet above the present levels of the banks of the streams, and 

 appear to be ancient lake- or river-terraces ; leading to a belief that, 

 great as is the present extent of freshwater surface in the North 



* In the Appendix to Dr. Scoresby's ' Journal of a Voyage to the Northern 

 Whale Fishery,' Professor Jameson enumerates among the specimens found on an 

 iceherg near Cape Brewster the following : — 



1. Transition clay-slate. 4. Hornblende mica-slate. 



2. Slaty talcose granite. 5. Gneiss. 



3. Granular felspar. 6. Basaltic greenstone. 



