500 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 16, 



gether a geological horizon of a grandeur and extent unequalled pro- 

 bably in any other part of the world, largely as the researches of Sir 

 Roderick Murchison, Sir Charles Lyell, and others have shown such 

 formations to be developed in Russia and the United States. 



A slight sketch of the chief physical features of this wide region 

 will demonstrate the remarkable symmetry and unbroken condition 

 of its sedimentary deposits, and to what an unusual degree they have 

 apparently been exempted from those igneous disturbances which 

 have complicated the geological structure of many other countries 

 of far less extent in other parts of the world. 



Territories East of the Rocky Mountains. 



Physical Features ; and Range of the Crystalline Rocks. — 

 Separated from Canada by the great granitic range of the Laurentine 

 or Canadian Mountains, which form the division between the hy- 

 drographic basins of these northern regions and those of the St. 

 Lawrence and its great lakes, the Hudson's Bay Territories may be 

 considered as forming one vast plain, diversified only by a single 

 low granitic ridge running northwards from the west end and 

 almost the whole north shore of Lake Superior as far as Great Bear 

 Lake, in a direction nearly parallel with the range of the Rocky 

 Mountains. This low belt of crystalline rocks (see Map, PI. XIV,) 

 averages about 200 miles in breadth, and is evidently the northern 

 continuation of the Laurentine range, which, after extending unin- 

 terruptedly along the northern frontiers of Canada until it comes in 

 contact with the northern spurs of the Alleghanies near the mouth 

 of the St. Lawrence, is deflected northwards in a direction again 

 nearly parallel with the Rocky Mountains through Labrador and 

 along the shores of Hudson's Straits and Baffin's Bay until it finally 

 disappears beneath the limestones of Lancaster Sound and Barrow's 

 Straits. The striking correspondence between the direction of this 

 granitic range, as thus traced, and the general contour of Hudson's 

 Bay will be at once obvious from an inspection of the Map (PI. XIV.), 

 and would appear to point out this vast mass of crystalline rocks as 

 the probable axis of elevation of the great movement by which the 

 Hudson's Bay Territories, as well as Labrador and the lands and 

 islands along the west coast of Baffin's Bay, were first upheaved from 

 the primeval ocean under which they once reposed. The grand 

 chain of the Rocky Mountains may be considered also as forming 

 a new axis of elevation, at nearly an equal distance farther west, up- 

 heaving in a similar manner the wide-spread strata which repose on 

 its flanks. 



The existence of lines of division, pursuing a parallel course, in a 

 general meridional direction, like those just mentioned, is one of the 

 most prominent general circumstances hitherto ascertained respecting 

 the geology of this part of America. The course of the Rocky 

 Mountain chain, from the Sierra of Mexico in lat. 30° to its termina- 

 tion on the coast of the Arctic Sea in lat. 69°, is about N. by W., 

 with very little deviation anywhere. This is also the general direction 



