330 Miscellaneous, 



by steppes, which exhibit lines of ancient denudation at three 

 different levels ; the lowest is of fresh-water origin ; the next 

 belongs to the Drift-deposits, and the highest is the great Prairie- 

 level of undenuded Cretaceous strata. This plateau has once 

 been complete to the eastern axis, but is now incomplete along its 

 eastern edge, the soft strata having been removed in the region of 

 Lake Winipeg. 



The eastern axis sends off a spur that encircles the west shore 

 of Lake Superior, and is composed of metamorphic rocks and 

 granite of the Laurentian Series. To the west of this follows a 

 belt where the floor of the plateau is exposed, consisting of Lower 

 Silurian and Devonian rocks. On these rest Cretaceous strata, 

 which prevail all the way to the Rocky Mountains, overlaid here 

 and there by detached tertiary basins. 



The Rocky Mountains are composed of Carboniferous and De- 

 vonian limestones, with massive quartzites and conglomerates, 

 followed to the west by a granitic tract which occupies the bottom 

 of the great valley between the Rocky and the Cascade Mountains. 

 The Cascade chain is volcanic, but the volcanos are now inactive ; 

 to the west of it, along the Pacific coast. Cretaceous and Tertiary 

 strata prevail. The description of these rocks was given with con- 

 siderable detail on account of their containing a lignite, which for 

 the first time have been determined to be of Cretaceous age. This 

 lignite, which is of a very superior quality, has been worked for 

 some years past by the Hudson Bay Company, and is in great 

 demand for the steam-navy of the Pacific station, and for the 

 manufacture of gas. Extensive lignite-deposits in the Prairie 

 were also alluded to ; and, like those above-mentioned, were con- 

 sidered to be of Cretaceous age ; but, besides these, there are also 

 lignites of the Tertiary period. 



The general conclusion was that the existence of a supply of 

 fuel in the Islands of Formosa and Japan, in Vancouver's Island, 

 in the Cretaceous strata of the western shores of the Pacific, but 

 principally within the British territory, and in the plains along 

 the Saskatchewan, will exercise a most important influence in 

 considering the practicability of a route to our Eastern possessions 

 through the Canadas, the Prairies, and British Columbia. 



"On Elevations and Depressions of the Earth in North Ame- 

 rica." By Dr. A. Gesner, F. Gr. S. 



After some observations on the differences between volcanic 

 uplifts of the land and the slow upward and downward shiftings 



