516 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 16, 



Territories West of the Rocky Mountains. — Physical Features. — 

 " The great contrast between the east and west sides of the Rocky 

 Mountains has been often mentioned, — the one abounding in sand- 

 stone with argillaceous limestones, without volcanos or volcanic 

 rocks, while on the other side recent igneous rocks prevail (basalts, 

 basaltic lavas, and trachytes) *, and the sandstones are comparatively 

 of small extent." This remark, which I quote from the learned and 

 beautiful work of Professor Dana, ' The Geology of the United 

 States Exploring Expedition under Commodore Wilkes,' will pre- 

 pare the reader for the examination of a country of a different cha- 

 racter from what has above formed the subject of investigation. 



The grand features of the country on the Pacific side of the Rocky 

 Mountains arise from the development of three ranges of mountains, 

 intersecting the country in a direction parallel with the general course 

 of the coast-line. Three of these are north and south ranges, — the 

 Coast Range, the Cascade Range, and the Blue Mountain Range. 

 The first lies near the coast, the second 130 miles inland, and the 

 third 350 miles from the sea. 



The Cascade Range is much the most extensive of the three, and 

 even rivals the Rocky Mountains in the height of some of its peaks. 

 It may be traced, according to Professor Dana, far into California, 

 and northward into Russian America ; retaining throughout a direc- 

 tion nearly parallel with the coast. It terminates northward, accord- 

 ing to Grewingk, in the lofty volcano of Mount Wrangell, in lat. 

 62° N., where it blends with the lateral volcanic range, forming the 

 remarkable promontory of Aliaska. The main body of the Cascade 

 Range, in Oregon, is seldom over 5000 or 6000 feet in elevation. 



The Blue Mountains form the western boundary of the Valley of 

 the Snake River (of Lewis and Clarke), flowing into the Columbia. 

 Immediately to the north of this river, as far as Fort Colville, they 

 are interrupted by an extensive level tract ; but to the north of Fort 



Forbes, respecting the probability of the passage of the Gulf Stream at some 

 former period up the valley of the Mississippi (Quart. Journ. Geol. Soc. vol. viii. 

 p. 89, &c.), — a theory of the highest interest aud importance in accounting for 

 the changes of temperature and climate on the surface of our globe, and which, 

 though based by its author upon purely physical considerations, is in harmony 

 with all the geological facts and evidence which have come under the writer's 

 notice. 



The age of freshwater accumulations and deposits suggested in the text comes 

 much nearer to our own times. 



* Dr. Grewingk, in his Map of Russian America, assigns the localities of fifty- 

 eight active volcanos on the North-west Coast of America. They lie in a line 

 running from the north end of Prince of Wales Island, in lat. 56° N., following the 

 course of the coast through the peninsula of Aliaska and the Aleutian Islands. 

 Many of their summits rise into the region of perpetual snow. The line in which 

 the volcanic peaks of Aliaska lie, when prolonged to the eastward, strikes the Big 

 Beaver Mountains on the Yukon. On the side of the Atlantic, modern volcanic 

 rocks occur in Jan Mayen's Island only, whose principal mountain, Beerenberg, 

 rises 6870 feet above the sea. 



I have been recently informed that the Basquiau Hills, which lie to the south 

 of Cumberland House, on the Saskatchewan River, are volcanic, and that an 

 eruption has been observed there within the last year. The report requires con- 

 firmation. No other example is known of the existence of a volcano in any part 

 of America east of the Rocky Mountains. 



