May 31, 1889.] 



SCIENCE. 



427 



places, true glaciers are found only about the heads of the Bow, North 

 Saskatchewan, and Athabasca. Some of the valleys penetrating this 

 range on the east are lightly timbered or in part prairie-like in 

 character, but as a rule the mountains are thickly wooded wherever 

 sufficient soil exists for the support of trees ; and, owing to the 

 greater rainfall on the western slopes of the range, the forests are 

 there often very dense. 



Crystalline schists and granite are scarcely known in any part of 

 the Rocky Mountains between the 49th and 60th parallels, the 

 ranges bemg built up chiefly of a great series of paleozoic rocks, 

 extending from the Cambrian to the carboniferous, with a total 

 thickness of more than 28,000 feet in the Bow River region. There 

 are also, however, more or less isolated basins of rocks of creta- 

 ceous age, which rocks were evidently at one time continuous with 

 those of the same age in the eastern foot-hills and Great Plains. 

 In these basins, beds of bituminous coal and of anthracite are found. 

 Deposits of copper ores and of galena are so far the most impor- 

 tant metalliferous minerals discovered in association with the older 

 rocks of this mountain system. 



The south-western side of the Rocky Mountain range is defined 

 by a very remarkable, straight, and wide valley, which can be traced 

 uninterruptedly from the 49th parallel to the head waters of the 

 Peace, — a distance of 700 miles or more. This valley is occupied 

 by the upper portions of several of the largest rivers, including the 

 Kootanie, Columbia, Fraser, Parsnip, and Finlay. Gold-placers 

 have been found and worked at a number of points along this val- 

 ley, and important discoveries of various ores are now being made 

 in its vicinity near the Upper Columbia and Upper Kootanie. It is 

 naturally adapted to become a main line of communication between 

 the southern and northern portions of the province, near its eastern 

 boundary. 



The next mountain system to the south-west of the Rocky Moun- 

 tains is referred to under the general name of the " Gold Range," 

 though really a complex and somewhat irregular mountainous belt, 

 which includes several more or less distinct and partly overlapping 

 ranges. The Purcell, Selkirk, and Columbia^ ranges constitute its 

 southern part, while to the north it is represented by the Cariboo 

 Mountains, and still farther northward — after an important inter- 

 ruption — by the Omenica and Cassiar Mountains. These moun- 

 tains are, generally speaking, less rugged in detail than the Rocky 

 Mountains, including extensive areas of high, rolling plateau coun- 

 try, and supporting in their southern and more massive portion 

 numerous glaciers and wide snow-fields. The highest summit so far 

 actually measured is Mount Donald, on the line of the Canadian Pa- 

 cific Railway, 10,645 i^^i- The forests of the Purcell, Selkirk, and 

 Columbia ranges are dense and tangled ; and these mountains are 

 much more difficult to traverse, and even less perfectly explored, 

 than the corresponding portion of the Rocky Mountains. Granites 

 and crystalline schists of great age are abundant in the Gold 

 Range, together with great masses of paleozoic rocks, respecting 

 the structural relations of which very little is as yet known. 



The Gold Range, as a whole, doubtless constitutes the most im- 

 portant metalliferous belt of the province. The richest gold-fields 

 are closely related to it, and discoveries of metalliferous lodes are 

 reported in abundance from all parts of it which have been ex- 

 plored. The deposits already made known are very varied in char- 

 acter, including highly argentiferous galenas and other silver-ores 

 and auriferous quartz veins. 



Between the Gold and Coast Ranges lies a region, which, for 

 purposes of description, has been named the " Interior Plateau of 

 British Columbia," having an average width of one hundred miles 

 and a mean elevation of about 3,500 feet. Its height, on the 

 whole, increases to the south ; while northward it falls gradually 

 toward the group of large lakes and the low country about the 

 head waters of the Peace. This has, over a considerable part of its 

 area, been covered by widespread flows of basalt and other volcanic 

 rocks in the later tertiary period. It is now traversed in various 

 directions by a system of deep, trough-like valleys of erosion, gen- 

 erally occupied by streams and rivers. Water standing at an ele- 

 vation of three thousand feet above the present sea-level would 

 flood most of these, and would divide its surface into a number of 



1 The name " Gold Range " is often specially applied to that here spoken of as the 

 Columbia Range. 



islands, while a large tract of country about the 53d and 54th par- 

 allels of latitude would be completely submerged. In some places 

 the plateau is pretty level and uniform, but many portions of it 

 attain an elevation much exceeding the mean above stated ; and it 

 is usually only when broadly viewed, and in contrast with its 

 bounding mountain ranges, that its character as a plateau is ap- 

 parent. Its main area is practically closed to the north, about lati- 

 tude 50" 30', by the ends of several intercalated mountain ranges, 

 in which many of the summits attain a height of 8,000 feet. 

 Nearly coincident with the 49th parallel is a second transverse 

 mountainous zone, formed in the same way, the only orographically 

 important gap in which is that found in the vicinity of the Okana- 

 gan River. The southern portion of the Interior Plateau includes 

 much open country, constitutes the best grazing region of British Co- 

 lumbia, and afi'ords, besides, some good agricultural land. To the 

 north, with increasing moisture, it becomes generally forested, but 

 embraces large areas which are suitable for eventual agricultural 

 occupation. 



The tertiary rocks of the Interior Plateau hold in many places 

 beds of lignite or of coal. Where not concealed by the later rocks, 

 the formations preponderantly represented belong to the paleozoic 

 age. These include very notable developments of materials origi- 

 nally volcanic in origin. The geological structure is scarcely less 

 complex than that of the mountain regions, and much yet remains 

 to be done toward its elucidation. The Interior Plateau also pre- 

 sents some important granitic areas, and, particularly toward its 

 south-western border, limited basins of cretaceous rocks. As a 

 metalliferous region, it is destined to take high rank, particularly, it 

 is believed, in respect to the precious metals, though its ores are too 

 varied in character to admit of description in a few words. Placer 

 deposits of gold have been worked in a number of widely sepa- 

 rated localities, and platinum is abundant in the Similkameen re- 

 gion. 



The Cascade Range of Oregon and Washington is largely com- 

 posed of erupted volcanic materials, to which its characteristic fea- 

 tures are due, though these materials rest upon a basis of older 

 rocks. Its course is north and south, and it is definitely terminated 

 in the vicinity of the international boundary. Near the mouth of 

 the Fraser River its place is taken by a new mountain system, geo- 

 graphically and geologically distinct, in the composition of which 

 volcanic ejectamenta play no prominent part. This forms the third 

 member of the Cordillera in British Columbia, and, under the name 

 of the " Coast Ranges," pursues a direct north-westward course 

 for over 900 miles, forming throughout this distance the bordering 

 mountain-zone of the continent. The Coast Ranges have an 

 average width of about one hundred miles, and consist of numerous 

 constituent ridges and minor mountain-axes with varied trends, 

 frequently separated by deep parallel and transverse valleys. The 

 average altitude of the higher summits is between 6,000 and 7,000 

 feet, while some exceed 9,000 feet. Glaciers are of frequent oc- 

 currence, and large in size, in the northern portions of the Coast 

 Ranges. The mountains are, as a rule, densely forested and ex- 

 tremely rugged, the flora of their seaward slopes being that char- 

 acteristic of the West Coast, and co-ordinated with its great hu- 

 midity, while on north-eastern flanks the forest resembles that of 

 the inland ranges. 



Geologically the Coast Ranges owe the greater part of their ele- 

 vation to a period later than the cretaceous, of which formation 

 patches are found in them at great heights. The rocks consist 

 chiefly of gray granites and granitoid materials, with which are 

 associated gneisses and other crystalline schists, as well as paleo- 

 zoic rocks resembling some of those of the Interior Plateau. In 

 association principally with the last-named rocks, gold-placers oc- 

 cur locally. Copper and iron ores are frequently found, and rich 

 silver ores have been discovered. 



The name " Vancouver Range " may be applied as a general one 

 to the fourth great mountain-axis, which, in a partially submerged 

 condition, appears in Vancouver and in the Queen Charlotte Is- 

 lands, and is continued southward nearly to the Columbia River by 

 the Olympian Mountains of Washington Territory. The islands 

 of the Alaskan archipelago have, on the map, the appearance of 

 constituting a northern continuation of the same mountain system ; 

 but they may be more appropriately regarded, from an oro- 



