coast, the further extension of these valleys, and of others running with the range, may be traced, the evidence being of great subaerial erosion, when the land previously stood at a higher stage. The cutting out of these deep valleys probably began in Eocene times, but was renewed and greatly increased in the later Pliocene. Outside the Coast Range, and in a partly submerged condition, lies another range, of which Vancouver Island and the Queen Charlotte Islands are projecting ridges. This stands on the edge of the Continental plateau, with the great depths of the Pacific beyond it. The rocks resemble those of the Coast Range, but include also masses of Triassic and Cretaceous strata which have participated in its folding, while horizontal Miocene and Pliocene beds skirt some parts of the shores.

In the inland portion of British Columbia, between the Coast and Rocky Mountain systems above particularly alluded to, are numerous less important mountain ranges which, while preserving a general parallelism in trend, are much less continuous. Thus, in travelling westward by the line of the Canadian Pacific Railway, after descending from the Rocky Mountain summit and crossing the Upper Columbia valley, the Selkirk Range has to be surmounted. Beyond this, the Columbia on its southern return is again crossed, and the Gold Range is traversed by the Eagle Pass before entering the Interior Plateau of British Columbia, which occupies the space remaining between this and the Coast Rånge. The system of ranges lying immediately to the west of the Rocky Mountains proper, notwithstanding its breaks and irregularities, is capable of approximate definition, and its components have been designated collectively the Gold Ranges. Further north it is represented by the Cariboo Mountains, in the mining district of the same name. The highest known summit of this system is Mount Sir Donald, 10,645 feet, one of the Selkirk Mountains. This mountain system is believed to be the

oldest in British Columbia. It comprises pre-Cambrian rocks with granites, and a great thickness of older Palaeozoic beds, much disturbed and altered.

The Interior Plateau region constitutes an important physical feature. Near the International Boundary it is terminated southward by a coalescence of rather irregular mountains, and again, to the northward, it ends about latitude 55° 30' in another plexus of mountains without wide intervals. Its breadth between the margins of the Gold Ranges and the Coast Range is about 100 miles, and its length is about 500 miles. It is convenient to speak of the country thus defined as a plateau, because of its difference, in the large, from the more lofty bordering mountains. Its early Tertiary topography has been greatly modified by volcanic accumulations of the Miocene, and by river-erosion, while it stood at a considerable altitude, in the Pliocene; but its plateau-like character is not obvious until some height has been gained above the lower valleys, where the eye can range along its level horizon-lines. It is highest to the southward, but most of the great valleys traversing it are less in elevation than 3,000 feet above the sea. the north, and particularly in the vicinity of the group of large lakes occuring there, its main area is less elevated than 3,000 feet, making its average height about 3,500 feet.

To

Beyond this plateau to the north, the whole width of the Cordillera, very imperfectly explored as yet, appears to be mountainous as far as the 59th parallel of latitude, when the ranges diverge or decline, and in the upper basin of the Yukon, rolling or nearly flat land, at moderate elevations, again begins to occupy wide intervening tracts.

As a whole, the area of the Cordillera in Canada may be described as forest-clad, but the growth of trees is more luxuriant on the western slopes of each of the dominant mountain ranges, in correspondence with the

greater precipitation occuring on these slopes. This is particularly the case in the coast region and on the seaward side of the Coast Range, where magnificent and dense forests of coniferous trees occupy almost the whole available surface. The Interior Plateau, however, constitutes the southern part of a notably dry belt, and includes wide stretches of open, grass-covered hills and valleys, forming excellent cattle ranges. Further north, along the same belt, similar open country appears intermittently, but the forest invades the greater part of the region. It is only toward the Arctic coast, in relatively very high latitudes, that the barren Arctic tundra country begins, which, sweeping in wider development to the westward, occupies most of the interior of Alaska.

With certain exceptions the farming land of British Columbia is confined to the valleys and tracts below 3,000 feet, by reason of the summer frosts occuring at greater heights. There is, however, a considerable area of such land in the aggregate, with a soil generally of great fertility. In some of the southern valleys of the interior, irrigation is necessary for the growth of crops. Fruit growing is becoming one of the important industries.

The geological structure of the Cordillera is extremely complicated, and it has as yet been studied in detail over limited tracts only. There have been no appropriate terms of comparison for the formation met with, and these it has consequently been necessary to investigate independently by the light of first principle. The difficulty is increased by the abundance of rocks of volcanic origin referable to several distinct periods, resembling those of the Appalachian mountain region, though on a vastly greater scale, and, like them, almost entirely devoid of organic remains. The recognition, early in their investigation, has rendered it possible, however, to understand the main geological features,