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146
[GEOGRAPHY
CANADA


carefully measured being Mount Robson (13,700 ft.). The next range to the east, the Selkirks, has several summits that reach 10,000 ft. or over, while the Coast Ranges scarcely go beyond 9000 ft. The snow line in the south is from 7500 to 9000 ft. above sea-level, being lower on the Pacific side where the heaviest snowfall comes in winter than on the drier north-eastern side. The snow line gradually sinks as one advances north-west, reaching only 2000 or 3000 ft. on the Alaskan coast. The Rockies and Selkirks support thousands of glaciers, mostly not very large, but having some 50 or 100 sq. m. of snowfield. All the glaciers are now in retreat, with old tree-covered moraines, hundreds or thousands of feet lower down the valley. The timber line is at about 7500 ft. in southern British Columbia and 4000 ft. in the interior of the Yukon Territory. On the westward slopes, especially of the Selkirks and Coast Ranges, vegetation is almost tropical in its density and luxuriance, the giant cedar and the Douglas fir sometimes having diameters of 10 ft. or more and rising to the height of 150 ft. On the eastern flanks of the ranges the forest is much thinner, and on the interior plateau and in many of the valleys largely gives way to open grass land. The several ranges of the Cordillera show very different types of structure and were formed at different ages, the Selkirks with their core of pre-Cambrian granite, gneiss and schists coming first, then the Coast Ranges, which seem to have been elevated in Cretaceous times, formed mainly by a great upwelling of granite and diorite as batholiths along the margin of the continent and sedimentary rocks lying as remnants on their flanks; and finally the Rocky Mountains in the Laramie or early Eocene, after the close of the Cretaceous. This latest and also highest range was formed by tremendous thrusts from the Pacific side, crumpling and folding the ancient sedimentary rocks, which run from the Cambrian to the Cretaceous, and faulting them along overturned folds. The outer ranges in Alberta have usually the form of tilted blocks with a steep cliff towards the north-east and a gentler slope, corresponding to the dip of the beds, towards the south-west. Near the centre of the range there are broader foldings, carved into castle and cathedral shapes. The most easterly range has been shown to have been actually pushed 7 m. out upon the prairies. In the Rocky Mountains proper no eruptive rocks have broken through, so that no ore deposits of importance are known from them, but in the Cretaceous synclines which they enclose valuable coal basins exist. Coal of a bituminous and also semi-anthracite kind is produced, the best mined on the Pacific slope of the continent, the coking coals of the Fernie region supplying the fuel of the great metal mining districts of the Kootenays in British Columbia, and of Montana and other states to the south. The Selkirks and Gold Ranges west of the Rockies, with their great areas of eruptive rocks, both ancient and modern, include most of the important mines of gold, silver, copper and lead which give British Columbia its leadership among the Canadian provinces as a producer of metals. In early days the placer gold mines of the Columbia, Fraser and Caribou attracted miners from everywhere, but these have declined, and lode mines supply most of the gold as well as the other metals. The Coast Ranges and islands also include many mines, especially of copper, but up to the present of less value than those inland. Most of the mining development is in southern British Columbia, where a network of railways and waterways gives easy access; but as means of communication improve to the north a similar development may be looked for there. The Atlin and White Horse regions in northern British Columbia and southern Yukon have attracted much attention, and the Klondike placers still farther north have furnished many millions of dollars’ worth of gold. Summing up the economic features of the Cordilleran belt, it includes many of the best coal-mines and the most extensive deposits of gold, copper, lead and zinc of the Dominion, while in silver, nickel and iron Ontario takes the lead. When its vast area stretching from the international boundary to beyond the Arctic circle is opened up, it may be expected to prove the counterpart of the great mining region of the Cordillera in the United States to the south.

Climate.—In a country like Canada ranging from lat. 42° to the Arctic regions and touching three oceans, there must be great variations of climate. If placed upon Europe it would extend from Rome to the North Cape, but latitude is of course only one of the factors influencing climate, the arrangement of the ocean currents and of the areas of high and low pressure making a very wide difference between the climates of the two sides of the Atlantic. In reality the Pacific coast of Canada, rather than the Atlantic coast, should be compared with western Europe, the south-west corner of British Columbia, in lat. 48° to 50°, having a climate very similar to the southern coast of England. In Canada the isotherms by no means follow parallels of latitude, especially in summer when in the western half of the country they run nearly north-west and south-east; so that the average temperature of 55° is found about on the Arctic circle in the Mackenzie river valley, in lat. 50° near the Lake-of-the-Woods, in lat. 55° at the northern end of James Bay, and in lat. 49° on Anticosti in the Gulf of St Lawrence. The proximity of the sea or of great lakes, the elevation and the direction of mountain chains, the usual path of storms and of prevalent winds, and the relative length of day and amount of sunshine in summer and winter all have their effect on different parts of Canada. One cannot even describe the climate of a single province, like Ontario or British Columbia, as a unit, as it varies so greatly in different parts. Details should therefore be sought in articles on the separate provinces. In eastern Canada Ungava and Labrador are very chill and inhospitable, owing largely to the iceberg-laden current sweeping down the coast from Davis Strait, bringing fogs and long snowy winters and a temperature for the year much below the freezing-point. South of the Gulf of St Lawrence, however, the maritime provinces have much more genial temperatures, averaging 40° F. for the year and over 60° for the summer months. The amount of rain is naturally high so near the sea, 40 to 56 in., but the snowfall is not usually excessive. In Quebec and northern Ontario the rainfall is diminished, ranging from 20 to 40 in., while the snows of winter are deep and generally cover the ground from the beginning of December to the end of March. The winters are brilliant but cold, and the summers average from 60° to 65° F., with generally clear skies and a bracing atmosphere which makes these regions favourite summer resorts for the people of the cities to the south. The winter storms often sweep a little to the north of southern Ontario, so that what falls as snow in the north is rain in the south, giving a much more variable winter, often with too little snow for sleighing. The summers are warm, with an average temperature of 65° and an occasional rise to 90°. As one goes westward the precipitation diminishes to 17.34 in. in Manitoba and 13.35 for the other two prairie provinces, most of this, however, coming opportunely from May to August, the months when the growing grain most requires moisture. There is a much lighter snowfall in winter than in northern Ontario and Quebec, with somewhat lower temperatures. The snow and the frost in the ground are considered useful as furnishing moisture to start the wheat in spring. The precipitation in southern Saskatchewan and Alberta is much more variable than farther east and north, so that in some seasons crops have been a failure through drought, but large areas are now being brought under irrigation to avoid such losses. The prairie provinces have in most parts a distinctly continental climate with comparatively short, warm summers and long, cold winters, but with much sunshine in both seasons. In southern Alberta, however, the winter cold is often interrupted by chinooks, westerly winds which have lost their moisture by crossing the mountains and become warmed by plunging down to the plains, where they blow strongly, licking up the snow and raising the temperature, sometimes in a few hours, from 20° to 40° F. In this region cattle and horses can generally winter on the grass of the ranges without being fed, though in hard seasons there may be heavy losses. Northwards chinooks become less frequent and the winter’s cold increases, but the coming of spring is not much later, and the summer temperatures, with sunshine for twenty hours out of twenty-four in June, are almost the same