derived from that given to the old crystalline rocks of which it is chiefly composed, these, in turn, having been named from the St. Lawrence river, in the vicinity of which they were first recognised by geologists.

The Laurentian plateau, in certain places rugged and irregular, and sometimes incorrectly spoken of as a mountain range, has an average elevation of about 1500 feet only, and is several hundred miles in width. There is, however, every reason to believe that though now reduced to the condition of an irregular plateau of moderate elevation, this region holds the position of a former very ancient mountain system, much older even than the Appalachian system, which has gradually been worn down and has been the source of the material of a large part of the newer rocks of the continent. It represents the largest remaining portion of the oldest known beginning of the North American land-mass.

This plateau presents some peculiar physical characteristics, which are referred to elsewhere (see p. 94). Here it is necessary only to note its extent and form with its relation to the other main features of Canada. This is most easily done by examining a geological map of the continent, on which the colour representing the oldest rocks may be taken as defining in a general way the limits of the Laurentian plateau. It will be observed that the region thus marked out has a horse-shoe-like form surrounding the great central depression of Hudson Bay, and running from the Labrador Peninsula at one end to the Arctic Ocean at the other. The southern edge of the plateau forms the north side of the Gulf and River St. Lawrence nearly as far up as the city of Quebec, beyond which its main outline runs to the north shore of Lake Huron, and thence along the north side of Lake Superior to the Lake of the Woods and Lake Winnipeg, whence it continues in a north-westward direction to within the Arctic circle. It will further be remarked that all the great lakes of Canada lie on or near the southern or southwestern margin of this plateau.

Having thus traced out the dominant physical features of the northern part of the continent, we are in a position

to understand the principal characteristics of the surface of Canada. No classification of these can be complete or correct in every particular, but as an aid to the comprehension of the broader aspects of the country it may be divided as follows: (1) Eastern lowlands and hills, including the entire region to the south of the Laurentian plateau east of Lake Huron. This is almost entirely based on old and hard rocks included in the Paleozoic division of geologists. (2) The Laurentian plateau, with the limits above given, and consisting of still older and harder crystalline rocks. (3) The inland plains, comprised between the western part of the Laurentian plateau and the Cordillera, and principally based on the comparatively soft rocks of the Mesozoic or middle period of geological history, which still lie nearly as flat as when they were originally deposited. (4) The Cordilleran or western mountain region.

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Lying open as the region of the eastern lowlands and hills does to communication with the Old World, it was the first to be occupied by colonists, and is still more thickly peopled than other parts of the country. consequence of the rough and rocky character of much of the Laurentian plateau it has been only in small part, and by slow degrees, penetrated by settlement, while it forms an almost complete barrier to the connected spread of agriculture where it borders on the Great Lakes. thus only of late years that the fertile region of the inland plain of Canada has been reached by any considerable number of settlers, and the population to be found there is still very scanty in comparison to the area and to the extent of arable and pasture land. The distance separating the western mountain region from the earlier settlements of the eastern part of the continent is so great that, like the inland plain, it long remained practically unknown except to the fur trader. But the discovery of gold in British Columbia initiated a flow of adventurers and miners to this region, which they were enabled to reach by sea from the west.

d. Drainage System.-In order to complete a general survey of the surface features of Canada it will now be

necessary to note the principal elements of the drainage system. Further details are given in connection with the various provinces, but several of the larger rivers extend through more than one of these. There is perhaps no single feature more characteristic of Canadian topography than the length and magnitude of the rivers, and the manner in which these, with thousands of smaller tributary streams fed by countless lakes, penetrate the country in all its parts.

There are in North America three great hydrographic basins corresponding to the three sides of the triangular land-mass the Atlantic, Pacific, and Arctic. Of these the Atlantic basin is further subdivided into that of the Atlantic proper, and that of the Gulf of Mexico; the Arctic into that of the Arctic proper, and that of Hudson Bay. Rivers belonging to all these systems with their subdivisions are found within the limits of Canada, but those flowing to the Gulf of Mexico merely enter the southern border of the country, while those of both subdivisions of the Arctic basin are almost wholly included in it. The slope of the continent towards the Pacific is short and steep, and its rivers are consequently, as a rule, comparatively small and rapid, and only occasionally, and for short distances, suited to navigation. Much the greater part of Canada drains toward the Arctic or Atlantic, and on both these slopes we find very large rivers with relatively moderate currents and long unbroken navigable stretches.

Beginning on the Atlantic side, and again referring to the map, it will be observed that in the United States the inland slopes of the Appalachians are drained by tributaries of the Mississippi, while on the Atlantic slope proper, all the way from Florida to the Gulf of St. Lawrence, there are numerous short and small rivers draining a belt of country, which has a width of 50 to 200 miles only. Coming to the St. Lawrence, however, we find a river of the first magnitude, which rises almost in the centre of the continent, and is the outlet of the greatest system of ,lakes in the world. The whole history of Canada is intimately connected with this great river, by means of

which pioneers starting from Quebec or Montreal had overrun a great part of the interior of the continent before the settlers of the Atlantic coast had crossed the Appalachians. The length of the St. Lawrence measuring from the lower end of the Island of Anticosti to its farthest source is 2100 miles, and the area drained by it 530,000 square miles (see p. 89).

To the north of the St. Lawrence basin the Labrador peninsula is drained by a number of large rivers, some of which are as much as 400 miles in length. Most of these flow westward and form part of a converging series of rivers which tend toward Hudson Bay from all sides. The most important of the rivers entering Hudson Bay is, however, the Nelson. This great river is the outlet of Lake Winnipeg and other large neighbouring lakes which receive the waters of the Saskatchewan, Red, and Winnipeg rivers, besides many smaller streams. While the Nelson itself runs across the Laurentian plateau, and the Winnipeg and some smaller tributaries rise within the area of this plateau, its larger feeders come from the west, the Saskatchewan drawing its waters even from the Cordillera. These western tributaries drain almost the whole southern portion of the Canadian part of the interior plain. This great river system was at one time the principal route for the fur trade of the Hudson's Bay Company. The length of the Nelson and Saskatchewan rivers is together about 1250 miles, the entire area of the drainage basin of the Nelson within the boundaries of Canada being 367,000 square miles.

The Mackenzie river flows directly to the Arctic Ocean, and with the Nelson and Mississippi shares in draining the interior plain of the continent. Its drainage basin is not, however, confined to this plain, but overlaps the Laurentian plateau on the east, and the Cordillera on the west, the manner in which some of its tributaries rise far back in the Cordillera belt being particularly remarkable. Its principal affluents are the Peace (length 730 miles), Athabasca1 (length 600 miles), Liard2 (length 470 miles),

1 An Indian name meaning a grassy swamp, and probably referring to the marshes at the mouth of the river.

2 French, Rivière au Liard, "Cottonwood river."

Great Bear and Peel. All these are themselves large rivers, and the main stream carries an enormous volume of water to the north. Athabasca and Great Slave Lakes, two of the largest of those previously noted as lying on the western margin of the Laurentian plateau, are on the main stream of the Mackenzie, and a third, Great Bear Lake, discharges into it by a short river. The Mackenzie constitutes the chief means of communication in the country through which it flows, but has never served as a route from the sea, because of the quantity of Arctic ice which blocks its mouth. The length of the Mackenzie is about 1800 miles, the area of its drainage basin 677,000 square miles.

The last of the great rivers which requires special mention in connection with the general surface features of Canada is the Yukon. This drains the greater portion of the northern part of the Cordillera belt. Its drainage basin slopes northward for the upper half of its length, and in reality belongs to the Arctic slope of the continent; but in the lower portion of its course the river makes an abrupt bend to the west, and flowing across the entire breadth of Alaska, eventually reaches the Pacific instead of the Arctic Ocean. The country drained by this great river is yet almost uninhabited, except by a scanty native population and a few roaming gold miners and traders. The river has therefore never assumed any importance as a means of communication, though much of it is navigable. The length of the Yukon is about 1450 miles, the area of its drainage basin about 331,000 square miles; but of this about one-half is comprised in the territory of Alaska.

Other rivers of the Pacific slope of Canada are mentioned in connection with British Columbia (p. 150), within which province their entire courses are included. The Fraser is the most important of these.

There are thus in Canada four great rivers of the first class the St. Lawrence, Nelson, Mackenzie, and Yukon; but in addition to these there are many others which would in any less extensive and less well-watered region rank as important streams. By tracing on the map the courses of the remaining larger streams, and noting their relations to