39 Other Large Lakes : Other lakes large enough to be of considerable importance though not large enough to be classed with the great lakes, are lake MacKay, Aylmer and Clinton- Colden lakes, and lac La Martre. Lake MacKay is situated north of Great Slave lake on the edge of the Barren lands. It was discovered by Warburton Piket in 1890 and estimated by him to be about 100 miles in length, though he saw only about 50 miles of it. The lake is cut by a number of long points and has numerous islands. The south shore is sparsely timbered, and the north shore is entirely devoid of timber. The shores are all rocky-and the hills at the northeast end are grouped in a regular range. Aylmer and Clinton-Colden lakes? are separated from each other by only a narrow strait, known as the strait of the Sandhill. Their combined length is said to be about 100 miles and the greatest width 30 miles. The shores are low and shelving, 80 to 100 feet high, and islands are numerous. Both shores are practi- eally devoid of timber, for both the lakes are situated within the limits of the Barren. lands. Lae La Martre northwest of Great Slave lake is also one of the larger lakes, but its general character and surroundings have never been described by any writer. Lesser Slave lake is 61 miles long and has a maximum width of 12 miles, ~ embracing an area of 484 square miles. It is very shallow and seldom exceeds 10 feet in depth at low water. : AGRICULTURE The division of the whole basin of Mackenzie river into three great physio- graphic provinces, namely, the Laurentian plateau on the east, the Cordillera on the west, and between them the Great Central plain, makes it possible to delimit the possible agricultural portion of the basin from that which is impossible of cultivation. | - The Laurentian Plateau portion which forms about one-fifth of the whole - basin and which is outlined on the accompanying physiographic map (Figure 1), because of its rocky character, its absence of soil, and its low average temperature, is not generally suitable for agricultural purposes and can never be considered as part of Canada’s reserves of agricultural lands.. Except in a few localities where areas of clay land occur or where deposits of alluvium have accumulated no crops of any kind are at present being raised within the limits of this portion of the basin. Such localities are Chipewyan and Fort Smith,where excellent crops of garden vegetables and some hardy grain are grown. These localities, however, are so close to the border of the Great Central plain as to partake very largely of the characteristics of that region. In the Cordilleran portion of the basin only a very small proportion ean be considered to have any agricultural possibilities, and this is confined to the main valleys such as the Peace and Athabaska and to the lower branches along these valleys. The Great Central plain of the Mackenzie basin is pre-eminently that portion of the basin best adapted to agricultural pursuits (Plate VI). This portion con- stitutes about one-half of the whole basin; but it must not be assumed that the 1 Barren grounds of northern Canada, 1892, p. 58. . 2 Back, Captain, “Arctic land expedition, isa. 34- SOF De, Lose King, Richard, “Narrative of a journey to the Arctic ocean,” p. 188.