TOPOGRAPHY. The province belongs to the great central prairie region, except the north eastern portion, which is a part of the Laurentian country, and is broken and hilly-, with a higher altitude than the adjoining region. The south eastern and central parts eonsist of an almost perfectly level laeustrine bed, the bottom of the Pleistocene Lake Agassiz. (See LAKE AGAsstz.) It slopes very gently northward, being 800 feet above the sea in the south and 710 feet in the north. Its western boundary is formed by a line of escarpments with a maximum height of 500 feet above the plain and running southeast to northwest. These are the ancient shore lines of Lake Agassiz, and above them stretches more elevated and undulating plain known as the Riding and Duek Mountains, which cover the western and southwestern parts of the province. Both this plain and the laeustrine plain below are treeless prairies, becoming gradually wooded northward, first along the river courses and in isolated clumps of poplars, and finally thickening into dense pine forests on the Duck Mountain in the northwest. The principal river is the Red
River of the North, which enters the province from the south and flows through the prairies into Lake Winnipeg near the centre of the prov ince. Its chief tributary is the Assiniboine, cut ting through the western upland. Nearly all the rivers of the province have cut their beds through the soft drift deposits, so that they flow in nar row valleys from 30 to nearly 100 feet below the surrounding plains. As the waters of Lake Agassiz were drained off, the lowest depressions of its bed remained flooded and now form the great lakes of the province. Of these Lake Win nipeg is 270 miles long and from 20 to 60 miles broad; Lake Winnipegoosis 150, and Lake Mani toba 135 miles long. The last-named is very shallow, and the shores of all are low and marshy.