[TYRRELL] PRESIDENTIAL ADDRESS 7 
them. After the removal of the buildings the old location was used as 
a cemetery. The land at the new site has an elevation of twenty- 
five feet above the top of high tide, which is about five feet higher 
than that at the old site. 
From this time onward until the Canadian Pacific Railway was 
built across the continent York Factory was the central depot from 
which supplies were distributed southward to the Red River valley 
and westward to the Saskatchewan and Mackenzie valleys and even 
across the mountains to British Columbia and the Yukon Territory. 
PHY SIOGRAPHY 
Nelson river rises in Lake Winnipeg, which forms a great reser- 
voir or cachment basin for the water of all its upper tributaries. 
The lake has an area of 9,414 square miles, and lies in the bottom of 
the old curved continental trough which extends around the margin 
of the Archaean protaxis of the continent. Unlike most of the 
other great Canadian lakes, however, its basin is continuous with a 
wide depression, which strikes directly northward across the protaxis, 
and through this depression it discharges its waters northward into 
Hudson Bay. : 
On its western side the land rises gently from a height of 714 
feet above the sea at its shore to the summits of the Duck and Riding 
Mountains, with elevations of about 2,600 feet above the sea, the low- 
est 700 feet of this rise being an old lake floor which in places is washed 
clean to the underlying till or soft Cretaceous rock while in other places 
it is covered with sediment, either fine clay and silt deposited in still 
water, or sand and gravel distributed along ancient shore lines of the 
extra-glacial Lake Agassiz. 
East of lake Winnipeg the land rises with an undulating surface 
contour to a height of about 1,500 feet above the sea near the sources 
of the Albany and Severn rivers. Most of this country is underlain 
by granites and metamorphosed schists with almost unweathered 
surfaces exposed over large areas. Unlike the country to the west, 
the surface is mammillated or lumpy, and the slopes are often’ covered 
with loose till or glacial debris, while the bottoms of the depressions 
are either hidden by a covering of moss or are filled with water. For 
a few miles back from the eastern border of the lake, where the land 
is not too high, a little stratified sand is usually present. All is covered 
with a continuous though usually scattered forest of spruce, larch, 
and poplar. 
At its north end Lake Winnipeg is retained by a dam of glacial 
clay, probably morainic, which extends for about forty-five miles 
from granite knolls on the east to limestone cliffs on the west. At 
