Great Bear Lake

Great Bear Lake

Great Bear Lake, largest lake of Canada and fourth largest of North America, c.12,275 sq mi (31,800 sq km), c.190 mi (310 km) long and from 25 to 110 mi (40-177 km) wide, Northwest Territories, on the edge of the Canadian Shield. It is drained to the W by the Great Bear River (c.100 mi/160 km long), which flows into the Mackenzie River. Even though it is one of North America's deepest (1,356 ft/413 m) lakes, its waters are open only about four months each year. The lake was explored (c.1800) by traders of the North West Company, and a trading post was later established there. Déline (formerly Fort Franklin), on the southwest shore, was built by Sir John Franklin, a British explorer, in 1825. Discoveries of rich radium ores, which are now exhausted, on the eastern side of the lake in 1930 caused much mining activity in the years immediately following; the Eldorado Mines, at Port Radium, were located there.

Great Bear Lake (Slavey: Sahtú, French: Grand lac de l'Ours) is the largest lake entirely within Canada (Lake Superior and Lake Huron straddling the Canada-US border are larger), the third largest in North America, and the seventh largest in the world. The lake is situated on the Arctic Circle between 65 and 67 degrees of northern latitude and between 118 and 123 degrees western longitude, 186 m (610 ft) above sea level.

The lake has a surface area of 31,153 km² (12,028 mi²) and a total volume of 2,236 km³ (536 mi³). Its maximum depth is 446 m (1,463 ft) and its average depth 71.7 m (235 ft). The total shoreline is 2,719 km (1,690 mi) and the total catchment area of the lake is 114,717 km² (44,293 mi²).

The lake empties through the Great Bear River (Sahtúdé) into the Mackenzie River. The only community on the lake is Deline, Northwest Territories at the southwest end.

In 1930 Gilbert LaBine discovered uranium in the Great Bear Lake region.

The Sahtú Dene people took their name from the lake.


Great Bear Lake lies between two major physiographic regions: the Kazan Uplands portion of the Canadian Shield and the Interior Plains. Originally it was part of preglacial valleys that were reshaped by erosional effects of ice during the Pleistocene. Since then, the lake has undergone various changes resulting from rebound following the melting of the ice.

Precambrian rocks of the Canadian Shield form the eastern margin of the McTavish Arm. These rocks of the Precambrian are made up of sedimentary and metamorphic deposits supplemented by igneous intrusions forming dikes and sills.


Great Bear Lake is covered with ice from late November to July. Between 1950 and 1974, this climatic data was collected at Port Radium:

Month Temperature
Bright sunshine
Jan –27.0 11 0.19
Feb –27.0 8 1.82
Mar –19.1 14 7.57
Apr –10.7 6 16.03
May align=right
14 21.76
Jun align=right
14 23.16
Jul align=right
35 18.54
Aug align=right
43 11.97
Sep align=right
25 6.20
Oct –3.2 27 2.85
Nov –14.8 25 0.39
Dec –23.0 14 0.00
Average –7.2 10
Total 236

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