Mackenzie

Geography

Through its many tributaries, the Mackenzie River basin covers portions of five Canadian provinces and territories — British Columbia (BC), Alberta, Saskatchewan, Yukon, and the Northwest Territories. Thutade Lake, in the Northern Interior of BC, is the ultimate source of the Mackenzie River via the Finlay–Peace River system, which stretches 1,923 kilometres (1,195 mi) through BC and Alberta. The 1,231-kilometre (765 mi) Athabasca River originates further south, in Jasper National Park in southwest Alberta. Together, the Peace and Athabasca rivers drain a significant portion of the eastern slope of the Rocky Mountains and the central Alberta prairie.

History

The Mackenzie valley is believed to have been the path taken by prehistoric peoples during the initial human migration from Asia to North America more than 10,000 years ago. However, archaeological evidence of human habitation along the Mackenzie is scant, despite the efforts of many researchers. Many archaeological sites have probably been destroyed by flooding, freeze-thaw and erosion. The Inuvialuit, Gwich'in and other Indigenous peoples have lived along the river for thousands of years; however, the oldest known evidence of continuous occupation stretches back only about 1300–1400 years, at the Gwich'in community of Tsiigehtchic.

The Mackenzie provided the major route into Canada's northern interior for European explorers as early as the late 18th century.

Ecology

The Mackenzie River's watershed is considered one of the largest and most intact ecosystems in North America, especially the northern half. Approximately 63% of the drainage basin, or 1,137,000 square kilometres (439,000 sq mi), is forested (mostly boreal forest). Wetlands comprise about 18%, or about 324,900 square kilometres (125,400 sq mi), of the basin. More than 93% of forested areas are virgin old-growth forest. However, human activities such as oil extraction have threatened water quality in the headwaters of the Mackenzie River. In addition, a warming climate in northern parts of the watershed is melting permafrost and destabilizing soil through erosion.

Most of the taiga consists of black spruce, aspen and poplar forest.

Geology

As recently as the last glacial maximum about 30,000 years ago, the majority of northern Canada was buried under the enormous continental Laurentide Ice Sheet. The tremendous erosive powers of the Laurentide and its predecessors, at maximum extent, completely buried what is now the Mackenzie watershed under thousands of metres of ice and flattened the eastern portions of the watershed. When the ice sheet receded for the last time, it left a 1,100-kilometre (680 mi) long proglacial lake, Lake McConnell, of which Great Bear, Great Slave and Athabasca Lakes are remnants.