What are the Mackenzie Mountains?

The Mackenzie Mountains are an 800-kilometre mountain range running along the Yukon-Northwest Territories border, from the Liard River in the south to the Peel River in the north. The range is part of the Cordillera physiographic region of western Canada and forms a watershed dividing rivers flowing east into the Mackenzie River from rivers flowing west into the Yukon River. Major peaks include Keele Peak (2,952 metres) and Mount Sir James MacBrien (2,762 metres). The range is sparsely populated and largely undeveloped.

The Mackenzie Mountains were named by the explorer John Rae in 1854 after Sir Alexander Mackenzie, the Scottish-born North West Company fur trader who reached the mouth of the Mackenzie River in 1789. The range is geologically distinct from the Rocky Mountains to the south, having been formed about 175 to 100 million years ago during the Mesozoic by collisions of island-arc terranes with the North American Plate. The mountains are dominantly limestone and dolomite, with extensive fossil-bearing layers including some of the world's best preserved Cambrian, Ordovician, and Silurian marine fossil assemblages.

Nahanni National Park Reserve, in the southern Mackenzie Mountains, was established in 1976 and was one of the first four UNESCO World Heritage Sites in 1978 (alongside Wood Buffalo National Park, L'Anse aux Meadows, and Rocky Mountain Parks). The park covers 30,050 square kilometres along the South Nahanni River. The South Nahanni Falls (Naili Cho), at 96 metres, is twice the height of Niagara Falls and falls into a deep canyon. The park was expanded in 2009 to include the entire South Nahanni River basin under the Nahanni Expansion Act, making it the third-largest national park reserve in Canada.

Naats'ihch'oh National Park Reserve, established in 2014, protects the headwaters of the South Nahanni in the northern Mackenzie Mountains adjacent to Nahanni. Together the two parks protect about 35,000 square kilometres. The Mackenzie Mountains are the homeland of the Sahtu Dene, the Kaska Dena, and the Tlicho peoples. The Mackenzie Valley environmental assessment process and the Sahtu Dene and Metis Comprehensive Land Claim Agreement of 1993 govern resource management. The Wernecke Mountains form a sub-range of the Mackenzie Mountains in north-central Yukon, and the proposed Peel Watershed Regional Land Use Plan (settled by the Supreme Court of Canada in First Nation of Nacho Nyak Dun v. Yukon, 2017) governs northern Mackenzie Mountains land use.