Mackenzie River great depths to bedrock. A characteristic feature of the delta is its numerous pingos, or hills of earth-covered-ice – some 1,400 of them. The Peel River, carrying much of the runoff from the northern Yukon, joins in the delta at a point northeast of Fort McPherson. Below there, the Mackenzie diverges into several large channels with the largest heading north-northeast, emptying into the Beaufort Sea west of Tuktoyaktuk. At , the Mackenzie River drainage basin encompasses nearly 20 percent of Canada. About , or 54 percent of the basin, lies above Great Slave Lake. Permafrost underlies about three-quarters of the
Clearwater River (Saskatchewan) at Fort McMurray. The section of the river in Fort McMurray is affectionately referred to as The Chant. From Broach Lake at an elevation of above sea level, the Clearwater drops about to the confluence at Fort McMurray. Its waters eventually reach the Arctic Ocean via the Athabasca and Mackenzie Rivers. Tributaries of the Clearwater River include Descharme River and McLean River in Saskatchewan and the Christina River in Alberta. In its upper reaches, the Clearwater River flows over the Precambrian rocks of the Canadian Shield. That section of the river is rough, characterized by rapids, small waterfalls, and a