The Clearwater River is located in the Canadian provinces of Saskatchewan and Alberta. It rises in the northern forest region of north-western Saskatchewan and joins the Athabasca River in north-eastern Alberta. It was part of an important trade route during the fur trade era and has been designated as a Canadian Heritage River. Course The Clearwater River has a total length of . It flows south-eastward from its headwaters at Broach Lake and turns to the south-west from Careen Lake to the Alberta / Saskatchewan border. From there it flows westward for a distance of to join the Athabasca River 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. Geology 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 gorge. The river leaves the Shield near the Alberta border and enters the Interior Plains where it becomes meandering, with numerous sand bars and small islands. There it is flanked by outcrops of the Devonian limestones, dolomite, and shales of the La Loche, Contact Rapids, Keg River, and Waterways Formations, as well as the Cretaceous oil sands of the McMurray Formation. The Clearwater River is an underfit stream; that is, its present flow is insufficient to have carved its broad, steep-sided valley. Instead, its morphology may be the result of a catastrophic paleoflood that originated from Glacial Lake Agassiz during late Pleistocene time and flowed through the Clearwater and Athabasca river valleys on its way to the Arctic Ocean. The channel cut by that flood is known as the Clearwater Spillway. There are several salt springs and saline marshes that discharge into the Clearwater River in northeastern Alberta. The water, which comes from the underlying Devonian rock formations, is effervescent in places and smells of sulfur. History Rock-paintings along the upper portion of the river, shapes and symbols on rock surfaces, suggest that the area was already inhabited 5,000 years ago. Before the European colonisation, native groups of Beaver,