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.
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.
Clearwater River (Saskatchewan)