Cardium Formation, Geological formation in Alberta, Canada

The Cardium Formation is a Late Cretaceous stratigraphic unit of the Western Canada Sedimentary Basin, present throughout western Alberta and northeastern British Columbia. It consists mainly of massive, fine-grained to conglomeratic sandstone beds separated by thick shale layers, with members including the Sturrock, Leyland, Cardinal, Kiska, Moosehound and Ram. The sandstone is between 5 and 30 metres thick in Alberta.

James Hector first described the Cardium Formation in 1895 along the banks of the Bow River. The sediments were deposited during the Turonian and Coniacian stages of the Late Cretaceous, about 90 million years ago, along the western edge of the Alberta Foreland Basin. The formation extends from the Canada–United States border north to northeastern British Columbia near Dawson Creek.

The name of this formation comes from a heart-shaped shellfish whose fossils appear throughout its rock layers. Visitors interested in these fossils can see related specimens on display at natural history museums across Alberta.

Because this formation lies entirely underground, it cannot be visited directly without drilling or technical surveys. Natural history museums across Alberta offer displays that explain the region's geology and allow visitors to see related fossils up close.

The formation's name comes from fossil heart-shaped cockle shells of the family Cardiidae, from Greek kardiā, "heart"; the genus Cardium itself is not extinct. James Hector first described the formation along the Bow River banks in 1895. Its sandstones, 5 to 30 metres thick in Alberta, also hold gas in the Athabasca River area and foothills.