Stratigraphic range: Late Famennian to Middle Tournaisian
|Sub-units||Lower and Upper Exshaw|
|Overlies||Wabamun Formation, Kotcho Formation, Palliser Formation|
|Thickness||up to 50 metres (160 ft)|
|Named for||Exshaw, Alberta|
|Named by||Warren, 1937|
It takes the name from the hamlet of Exshaw, Alberta, and was first described in outcrops on the banks of Jura Creek, north of Exshaw by P.S. Warren in 1937. The formation is late Famennian to middle Tournaisian, and includes the Devonian-Carboniferous limit. The strata were deposited during the Hangenberg event, an anoxic period associated with the Late Devonian extinction.
The Exshaw Formation has a thickness of 46.7 metres (150 ft) at its type locality in the Canadian Rockies. It occurs from the prairies of northern Montana to southern Northwest Territories. A hiatus is observed in the Peace River Arch.
Relationship to other units
The Exshaw Formation is unconformably overlain by the Banff Formation and unconformably underlain by the Wabamun Formation in Alberta, the Kotcho Formation in north-eastern British Columbia and the Palliser Formation in the Canadian Rockies and foothills.
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