Oldman Formation

The Oldman Formation is a Late Cretaceous rock unit underlying much of southern Alberta, named for exposures along the Oldman River near Lethbridge. Deposited during the middle Campanian about 77.5 to 76.5 million years ago, it preserves a record of ancient river channels and floodplains built from sand, silt, and mud, with northwestern Montana likely supplying much of the sediment. Part of the Belly River Group, it lies above the Foremost Formation and below the Dinosaur Park Formation, separated from the latter by a regional disconformity. It is especially significant for its dinosaur remains and for revealing how Campanian river landscapes developed and were preserved in western North America.

Alberta · Canada