Oldman Formation

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Oldman Formation is a Late Cretaceous geological formation in southern Alberta, Canada. It dates to the middle Campanian, about 77.5 to 76.5 million years ago. It’s part of the Belly River Group and sits on top of the Foremost Formation, with the Dinosaur Park Formation above it, separated by a regional disconformity. The rocks are mainly light-colored, fine sandstones formed by ancient rivers, with some siltstone and mudstone from floodplains. It is up to about 100 meters thick and thickens toward the southwest, with sediments mainly coming from what is now northwestern Montana. The Oldman Formation is famous for dinosaur fossils. It was named after the Oldman River near Lethbridge, Alberta, by Russell and Landes in 1940. In regional terms, it is roughly equivalent to parts of the Judith River Formation and to parts of the Two Medicine Formation in Montana.