Horseshoe Canyon Formation

The Horseshoe Canyon Formation is a stratigraphic unit of the Western Canada Sedimentary Basin in southwestern Alberta, part of the Edmonton Group, made up of mudstone, sandstone, carbonaceous shale and coal seams laid down across floodplains, estuarine channels and coal swamps. It dates to the Late Cretaceous, roughly 73.1 to 68 million years ago, spanning the Campanian to early Maastrichtian stages, and takes its name from the badlands around Drumheller, where it crops out extensively along with exposures near Trochu and Edmonton. Its type section at Drumheller measures about 250 meters thick, thickening to more than 500 meters near Calgary, and its coal beds have been mined since 1911 and are now targeted for coalbed methane. The formation has yielded a rich fossil record including the dinosaurs Albertosaurus, Edmontosaurus, Hypacrosaurus and Pachyrhinosaurus, alongside mammals, other reptiles, amphibians, fish and invertebrates.