The Foremost Formation is a stratigraphic unit of Late Cretaceous (Campanian) age that underlies much of southern Alberta, Canada.

It was named for outcrops in Chin Coulee near the town of Foremost[1] and is known primarily for its dinosaur remains and other fossils.

It consists of sediments that were eroded from the mountains to the west and carried northeastward by river systems, where they gradually prograded into the Western Interior Seaway.

[4] A variety of insects preserved in amber such as the ants Haidoterminus and Boltonimecia have been recovered from the Foremost Formation at a site near Grassy Lake, Alberta.

[8] This is primarily due to their lower total fossil quantity and neglect from collectors who are hindered by the isolation and scarcity of well-exposed outcrops.