The Cypress Hills Formation is a stratigraphic unit of middle Eocene to early Miocene age[4] in the Western Canada Sedimentary Basin.

[4] The Cypress Hills Formation is composed primarily of gravel and sand, some of which has been cemented to conglomerate and sandstone.

[1][2][4][5][6] The gravels and sands of the Cypress Hills Formation were derived primarily from the Rocky Mountains of northwestern Montana and southernmost Alberta and British Columbia when those areas were uplifted during the Laramide Orogeny.

Small mammals, represented primarily by teeth and jaw fragments, include rabbits and many kinds of rodents,[8] as well as proscalopid insectivores.

Its vertebrate fossils indicate North American Land Mammal Ages of Uintan (middle Eocene) to Hemingfordian (early Miocene).

[4][10] It is exposed on the present day erosional surface, or covered by glacial drift and loess that were deposited during and after the Wisconsin glaciation.