Outram Formation

The Outram Formation is a stratigraphic unit of Early Ordovician age that is present on the western edge of the Western Canada Sedimentary Basin in the Canadian Rockies of Alberta and British Columbia.^[3] It was named for Mount Outram in Banff National Park by J.D. Aitken and B.S. Norford in 1967.^[2] The Outram Formation is fossiliferous and includes remains of trilobites and other marine invertebrates, as well as stromatolites and thrombolites.^[1][2]

Outram Formation
Stratigraphic range: Early Ordovician ~485–470 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Formation
Underlies	Skoki Formation
Overlies	Survey Peak Formation
Thickness	Up to 443 metres (1453 ft)[1]
Lithology
Primary	Limestone, siltstone
Other	Shale, chert
Location
Coordinates	51°52′54″N 116°52′31″W
Region	Canadian Rockies
Country	Canada
Type section
Named for	Mount Outram
Named by	J.D. Aitken and B.S. Norford[2]

Lithology and deposition

The Outram Formation formed as a shallow and at times emergent marine shelf along the western shoreline of the North American Craton during Early Ordovician time.^[2][3] It consists primarily of nodular limestone, calcareous quartzose siltstone, limestone pebble-conglomerate, and brown shale. Nodules of grey chert occur throughout the formation.^[1][2]

Distribution and stratigraphic relationships

The Outram is present in the Rocky Mountains of Alberta and British Columbia. Its thickness and shale content increase toward the west.^[1][2] It overlies the Survey Peak Formation and underlies the Skoki Formation.^[4] Both contacts are gradational.^[1][2]

Paleontology

The Outram Formation contains several genera of trilobites, as well as brachiopods, conodonts, gastropods, sponges, echinoderms, bivalves, gastropods, stromatolites, thrombolites, oncolites, rare graptolites, and others.^[1][2]