Crowsnest Formation

Crowsnest Formation Stratigraphic range: Mid to Upper Albian PreЄ Є O S D C P T J K Pg N
The west end of the type section of the Crowsnest Formation, on the Crowsnest Highway west of Coleman, Alberta.
Type	Geological formation
Unit of	Blairmore Group
Underlies	Blackstone Formation
Overlies	Ma Butte Formation
Thickness	up to 488 metres (1,600 ft)
Lithology
Primary	Volcanic rocks, pyroclastic breccia
Other	Sandstone
Location
Coordinates	49°38′51″N 114°31′48″W / 49.64750°N 114.53000°W / 49.64750; -114.53000 (Crowsnest Formation)Coordinates: 49°38′51″N 114°31′48″W / 49.64750°N 114.53000°W / 49.64750; -114.53000 (Crowsnest Formation)
Region	Alberta
Country	Canada
Type section
Named for	Crowsnest Pass
Named by	G.M. Dawson, 1886

The Crowsnest Formation, also called the Crowsnest Volcanics, is a geological formation in southwestern Alberta, Canada, on the southwestern margin of the Western Canada Sedimentary Basin. It was named for the Crowsnest Pass near Coleman, Alberta. The formation consists mostly of pyroclastic rocks that were laid down in a series of explosive eruptions about 100 million years ago during the Albian stage of the Early Cretaceous epoch. It contains unusual minerals such as melanite (a variety of andradite garnet) and analcime (a variety of zeolite).

The formation contains pyroclastic flows, lahars, agglomerates, tuffs and ash-fall deposits, as well as volcanic-rich sandstones and other sediments. The whole-rock chemistry of the volcanics is relatively normal, ranging from trachyandesite (latite) to phonolite and trachyte, but the mineralogy is unusual. In addition to analcime and melanite, common minerals include sanidine, aegerine-augite and chlorite.Blairmorite, a rare analcime-rich rock-type named for the town of Blairmore, Alberta, is known only from the Crowsnest Formation and a locality in Mozambique.