Gypsum Spring Formation

The Gypsum Spring Formation is a stratigraphical unit of Middle Jurassic age in the Williston Basin.

Gypsum Spring Formation
Stratigraphic range: Middle Jurassic PreꞒ Ꞓ O S D C P T J K Pg N
Gypsum Spring Formation (in grey on top of red colored Spearfish Formation), near Devils Tower National Monument (Wyoming)
Type	Geological formation
Underlies	Sundance Formation
Thickness	up to 76 metres (250 ft)[1]
Lithology
Primary	Gypsum
Other	Shale, dolomite, limestone
Location
Region	Williston Basin
Country	Canada, United States
Type section
Named for	Gypsum Spring, Wyoming
Named by	J.D. Love, 1939

It takes the name from Gypsum Spring in Wyoming, and was first described in outcrop in Freemont County by J.D. Love in 1939.^[2]

Lithology

The Gypsum Spring Formation is composed of massive white gypsum in the lower part, and alternating gypsum, red shale, dolomite and limestone. ^[1]

Distribution

The Gypsum Spring Formation reaches a maximum thickness of 76 metres (250 ft) in central Wyoming.^[1] It occurs from the Black Hills in South Dakota through Wyoming and into southern Saskatchewan.

Relationship to other units

It is equivalent to the upper part of the Watrous Formation and the lower part of the Gravelbourg Formation in Saskatchewan.