Unit Name: Piper Formation
Unit Type: Lithostratigraphic
Rank: Formation
Status: Formal
Usage: Currently in use
Age Interval: Middle Jurassic (175.6 - 161.2 ma)
Province/Territory: Montana

Originator: Imlay, R.W., et al., 1948.

Type Locality:
Piper Junction, about 17.6 km (11 mi) southeast of Lewistown, central Montana.

Distribution:
The type section, from base to top consists of about 3.6 m (12 ft) of massive white gypsum, 1.8 m (6 ft) of chocolate grey limestone, 17.4 m (57 ft) of maroon and green siltstone and shale, 1.5 m (5 ft) of grey, papery to chunky shale, and 1.2 m (4 ft) of yellowish grey, sandy limestone. West of a line in Montana linking the Sweetgrass Arch to the Big Belt Mountains the Piper yields much of its evaporitic, red-bed character to the tan sandstone and grey shale facies of the Sawtooth Formation.

Relationship:
Equivalent in Saskatchewan to the upper member of the Watrous Formation as well as the Gravelbourg and Shaunavon formations. (Francis, 1956; Christopher, 1984a). The name Piper Formation has not come into formal general usage in Canada.

Other Citations:
Christopher, 1984a; Francis, 1956; Imlay, Gardiner, Rogers and Hadley, 1948.

Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: J.E. Christopher
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 13 Jun 2004