Fernie Formation

Fernie Formation (Group) Stratigraphic range: Jurassic
Fernie shales are exposed in the mountains near Fernie PreЄ Є O S D C P T J K Pg N
Type	Geological formation
Sub-units	Nordegg Member, Red Deer Member, Poker Chip Shale, Lille Member, Rock Creek Member, Highwood Member, Pigeon Creek Member, Ribbon Creek Member
Underlies	Morrissey Formation, Nikanassin Formation, Monteith Formation
Overlies	Schooler Creek Group, Montney Formation, Rundle Group
Thickness	up to 400 metres (1,310 ft)
Lithology
Primary	Shale
Other	Sandstone, siltstone, limestone
Location
Coordinates
Region	Alberta, British Columbia
Country	Canada
Type section
Named for	Fernie, British Columbia
Named by	Leach, 1914.

The Fernie Formation is a stratigraphic unit of Jurassic age. It is present in the western part of the Western Canada Sedimentary Basin in western Alberta and northeastern British Columbia. In some interpretations it has Group status. It takes its name from the town of Fernie, British Columbia, and was first defined by Leach in 1914.

Depositional history

The Fernie Formation is a marine unit that was deposited in the Western Interior Seaway. Deposition took place throughout most of the Jurassic period, from the Hettangian stage to the mid-Tithonian. The age is based on its fossil content, including ammonites, molluscs and microfossils.

The sediments were sourced from the east during the deposition of the lower and middle units of the Fernie, where the coarser facies occur in the eastern part of the formation. In the uppermost Fernie, the coarsest material is found in the west, however, indicating a shift to sources in the west and south.

Lithology

The Fernie Formation is composed primarily of brown and dark gray to black shales that range from massive with conchoidal fracture to laminated and highly fractured or papery. Phosphatic sandstone and limestone, including cherty limestone, occur locally in the lower parts of the formation; siltstone, sandstone, coquinas and oolitic limestone interbeds can occur in the center; glauconitic sandstone and siltstone can be present in the upper parts.

Distribution

The Fernie Formation reaches a maximum thickness of 400 metres (1,310 ft) near Mount Allan in Alberta, and typically is about 70 to 150m thick. It thins toward the east, disappearing at about the longitude of Calgary. The formation is exposed in outcrops in the Kootenay region of southeastern British Columbia, in the foothills and front ranges of the Canadian Rockies in southwestern Alberta, and as far north as the Peace River Country in northeastern British Columbia.

Relationship to other units

The Fernie Formation is conformably overlain by the Morrissey Formation in the south, by the Nikanassin Formation in central Alberta and by the Monteith Formation in northeastern British Columbia. It rests disconformably on Triassic units in the west, and unconformably on upper Paleozoic units such as the Schooler Creek Group and the Montney Formation farther east.

Subdivisions

The Fernie Group has the following subdivisions from top to base:

Sub-unit	Age	Lithology	Reference
Passage Beds	Oxfordian to Tithonian	dark grey splintery shale interbedded with siltstone
Ribbon Creek Member	Bathonian	silty shale
Green Beds	Oxfordian	glauconitic sandstone and siltstone, calcareous concretions, various fossils
Grey Beds		shale
Gryphaea Bed	Bathonian	coquina with Gryphaea impressimarginata, ammonites and belemnites, calcareous siltstone
Corbula munda Beds	Bathonian	silty shale, calcareous sandstone
Pigeon Creek Member	Callovian	calcareous siltstone and grey shale
Highwood Member	Bajocian	dark grey shale, bioturbated sandstone
Rock Creek Member	Bajocian	also called "Belemnite zone" - sandstone which may contain commercial gas reserves
Lille Member	Bajocian	coquina with Gryphaea and Ostrea
Poker Chip Shale	Toarcian	papery shale
Red Deer Member	Pliensbachian	black shale, black laminated limestone
Oxytoma Bed	Sinemurian
Nordegg Member	Sinemurian	dark chert, phosphate limestone, silty shale