Unit Name: Fernie Formation
Unit Type: Lithostratigraphic
Usage: Partly superseded
Age Interval: Jurassic (199.6 - 145.5 ma)
Province/Territory: Alberta; British Columbia
Originator: Leach, 1914.
Fernie area, southeastern British Columbia; no specific locality designated. In no single section are all units within the Fernie Formation exposed. Some of the more complete and representative sections in southwestern Alberta are at Daisy Creek (grid reference 894139, Blairmore 1:50,000 topographic sheet, 82G/9); above Burns' Mine on Sheep River (grid reference 516065, Mount Rae 1:50,000 topographic sheet, 82 J/10W); and in Pigeon Creek on Mount Allan (grid reference 271498, Canmore 1:50,000 topographic sheet, 82 O/3E).
Due to the recessive weathering character and the unusually deformed nature of the dominant shales of the Fernie Formation measured thickness vary considerably. Apparently undisturbed sections in southern Alberta have thicknesses of 138 m (453 ft) at Daisy Creek, 227 m (745 ft) above Burns' Mine on Sheep River, 402 m (1,319 ft) in Pigeon Creek on Mount Allan, but only 67 m (220 ft) in Canyon Creek, in the Moose Mountain area (grid reference 577396, Bragg Creek, 1:50,000 topographic sheet, 82 J/15). In none of these sections are all of the recognized subdivisions of the Fernie present. Outcrops of the Fernie Formation occur from southeastern British Columbia throughout the foothills and front ranges of Alberta, and into the foothills north of the Peace River in northeastern British Columbia. Thickness generally decreases toward the east and northeast, the zero edge being along a line trending northwest through Calgary, in southernmost Alberta Jurassic rocks extend farther east and the Fernie Formation grades into the subsurface Jurassic units of the Williston Basin to the east and southeast. Throughout the lower and middle parts of the Fernie many units exhibit coarser facies toward the east, from which direction they were derived, but, approaching the top of the formation coarser detritus to the west indicates a shift in source direction to the west and south (Hamblin and Walker, 1979).
Predominantly brownish, medium to dark grey and black shales; some massive with conchoidal fracture, others laminated and highly fractured or papery, recessive. Interbedded units include dark phosphatic sandstones and limestones, and black, cherty limestones in the lower parts; resistant, well-bedded siltstones, sandstones and black, oolitic limestones; coquinas and concretionary bands in the middle parts; and, in the upper parts glauconitic sands, concretionary bands and brown weathering siltstones and sandstones. Five shallowing-upwards depositional cycles are recognized within the formation (Stronach, 1984).
In more westerly sections the Fernie Formation rests disconformably on Triassic units; farther east it overlies upper Paleozoic units, indicating a significant hiatus with erosion prior to deposition of the first Jurassic sediments. Rocks belonging to the basal Hettangian Stage of the Jurassic have only been recognized by fossils at one locality: Black Bear Ridge, north of Williston Lake in northeastern British Columbia (Tozer, 1982, p. 387). Elsewhere the basal Fernie strata are Sinemurian and occasionally Toarcian in age. The Passage Beds, representing the uppermost unit in the Fernie are overlain conformably by the Weary Ridge Member of the Morrissey Formation (Kootenay Group) in southern areas; Gibson (1979) placed this contact at the base of the first continuous sandstone devoid of interbedded siltstones and shales which typify the underlying Passage Beds of the Fernie. A similar relationship exists between the Passage Beds and the overlying Nikanassin Formation in the foothills of central-northern Alberta and also in northeastern British Columbia with the overlying Monteith Formation (Minnes Group).
This unit was designated as the "Fernie Shales" on a map of the Crowsnest coal fields by McEvoy and Leach (1902) and again in a report on the Blairmore-Frank coalfields by Leach (1903). Lithological descriptions and recognition of the Jurassic age of the Fernie first appeared in Leach (1912), and he later introduced the term "Fernie formation" on a map legend (1914, p. 234). The first use of the term "Fernie Group" was by Henderson (1944, p. 2), and the Fernie has subsequently been described as "formation" or "group" by various authors, though never formally defined in either sense. Numerous subdivisions have been established within the Fernie, but very few have been properly defined as lithostratigraphic units. Indeed, many of these informally named subdivisions (variously called "members" and "beds") have come to be defined as much by biostratigraphic as lithologic characters and now often incorporate a variety of rock types in their lateral extensions. The formational status of this unit should be retained, as few of the "members" and "beds" within it can be mapped as "formations", should the Fernie be raised to group status. Commonly used subdivisions of the Fernie Formation which are indexed in this volume are (from base to top, approximately); Nordegg Member ("Black chert member"), Oxytoma Bed, Red Deer Member, Poker Chip Shale ("Paper Shale"), Lille Member, Rock Creek Member ("Belemnite zone"), Highwood Member, Pigeon Creek Member, Corbula munda Beds, Gryphaea Bed, Grey Beds, Green Beds, Ribbon Creek Member and Passage Beds.
Frebold, 1957; Gibson, 1979; Hall, 1984; Hamblin and Walker, 1979; Henderson, 1944; McEvoy and Leach, 1902; Leach, 1903, 1912, 1914; Poulton, 1984; Stott, 1967; Stronach, 1984; Tozer, 1982.
Leach, W.W., 1914. Blairmore map-area, Alberta; Geological Survey of Canada, Summary Report 1912, p. 234. with Map 107A, Blairmore, Alberta, Scale: 1 inch to 2 miles.
Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: R.L. Hall
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 09 Nov 2009