Unit Name: Bullhead Group
Unit Type: Lithostratigraphic
Usage: Currently in use
Age Interval: ? Barremian - early Albian (130 - 108.8 ma)
Age Justification: The lower Blairmore flora, ranging from Aptian to Early Albian in age occurs in the group. A small assemblage of microflora was reported to be similar to the Mannville assemblage of Late Barremian to Early or early Middle Albian age. Dinosaur tracks of both herbivorous and carnivorous dinosaurs were first studied by Sternberg (1932), and more recently by P. Currie of the Tyrrell Museum of Palaeontology. Microfauna recovered from marine strata of the Gething have been dated as Barremian to Early Albian.
Province/Territory: British Columbia
Originator: McLearn, 1918.
No specific location was designated as type, although the type section of Gething Formation (Stott, 1973) provides the most complete exposure of the group. The section is found on the west bank of the upper Peace River immediately downstream from the Bennett Dam, 56° 01'N, 122° 14'W, Halfway River (94B) and Pine Pass (93O) map-areas, northeastern British Columbia. Only the uppermost beds of the Cadomin are exposed at the base of the Gething Formation, although much more was exposed prior to the construction of the dam. Almost all of the Gething Formation is exposed downstream from the dam and in side tributaries flowing into Peace River from the south between Moosebar and Gething creeks.
The group forms a wedge that decreases from more than 900 m (3,000 ft) in the western foothills of northeastern British Columbia to about 100 m (328 ft) in the Peace River Plains and to a zero edge north of Fort St. John. The group occurs throughout the foothills of northeastern British Columbia as far south as Smoky River and as far north as Tuchodi River.
The Bullhead Group comprises a thick succession of piedmont fan, alluvial plain and transitional sediments (Stott, 1968b, 1973). The basal part is characterized by massive, resistant conglomerate comprising well rounded pebbles, cobbles and boulders of chert, quartz and quartzite. The upper part of the group contains a cyclical succession of fine-grained sandstone, siltstone and mudstone. The succession is coal bearing south of the Peace River, but grades northward into fine-grained sandstone of deltaic to marine origin.
The Bullhead Group lies unconformably on successively older rocks from west to east and also northward from Peace River. It is overlain conformably, or possibly disconformably locally by shales of the Fort. St. John Group. Equivalent beds are included in the basal Luscar Group of the northern and central Foothills of Alberta and in the basal Blairmore Group of southwestern Alberta and southeastern British Columbia. In the central and southern Plains of Alberta equivalent beds are included in the lower Mannville subgroup. In the foothills north of Tuchodi River the marine sandstone of the Bullhead Group grades laterally into marine shale of the Fort St. John Group.
McLearn (1918, p. 16c) originally applied the name "Bull Head Mountain Formation" to a thick series of strata of fresh water origin lying between Triassic Shale below and the St. John Shale above. When McLearn realized that Jurassic Shale is present within the succession the definition was modified (McLearn and Kindle, 1950, p. 63) to include only the overlying sandy strata. The formation was raised to group status and the name shortened to Bullhead by Wickenden and Shaw (1943, p. 2). McLearn originally had divided the formation into two members; the upper was named Gething by McLearn (1923, p. 4b) and the lower was named Dunlevy by Beach and Spivak (1944, p. 4). Mathews (1947, p. 9), working in Carbon Creek Basin recognized three formations which he considered equivalent to the lower Dunlevy, and to which he referred to as the "marine Bullhead". The upper, continental, coal bearing part was included in the "nonmarine Bullhead". The Alberta Study Group (1954, p. 277) recognized the Nikanassin, Cadomin and Gething formations within the succession and restricted the Bullhead Group to beds overlying the unconformity at the top of the Nikanassin Formation. Subsequently Hughes (1964) proposed two new groups, the Beaudette Group and Crassier Group within the Bullhead "supergroup". Stott (1967a, 1968b, 1973) restricted the Bullhead Group to include only the Gething and Cadomin formations.
Alberta Study Group, 1954. Lower Cretaceous of the Peace River region. In: Western Canada Sedimentary Basin; Clark, L.M. (Ed.). Amer. Assoc. Petrol. Geol., p. 268-278.
Beach, H.H. and Spivak, J., 1944. Dunlevy-Portage Mountain map-area, British Columbia. Geol. Surv. Can., Paper 44-19.
Hughes, J.E., 1964. Jurassic and Cretaceous strata of the Bullhead succession in the Peace and Pine River Foothills. British Columbia Dept. Mines and Petrol. Res., Bull. 51.
Mathews, W.H., 1947. Geology and coal resources of the Carbon Creek-Mount Bickford map-area, 1946 British Columbia Dept. of Mines, Bull. 24.
McLearn, F.H. and Kindle, E.D., 1950. Geology of northeastern British Columbia; Geological Survey of Canada, Memoir 259, 236 p.
McLearn, F.H., 1918. Peace River Section, Alberta; Geological Survey of Canada, Summary Report 1917, Part C, pp. 14-21.
McLearn, F.H., 1923. Peace River Canyon Coal Area, British Columbia; Geological Survey of Canada, Summary Report 1922, Part B, pp. 1-46.
Sternberg, C.M., 1932. Dinosaur tracks from Peace River, British Columbia. Nat. Mus. Canada, Ann. Rept. 1930, Bulletin 63, p. 59-86.
Stott, D.F., 1967a. Jurassic and Cretaceous stratigraphy between Peace and Tetsa rivers, northeastern British Columbia; Geological Survey of Canada, Paper 66-7.
Stott, D.F., 1968b. Lower Cretaceous Bullhead and Fort St. John groups, between Smoky and Peace rivers, Rocky Mountain Foothills, Alberta and British Columbia; Geological Survey of Canada, Bulletin 152, 279 p.
Stott, D.F., 1973. Lower Cretaceous Bullhead Group between Bullmoose Mountain and Tetsa River, Rocky Mountain Foothills, northeastem British Columbia; Geological Survey of Canada, Bulletin 219, 228 p. + 5 figures in back pocket.
Wickenden, R.T.D. and Shaw, G., 1943. Stratigraphy and structure in Mount Hulcross - Commotion creek map-area, British Columbia; Geological Survey of Canada, Paper 43-13, 14 p.
Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: D.F. Stott
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 09 Jul 2009