Unit Name: Vermilion River Formation
Unit Type: Lithostratigraphic
Usage: Currently in use
Age Interval: Turonian - Campanian (93.6 - 70.6 ma)
Province/Territory: Manitoba; Saskatchewan
Originator: Kirk, S.R., 1930.
Exposures along the Vermilion River, in the central part of Twp. 23, Rge. 20WPM, Manitoba. (A dam has been erected on the Vermilion River in the type area; high water now makes the exposures inaccessible. See Wickenden (1945) or McNeil and Caldwell (1981) for illustrations and descriptions of the type beds.
The Vermilion River Formation is exposed along the Manitoba escarpment and extends into the subsurface of southeastern Saskatchewan. It is 130 m (426 ft) thick at Pembina Mountain in southern Manitoba, but only 35 m (115 ft) in the Pasquia Hills of east-central Saskatchewan. The northwestward decrease in thickness is due primarily to a gradual thinning of the Morden Shale and a marked decrease in thickness of the Boyne Member north of Pembina Mountain due to the virtual disappearance of the upper chalky shale facies.
Thickness(m): Minimum 35, Maximum 130.
Greyish black shale; chalk-speckled, olive-black calcareous shale; and buff weathering chalky shale or marlstone. The basal Morden Member consists of uniform greyish black to black shale, with rare thin bentonite beds. Large septarian concretions are characteristic, and lenses of quartzose silt and sand mark the uppermost beds in the area of Pembina Mountain. The overlying Boyne Member consists of olive-black chalk-speckled shale and an upper chalky shale or marlstone; both contain minor beds of greyish black, noncalcareous shale and thin bentonite beds. The lowest few metres of the Boyne Shale contain lenses of silt or sand in the Pembina Mountain area. The upper chalky lithotype is developed prominently in Pembina Mountain, but disappears northwestward toward Riding Mountain and reappears to the far northwest in the Pasquia Hills. In Riding Mountain the Gammon Ferruginous Member, consisting of greyish black chunky shale with numerous ferruginous concretions lies between the Boyne and Pembina Members (Bannatyne, 1970; McNeil and Caldwell, 1981). The Pembina Member is a greyish black shale distinguished by as many as 30 yellowish grey weathering bentonite beds.
The Vermillion River rests with sharp and unconformable contact on the Favel Formation. McNeil and Caldwell (1981) have shown that the upper contact with the Millwood Member of the Riding Mountain Formation (now within the Pierre Shale) is sharp and disconformable in the Pembina Mountain area, but sharp and probably paraconformable to the northwest. The Vermilion River correlates westward in Saskatchewan with the "unnamed" and "first (upper) white-speckled" shale units of the upper Colorado Group and the lower two-thirds of the Lea Park Formation of the Montana Group. To the south, in North Dakota the formation correlates with the Blue Hill Shale Member and the Carlile Shale. The Niobrara Formation and the Gammon Ferruginous and Pembina members of the Pierre Shale.
McNeil and Caldwell (1981) have proposed that the name Vermilion River be abandoned in favor of raising its Morden and Boyne members to formational status, referred to as the Morden Shale and Niobrara Formation respectively and assigning its Pembina Member to the Pierre Shale.
Bannatyne, 1970; Kirk, 1930; McNeil and Caldwell, 1981; Wickenden, 1945.
Bannatyne, B.B., 1970. The clays and shales of Manitoba; Manitoba Dept. of Mines and Nat. Res., Mines Branch, Pub. 67-1.
Kirk, S R., 1930. Cretaceous Stratigraphy of the Manitoba Escarpment; Geological Survey of Canada, Summary Report 1929, Part B, pp. 112-135.
McNeil, D.H. and Caldwell, W.G.E., 1981. Cretaceous rocks and their Foraminifera in the Manitoba escarpment. Geol. Assoc. Can., Spec. Paper 21
Wickenden, R.T.D., 1945. Mesozoic stratigraphy of the eastern plains, Manitoba and Saskatchewan; Geological Survey of Canada, Memoir 239, 87 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: L.L. Price; D.H. McNeil
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 16 Feb 2009