Unit Name: Eastend Formation
Unit Type: Lithostratigraphic
Usage: Currently in use
Age Interval: Maastrichtian (70.6 - 65.5 ma)
Originator: Russell, L.S., 1932, p. 132.
Area around Eastend, southwestern Saskatchewan. Type section designated by Kupsch (1956) southwest of Eastend, north of Highway 13 in large gully east of Murphy's claypit, in Lsd. 6, Sec. 25, Twp. 6, Rge. 22W3M.
All published reports describe the Eastend as being of variable thickness, and in reports published before 1932 sediments now assigned to the Bearpaw Formation were included in the Eastend. In the area around the town of Eastend it is about 20 to 30 m (66 to 99 ft) thick. In the valley of Swift Current Creek north of 49 deg 42'N, and in the valley of the Frenchman River east of 108 deg 31'W the Eastend Formation was removed by erosion before deposition of the Upper Cretaceous Frenchman Formation.
Yellow to buff, greenish and brownish, fine-grained silty and clayey, volcanic, lithic sands with siltstone and sandstone ledges and concretionary layers; thin beds (up to 30 cm, 12 in) of grey and greenish grey shale are present throughout. In Alberta it contains lignite beds. Bedding is thin and cross-bedding is present. Contains poorly preserved marine bivalves in lower part (Russell, 1932, 1943). There are some abrupt lateral changes from sand to shale.
The lower contact of the Eastend with the Bearpaw Formation is gradational over as much as 16 m (53 ft), where light colored sandy beds of Eastend alternate with grey shales of the Bearpaw; the number and thickness of shale beds increase downwards. The upper contact with the Whitemud Formation takes place in only a few decimetres, where the buff silt or sand of the Eastend is replaced by light grey or white, feldspathic sandstones of the Whitemud Formation. Both upper and lower contacts of the Eastend Formation are conformable, except to the northeast and southeast of Eastend, in the valley of Swift Current Creek and the Frenchman River, where the Eastend Formation is overlain erosional by the Frenchman Formation. East of Twelvemile Lake, Saskatchewan the Eastend is overlain by the Whitemud Formation. The Eastend Formation is correlative with the St. Mary River and Horseshoe Canyon Formations of the Alberta Plains, and with the Fox Hills in Montana and North Dakota.
Formerly named: "Division Y of Foothills" by Dawson (1895); "Fox Hills" by McConnell (1885); "Phase A of the Basal Sandstone" by McLearn (1929); "Sandstone D" by McLearn (1930).
Dawson, 1875; Kupsch, 1956; McConnell, 1885; McLearn, 1929, 1930; Russell, 1932, 1943.
Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: H.E. Hendry
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 29 Apr 2003