Unit Name: Judith River Formation
Unit Type: Lithostratigraphic
Usage: Currently in use
Age Interval: Campanian (83.5 - 70.6 ma)
Age Justification: Dinosaur remains are important in the upper part of the formation in some areas.
Province/Territory: Alberta; Saskatchewan; Montana; South Dakota; Wyoming
Originator: Hayden, 1871; Meek, 1876.
Badlands area bordering Judith River near its confluence with the Missouri River in Montana (47 deg 40'N, 109 deg 39'W).
Extends from the United States border to about 54 deg N in the Edmonton area and from the eastern margin of the foothills in southwestern Alberta to central Saskatchewan. Thickness is about 120 m (394 ft) at the type area, maximum thickness is 360 m (1,180 ft), thinning to depositional edge eastward in central Saskatchewan.
Predominantly interbedded mudstone, siltstone and sandstone in varying proportions. Coal, bentonite and mollusc coquinas are minor but prominent constituents in part. Lower beds often darker colors (yellows and browns), upper part lighter, grey to white. Generally recessive, but coarser sandstone beds often well-indurated and form resistant ribs. Lateral variability in proportion and character of lithologies is characteristic. Coal is confined to the lower 100 to 150 m (328 to 492 ft) and to the upper 25 m (82 ft) of the formation.
Conformable and transitional with the Claggett and Pakowki formations below. The Bearpaw Formation overlies the Judith River abruptly but conformably. Intertongueing of sandstones of the Judith River Formation occurs with dark shales of both the Claggett-Pakowki and Bearpaw formations. It is equivalent to the upper part of the Belly River Formation in the southern Alberta Foothills, a lower part of the Brazeau Formation in the central Alberta Foothills and the lower part of the Wapiti Formation in the northwestern Alberta Plains. It is equivalent to the combined Oldman and Foremost formations (McLean, 1971). In east-central Alberta the names Pale and Variegated beds were used for the same interval, but these are now obsolete. Several formal members are recognized in east-central Alberta. Only two are named - Birch Lake and Ribstone Creek members. Other members names (lower Birch Lake, Brosseau, Victoria) have been used inconsistently or are not proper lithostratigraphic names and have been discontinued (McLean, 1971). The Mulga Tongue, Grizzly Bear Tongue, Vanesti Member and Shandro Member, formerly included in the Judith River formation are now considered members of the Lea Park Formation. The informal names Verdigris sandstone, McKay coal zone, Taber coal zone and Lethbridge coal zone are used locally in the southern Alberta Plains (Crockford, 1949; McLean, 1971).
Crockford, 1949; Hayden, 1871; Meek, 1876; McLean, 1971; Russell and Landes, 1940; Shaw and Harding, 1949; Stanton and Hatcher, 1905; Williams and Dyer, 1930.
Hayden, F.V., 1871. Geology of the Missouri Valley: Preliminary report (4th annual) of the Geol. Surv. of Wyoming and portions of contiguous territories.
Meek, Fielding Bradford, 1876. A report on the invertebrate Cretaceous and Tertiary fossils of the upper Missouri country, Hayden, F.V., Geologist in Charge; United States Geologic and Geographic Survey of the Territories, vol. 9, 629 p., 85 figures and 45 plates.
Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: J.R. McLean
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 28 May 2008