Frenchman Formation

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Frenchman Formation
Stratigraphic range: Upper Cretaceous
Type Geological formation
Underlies Ravenscrag Formation
Overlies Battle Formation, Whitemud Formation, Eastend Formation, Bearpaw Formation
Thickness up to 113 meters (371 ft)[1]
Lithology
Primary Sandstone
Other Claystone, conglomerate
Location
Coordinates 49°29′27″N 108°54′17″W / 49.49073°N 108.90467°W / 49.49073; -108.90467 (Frenchman Formation)Coordinates: 49°29′27″N 108°54′17″W / 49.49073°N 108.90467°W / 49.49073; -108.90467 (Frenchman Formation)
Region Western Canada Sedimentary Basin
Country  Canada
Type section
Named for Frenchman River
Named by Furnival, 1942

The Frenchman Formation is stratigraphic unit of Late Cretaceous (late Maastrichtian) age in the Western Canada Sedimentary Basin. It is present in southern Saskatchewan and the Cypress Hills of southeastern Alberta. The formation was defined by G.M. Furnival in 1942[2] from observations of outcrops along the Frenchman River, between Ravenscrag and Highway 37. It contains the youngest of dinosaur genera, much like the Hell Creek Formation in the United States.

Lithology[edit]

The Frenchman Formation consists of olive-green to brown, fine- to coarse-grained, cross-bedded sandstone with interbedded claystone bands and minor beds and lenses of intraformational clay-clast conglomerate.[1] A conglomerate layer with well-rounded quartzite pebbles is present above the basal unconformity in some areas.[3]

Thickness and distribution[edit]

The Frenchman Formation is present in southwestern Saskatchewan and the Cypress Hills area of southeastern Alberta. Its maximum reported thickness is about 113 m.[3]

Age[edit]

The Frenchman Formation is of latest Maastrichtian age, and the top of the formation coincides with the Cretaceous-Paleogene boundary, as evidenced by biostratigraphic changes and, in some areas, the presence of the terminal Cretaceous iridium anomaly.[4]

Relationship to other units[edit]

Although some early workers included the Frenchman Formation in the overlying Ravenscrag Formation, the two are separated by the Cretaceous-Paleogene boundary and are now treated separately. The contact is abrupt but conformable, and occurs at the base of the No. 1 or Ferris coal seam of the Ravenscrag Formation.[3]

The Frenchman is separated from the underlying formations by an erosional unconformity, and depending on the depth of the erosion, the Frenchman rests on the Whitemud Formation, the Battle Formation, the Eastend Formation, or the Bearpaw Formation.[3] It is equivalent in age to the lower part of the Scollard Formation, the lower part of the Willow Creek Formation, and the lower part of the Coalspur Formation in Alberta, and the Hell Creek Formation in Montana and North Dakota.

Paleontology[edit]

Dinosaurs reported from the Frenchman Formation
Genus Species Location Stratigraphic position Material Notes Images

Edmontosaurus

E. annectens

"Complete skull, [three or four] partial skulls."[5]

A hadrosaurid[6]

E. saskatchewanensis

Junior synonym of E. annectens[6]

Thescelosaurus

T. assiniboiensis

Torosaurus

T. latus

Chasmosaurinae indet.

[7]

Triceratops

Triceratops horridus & Triceratops prorsus

[7]

Tyrannosaurus

Tyrannosaurus rex

See also[edit]

References[edit]

  1. ^ a b Lexicon of Canadian Geological Units. "Frenchman Formation". Retrieved 2010-01-17. 
  2. ^ Furnival, G.M., 1942. Preliminary Map, Cypress Lake, Saskatchewan; Geological Survey of Canada, Paper 42-5, contains Preliminary Map 42-5, Cypress Lake, West of Third Meridian, Saskatchewan, Scale: 1 inch to 2 miles.
  3. ^ a b c d Glass, D.J., editor, 1997. Lexicon of Canadian Stratigraphy, vol. 4, Western Canada. Canadian Society of Petroleum Geologists, Calgary, Alberta, 1423 p. on CD-ROM, ISBN 0-920230-23-7.
  4. ^ Lerbekmo, J.F., Sweet, A.R. and St. Louis, R.M. 1987. The relationship between the iridium anomaly and palynofloral events at three Cretaceous-Tertiary boundary localities in western Canada. Geological Society of America Bulletin, 99:25-330.
  5. ^ "Table 20.1," in Weishampel, et al. (2004). Page 440.
  6. ^ a b Campione, N.E. and Evans, D.C. (2011). "Cranial Growth and Variation in Edmontosaurs (Dinosauria: Hadrosauridae): Implications for Latest Cretaceous Megaherbivore Diversity in North America." PLoS ONE, 6(9): e25186. doi:10.1371/journal.pone.0025186
  7. ^ a b Tokaryk, T. 1986. Ceratopsian dinosaurs from the Frenchman Formation (Upper Cretaceous) of Saskatchewan. Canadian Field-Naturalist 100:192–196.