Scollard Formation

Scollard Formation
Stratigraphic range: Maastrichtian-Danian ~70–65 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Scollard Formation exposed along the Red Deer River, Alberta. The Tyrannosaurus rex skeleton on display at the Royal Tyrrell Museum of Palaeontology was excavated in the center of image.
Type	Geological formation
Unit of	Edmonton Group
Sub-units	Ardley coal zone
Underlies	Paskapoo Formation
Overlies	Battle Formation
Thickness	Up to 300 metres (980 ft)[1]
Lithology
Primary	Sandstone, siltstone, shale
Other	Coal, bentonite
Location
Coordinates	51°56′19″N 112°55′37″W
Approximate paleocoordinates	62.8°N 86.2°W / 62.8; -86.2
Region	Alberta
Country	Canada
Extent	Western Canada Sedimentary Basin
Type section
Named for	Scollard Canyon at Dry Island Buffalo Jump Provincial Park
Named by	Irish, E.J.W[2]
Year defined	1970
Scollard Formation (Canada) Show map of Canada Scollard Formation (Alberta) Show map of Alberta

The Scollard Formation is an Upper Cretaceous to lower Palaeocene stratigraphic unit of the Western Canada Sedimentary Basin in southwestern Alberta.[1][3] Its deposition spanned the time interval from latest Cretaceous to early Paleocene, and it includes sediments that were deposited before, during, and after the Cretaceous-Paleogene (K-Pg) extinction event. It is significant for its fossil record, and it includes the economically important coal deposits of the Ardley coal zone.

Lithology

The Scollard Formation consists primarily of sandstones and siltstones, interbedded with mudstones and, in the upper portion, coal seams, as well as minor amounts of bentonite.[1] The sediments were eroded from the Canadian Cordillera, and were transported eastward by river systems and deposited in fluvial channel and floodplain environments.

Stratigraphy

The Scollard is usually classified as the uppermost formation of the Edmonton Group, although some early workers included it in the overlying Paskapoo Formation.[4] It is subdivided into an upper, coal-bearing member that consists of the Ardley coal zone, and a lower member that lacks significant coal.[1] Neither member has been formally named.

Age

The K-Pg boundary in the Scollard Formation. The coals are earliest Paleocene in age, lighter shales below are Maastrichtian. The lighter rock at the very base of the dark coals represents the K-Pg boundary.

The K-Pg boundary occurs at the base of the lowermost seam of Ardley coal zone, based on dinosaurian and microfloral evidence,[5] as well as the presence of the terminal Cretaceous iridium anomaly.[6] The upper member is therefore of early Danian age, while the lower member is of latest Maastrichtian age.

Distribution

The Scollard Formation is present in the subsurface throughout much of southwestern Alberta,[7] and it outcrops extensively along the banks of the Red Deer River in the area of Trochu.[8] Both the upper and lower members thin from west to east. Thicknesses for each member range from more than 300 metres (980 ft) near the foothills of the Canadian Rockies to less than 100 metres (330 ft) near the outcrops in south-central Alberta.[1]

Relationship to other units

The Scollard Formation rests disconformably on the Late Cretaceous Battle Formation in the southwestern Alberta plains, on the Wapiti Formation in the northwestern plains, and on the Brazeau Formation in the foothills. It is unconformably overlain by the Paskapoo Formation, and where the Paskapoo has been removed by erosion, the Scollard is exposed at surface or covered by Quaternary sediments.

The Scollard grades into the Willow Creek Formation in the southern Alberta plains and the Coalspur Formation in the Alberta foothills. The Ardley coal zone in the upper portion is equivalent to the lower part of the Coalspur coal zone of the Coalspur Formation,[9] and is correlated with the lower part of the Ravenscrag Formation of southern Saskatchewan, which is also coal bearing.[10] The Late Cretaceous member is equivalent in age to the Frenchman Formation of Saskatchewan, the Hell Creek Formation of Montana, and the Lance Formation of Wyoming .[1]

Coal deposits

Metasequoia occidentalis, upper Scollard Formation, central Alberta

The coal seams of the Ardley coal zone attain thicknesses in excess of 7 metres (20 ft) in some areas. The zone is present at shallow depths and, in places, exposed at surface, along a trend between Red Deer and Edmonton. The coal is typically of sub-bituminous B to C rank, although more deeply buried Scollard coals farther to the west reach high-volatile bituminous rank. The Ardley coal has been mined in the Red Deer area, and is currently being mined west of Edmonton to fuel mine-mouth electric power generating stations.[11]

Paleontology

The Scollard Formation preserves the remains of vertebrates, especially dinosaurs and, rarely, mammals, as well as a wide range of plant fossils. The Scollard strata span the K-Pg boundary, therefore the lower member of the Scollard provides a record of the last of the dinosaurs, while the upper member records the dawn of the Age of Mammals after the K-Pg extinction event.

Flora

Plant fossils from the upper, early Paleocene member of the Scollard Formation include species of the ferns Botrychium, Woodwardia and Azolla; the conifers Metasequoia and Glyptostrobus; the monocot Limnobiophyllum (a relative of duckweeds); and the dicots Cercidiphyllum and Platanus.[12][13]

Vertebrates

Crocodylian Albertosuchus, acanthomorph fish Lindoeichthys and unnamed esocid fish are known.[14][15][16]

Theropods

Ornithomimus remains have been unearthed here.[17] Two caenagnathid taxa, a large-bodied one similar to Caenagnathus and a small-bodied one similar to Leptorhynchos have been found.[18]

Theropods
Genus	Species	Location	Stratigraphic position	Material	Description	Images
cf. Dromaeosaurus[19]	Indeterminate[19]			Teeth	A dromaeosaurid	Dromaeosaurus Saurornitholestes Troodon Tyrannosaurus
Red Deer River, Alberta Canada cf. Paronychodon[20]	Indeterminate[19]
cf. Richardoestesia[21]	cf. R. gilmorei[22]
	cf. R. isosceles[23]
cf. Saurornitholestes[19]	cf. S. langstoni[19]
Troodon[24]	Indeterminate[19]			A Single Tooth
Tyrannosaurus[19]	T. rex[19]	Red Deer River, Alberta Canada		Partial Skeleton

Ornithischians

Torosaurus remains have also been unearthed in this region.[25] Edmontonia remains have also been unearthed here and in the nearby areas.[17]

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Ornithischians
Genus	Species	Location	Stratigraphic position	Material	Description	Images
Ankylosaurus[19]	A magniventris[19]			Complete skull, both mandibles, ribs, caudal vertebrae, tail club, both humeri, left ischium, left femur, right fibula, and osteoderms.	An ankylosaurine ankylosaurid also found in the Lance, Frenchman, Ferris and Hell Creek Formations.	Ankylosaurus Edmontosaurus Leptoceratops Pachycephalosaurus Thescelosaurus Triceratops
Edmontosaurus[19]	E. annectens[19]
Leptoceratops[19]	L. gracilis[19]			Partial Skull
cf. Pachycephalosaurus[19]	P. wyomingensis[19]			Domed Parietal
Thescelosaurus[19]	T. edmontonensis[19]			Partial Skull	Referred to Thescelosaurus sp.[26]
Triceratops[19]	T. Prorsus [19]	Drumheller, Alberta Canada		Nearly Complete Skull

See also

• List of dinosaur-bearing rock formations

References

1. Mossop, G.D. and Shetsen, I., (compilers), Canadian Society of Petroleum Geologists (1994). "The Geological Atlas of the Western Canada Sedimentary Basin, Chapter 24: Upper Cretaceous and Tertiary strata of the Western Canada Sedimentary Basin". Archived from the original on 2013-07-21. Retrieved 2013-08-01.
2. Irish, E.J.W., 1970. The Edmonton Group of south-central Alberta; Canadian Society of Petroleum Geologists (CSPG), Bulletin of Canadian Petroleum Geology, vol. 18, no. 2 (June), pp. 125-155.
3. Lexicon of Canadian Geological Units. "Scollard Formation". Archived from the original on 2013-02-21. Retrieved 2009-02-06.
4. Hamblin, A.P. (2004). "Paskapoo-Porcupine Hills Formation in western Alberta: Synthesis of regional geology and resource potential. Geological Survey of Canada, Open File 4679". Retrieved 2013-08-01.
5. Lerbekmo, J.F., Singh, C., Jarzen, D.M., and Russel, D.A. 1979. The Cretaceous-Tertiary boundary in south-central Alberta - a revision based on dinosaurian and microfloral evidence. Canadian Journal of Earth Science, 16: 325-330.
6. Lerbekmo, J.F. and St. Louis, R.M. 1985. The terminal Cretaceous iridium anomaly in the Red Deer Valley, Alberta. Canadian Journal of Earth Science, 23: 120-124.
7. Prior, G. J., Hathaway, B., Glombick, P.M., Pana, D.I., Banks, C.J., Hay, D.C., Schneider, C.L., Grobe, M., Elgr, R., and Weiss, J.A. (2013). "Bedrock Geology of Alberta. Alberta Geological Survey, Map 600". Archived from the original on 2013-09-25. Retrieved 2013-08-13.
8. "Introduction," Ryan and Russel (2001); page 279.
9. Langenberg, C.W., Berhane, H., Sweet, A.R., Marchioni, D. and Heamann, L.M. 2007. Regional correlations of the Ardley coal zone, Alberta. Alberta Geological Survey, Earth Sciences Report 2007-5, 21 p.
10. Alberta Geological Survey, 2013. "Alberta Table of Formations; Alberta Energy Regulator" (PDF). Retrieved 2016-06-20.
11. Mossop, G.D. and Shetsen, I., (compilers), Canadian Society of Petroleum Geologists (1994). "The Geological Atlas of the Western Canada Sedimentary Basin, Chapter 33: Coal Resources of the Western Canada Sedimentary Basin". Archived from the original on 2013-09-30. Retrieved 2013-08-01.
12. Chandrasekharam, A., 1974. Megafossil flora from the Genesee locality, Alberta, Canada. Palaeontographica, Abt. A, Band 147, 41 p.
13. Christophel, D.C., 1976. Fossil floras from the Smoky Tower locality, Alberta, Canada. Palaeontographica, Abt. B, Band 157, 43 p.
14. Wu, Xiao-Chun; Brinkman, Donald B. (2015). "A new crocodylian (Eusuchia) from the uppermost Cretaceous of Alberta, Canada". Canadian Journal of Earth Sciences. 52 (8): 590–607. Bibcode:2015CaJES..52..590W. doi:10.1139/cjes-2014-0133. ISSN 0008-4077.
15. Murray, Alison M.; Brinkman, Donald B.; Newbrey, Michael G.; Neuman, Andrew G. (2020). "Earliest North American articulated freshwater acanthomorph fish (Teleostei: Percopsiformes) from Upper Cretaceous deposits of Alberta, Canada". Geological Magazine. 157 (7): 1087–1096. Bibcode:2020GeoM..157.1087M. doi:10.1017/S0016756819001328. ISSN 0016-7568. S2CID 212927875.
16. Brinkman, Don; Van Loon, Lisa L.; Banerjee, Neil R. (2021). "3D Non-Destructive Identification of Fossil Fish from the Late Cretaceous of Alberta, Canada using Synchrotron Micro Computed Tomography". Microscopy Today. 29 (2): 26–31. doi:10.1017/s155192952100047x. ISSN 1551-9295. S2CID 232249820.
17. Carpenter, Kenneth; Young, D. Bruce (2002). "Late Cretaceous dinosaurs from the Denver Basin, Colorado". Rocky Mountain Geology. 37 (2): 237–254. Bibcode:2002RMGeo..37..237C. doi:10.2113/11 – via GeoScienceWorld.
18. Voris, Jared T.; Zelenitsky, Darla K.; Therrien, François (2023-09-11). "Caenagnathids (Theropoda, Oviraptorosauria) from the uppermost Maastrichtian of the Scollard Formation of Alberta, Canada". Cretaceous Research. 153: 105708. doi:10.1016/j.cretres.2023.105708. ISSN 0195-6671. S2CID 261779584.
19. "Dinosaur distribution (Late Cretaceous; North America; Yukon Territory, Canada)." In: Weishampel et al. Page 578.
20. Listed as "cf. Paronychodon sp." in Weishampel et al. Page 578.
21. Referred to by the obsolete spelling "Ricardoestesia" in Weishampel et al. Page 578.
22. Listed as "cf. Ricardoestesia gilmorei" in Weishampel et al. Page 578.
23. Listed as "cf. Ricardoestesia isosceles" in Weishampel et al. Page 578.
24. Listed as "cf. Troodon sp." in Weishampel et al. Page 578.
25. Mallon, Jordan C; Holmes, Robert B; Bamforth, Emily L; Schumann, Dirk (2022). "The record of Torosaurus (Ornithischia: Ceratopsidae) in Canada and its taxonomic implications". Zoological Journal of the Linnean Society. 195 (1): 157–171. doi:10.1093/zoolinnean/zlab120. ISSN 0024-4082.
26. Boyd, Clint A.; Brown, Caleb M.; Scheetz, Rodney D.; and Clarke, Julia A. (2009). "Taxonomic revision of the basal neornithischian taxa Thescelosaurus and Bugenasaura". Journal of Vertebrate Paleontology 29 (3): 758–770. doi:10.1671/039.029.0328.

Bibliography

• Ryan, M. J., and Russell, A. P., 2001. Dinosaurs of Alberta (exclusive of Aves): In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, pp. 279–297.
• Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. ISBN 0-520-24209-2.