| Stephen Formation | |
|---|---|
Stratigraphic range: | |
 The Walcott Quarry in the Stephen Formation shales | |
| Type | Geological formation |
| Underlies | Eldon Formation |
| Overlies | Cathedral Formation |
| Thickness | "Thin" Stephen: < 60 metres (200 ft)[1] "Thick" Stephen: up to 335 metres (1,100 ft)[2] |
| Lithology | |
| Primary | Shale, limestone |
| Other | Siltstone |
| Location | |
| Coordinates | 51°27′51″N 116°19′28″W / 51.46425°N 116.32443°W |
| Region | Canadian Rockies |
| Country |  Canada |
| Type section | |
| Named for | Mount Stephen (from George Stephen) |
| Named by | Charles Doolittle Walcott, 1908[3][4] |
The Stephen Formation is a geologic formation exposed in the Canadian Rockies of British Columbia and Alberta, on the western edge of the Western Canada Sedimentary Basin. It consists of shale, thin-bedded limestone, and siltstone that was deposited during Middle Cambrian time (513 to 497 million years ago).[5] It is famous for the exceptional preservation of soft-bodied fossils: the Burgess Shale biota.[6][7] The formation overlies the Cathedral escarpment, a submarine cliff; consequently it is divided into two quite separate parts, the 'thin' sequence deposited in the shallower waters atop the escarpment, and the 'thick' sequence deposited in the deeper waters beyond the cliff. Because the 'thick' Stephen Formation represents a distinct lithofacies, some authors suggest it warrants its own name, and dub it the Burgess Shale Formation.[8] The stratigraphy of the Thin Stephen Formation has not been subject to extensive study, so except where explicitly mentioned this article applies mainly to the Thick Stephen Formation.
- ^ Cite error: The named reference
Caron2010was invoked but never defined (see the help page). - ^ Lexicon of Canadian Geologic Units. "Stephen Formation". Retrieved 2010-01-02.
- ^ Walcott, C.D., 1908a. Nomenclature of some Cambrian Cordilleran formations; Smithsonian Miscellaneous Collections, vol. 35, no. 1.
- ^ Walcott, C.D., 1908b. Cambrian geology and paleontology: Cambrian sections of the Condilleran area. Smithsonian Miscellaneous Collections, vol. 53, no. 5, pp. 204-208.
- ^ "Lithological Unit Search". Lexicon of Canadian Geologic Units. Natural Resources Canada. Retrieved 1 August 2018.
- ^ Collom, C. J.; Johnston, P. A.; Powell, W. G. (2009). "Reinterpretation of 'Middle' Cambrian stratigraphy of the rifted western Laurentian margin: Burgess Shale Formation and contiguous units (Sauk II Megasequence); Rocky Mountains, Canada". Palaeogeography, Palaeoclimatology, Palaeoecology. 277 (1–2): 63–85. Bibcode:2009PPP...277...63C. doi:10.1016/j.palaeo.2009.02.012.
- ^ Slind, O.L., Andrews, G.D., Murray, D.L., Norford, B.S., Paterson, D.F., Salas, C.J., and Tawadros, E.E., Canadian Society of Petroleum Geologists and Alberta Geological Survey (1994). "The Geological Atlas of the Western Canada Sedimentary Basin (Mossop, G.D. and Shetsen, I., compilers), Chapter 8: Middle Cambrian and Early Ordovician Strata of the Western Canada Sedimentary Basin". Retrieved 2018-07-13.
{{cite web}}: CS1 maint: multiple names: authors list (link) - ^ Fletcher, T. P.; Collins, D. (1998). "The Middle Cambrian Burgess Shale and its relationship to the Stephen Formation in the southern Canadian Rocky Mountains". Canadian Journal of Earth Sciences. 35 (4): 413–436. Bibcode:1998CaJES..35..413F. doi:10.1139/cjes-35-4-413.