| 词条 | Big Snowy Group |
| 释义 |
| name = Big Snowy Group | image = | imagesize = | caption = | type = Geological formation | age = {{Fossil range|Visean|Serpukhovian|Chesterian}} | period = Mississippian | prilithology = Shale, limestone, sandstone | otherlithology = | namedfor = Big Snowy Mountains | namedby = H.W. Smith | year_ts = 1935 | region = Williston Basin WCSB | country = {{flag|United States}} {{flag|Canada}} | coordinates = | unitof = | subunits = Heath, Otter & Kibbey Formations | underlies = Tyler Formation Watrous Formation | overlies = Madison Group | thickness = up to {{convert|135|m|ft|-1}}[1] | extent = | area = {{convert|51800|km2|sqmi}} | map = | map_caption = }} The Big Snowy Group is a stratigraphical unit of Chesterian age in the Williston Basin. It takes the name from Big Snowy Mountains in Montana, and was first described on the north slopes of the mountain by H.W. Smith in 1935. LithologySubdivisionsThe Big Snowy Group is composed of three subdivisions, from top to base: [1]
DistributionThe Big Snowy Group reaches a maximum thickness of {{convert|135|m|ft|-1}} in the Williston Basin.[1] It is exposed in outcrop in the Big Snowy Mountains, Little Belt Mountains, Castle Mountains and Lombard Hills of central Montana. It occurs in the sub-surface throughout the central part of the Williston Basin and into a limited area of south-central Saskatchewan. Relationship to other unitsThe Big Snowy Group is unconformably overlain by the Tyler Formation in Montana, and by the Watrous Formation in Saskatchewan; It disconformably overlays the Madison Group.[1] References1. ^1 2 3 {{Cite web |url=http://cgkn1.cgkn.net/weblex/weblex_litho_detail_e.pl?00053:001329 |archive-url=https://archive.is/20130221073831/http://cgkn1.cgkn.net/weblex/weblex_litho_detail_e.pl?00053:001329 |dead-url=yes |archive-date=2013-02-21 |title=Big Snowy Group |author=Lexicon of Canadian Geologic Units |accessdate=2010-02-03 }} {{Western Canadian Sedimentary Basin|Saskatchewan=yes}} 6 : Geologic formations of Montana|Geologic formations of Saskatchewan|Western Canadian Sedimentary Basin|Carboniferous Montana|Carboniferous Saskatchewan|Carboniferous System of North America |
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