The Beaver Mines Formation is a
stratigraphic unit of
Early Cretaceous
The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma.
Geology
Pro ...
(
Albian) age in the
Western Canada Sedimentary Basin
The Western Canadian Sedimentary Basin (WCSB) underlies of Western Canada including southwestern Manitoba, southern Saskatchewan, Alberta, northeastern British Columbia and the southwest corner of the Northwest Territories. This vast sedimentary ...
that is present in southwestern
Alberta
Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...
and southeastern
British Columbia
British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...
,
Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
. It was established by G.B. Mellon in 1967 who named it for the hamlet of
Beaver Mines
Beaver Mines is a hamlet in southern Alberta, Canada within the Municipal District of Pincher Creek No. 9. It is located in the foothills of the Canadian Rockies on Highway 507, approximately west of Pincher Creek.
History
The community wa ...
, Alberta.
It contains a variety of
plant fossils.
Lithology
Fine- to coarse-grained greenish-grey
sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicates) ...
interbedded with greenish-grey
mudstone
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...
and
siltstone
Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, p ...
, and lesser amounts of
conglomerate
Conglomerate or conglomeration may refer to:
* Conglomerate (company)
* Conglomerate (geology)
* Conglomerate (mathematics)
In popular culture:
* The Conglomerate (American group), a production crew and musical group founded by Busta Rhymes
** Co ...
,
bentonite, and
tuff
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock cont ...
. Some conglomerate beds contain pebbles of volcanic origin. Minor
argillaceous limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
is present at the top in some areas. The sandstones are
feldspathic
Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feldspa ...
, in contrast to the
quartz
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...
ose sandstones of the overlying
Ma Butte Formation.
[Glass, D.J. (editor) 1997. Lexicon of Canadian Stratigraphy, vol. 4, Western Canada including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba. Canadian Society of Petroleum Geologists, Calgary, 1423 p. on CD-ROM. .]
Environment of deposition and paleontology
The Beaver Mines Formation was deposited in
floodplain
A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...
and
fluvial channel
In physical geography, a channel is a type of landform consisting of the outline of a path of relatively shallow and narrow body of water or of other fluids (e.g., lava), most commonly the confine of a river, river delta or strait. The word is ...
environments by
meander
A meander is one of a series of regular sinuous curves in the channel of a river or other watercourse. It is produced as a watercourse erodes the sediments of an outer, concave bank ( cut bank) and deposits sediments on an inner, convex bank ...
ing river systems.
[Taylor, D.R. and Walker, R.G. 1984. Depositional environments and paleogeography of the Albian Moosebar Formation and adjacent fluvial Gladstone and Beaver Mines Formations, Alberta. Canadian Journal of Earth Sciences, vol. 21, p. 698-714.] It contains a variety of
plant fossils including remains of
fern
A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes except t ...
s,
cycad
Cycads are seed plants that typically have a stout and woody (ligneous) trunk (botany), trunk with a crown (botany), crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants o ...
s,
cycadeoids,
Ginkgos and extinct
conifer
Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single ...
s, but remains of
flowering plant
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
s do not appear until the overlying Ma Butte Formation.
[Bell, W.A. 1949. Lower Cretaceous floras of western Canada. Geological Survey of Canada, Memoir 285, 331 p.][McLean, 1980. Lithostratigraphy of the Lower Cretaceous coal-bearing sequence, foothills of Alberta. Geological Survey of Canada, Paper 80-29.]
Distribution and thickness
The Beaver Mines Formation is present in the southern foothills of southwestern Alberta and southeastern British Columbia and extends as far north as the
Clearwater River where it grades into the
Gates Formation
The Fort St. John Group is a stratigraphic unit of Lower Cretaceous age in the Western Canada Sedimentary Basin. It takes the name from the city of Fort St. John, British Columbia and was first defined by George Mercer Dawson in 1881.
Lithology
...
of the
Luscar Group.
[Langenberg, C.W. and McMechan, M.E. 1985. Lower Cretaceous Luscar Group (revised) of the northern and north-central foothills of Alberta. Bulletin of Canadian Petroleum Geology, vol. 33, p. 1-11.] It reaches a maximum thickness of about at Ma Butte north of the
Crowsnest Pass.
Relationship to other units
The Beaver Mines Formation is part of the
Blairmore Group
The Blairmore Group, originally named the Blairmore Formation, is a geologic unit of Early Cretaceous age in the Western Canada Sedimentary Basin that is present in southwestern Alberta and southeastern British Columbia. It is subdivided into ...
. It
disconformably overlies the
Gladstone Formation
The Gladstone Formation is a stratigraphic unit of Early Cretaceous (Aptian) age in the Western Canada Sedimentary Basin. It is present in the foothills of southwestern Alberta and is named for outcrops along Gladstone Creek, a tributary of the ...
and grades into the Gates Formation of the
Luscar Group north of the
Clearwater River. It is disconformably overlain by the
Ma Butte Formation in the southern foothills and by the
Blackstone Formation north of the
Red Deer River. To the east, it is correlated with the upper part of the
Mannville Group
The Mannville Group is a stratigraphical unit of Cretaceous age in the Western Canadian Sedimentary Basin.
It takes the name from the town of Mannville, Alberta, and was first described in the ''Northwest Mannville 1'' well by A.W. Nauss in 1945 ...
.
See also
*
*
References
{{reflist
Western Canadian Sedimentary Basin
Geologic formations of Alberta
Cretaceous Alberta
Geologic formations of British Columbia
Cretaceous British Columbia
Albian Stage