View source for Earth:Paskapoo Formation

{{Short description|Stratigraphic unit in Western Canada}}
{{Infobox Rockunit
| name           = Paskapoo Formation
| image          = Peskapoo Sandstone.JPG
| caption        = [[Earth:Outcrop|Outcrop]] of Paskapoo sandstone in Calgary
| type           = [[Earth:Geological formation|Geological formation]]
| period         = Paleocene
| age            = {{Fossil range|65|55|[[Earth:Paleocene|Paleocene]]}}
| prilithology   = mudstone, [[Earth:Siltstone|siltstone]], [[Earth:Sandstone|sandstone]]
| otherlithology = [[Earth:Conglomerate (geology)|conglomerate]], [[Earth:Coal|coal]]
| namedfor       = {{lang-cr|script=Latn|paskapiw|lit=He is blind}}, from Blindman River
| namedby        = J.B. Tyrrell, 1887
| region         = Alberta
| country        = Canada
| coordinates    = {{coord|52.355031|-113.757797|name=Paskapoo|region:CA-AB}} 
| unitof         = 
| subunits       = 
| underlies      = [[Earth:Tertiary|Tertiary]] [[Earth:Gravel|gravel]], [[Earth:Quaternary|Quaternary]] sediments, present erosional surface
| overlies       = [[Earth:Scollard Formation|Scollard Formation]], [[Earth:Coalspur Formation|Coalspur Formation]]
| thickness      = up to {{convert|600|m|ft|-1}}<ref name=lexicon/>
| extent         = 
| area           = 
| map            = 
| map_caption    = 
}}

The '''Paskapoo Formation''' is a [[Earth:Stratigraphic unit|stratigraphic unit]] of [[Earth:Paleocene|Middle to Late Paleocene]] age in the Western Canada Sedimentary Basin.<ref name=Mossop24 /> The Paskapoo underlies much of southwestern Alberta,<ref name=Map600>{{Cite web|url=http://ags.aer.ca/data-maps-models/maps.htm|title=Bedrock Geology of Alberta. Alberta Geological Survey, Map 600|author= 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.|year=2013|access-date=2016-06-20}}</ref> and takes the name from the Blindman River ({{lang|cr-Latn|paskapiw}} means 'He is blind' in [[Social:Cree language|Cree]]<ref>{{Cite web |title=Search results |url=http://www.creedictionary.com/search/index.php?q=paskapiw&scope=1&cwr=18074 |access-date=2023-01-11 |website=www.creedictionary.com}}</ref>). It was first described from [[Earth:Outcrop|outcrop]]s along that river, near its confluence with the [[Earth:Red Deer River|Red Deer River]] north of the city of Red Deer, by Joseph Tyrrell in 1887.<ref name="Tyrrell">Tyrrell, J.B., 1887. ''Report on a part of northern Alberta and portions of adjacent Districts of Assiniboia and Saskatchewan;'' Geological Survey of Canada, Annual Report 1886, v.11, Part E, p.1-176</ref> It is important for its freshwater aquifers, its [[Earth:Coal|coal]] resources, and its fossil record, as well as having been the source of sandstone for the construction of fire-resistant buildings in Calgary during the early 1900s.

==Lithology and environment of deposition==
The Paskapoo Formation is of fluvial origin and consists primarily of [[Earth:Sandstone|sandstone]]s, [[Earth:Siltstone|siltstone]]s and mudstones, with lesser amounts of [[Earth:Conglomerate (geology)|pebble-conglomerate]] and [[Earth:Coal|coal]], and minor [[Chemistry:Bentonite|bentonite]].  The sediments were derived from the Canadian Cordillera during tectonic uplift and erosion in the late stages of the Laramide Orogeny. They were transported eastward by river systems and deposited in fluvial and [[Earth:Floodplain|floodplain]] environments.<ref name="Hamblin2004">{{Cite web|url= http://geoscan.ess.nrcan.gc.ca/cgi-bin/starfinder/0?path=geoscan.fl&id=fastlink&pass=&format=FLSHORTORG&search=R=215631|title= Paskapoo-Porcupine Hills Formation in western Alberta: Synthesis of regional geology and resource potential. Geological Survey of Canada, Open File 4679.|author=Hamblin, A.P.|year=2004|access-date=2013-08-01}}</ref>

The sandstones were deposited in river channels. They are [[Earth:Cross-bedding|cross-bedded]], medium- to coarse-grained, and locally conglomeratic. The siltstones and mudstones represent [[Earth:Crevasse splay|crevasse splay]], [[Earth:Overbank|overbank]] and shallow [[Earth:Pond|pond]] environments.  They include [[Biology:Paleobotany|plant fossils]], rooted horizons and paleosols.<ref name="Hoffman1999">Hoffman, G.L. and Stockey, R.A., 1999. Geological setting and paleobotany of the Joffre Bridge Roadcut fossil locality (Late Paleocene), Red Deer Valley, Alberta. Canadian Journal of Earth Science, 36: 2073-2084.</ref>  Carbonaceous mudstones and coaly beds that represent oxygen-poor, swampy settings are thin and discontinuous, but common.  Thick coal seams that formed in well-developed swamps are present only in the youngest portion of the formation, which is preserved near Hinton.<ref name="Hamblin2004" />

==Stratigraphy==
[[File:Paskapoo Mudstones Red Deer.jpg|thumb|left|Mudstones and siltstones of the Paskapoo Formation exposed along the Red Deer River, downstream from its confluence with the Blindman River.]]
Although some early workers included the underlying [[Earth:Scollard Formation|Scollard Formation]] as the lower part of the Paskapoo, the two are now treated separately.<ref name="Hamblin2004" /> The base of the Paskapoo Formation, designated the '''Haynes Member''', consists primarily of cliff-forming sandstones and pebble-conglomerates, interbedded with lesser amounts of siltstone and mudstone.  In the overlying '''Lacombe Member''', siltstones and mudstones are dominant, with interbeds of fine-grained sandstone, carbonaceous mudstones, paleosols, and thin coals.  The '''Dalehurst Member''' at the top of the formation consists of the '''Obed coal zone'''.<ref name="Demchuk1991">Demchuk, T.D. and Hills, L.V., 1991. A re-examination of the Paskapoo Formation in the central Alberta Plains: the designation of three new members. Canadian Journal of Earth Science 27: 1263-1269.</ref> The Dalehurst strata are similar to those of the Lacombe Member, but the Dalehurst sequence includes up to six coal seams, with individual seams up to {{convert|5|m|ft|-1}} thick.<ref name="Mossop33" />
[[File:Blindman River Mouth.jpg|thumb|right|The Blindman River is deeply incised into Paskapoo Formation bedrock at its confluence with the Red Deer River.]]

===Distribution===
The Paskapoo Formation underlies much of southwestern Alberta.<ref name=Map600 /> It is thickest in the foothills of the Canadian Rockies, and thins eastward to the 112th meridian west in the plains.  The formation is more than {{convert|750|m|ft|-1}} thick in the foothills,<ref name="Lerbekmo2008" /> and about {{convert|600|m|ft|-1}} near Calgary.<ref name=lexicon>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. {{ISBN|0-920230-23-7}}.</ref> It is assumed that it originally reached thicknesses as great as {{convert|1000|m|ft|-1}} in some areas prior to erosion.

The formation is exposed at the surface along a trend that extends from Calgary to west of Edmonton. Good outcrops can be seen in the eastern reaches of the foothills, and along the Bow River in and around Calgary (for example at Paskapoo Slopes), the [[Earth:Red Deer River|Red Deer River]] near Red Deer, the North Saskatchewan River west of Edmonton, and the Athabasca River. The Dalehurst Member is an erosional remnant and is confined to an area adjacent to the foothills near Hinton and Obed.<ref name="Demchuk1991" />

===Relationship to other units===
The Paskapoo Formation underlies the present day erosional surface and it is exposed in outcrop in many areas. Cover, where present, consists of [[Earth:Quaternary|Quaternary]] sediments or, on a few localized plateaus, of younger [[Earth:Tertiary|Tertiary]] gravels.<ref name="Hamblin2004" />

The Paskapoo rests on the [[Earth:Scollard Formation|Scollard Formation]] in the Alberta plains, and on the equivalent [[Earth:Coalspur Formation|Coalspur Formation]] in the Alberta foothills.<ref name=Table>{{Cite web|url= http://ags.aer.ca/activities/table-of-formation.htm|title=Alberta Table of Formations; Alberta Energy Regulator|author= Alberta Geological Survey, 2013.|access-date=2016-06-20}}</ref> The lower boundary has been defined as the erosional base of the first prominent sandstone above the Ardley coal zone of the Scollard Formation.<ref>{{Cite web|url=http://www.ags.gov.ab.ca/energy/buck_lake/scollard_formation.html|title=Scollard & Paskapoo Formations|author=Alberta Geological Survey|access-date=2009-05-30}}</ref> It has been established that, in the type area near Red Deer, this erosional surface represents a hiatus of about 1-2 million years.<ref name="Hamblin2004" /> In the foothills, the contact with the underlying Coalspur Formation is less distinctive but is again placed at the base of the first dominantly sandstone unit overlying a dominantly coal and mudstone unit.<ref name="Lerbekmo2008">Lerbekmo, J.F. and Sweet, A.R., 2008. Magnetobiostratigraphy of the continental Paleocene upper Coalspur and Paskapoo formations near Hinton, Alberta. Bulletin of Canadian Petroleum Geology 56: 118-146.</ref>

The Paskapoo grades into the equivalent [[Earth:Porcupine Hills Formation|Porcupine Hills Formation]] south of Calgary.<ref name="Map600" /> It is correlated with upper part of the [[Earth:Ravenscrag Formation|Ravenscrag Formation]] of southern Saskatchewan and the [[Earth:Fort Union Formation|Fort Union Formation]] of Montana and North Dakota, which are not contiguous with it but are of similar age.<ref name=Mossop24>{{Cite web|url=http://ags.aer.ca/reports/atlas-of-the-western-canada-sedimentary-basin.htm|title=The Geological Atlas of the Western Canada Sedimentary Basin, Chapter 24: Upper Cretaceous and Tertiary strata of the Western Canada Sedimentary Basin|author=Mossop, G.D. and Shetsen, I. (compilers), Canadian Society of Petroleum Geologists|year=1994|access-date=2016-06-20|archive-url=https://web.archive.org/web/20160701131122/http://ags.aer.ca/reports/atlas-of-the-western-canada-sedimentary-basin.htm|archive-date=2016-07-01|url-status=dead}}</ref>

===Age===
The middle to late Paleocene age of the Paskapoo Formation is based primarily on Paskapoo mammal fossils, which indicate [[Earth:North American land mammal age|North American land mammal age]]s of middle to late [[Biology:Tiffanian|Tiffanian]].<ref name="Fox1990" /> It is supported by detailed [[Earth:Palynology|palynostratigraphic]] and [[Earth:Magnetostratigraphy|magnetostratigraphic]] studies.<ref name="Hamblin2004" /><ref>Lerbekmo, J.F., Demchuk, T.D., Evans, M.E. and Hoye, G.S., 1992. Magnetostratigraphy and biostratigraphy of the continental Paleocene of the Red Deer Valley, Alberta, Canada. Bulletin of Canadian Petroleum Geology, 40: 24-35.</ref> It is equivalent to a [[Physics:Radiometric dating|radiometric age]] of approximately 62.5 to 58.5 million years.<ref name="Hamblin2004" />

==Paleontology==
[[File:Fossil Platanus leaf.jpg|thumb|left|Fossil Platanus leaf from the Paskapoo Formation near Red Deer.]]The Paskapoo Formation contains remains of vertebrates,<ref>{{Cite web|url=http://www.canadatracks.com/Vertebratre%20Tracksites%20of%20Canada/Western%20Canada/Paskapoo%20Formation/Paskapoo%20Formatoin.htm|title=Paskapoo Formation|author=Vertebrate track sites of Canada|access-date=2009-05-30}}</ref> especially mammals, and plants. Material from the following groups of mammals has been reported from the Paskapoo Formation: Multituberculata, Marsupicarnivora, Lyptophyla, Dermoptera, Primates, Carnivora, Condylartha, and Pantodonta, as well as the small, possibly venomous mammal ''Bisonalveus''.<ref name="Fox1990">Fox, R.C., 1990.  The succession of Paleocene mammals in western Canada.  Geological Society of America, Special Paper 243, pp. 51-70.</ref> The Paskapoo has also yielded articulated and fragmentary skeletons of freshwater fish, impressions of insect wings and larvae, and shells of freshwater molluscs.<ref name="Hoffman1999" /> An unnamed species of the amphibian ''Albanerpeton'' is known from the formation, which is the final record of [[Biology:Albanerpetontidae|albanerpetontids]] from North America.<ref name=":1">{{Cite journal|last=Fox|first=Richard C.|last2=Naylor|first2=Bruce G.|date=1982-01-01|title=A reconsideration of the relationships of the fossil amphibian Albanerpeton|journal=Canadian Journal of Earth Sciences|volume=19|issue=1|pages=118–128|doi=10.1139/e82-009|issn=0008-4077}}</ref>

[[Biology:Paleobotany|Plant fossils]] were first collected from the Paskapoo Formation by Tyrrell in 1886,<ref name="Tyrrell" /> and since that time a wide variety have been described. These include specimens of the [[Biology:Fern|fern]]s ''[[Biology:Azolla|Azolla]]'',<ref name="Hoffman1994">Hoffman, G.L. and Stockey, R.A., 1994. Sporophytes, megaspores and massulae of ''Azolla stanleyi'' from the Paleocene Joffre Bridge locality, Canada.  Canadian Journal of Botany, 72: 301-308.</ref> ''[[Biology:Onoclea|Onoclea]]'',<ref name="Rothwell1991">Rothwell, G.W. and Stockey, R.A., 1991.  ''Onoclea sensibilis'' in the Paleocene of North America, a dramatic example of structural and ecological stasis.  Review of Palaeobotany and Palynology, 70: 113–124.</ref> and ''Speirseopteris'';<ref name="Stockey2006">Stockey R.A., Lantz, T.C. and Rothwell, G.W. 2006.  ''Speirseopteris orbiculata'' (Thelypteridaceae), a derived fossil filicalean from the Paleocene of western North America.  International Journal of Plant Sciences, 167: 729–736.</ref> the [[Biology:Conifer|conifer]]s ''[[Biology:Metasequoia|Metasequoia]]'' (including ''[[Biology:Metasequoia foxii|Metasequoia foxii]]'') and ''[[Biology:Glyptostrobus|Glyptostrobus]]''; and the dicots ''Palaeocarpinus''<ref name="Sun1992">Sun, F. and Stockey, R.A., 1992.  A new species of ''Palaeocarpinus'' (Betulaceae) from the Paleocene of Alberta, Canada.  International Journal of Plant Sciences, 153: 136–146.</ref> (a member of the [[Biology:Betulaceae|birch family]]), ''[[Biology:Cercidiphyllum|Cercidiphyllum]]'' (including ''Joffrea''<ref name="Crane1985">Crane, P.R., and Stockey, R.A. 1985.  Growth and reproductive biology of ''Joffrea speirsii'', a ''Cercidiphyllum''-like plant from the Late Paleocene of Alberta, Canada.  Canadian Journal of Botany, 63: 340–364.</ref>), ''[[Biology:Platanus|Platanus]]'',<ref name=Pigg1991>Pigg, K.B. and Stockey, R.A., 1991. Platanaceous plants from the Paleocene of Alberta. Rev. Palaeobot. Palynol. 70:125-146.</ref> and ''Beringiaphyllum''<ref name="Manchester1999">Manchester, S.R., Crane, P.R. and Golovneva, L.B., 1999.  An extinct genus with affinities to extant ''Davidia'' and ''Camptotheca'' (Cornales) from the Paleocene of North America and eastern Asia.  International Journal of Plant Sciences, 160: 188–207.</ref> (a relative of [[Biology:Cornales|dogwoods]]).

==Resources==
===Building stone===
[[File:Sandstone Building Lougheed House Calgary.jpg|thumb|An example of Paskapoo sandstone used in construction: the east wall of the Lougheed House, Calgary.]]During the early 1900s, outcrops of Paskapoo sandstone in the Calgary area were quarried for building stone due to the requirement for fire-resistant buildings following the Calgary Fire of 1886. Many of Calgary's early landmark buildings, such as Lougheed House, Burns Manor, and some of the buildings along Stephen Avenue, were built using Paskapoo sandstone, and Calgary became known as the Sandstone City.<ref>{{cite news|url=http://thegauntlet.ca/story/8857 |title=The Sandstone City |date=2002-11-21 |access-date=2013-08-04 |url-status=dead |archive-url=https://web.archive.org/web/20110813194522/http://thegauntlet.ca/story/8857 |archive-date=August 13, 2011 }}</ref> Paskapoo sandstone is still used in landscaping in the Calgary area today.{{when|date=November 2018}}

===Coal===
Coal has been mined from the '''Obed coal zone''' in the Paskapoo Formation near Hinton. It is of high-volatile bituminous rank with a low sulphur content, and it was shipped to markets in eastern Canada and the Pacific Rim.<ref name=Mossop33>{{Cite web|url=http://ags.aer.ca/reports/atlas-of-the-western-canada-sedimentary-basin.htm|title=The Geological Atlas of the Western Canada Sedimentary Basin, Chapter 33: Coal Resources of the Western Canada Sedimentary Basin|author=Mossop, G.D. and Shetsen, I. (compilers), Canadian Society of Petroleum Geologists|year=1994|access-date=2016-06-20|archive-url=https://web.archive.org/web/20160701131122/http://ags.aer.ca/reports/atlas-of-the-western-canada-sedimentary-basin.htm|archive-date=2016-07-01|url-status=dead}}</ref>

===Groundwater===
Paskapoo Formation [[Earth:Aquifer|aquifer]]s are a very important source of water for [[Earth:Irrigation|irrigation]] and drinking in southwestern Alberta.<ref name="Hamblin2004" />

==References==
{{reflist|26em}}


[[Category:Thanetian Stage]]
[[Category:Geologic formations of Alberta]]
[[Category:Mudstone formations]]
[[Category:Siltstone formations]]

{{Sourceattribution|Paskapoo Formation}}