The Pakowki Formation is a

stratigraphic unit A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features ( facies) that characteriz ...

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

age Age or AGE may refer to: Time and its effects * Age, the amount of time someone has been alive or something has existed ** East Asian age reckoning, an Asian system of marking age starting at 1 * Ageing or aging, the process of becoming older ...

in the

Western Canadian Sedimentary Basin The Western Canada 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 b ...

. It takes the name from Pakowki Lake, and was first described in outcrop along the Pakowki Coulee by D.B. Dowling in 1916.Dowling, D.B., 1916. Water Supply, Southeastern Alberta (Contains Geological Map 1604);

Geological Survey of Canada The Geological Survey of Canada (GSC; , CGC) is a Canadian federal government agency responsible for performing geological surveys of the country developing Canada's natural resources and protecting the environment. A branch of the Earth Science ...

, Summary Report 1915, pp. 102-110.

Lithology

The Formation is composed of 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.Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' New York, New York, ...

. Olive

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. Although its permeabil ...

and very fine grained

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

can occur locally. A thin pebble conglomerate marks the base.

Distribution

The Pakowki Formation reaches a maximum thickness of in central

Saskatchewan Saskatchewan is a Provinces and territories of Canada, province in Western Canada. It is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and to the south by the ...

. It reaches into

southern Alberta Southern Alberta is a region located in the Canadian province of Alberta. In 2016, the region's population was approximately 291,112. The primary cities are Lethbridge and Medicine Hat. The region is known mostly for agricultural production, but o ...

, thinning out as it progresses westwards towards the

Canadian Rockies The Canadian Rockies () or Canadian Rocky Mountains, comprising both the Alberta Rockies and the British Columbian Rockies, is the Canadian segment of the North American Rocky Mountains. It is the easternmost part of the Canadian Cordillera, w ...

foothills.

Relationship to other units

The Pakowki Formation is abruptly overlain by the

Milk River Formation The Milk River Formation is a sandstone-dominated stratigraphic unit of the Western Canada Sedimentary Basin in southern Alberta, Canada. It was deposited in near-shore to coastal environments during Late Cretaceous (late Santonian to early Campa ...

and gradationally overlays the

Judith River Formation The Judith River Formation is a fossil-bearing geologic formation in Montana, and is part of the Montana Group. It dates to the Late Cretaceous, between 79 and 75.3 million years ago, corresponding to the "Judithian" land vertebrate age. It was ...

Foremost Formation The Foremost Formation is a stratigraphic unit of Late Cretaceous (Campanian) age that underlies much of southern Alberta, Canada. It was named for outcrops in Chin Coulee near the town of ForemostGlass, D.J. (editor) 1997. Lexicon of Canadian ...

. It is equivalent to the upper part of the Lea Park Formation in

central Alberta Central Alberta is a region located in the Canadian province of Alberta. Central Alberta is the most densely populated rural area in the province. Agriculture and energy are important to the area's economy. Geography Central Alberta is bordered ...

. It is not differentiated from the Riding Mountain Formation to the east into eastern

and

Manitoba Manitoba is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population ...

References

{{Western Canadian Sedimentary Basin, South AB=yes, Saskatchewan=yes Geologic formations of Alberta Cretaceous Alberta Western Canadian Sedimentary Basin Shale formations of Canada Siltstone formations of Canada Sandstone formations of Canada