The Besa River 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 ...

Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...

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

Besa River Besa River is a river in northern British Columbia, Canada. It is a tributary of the Prophet River. The river flows through the Muskwa Ranges, and is the backbone of the Redfern-Keily Provincial Park, part of the larger Muskwa-Kechika Managemen ...

, a tributary of the

Prophet River The Prophet River is a river in northern British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the pro ...

, and was first described in outcrop near the

Muskwa River The Muskwa River flows through northern British Columbia, Canada. It is a major tributary of the Fort Nelson River - part of the Mackenzie River system. The river rises at Fern Lake in the Bedaux Pass in the Northern Rocky Mountains. From ther ...

, in the

Muskwa Ranges The Muskwa Ranges are a group of mountain ranges in northern British Columbia, Canada. They are part of the Northern Rockies section of the Rocky Mountains and are bounded on their west by the Rocky Mountain Trench and on their east by the Roc ...

by F.A. Kidd in 1963.Kidd, F.A., 1963. The Besa River Formation: Bulletin of Canadian Petroleum Geology, vol. 11, no. 4, pp. 369-372.

Lithology

The Besa River Formation is composed primarily of dark

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...

. Sandstone, bedded chert or limestone beds can occur at the top of the formation. The shale is slightly calcareous or siliceous and contains

sponge Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and a ...

spicules and

radiolarian The Radiolaria, also called Radiozoa, are unicellular eukaryotes of diameter 0.1–0.2 mm that produce intricate mineral skeletons, typically with a central capsule dividing the cell into the inner and outer portions of endoplasm and ecto ...

Distribution

The Besa River Formation reaches a maximum thickness of in the foothills . The lower Besa River Formation is faulted and folded in the

Northern Rockies The Northern Rocky Mountains, usually referred to as the Northern Rockies, are a subdivision of the Canadian Rockies comprising the northern half of the Canadian segment of the Rocky Mountains. While their northward limit is easily defined as the ...

. It occurs in the sub-surface in east-central

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

, in the folded Rocky Mountain Thrust Belt and southern Mackenzie Fold Belt.

Relationship to other units

The Besa River Formation is conformably overlain by the Prophet Formation or

Banff Formation The Banff Formation is a stratigraphic unit of Devonian age in the Western Canadian Sedimentary Basin. It takes the name from the town of Banff, Alberta, and was first described on the north-west slope of Mount Rundle, near Banff by E.M. Kindle in ...

in its eastern extent, while to the west it is overlain by the Mattson Formation and Stoddart Group, and abruptly overlays the Dunedin Formation in the west of its extent in

, and the

Slave Point Formation The Slave Point Formation is a stratigraphic unit of Middle Devonian age in the Western Canadian Sedimentary Basin. It takes the name from Slave Point, a promontory on the north-west shore of the Great Slave Lake, and was first described in outc ...

in the east. In the

Northwest Territories The Northwest Territories is a federal Provinces and territories of Canada, territory of Canada. At a land area of approximately and a 2021 census population of 41,070, it is the second-largest and the most populous of Provinces and territorie ...

, it rests on the

Nahanni Formation The Nahanni Formation is a stratigraphic unit of Givetian age in the Western Canadian Sedimentary Basin. It takes the name from Nahanni Butte, a prominent ridge at the confluence of the South Nahanni River and Liard River, and was first describe ...

in the east and the Road River Formation in the west. Towards the southwest, it passes laterally into the Fort Simpson Formation and

Exshaw Formation The Exshaw Formation is a stratigraphic unit in the Western Canada Sedimentary Basin. It takes the name from the hamlet of Exshaw, Alberta, in the Canadian Rockies, and was first described from outcrops on the banks of Jura Creek north of Exshaw b ...

. To the south, it passes into the Dunedin Formation,

Horn River Formation The Horn River Formation (also ''Horn River Shale'') is a stratigraphic unit of Devonian (early Givetian to late Frasnian) age in the Western Canadian Sedimentary Basin. It is a thick sequence of marine sediments that was first described in outc ...

and

. To the east it transforms into the calcareous

Rundle Group The Rundle Group is a stratigraphic unit of Mississippian age in the Western Canadian Sedimentary Basin. It takes the name from Mount Rundle (itself taking the name from Robert Terrill Rundle), and was first described in outcrops at the nort ...

and Stoddart Group. It is stratigraphically equivalent with the Fort Simpson Formation, as well as the Canol Formation and Earn Group.

References

{{Western Canadian Sedimentary Basin, Liard_River=yes Geologic formations of British Columbia Devonian British Columbia Shale formations of Canada Sandstone formations of Canada Limestone formations of Canada Western Canadian Sedimentary Basin Chert formations