The Fort Simpson Formation is a

stratigraphical Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithostrati ...

unit of

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...

age Age or AGE may refer to: Time and its effects * Age, the amount of time someone or something has been alive or 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. It takes the name from the settlement of Fort Simpson, and was first described in well Briggs Turkey Lake No. 1 (located south-east of Fort Simpson) by A.E. Cameron in 1918.Cameron, A.E., 1918. Explorations in the vicinity of Great Slave Lake. Geological Survey of Canada, Summary Report, 1917, Part C, p. 21-27.

Lithology

The Fort Simpson Formation is composed of grey

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...

and

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. ...

. The shale can be calcareous, silty or sandy.

Distribution

The Fort Simpson Formation reaches a thickness of over in the sub-surface of the Mackenzie River plain. It extends from northern Alberta to south-western

northwest Territories The Northwest Territories (abbreviated ''NT'' or ''NWT''; french: Territoires du Nord-Ouest, formerly ''North-Western Territory'' and ''North-West Territories'' and namely shortened as ''Northwest Territory'') is a federal territory of Canada. ...

and in north-eastern British Columbia (north of

Peace River Arch Peace is a concept of societal friendship and harmony in the absence of hostility and violence. In a social sense, peace is commonly used to mean a lack of conflict (such as war) and freedom from fear of violence between individuals or groups. ...

Relationship to other units

The Fort Simpson Formation is overlain by the Jean Marie Member of the

Redknife Formation The Redknife Formation is a stratigraphical unit of Devonian age in the Western Canadian Sedimentary Basin. It takes the name from Redknife River, a tributary of the Mackenzie River, and was first described in the banks of the Trout River, nor ...

in its eastern reaches, and progressively by the

Kakisa Formation The Kakisa Formation is a stratigraphical unit of Frasnian age in the Western Canadian Sedimentary Basin. It takes the name from the Kakisa River, a tributary of the Mackenzie River, and was first described in outcrop on the banks of the Trout ...

, Trout River Formation or

Tetcho Formation The Tetcho Formation is a stratigraphical unit of Famennian age in the Western Canadian Sedimentary Basin. It takes the name from Tetcho Lake, and was first described in the ''Imperial Island River No. 1'' well (located south of Trout Lake by ...

towards the west. It is conformably underlain by the Muskwa Member of the

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 out ...

. It is replaced by the

Besa River Formation The Besa River Formation is a stratigraphical unit of Devonian age in the Western Canadian Sedimentary Basin. It takes the name from Besa River, a tributary of the Prophet River, and was first described in outcrop near the Muskwa River, in the ...

in the

Liard River The Liard River of the North American boreal forest flows through Yukon, British Columbia and the Northwest Territories, Canada. Rising in the Saint Cyr Range of the Pelly Mountains in southeastern Yukon, it flows southeast through British Co ...

area. It is equivalent to the Imperial Formation to the north, the Tathlina Formation, Twin Falls Formation and

Hay River Formation The Hay River Formation is a geologic formation in Northwest Territories. It preserves fossils dating back to the Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end o ...

to the east, and the Woodbend Group in Alberta.

References

{{Western Canadian Sedimentary Basin, Fort_Nelson=yes, Northwest_Plains=yes Geologic formations of Alberta Geologic formations of British Columbia Geologic formations of the Northwest Territories Devonian southern paleotropical deposits Shale formations Devonian Alberta Devonian British Columbia Devonian Northwest Territories