The Tetcho Formation is a stratigraphical

Stratigraphy

Stratigraphy, a branch of geology, studies rock layers and layering . It is primarily used in the study of sedimentary and layered volcanic rocks....

 unit of Famennian

Famennian

The Famennian is one of two faunal stages in the Late Devonian epoch. It lasted from 374.5 ± 2.6 million years ago to 359.2 ± 2.5 million years ago. It was preceded by the Frasnian stage and followed by the Tournaisian stage and is named after Famenne, a natural region in southern Belgium.It was...

 age

Geochronology

Geochronology is the science of determining the age of rocks, fossils, and sediments, within a certain degree of uncertainty inherent to the method used. A variety of dating methods are used by geologists to achieve this, and schemes of classification and terminology have been proposed...

 in the Western Canadian Sedimentary Basin

Western Canadian Sedimentary Basin

The Western Canadian Sedimentary Basin is a vast sedimentary basin underlying of Western Canada including southwestern Manitoba, southern Saskatchewan, Alberta, northeastern British Columbia and the southwest corner of the Northwest Territories. It consists of a massive wedge of sedimentary rock...

.

It takes the name from Tetcho Lake, and was first described in the Imperial

Imperial Oil

Imperial Oil Limited is Canada's largest petroleum company. The company is engaged in the exploration, production and sale of crude oil and natural gas. It is controlled by US based ExxonMobil, which owns 69.6% of its stock...

 Island River No. 1 well (located south of Trout Lake

Trout Lake, Northwest Territories

Trout Lake is a "Designated Authority" in the Dehcho Region of the Northwest Territories, Canada. The community is located near the Alberta border, east of Fort Liard, in the southern NWT. It has no all-weather road, but can be reached by winter road early in the year.Population is 86 according to...

 by H.R. Belyea and D.J. McLaren in 1962.

Lithology

The Tetcho Formation is composed of fine grained limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

 with shale

Shale

Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...

 partings, silty

Siltstone

Siltstone is a sedimentary rock which has a grain size in the silt range, finer than sandstone and coarser than claystones.- Description :As its name implies, it is primarily composed of silt sized particles, defined as grains 1/16 - 1/256 mm or 4 to 8 on the Krumbein phi scale...

 at the base.

Distribution

The Tetcho Formation reaches a maximum thickness of 75 metres (246.1 ft). it occurs in the sub-surface in north-eastern British Columbia

British Columbia

British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

 and southern Northwest Territories

Northwest Territories

The Northwest Territories is a federal territory of Canada.Located in northern Canada, the territory borders Canada's two other territories, Yukon to the west and Nunavut to the east, and three provinces: British Columbia to the southwest, and Alberta and Saskatchewan to the south...

.

Relationship to other units

The Tetcho Formation is conformably overlain by the Kotcho Formation

Kotcho Formation

The Kotcho Formation is a stratigraphical unit of middle Famennian age in the Western Canadian Sedimentary Basin.It takes the name from Kotcho Lake, and was first described in the Imperial Island River No. 1 by H.R. Belyea and D.J...

 and conformably overlays the Trout River Formation

Trout River Formation

The Trout River Formation is a stratigraphical unit of Late Devonian age in the Western Canadian Sedimentary Basin.It takes the name from the Trout River, and was first described on the banks of the river, upstream from the Mackenzie River, by C.H...

 and Fort Simpson Formation

Fort Simpson Formation

The Fort Simpson Formation is a stratigraphical unit of Devonian age 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 by A.E...

.

It is equivalent to the lower Wabamun Group in Alberta

Alberta

Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...

 and to parts of the Besa River Formation

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 Muskwa Ranges by F.A. Kidd in 1963.-Lithology:The Besa...

 in the Liard

Liard River

The Liard River 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 Columbia, marking the northern end of the Rocky Mountains and then curving northeast back...

area of British Columbia.