The Bishop Cap Formation is a

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

in the Franklin Mountains of southern

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

and western

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

and the Hueco Mountains of western Texas. It preserves

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

dating back to the

Moscovian Moscovian may refer to: *An inhabitant of Moscow, the capital of Russia *Something of, from, or related to Moscow *Moscovian (Carboniferous) The Moscovian is in the International Commission on Stratigraphy, ICS geologic timescale a stage (strat ...

Kasimovian The Kasimovian is a geochronologic age or chronostratigraphic stage in the ICS geologic timescale. It is the third stage in the Pennsylvanian (late Carboniferous), lasting from to Ma.; 2004: ''A Geologic Time Scale 2004'', Cambridge Unive ...

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 ...

s of the early Pennsylvanian.

Description

The formation consists of brown to gray

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 ...

alternating with thin ray ledges of

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

. Shale makes up 65 to 75 percent of the formation. The total thickness is up to . The formation rests on the Berino Formation and is overlain by the Panther Seep Formation.

Fossils

The formation is highly fossiliferous, with a fauna dominated by

snail A snail is a shelled gastropod. The name is most often applied to land snails, terrestrial molluscs, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gas ...

brachiopod Brachiopods (), phylum (biology), phylum Brachiopoda, are a phylum of animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear e ...

s ('' Neospirifer'', '' Crurithyris'', '' Mesolobus''), and

clam Clam is a common name for several kinds of bivalve mollusc. The word is often applied only to those that are deemed edible and live as infauna, spending most of their lives halfway buried in the sand of the sea floor or riverbeds. Clams h ...

s, but is less diverse than the underlying Berino Formation. The lower beds contain the

fusulinid The Fusulinida is an extinct order within the Foraminifera in which the tests are traditionally considered to have been composed of microgranular calcite. Like all forams, they were single-celled organisms. In advanced forms the test wall was d ...

s '' Wedekindellina euthysepta'' and '' Fusulina distenta''. Opercula of

cephalopod A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...

s (possibly '' Liroceras'') have been found in the formation, as have shells of ''

Bellerophon Bellerophon or Bellerophontes (; ; lit. "slayer of Belleros") or Hipponous (; lit. "horse-knower"), was a divine Corinthian hero of Greek mythology, the son of Poseidon and Eurynome, and the foster son of Glaukos. He was "the greatest her ...

'', '' Phestia'', and ''

Euphemites ''Euphemites'' is an extinct genus of gastropod belonging to order Bellerophontida and family Euphemitidae Euphemitidae is an extinct family (biology), family of Paleozoic fossil molluscs of uncertain position. They have isostrophically coil ...

''.

History of investigation

The unit was designated the Bishop Cap Member of the Magdalena Group by L.A. Nelson in 1937. In 2001, B. Kues recommended abandoning the Magdalena Group and raising its members, including the Bishop Cap, to formation rank.

References

{{Reflist Carboniferous Texas Carboniferous formations of New Mexico Carboniferous southern paleotropical deposits Shale formations of the United States Limestone formations of the United States

Description

Fossils

History of investigation

See also

References