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 ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...

and western

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

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 (strati ...

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 Universi ...

Ages of the

early Pennsylvanian The Pennsylvanian ( , also known as Upper Carboniferous or Late Carboniferous) is, in the International Commission on Stratigraphy, ICS geologic timescale, the younger of two period (geology), subperiods (or upper of two system (stratigraphy), s ...

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 minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especia ...

alternating with thin ray ledges of

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms wh ...

. 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 The Panther Seep Formation is a geologic formation found in the mountain ranges of south-central New Mexico. It preserves fossils dating back to the late Pennsylvanian to early Permian. Description The formation is highly variable in lithology, ...

Fossils

The formation is highly fossiliferous, with a fauna dominated by

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

brachiopod Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan 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 end, ...

s (''

Neospirifer ''Neospirifer'' is an extinct genus of articulate brachiopod fossils belonging to the family Trigonotretidae. These stationary epifaunal suspension feeders lived in the Carboniferous The Carboniferous ( ) is a geologic period and system o ...

'', '' Crurithyris'', ''

Mesolobus ''Mesolobus'' is an extinct genus of brachiopod belonging to the order Productida and family Rugosochonetidae Rugosochonetidae is an extinct family of brachiopods in the extinct order Productida Productida is an extinct order of brachiopod ...

''), and

clam Clam is a common name for several kinds of bivalve molluscs. The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds. Clams have two sh ...

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 dif ...

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

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

s (possibly ''

Liroceras ''Liroceras'' is a genus of nautiloid cephalopod. It is the type genus of the clydonautiliacean family, Liroceratidae Liroceratidae is an extinct family of nautilids, shelled marine molluscs, belonging to the Clydonautiloidea, consisting ...

'') have been found in the formation, as have shells of ''

Bellerophon Bellerophon (; Ancient Greek: Βελλεροφῶν) or Bellerophontes (), born as Hipponous, was a hero of Greek mythology. He was "the greatest hero and slayer of monsters, alongside Cadmus and Perseus, before the days of Heracles", and his ...

'', ''

Phestia ''Phestia'' is an extinct genus of clam belonging to order Nuculanida Nuculanida is an order of very small saltwater clams, marine bivalve molluscs in the subclass Protobranchia. Description These bivalves are distinguished by the presence ...

'', and ''

Euphemites ''Euphemites'' is an extinct genus of gastropod belonging to order Bellerophontida and family Euphemitidae Euphemitidae is an extinct family of Paleozoic fossil molluscs of uncertain position. They have isostrophically coiled shells and may b ...

''.

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 geology of Texas Carboniferous formations of New Mexico Carboniferous southern paleotropical deposits

Description

Fossils

History of investigation

See also

References