The Gracias Formation is a geologic formation in

Honduras Honduras, officially the Republic of Honduras, is a country in Central America. The republic of Honduras is bordered to the west by Guatemala, to the southwest by El Salvador, to the southeast by Nicaragua, to the south by the Pacific Oce ...

. The mainly sandstones,

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, p ...

s and

claystone Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone, slate, and shale. Most of the particles of which the stone is composed are less than and are too sm ...

s preserve vertebrate

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 in ...

dating back to the

Neogene The Neogene ( ), informally Upper Tertiary or Late Tertiary, is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period Mya. ...

period.Gracias Formation
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...

.org

Description

The Gracias Formation is a sedimentary unit, consisting of sandstone,

and a few conglomeratic beds. The formation crops out in western Honduras and ranges from in thickness. The formation overlies the Padre Miguel Group, while it is overlain by Pleistocene basalts.N.N., s.a., Informe de Apoyo, A-9 The Padre Miguel Group provided the

provenance Provenance (from the French ''provenir'', 'to come from/forth') is the chronology of the ownership, custody or location of a historical object. The term was originally mostly used in relation to works of art but is now used in similar senses i ...

for the sedimentary material for the Gracias Formation. The clasts in the formation are largely composed of

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...

, rhyodacite, pumice, vitric ash, quartz, feldspar, and minor

biotite Biotite is a common group of phyllosilicate minerals within the mica group, with the approximate chemical formula . It is primarily a solid-solution series between the iron-endmember annite, and the magnesium-endmember phlogopite; more alumino ...

fragments.Sánchez Barreda, 1999, p.25

Fossil content

* '' Borophagus secundus'' * ''

Calippus hondurensis Callippus may refer to: * Callippus of Syracuse (died 352/51 BC), an Athenian student of Plato and tyrant of Syracuse * Callippus (Calippus of Cyzicus, c. 370–300 BC), a Greek astronomer and mathematician * Callippus of Athens (fl. 279 BC), an ...

''Hulbert, 1988, p.272 * '' Cormohipparion ingenuum'' * '' Procamelus cf. grandis'' * '' Prosthennops cf. serus'' * '' Protolabis cf. heterodontus'' * '' Pseudoceras skinneri'' * '' Rhynchotherium cf. blicki'' * '' Teleoceras sp.'' * Rhinocerotidae indet.

References

Bibliography

* * * {{cite LSA , last=N. , first=N , year=s.a , title=Informe de Apoyo - Estudio Geológico para la ciudad Tegucigalpa , url=http://open_jicareport.jica.go.jp/pdf/11617651_02.PDF , publisher=_ , pages=A1-57 , accessdate=2019-02-09

Description

Fossil content

See also

References

Bibliography

Further reading