Gracias Formation

Gracias Formation
Stratigraphic range: Miocene
TypeFormation
UnderliesPleistocene basalt
OverliesPadre Miguel Group
Thickness200–300 m (660–980 ft)
Lithology
PrimarySandstone, siltstone, claystone
OtherConglomerate
Location
Coordinates21°12′N 100°42′W / 21.2°N 100.7°W / 21.2; -100.7
Approximate paleocoordinates21°42′N 98°00′W / 21.7°N 98.0°W / 21.7; -98.0
RegionLempira Department
Country Honduras
Type section
Named forGracias
Named byWilliams & McBirney
Year defined1969
Gracias Formation is located in Honduras
Gracias Formation
Gracias Formation (Honduras)

The Gracias Formation is a geologic formation in Honduras. The mainly sandstones, siltstones and claystones preserve vertebrate fossils dating back to the Neogene period.[1]

Description

The Gracias Formation is a sedimentary unit, consisting of sandstone, siltstone, claystone and a few conglomeratic beds. The formation crops out in western Honduras and ranges from 200 to 300 metres (660 to 980 ft) in thickness. The formation overlies the Padre Miguel Group, while it is overlain by Pleistocene basalts.[2] The Padre Miguel Group provided the provenance for the sedimentary material for the Gracias Formation. The clasts in the formation are largely composed of rhyolite, rhyodacite, pumice, vitric ash, quartz, feldspar, and minor biotite fragments.[3]

Fossil content

See also

References

  1. ^ Gracias Formation at Fossilworks.org
  2. ^ N.N., s.a., Informe de Apoyo, A-9
  3. ^ Sánchez Barreda, 1999, p.25
  4. ^ Hulbert, 1988, p.272

Bibliography

  • Hulbert, Jr., R.C (1988), "Calippus and Protohippus (Mammalia, Perissodactyla, Equidae) from the Miocene (Barstovian-early Hemphillian) of the Gulf Coastal Plain", Bulletin of the Florida State Museum, Biological Sciences, 32: 221–340, retrieved 2019-02-09
  • Sánchez Barreda, Luis A (1999), Geology of Mosquitía and Tela Basins, Honduras (PDF), University of Texas at Austin, pp. 1–55, retrieved 2019-02-09
  • N., N, Informe de Apoyo - Estudio Geológico para la ciudad Tegucigalpa (PDF), pp. A1-57, retrieved 2019-02-09

Further reading

  • E. C. Olson and P. O. McGrew. 1941. Mammalian fauna from the Pliocene of Honduras. Bulletin of the Geological Society of America 52:1219-1244
  • S. D. Webb and S. C. Perrigo. 1984. Late Cenozoic Vertebrates from Honduras and El Salvador. Journal of Vertebrate Paleontology 4(2):237-254