Guiana Shield

Coordinates: 5°08′36″N 60°45′45″W / 5.14333°N 60.76250°W / 5.14333; -60.76250
Source: Wikipedia, the free encyclopedia.
Guiana Shield
Political map of the Guiana Shield
Political map of the Guiana Shield
Coordinates: 5°08′36″N 60°45′45″W / 5.14333°N 60.76250°W / 5.14333; -60.76250
RegionSouth America
Cerros de Mavecure, Guainía department, Colombia
Devil's Canyon in the Canaima National Park, Venezuela
Map of the Guianas

The Guiana Shield[1] (French: Plateau des Guyanes, Bouclier guyanais; Dutch: Hoogland van Guyana, Guianaschild; Portuguese: Planalto das Guianas, Escudo das Guianas; Spanish: Escudo guayanés) is one of the three cratons of the South American Plate. It is a 1.7 billion-year-old Precambrian geological formation in northeast South America that forms a portion of the northern coast.[2] The higher elevations on the shield are called the Guiana Highlands, which is where the table-like mountains called tepuis are found. The Guiana Highlands are also the source of some of the world's most well-known waterfalls such as Angel Falls, Kaieteur Falls and Cuquenan Falls.

The Guiana Shield underlies

shales and conglomerates intruded by sills of younger mafic intrusives such as gabbros.[3]

Geology

The oldest rocks in the shield consist of

Ga in age.[4][5]

Geomorphology

There are three upland areas of the Guiana Shield:

  1. The
    Guiana Highlands proper are in Venezuela east of the Orinoco and extend across much of west-central Guyana and into the northern Roraima
    state in Brazil.
  2. The Tumucumaque Uplands which are a series of central massifs in an arc from the
    Atlantic
    .
  3. The
    Chiribiquete Plateau is a sandstone topped plateau with an elevation of 900 m (2,953 ft) that forms the western edge of the shield. The plateau is separated from the eastern Andes by the thick Neogene
    sediments of the Sub-Andean Trough that runs along the northern and western rim of the Guiana Shield.

The north-central part of the

Neblina massif, a highly eroded sandstone plateau that straddles the Venezuela-Brazil border and that has lost the typical tabletop shape of the other tepuis in the region.[citation needed
]

Ecology

Heliamphora chimantensis, endemic to the Chimantá Massif (a Venezuelan part of the Guiana Shield)

The Guiana Shield is one of the regions of highest biodiversity in the world, and has many endemic species. The region houses over 3000 vertebrate species: 1168 fresh water fish, 269 amphibians (54% endemics), 295 reptiles (29%), 1004 birds (7.7%), and 282 mammals (11%).[7][8][9] Diversity of invertebrates remains largely undocumented, but there are several species of endemic butterflies and dung beetles.[10][11]

Plant life is equally rich and 13,367 species of

Tumucumaque National Park in the Amapá State of Brazil. In Venezuela the forests are protected by Canaima, Parima-Tapirapeco and Serranía de la Neblina national parks. In 2014, the Government of Colombia designated a 250 hectare area of the Guiana Shield, as a Ramsar Wetland, thus becoming a protected area of international importance in accordance to the Ramsar Convention.[14]

According to recent researches, although ecosystems of the Guayana Highlands remain vibrant, emerging issues (including "a well-known invasive plant elsewhere" Poa annua and "one of the most aggressive weeds" Polypogon elongatus) and infectious faecal bacteria Helicobacter pylori have been documented.[15]

See also

References

  1. Guianas is often used as a collective name for Guyana, Suriname and French Guiana, and sometimes even includes the portions of Colombia, Venezuela and Brazil (including most of the state of Roraima
    ) which are on the Guiana Shield.
  2. ^ Hammond, David S. (ed.) (2005) Tropical Forests of the Guiana Shield CABI Publishing, Wallingford, UK, ISBN
  3. ^ Gibbs, A.K. and Barron,C.N. (eds) (1993) The Geology of the Guiana Shield Oxford University Press, Oxford, UK, ISBN
  4. ^ Geology and Mineral Resource Assessment of the Venezuelan Guayana Shield, USGS Bulletin 2062. US Government Printing Office. 1993. pp. 10–15.
  5. ISBN 9789048130542
    .
  6. ^ "Geociências: IBGE revê as altitudes de site Pontos culminates" [Geosciences: IBGE revises the altitude of seven high points] (Press release) (in Portuguese). Brasília: Brazilian Institute of Geography and Statistics (IBGE). 2016-02-29. Retrieved 2016-03-02.
  7. ^ Hollowell, T.; Reynolds, R.P. (2005). "Checklist of the Terrestrial Vertebrates of the Guiana Shield" (PDF). Bulletin of the Biological Society of Washington. 13.
  8. doi:10.12933/therya-20-891
    .
  9. ^ Vari, R.P.; Ferraris Jr., C.J.; Radosavljevic, A.; Funk, V.A. (2009). "Checklist of the freshwater fishes of the Guiana Shield" (PDF). Bulletin of the Biological Society of Washington. 17.
  10. S2CID 17263106
    .
  11. ^ Costa, Mauro; Viloria, Ángel L.; Hubber, Otto; Attal, Stéphane; Orellana, Andrés (2013). "Lepidoptera del Pantepui. Parte I: Endemismo y caracterización biogeográfica". Entomotropica. 28 (3): 193–217. Archived from the original on 27 August 2016. Retrieved 25 June 2016.
  12. ^ Funk, V.; Hollowell, T.; Berry, P.; Kelloff, C.; Alexander, S.N. (2007). "Checklist of the Plants of the Guiana Shield (Venezuela: Amazonas, Bolivar, Delta Amacuro; Guyana, Surinam, French Guiana)" (PDF). Contributions from the United States National Herbarium. 55.
  13. ^ Hammond, David S. (ed.) (2005) Tropical Forests of the Guiana Shield CABI Publishing, Wallingford, UK, ISBN
  14. ^ "Colombia | Ramsar".
  15. S2CID 23002053
    .

External links
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