# Guiana Shield

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> Source: https://en.wikipedia.org/wiki/Guiana_Shield
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{{Short description|Precambrian geological formation in northeast South America}}
{{Infobox settlement
| name               = Guiana Shield
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| image_skyline      = Map of the Guiana shield.png
| image_caption      = Political map of the Guiana Shield
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| subdivision_name2  = [South America](/source/South_America)
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[[File:Cerros de Mavecure (Guainía, Colombia).JPG|thumb|[Cerros de Mavecure](/source/Cerros_de_Mavecure), [Guainía department](/source/Guain%C3%ADa_Department), Colombia]]
[[File:Salto Angel - Cañon del Diablo.JPG|thumb|right|Devil's Canyon in the [Canaima National Park](/source/Canaima_National_Park), Venezuela]]
thumb|right|Map of the Guianas
The '''Guiana Shield'''<ref>The term  ''Guiana''  or ''The [Guianas](/source/Guyanas)'' is often used as a collective name for [Guyana](/source/Guyana), [Suriname](/source/Suriname) and [French Guiana](/source/French_Guiana), and sometimes even includes the portions of [Colombia](/source/Colombia), [Venezuela](/source/Venezuela) and [Brazil](/source/Brazil) (including most of the state of [Roraima](/source/Roraima)) which are on the Guiana Shield.</ref> ({{langx|fr|Plateau des Guyanes, Bouclier guyanais}}; {{langx|nl|Hoogland van Guyana, Guianaschild}}; {{langx|pt|Planalto das Guianas, Escudo das Guianas}}; {{langx|es|Escudo guayanés}}) is one of the three [craton](/source/craton)s of the [South American Plate](/source/South_American_Plate). It is a 1.7 billion-year-old [Precambrian](/source/Precambrian) geological [formation](/source/Shield_(geology)) in northeast [South America](/source/South_America) that forms a portion of the northern coast.<ref>Hammond, David S. (ed.) (2005) ''Tropical Forests of the Guiana Shield'' CABI Publishing, Wallingford, UK, ISBN</ref> The higher elevations on the [shield](/source/Shield_(geology)) are called the '''Guiana Highlands''', which is where the table-like mountains called [tepui](/source/tepui)s are found. The Guiana Highlands are also the source of some of the world's most well-known waterfalls such as [Angel Falls](/source/Angel_Falls), [Kaieteur Falls](/source/Kaieteur_Falls), and [Cuquenan Falls](/source/Cuquenan_Falls).

The Guiana Shield underlies [Guyana](/source/Guyana) (previously ''British Guiana''), [Suriname](/source/Suriname) (previously ''Dutch Guiana''), and [French Guiana](/source/French_Guiana) (or ''Guyane''), much of southern [Venezuela](/source/Venezuela), most of [Brazil](/source/Brazil) north of the [Amazon River](/source/Amazon_River), and parts of eastern [Colombia](/source/Colombia). The first three are called [The Guianas](/source/The_Guianas), and most of the Guiana Shield coincides with [Guiana Island](/source/Guiana_Island_(South_America)). The rocks of the Guiana Shield consist of metasediments and metavolcanics ([greenstones](/source/Greenschist)) overlain by sub-horizontal layers of [sandstones](/source/sandstones), [quartzites](/source/quartzites), [shales](/source/shales) and [conglomerates](/source/Conglomerate_(geology)) intruded by sills of younger mafic intrusives such as [gabbro](/source/gabbro)s.<ref>Gibbs, A.K. and Barron, C.N. (eds) (1993) ''The Geology of the Guiana Shield'' Oxford University Press, Oxford, UK, ISBN</ref>

== Geology ==
The oldest rocks in the shield consist of [Archean](/source/Archean) Imataca Complex, composed of a [quartz](/source/quartz)-[feldspar](/source/feldspar) [gneiss](/source/gneiss) and subordinate [mafic](/source/mafic) gneiss. The Guri [Fault](/source/fault_(geology)) marks the southern boundary of the complex. South of that fault are Early [Proterozoic](/source/Proterozoic) rocks consisting of the [metavolcanic](/source/metavolcanic_rock) Pastora [Supergroup](/source/geological_unit) and the [granitic](/source/granitic) [plutonic](/source/plutonic) Supamo Complex. The Cuchivero Group consists of [ash flow](/source/ash_flow) [tuff](/source/tuff) and granitic plutonic rocks. The Early to Middle Proterozoic Roraima Group consists of continental [clastic sediment](/source/clastic_sediment)ary rocks. These [Precambrian](/source/Precambrian) sediments include quartz [sandstones](/source/sandstones), [quartzite](/source/quartzite)s, and [conglomerates](/source/conglomerate_(geology)) presumed to be 1.8 to 1.4 [Ga](/source/Giga_annum) in age.<ref>{{cite book|title=Geology and Mineral Resource Assessment of the Venezuelan Guayana Shield, USGS Bulletin 2062|date=1993|publisher=US Government Printing Office|pages=10–15}}</ref><ref>{{cite book|last1=Wray|first1=Robert|editor1-last=Migon|editor1-first=Piotr|title=The Gran Sabana: The World's Finest Quartzite Karst?, in Geomorphological Landscapes of the World|date=2010|publisher=Springer|isbn=9789048130542|pages=80–81}}</ref>

== Geomorphology ==
There are three upland areas of the Guiana Shield:
# The Guiana Highlands proper are in Venezuela east of the [Orinoco](/source/Orinoco) and extend across much of west-central Guyana and into the northern [Roraima](/source/Roraima) state in Brazil.
# The Tumucumaque Uplands are a series of central massifs in an arc from the [Wilhelmina Mountains](/source/Wilhelmina_Mountains) of south-central Suriname, along the southern boundary of Suriname and Guyana, forming the Acarai Mountains of Roraima state and the [Tumuc-Humac Mountains](/source/Tumuc-Humac_Mountains) of [Pará](/source/Par%C3%A1) and [Amapá](/source/Amap%C3%A1) states of Brazil. From this arc, the southern uplands slope gently downwards towards the Amazon River and the northern uplands slope gently downwards toward the [Atlantic](/source/Atlantic).
# The [Chiribiquete Plateau](/source/Chiribiquete_Plateau) is a sandstone-topped [plateau](/source/plateau) with an elevation of {{convert|900|m|ft|0|abbr=on}} that forms the western edge of the shield. The plateau is separated from the eastern [Andes](/source/Andes) by the thick [Neogene](/source/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 Guiana Highlands is dominated by high flat-topped peaks called [tepui](/source/tepui)s, of the Roraima supergroup and Quasi-Roraima formation, and the rounded granite peaks of the Parguaza and Imataca complexes to the north and southwestern edges of the area. The highest point in the shield is [Pico da Neblina](/source/Pico_da_Neblina) in Brazil at {{convert|2995|m|ft}}.<ref name="ibge2016">{{cite press release |url=http://saladeimprensa.ibge.gov.br/noticias?view=noticia&id=1&busca=1&idnoticia=3109 |title=Geociências: IBGE revê as altitudes de site Pontos culminates |language=pt |trans-title=Geosciences: IBGE revises the altitude of seven high points | location=Brasília |publisher=[Brazilian Institute of Geography and Statistics](/source/Brazilian_Institute_of_Geography_and_Statistics) (IBGE) |date=2016-02-29 |access-date=2016-03-02 }}</ref> Pico da Neblina is the highest summit of the larger [Neblina massif](/source/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|date=August 2015}}

== Ecology ==
[[File:H chimantensis2.jpg|thumb|upright|''[Heliamphora chimantensis](/source/Heliamphora_chimantensis)'', [endemic](/source/endemism) to the [Chimantá Massif](/source/Chimant%C3%A1_Massif) (a [Venezuela](/source/Venezuela)n part of the Guiana Shield)]]
The Guiana Shield is one of the world's most [biodiverse](/source/Biodiversity) regions, and has many [endemic](/source/endemism) species. The region houses over 3000 [vertebrate](/source/vertebrate) species: 1168 fresh water fish, 269 amphibians (54% endemics), 295 reptiles (29%), 1004 birds (7.7%), and 282 mammals (11%).<ref>{{cite journal|last1= Hollowell|first1= T.|first2= R.P. |last2= Reynolds|year= 2005|title= Checklist of the Terrestrial Vertebrates of the Guiana Shield|journal= Bulletin of the Biological Society of Washington|volume= 13|url= http://botany.si.edu/bdg/pdf/bswa_13_all.pdf}}</ref><ref>{{cite journal| last1 = Stachowicz | first1 = Izabela| last2 = Ferrer Paris | first2 = José Rafael| last3 = Quiroga-Carmona | first3 = Marcial| last4 = Moran | first4 = Lisandro| last5 = Lozano | first5 = Cecilia| date       = 2020| title      =  Baseline for monitoring and habitat use of medium to large non-volant mammals in Gran Sabana, Venezuela| journal    =  Therya| volume     =  11| issue = 2| pages      =  169–179| doi        =  10.12933/therya-20-891| doi-access = free| hdl = 1959.4/unsworks_67008| hdl-access = free}}</ref><ref>{{cite journal|last1= Vari|first1= R.P.|first2= C.J.|last2= Ferraris Jr.|first3= A.|last3= Radosavljevic|first4= V.A.|last4= Funk|year= 2009|title= Checklist of the freshwater fishes of the Guiana Shield|journal= Bulletin of the Biological Society of Washington|volume= 17|url= http://botany.si.edu/bdg/pdf/bswa_fish-chcklst_2009-complete.pdf}}</ref> Diversity of invertebrates remains largely undocumented, but there are several species of endemic butterflies and dung beetles.<ref name="IndicativeResponse">{{cite journal|last1=Ferrer-Paris|first1=José R|last2=Lozano|first2=Cecilia|last3=Cardozo-Urdaneta|first3=Arlene|last4=Thomas Cabianca|first4=Arianna|title=Indicative response of ''Oxysternon festivum'' Linné (Coleoptera: Scarabaidae) to vegetation condition in the basin of the Orinoco river, Venezuela|journal=Journal of Insect Conservation|volume=20 |issue=3|pages=527–538|doi=10.1007/s10841-016-9886-6|year=2016|s2cid=17263106}}</ref><ref name="ViloriaPantepui">{{cite journal|last1=Costa|first1=Mauro|last2=Viloria|first2=Ángel L.|last3=Hubber|first3=Otto|last4=Attal|first4=Stéphane|last5=Orellana|first5=Andrés|title=Lepidoptera del Pantepui. Parte I: Endemismo y caracterización biogeográfica|journal=Entomotropica|date=2013|volume=28|issue=3|pages=193–217|url=http://www.entomotropica.org/index.php/entomotropica/article/view/414/449|access-date=25 June 2016|archive-url=https://web.archive.org/web/20160827045133/http://www.entomotropica.org/index.php/entomotropica/article/view/414/449|archive-date=27 August 2016|url-status=dead}}</ref>

Plant life is equally rich and 13,367 species of [vascular plant](/source/vascular_plant)s have been found, approximately 40% of which is considered endemic.<ref>{{cite journal|last1= Funk|first1= V.|first2= T.|last2= Hollowell|first3= P.|last3= Berry|first4= C.|last4= Kelloff|first5= S.N.|last5= Alexander|year= 2007|title=Checklist of the Plants of the Guiana Shield (Venezuela: Amazonas, Bolivar, Delta Amacuro; Guyana, Surinam, French Guiana)|journal= Contributions from the United States National Herbarium|volume= 55|url= http://botany.si.edu/bdg/pdf/vol55web.pdf}}</ref> The shield is overlain by the largest expanse of tropical forest on any Precambrian shield area in the world.<ref>Hammond, David S. (ed.) (2005) ''Tropical Forests of the Guiana Shield'' CABI Publishing, Wallingford, UK, ISBN</ref> Guianan rain forest is similar in nature to [Amazonian rain forest](/source/Amazon_Rainforest) and known protected areas include the Iwokrama Forest of central Guyana, Kaieteur, [Kanuku](/source/Kanuku) National Park of southern Guyana, the UNESCO [World Heritage Site](/source/World_Heritage_Site) [Central Suriname Nature Reserve](/source/Central_Suriname_Nature_Reserve) of [Suriname](/source/Suriname), the [Guiana Amazonian Park](/source/Guiana_Amazonian_Park) in [French Guiana](/source/French_Guiana) and the [Tumucumaque National Park](/source/Tumucumaque_National_Park) in the [Amapá](/source/Amap%C3%A1) State of [Brazil](/source/Brazil). In Venezuela the forests are protected by [Canaima](/source/Canaima_National_Park), [Parima-Tapirapeco](/source/Parima_Tapirapec%C3%B3_National_Park) and [Serranía de la Neblina](/source/Serran%C3%ADa_de_la_Neblina_National_Park) 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](/source/Ramsar_Convention).<ref>{{Cite web | url=http://www.ramsar.org/es/complejo-de-humedales-de-la-estrella-fluvial-in%C3%ADrida-efi | title=Colombia &#124; Ramsar}}</ref>

According to recent researches, although ecosystems of the Guiana Highlands remain vibrant, emerging issues (including "a well-known [invasive](/source/Invasive_species) plant elsewhere" ''[Poa annua](/source/Poa_annua)'' and "one of the most aggressive weeds" ''[Polypogon elongatus](/source/Polypogon_elongatus)'') and infectious faecal bacteria ''[Helicobacter pylori](/source/Helicobacter_pylori)'' have been documented.<ref>{{cite journal |last1= Rull|first1= V.|last2= Vegas-Vilarrúbia|first2= T.|last3= Safont|first3= E.|date= 2016|title= The Lost World's pristinity at risk|journal= [Diversity and Distributions](/source/Diversity_and_Distributions)|volume= 22|issue= 10|pages= 995–999|doi= 10.1111/ddi.12469|bibcode= 2016DivDi..22..995R|url= https://digital.csic.es/bitstream/10261/137349/3/Rull_Diversity_and_Distributions_22_995_postprint.pdf|hdl= 10261/137349|s2cid= 23002053|hdl-access= free}}
</ref>

== See also ==
*{{annotated link|Gran Sabana}}
*{{annotated link|Tepui}}
*{{annotated link|Canadian Shield}}
*{{annotated link|Caribbean South America}}
*{{annotated link|Mount Roraima}}
*{{annotated link|Pico da Neblina}}
*{{annotated link|Great American Interchange}}
*{{annotated link|Geography of South America}}

== References ==
<!--<nowiki> 
See http://en.wikipedia.org/wiki/Wikipedia:Footnotes for an explanation of how to generate footnotes using the <ref> and </ref> tags.
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{{reflist}}

== External links ==
* {{Commons category-inline|Guiana Shield}}
* {{Commons-inline|Guiana Highlands}}
* {{Commons category-inline|Tepuis}}

{{Clear}}

{{Major South American geological formations}}
{{Physiographic regions}}
{{Tepuis|state=collapsed}}
{{Geographical Regions of Venezuela}}
{{Authority control}}

Category:Shields (geology)
.
Shield
Category:Plateaus of South America
Category:Plateaus of Brazil
Category:Plateaus of Venezuela
Category:Geographical regions of Venezuela
Category:Geography of Colombia
Category:Geography of French Guiana
Category:Geography of Guyana
Category:Geography of Suriname
Category:Natural regions of South America
Category:Geology of South America
Category:Geology of Brazil
Category:Geology of Colombia
Category:Geology of French Guiana
Category:Geology of Guyana
Category:Geology of Suriname
Category:Geology of Venezuela
.
Category:Natural history of South America
Category:North Region, Brazil
Category:Geography of Amapá
Category:Geography of Pará
Category:Geography of Roraima
Category:Precambrian South America

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Adapted from the Wikipedia article [Guiana Shield](https://en.wikipedia.org/wiki/Guiana_Shield) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Guiana_Shield?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.