Editing Mount Roraima (section)

==Geology==
Mount Roraima is composed of [[Proterozoic]] age [[sandstone]] formed about 1.7 to 2&nbsp;billion years ago,<ref name="climbing"/><ref name="Elms"/><ref name= "theseoultimes"/><ref name= "summitpost"/> and hence amongst the oldest rocks on Earth. It contains a large amount of [[quartz]] deposits,<ref name= "PNUD"/><ref name="Elms">{{cite news | first=Lindsay | last=Elms |title= Mount Roraima: An Island Forgotten by Time| via= shaw.ca|url= http://members.shaw.ca/beyondnootka/articles/roraima.html |accessdate= 2022-03-21 |archive-date=2007-05-09 |archive-url=https://archive.today/20070509092623/http://members.shaw.ca/beyondnootka/articles/roraima.html}}</ref><ref name= "theseoultimes"/><ref name= "summitpost"/> 98% are [[silica]] particles,<ref name="Audy">{{cite book |first1=Braňislav |last1=Šmída| first2=Marek | last2=Audy | first3= Lukáš | last3=Vlček |title=The speleological expedition Roraima 2003 Cueva Ojos de Cristal |page=20 |url= http://audy.speleo.cz/Roraima/Ojos/engl.html |access-date=2022-03-21 |archive-date=2022-01-09 |archive-url= https://web.archive.org/web/20220109141018/http://audy.speleo.cz/Roraima/Ojos/engl.html}}</ref> forming white or pink crystals several centimeters long.<ref name="Elms"/><ref name="theseoultimes"/> These rocks sit on a [[granite]] and [[gneiss]] base and were originally covered by layers of [[Mesozoic]] clay, conglomerate, and [[diorite]], but have been exposed by erosion and by [[orogeny]] over the past 180 million years, eroded by precipitation to form strange shapes.<ref name= "PNUD"/><ref name="inparques Ambiente"/> The soil of the sandstone matrix is highly acidic, poor in nutrients, and very fine.<ref name="inparques Ambiente"/> Intense rainfall prevents the fixation of nutrients and particles, thereby preventing the formation of hilltop vegetation and soil.<ref name="PNUD"/><ref name="summitpost"/>

The numerous caves and rifts in the interior of the plateau make Mount Roraima exhibit a pseudo-[[karst]] structure,<ref name="PNUD"/><ref name= "Carreño">{{cite journal |title=Notas sobre la exploración del sistema kárstico de Roraima Sur, Estado Bolívar |journal= Boletín de la Sociedad Venezolana de Espeleología | language = es |year=2004 |pages=8 |issn=0583-7731 |url=http://www2.scielo.org.ve/scielo.php?script=sci_arttext&pid=S0583-77312004000100006&lng=es&nrm=is |access-date=2022-03-21 |archive-date= 2014-01-17 |archive-url= https://web.archive.org/web/20140117023638/http://www2.scielo.org.ve/scielo.php?script=sci_arttext&pid=S0583-77312004000100006&lng=es&nrm=is}}</ref> and these caves form a network over {{cvt|15|km|sigfig=2}} long, with a total height difference of {{cvt|73.21|m|sigfig=4}}.<ref>{{cite web |last=Gulden |first=Bob |author-link= Robert Gulden |date=2013-07-31 | website = cavebob.com |title=World's longest caves |url= http://www.caverbob.com/wlong.htm |archive-url=https://web.archive.org/web/20210509051326/http://www.caverbob.com/wlong.htm |archive-date=2021-05-09 |url-status=usurped |access-date=2022-03-21}}</ref> It contains the largest quartz cave in the world, discovered by the Oxford University Cave Club and the Venezuelan Speleological Society.<ref>{{Cite web |last=Crosby |first=Pip |title=OUCC-SVE Roraima expedition |url=http://www.oucc.org.uk/expeditions/expedition2005/roraima_2005/pips_article.htm |access-date=2024-04-29 |website= oucc.org.uk}}</ref><ref name="Carreño"/> These caves are formed by the infiltration of surface water, so the water level inside them depends largely on the precipitation on the surface of the plateau: prolonged drought can dry up waterways, and dry caves can also become underground rivers.<ref name= "Audy"/> The water that poured into it rushed into the crevices of the rock and flowed out in the form of waterfalls on the mountainside, creating many streams at the foot of the mountain.<ref name= "Elms"/>