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Mount Roraima (; ) is the highest of the Pacaraima chain of (table-top mountain) or in South America. It is located at the junction of Brazil, Guyana and Venezuela. A characteristic large flat-topped mountain surrounded by cliffs high. The highest point of Mount Roraima is located on the southern edge of the cliff at an elevation of in Venezuela, and another protrusion at an elevation of at the junction of the three countries in the north of the plateau is the highest point in Guyana. The name Mount Roraima came from the native Pemon people. Roroi in the Pemon language means "blue-green", and ma means "great".
Leaching caused by intense rainfall has shaped the peculiar topography of the summit, and the geographical isolation of Mount Roraima has made it home to much endemic flora and fauna. Western exploration of Mount Roraima did not begin until the 19th century, when it was first climbed by a British expedition in 1884. Yet despite subsequent expeditions, its flora and geology remain largely unknown. The privileged setting and relatively easy access and climbing conditions on the south side of the cliffs make Mount Roraima a popular destination for hikers.
Mount Roraima is a flat-topped mountain, typical of the Guiana Shield, with an elevation of about in the southeast and only about in the northwest. The south, southeast, east, northeast and northwest faces are all formed by straight cliffs up to about high. At the southern end of the mountain, part of the cliff has collapsed, forming a natural boulder. The base of the cliff is surrounded by steep slopes to the south and east, and the north and west sides form river valleys leading to the summit.
The top of Mount Roraima has a length of more than , a maximum width of , an area of about , an elevation of more than , and an average elevation of . The plateau is a pseudo-karst surface etched by heavy rainfall. The highest point is above sea level, located at the southern end of the plateau and the highest point in the state of Bolívar, north of the summit is another high point with an elevation of , which is the highest point in Guyana. In the northern part of the plateau is the landmark of the border between Brazil, Venezuela and Guyana, with an elevation of .
Due to its height and proximity to the equator, Mount Roraima has a constant average annual temperature between and annual rainfall of more than , with in parts of the rainy season from April to November. The climatic conditions at the top of the mountain differ significantly from its base, the high cloudiness in the region is associated with the prevailing northeasterly and southeasterly winds, and the relative humidity of the air remains between 75% and 85%.
The numerous caves and rifts in the interior of the plateau make Mount Roraima exhibit a pseudo-karst structure, and these caves form a network over long, with a total height difference of . It contains the largest quartz cave in the world, discovered by the Oxford University Cave Club and the Venezuelan Speleological Society. 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. 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.
Endemic flora includes plants like Orectanthe sceptrum, Sauvagesia imthurnii, Celiantha imthurniana, Pitcher plant ( Heliamphora nutans), Gran Sabana sundew ( Drosera felix), Roraima bladderworts ( Utricularia quelchii), Roraima "azaleas" ( Bejaria imthurnii) and many more.
The fauna at the foot of the mountain are composed of a variety of mammals, and this huge diversity is particularly prominent in the Amazon rainforest, such as sloths, , , , , , agouti, , , deer, , and primates such as howler monkeys and Capuchin monkey. There are hundreds of species of birds, the most common of which include , , and . Some hummingbirds are endemic to the region. Due to low mobility relative to other species, reptiles and amphibians show large differences between individuals found at the bottom and top of Mount Roraima. While species inhabiting forests at the foot of the plateau are common, such as , , and Pythonidae, those found at the top are even rarer. Cave fauna consists of many species of , , and , but this fragile subterranean ecosystem is being disturbed by surface hikers, organic matter produced by tourists, and explorers over the years. Pollutants such as fuel are washed into the ground by rainwater, which leads to the proliferation of microorganisms and causes ecological imbalance.
Endemic species include rodents such as the Roraima climbing mouse ( Rhipidomys macconnelli roraimae) or the rarer Roraima mouse ( Roraima mouse), as well as many birds such as the Greater flowerpiercer ( Diglossa major) or the two subspecies of sparrow, Zonotrichia capensis roraimae and Zonotrichia capensis macconelli. One of the most well known endemic species is the Roraima toad ( Oreophrynella quelchii).
Although its vertical cliffs make access very difficult, Mount Roraima was the first large mesa to be climbed in the Guyana Plateau. Henry Whiteley, who studied the birds of the area, observed that the summit could be reached from the south with the help of ropes and ladders. Everard im Thurn and Harry Perkins led an expedition sponsored by the Royal Geographical Society that culminated on December 18, 1884, when the team met local people known as the Pemón who could have climbed to the top of Mount Roraima prior to their expedition. The explorers still believed the top of the cliff to be previously unknown to humans. Soon, many expeditions made up of botanists, zoologists and geologists made multiple expeditions to Mount Roraima to study the mostly unknown flora and fauna and special geological conditions of the area.
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