Gran Sabana
The Gran Sabana is a region in southeastern Venezuela which is part of the Guianan savanna ecoregion. It extends into the Guiana Highlands and south-east into Bolívar State to the borders with Brazil and Guyana. The Gran Sabana has an area of and is part of Canaima National Park, Venezuela's second-largest national park; only Parima Tapirapecó National Park is larger than Canaima. The average temperature is around and can drop to at night or lower at higher elevations. The region includes rivers, waterfalls, gorges, deep valleys and jungles, and savannas hosting a number and variety of plant species, diverse fauna, and isolated table-top mesas locally known as tepuis.
History
During the era of colonization in Venezuela, the territories of Guiana and its natural resources gave rise to the legend of El Dorado. This attracted the attention of adventurers, explorers and settlers who came in search of gold, gems, and other valuable products. The region still has several areas that few people have explored.Park
Due to its diverse biology, mineral reserves and geography, the government of Venezuela decided that it was necessary to protect the territory. Canaima was declared a national park with Executive Order 770, dated June 12, 1962. The park is Venezuela's second-largest.Canaima National Park covers about, among the world's six largest national parks. Its original area was, and did not include the Gran Sabana.
The park was enlarged in 1975 to cover several points of high ecological importance. They include the Carrao River basin, the headwaters of the Caroní River, the Sierra de Lema, the source of the Cuyuni River, and the Gran Sabana's rolling plains. The Gran Sabana covers.
In 1994, UNESCO named Canaima National Park a World Heritage Site. The park is used to promote environmental conservation and ecotourism; thousands of tourists visit it every year.
The Gran Sabana's areas of natural beauty include tepuis, waterfalls and streams, and the park's diverse fauna and flora. The latter attracts scientists from around the world, who study the region's ecological diversity. Forty percent of Venezuela's species are found only in the Gran Sabana23 percent of its reptiles and amphibians, including a number of endemic species.
The region's largest city is Santa Elena de Uairén, with a population of over 30,000. It was founded in 1923 by Lucas Fernández Peña, who was attracted by the area's increase in diamond production. Its average temperature is. At above sea level, it is from the border with Brazil, from Ciudad Guayana, and about from Caracas by road. The Gran Sabana's estimated population is 48,000.
Geology
The Gran Sabana formed atop the Precambrian Guyana Shield. Its bedrock is the Roraima Group, presumed to be 1.8–1.4 billion years old. Within this group is the resistant Mataui Formation, which forms the tepui cliffs and summits. The formation is thick, and consists of quartzite and quartzite arenites. Tepui summits are above the surrounding terrain. The low area surrounding the table mountains is the Wonkén planation surface. The Auyán-Tepui planation surface forms the quartzite tepui summits. Heavy precipitation, combined with a long period of weathering, has produced quartz and sandstone karst features. These include arches, towers, tower fields, dolines, collapse shafts, polje, corridors, grikes, and large cave systems extending many kilometers. The Roraima Sur–Los Ojos de Cristal cave system is long and up to in diameter. Portions of the summits have been described as ruinform.Geography
The region experienced several periods of uplift, subsidence and erosion. The large remaining isolated sandstone beds are known as tepuis in the indigenous language. The road from El Dorado to Santa Elena de Uairén rises from in less than in La Escalera. Rocky and sandy soils support savanna vegetation at higher elevations, with dense jungle vegetation in hollows and dense forests along the rivers.Hydrology
The Gran Sabana, and Venezuela in general, is rich in river networks. The main drainage sub-basins are formed by the Yuruaní, Aponwao, Kukenán, Suruku, Ikabarú, Karuay, Urimán, and Antabare Rivers.The Caroní River, long with a flow rate of, provides Venezuela with most of its electricity by hydropower. It is fed by the Aponwao, the Yuruaní and the Kukenaning Rivers, flowing from tepuis and mountains of the Gran Sabana.
Most rivers and streams in the region have dark water, with a color similar to tea. The waters are poor in dissolved nutrients and rich in humic acids and tannins, which give them their characteristic brown color. They are acid, with a pH of 3–4.
Tepuis
In the Gran Sabana, ancient, randomly-distributed massifs eroded in tabletop form and are known as tepuis. They are examples of inverted relief which form a typical plateau in the Guiana Highlands. The highest plateau in the Gran Sabana is Mount Roraima, a tepui reaching nearly above sea level.Auyán-tepui
, in northwestern Canaima National Park, is the Guiana Highlands' best-known tepui. Its Angel Falls is the world's tallest waterfall, with a drop of almost. The falls were first made known to outsiders by U.S.-born explorer-aviator Jimmy Angel in 1937. He attempted to land his plane on top of Auyán-tepui during an expedition, crashing without fatalities. It is the second-largest Guiana tepui, with an area of and an altitude of. Auyán-tepui is inclined, exceeding in height on its southern edge and barely on its northern edge.The southern Auyán-tepui is accessible and climbable. Ropes are needed in some sections, although the degree of difficulty is not high. It is necessary to reach the village of Kavak by plane or helicopter to access the tepui, since there are no vehicle-access routes.
Chimantá Massif
The Chimantá Massif is formation of plateaus and Venezuela's largest, covering. The tepui, in central-western Canaima National Park, is not easily accessible and rarely visited by tourists. While flying over the massif, Venezuelan scientist Charles Brewer Carías discovered a large entrance to a cave.Mount Roraima
, the highest tepui in Canaima National Park, is also known as Blue Mountain or Crystal Mountain and considered a divinity by the local indigenous population. The Pemon believe that most tepuis host powerful spirits or entities which they respect and fear. Some make offerings and say prayers at the top in their infrequent visits to the tepui, usually as tour guides in exchange for money or food). Its height is about, and it covers an area of. Its vertical walls may reach high.Among its attractions are the Valley of the Crystals, the Jacuzzi area, the viewpoints of La Ventana and El Abismo, the North Mazes, la Proa, Lake Gladys, and the Triple Point. This point, in the northeast of the tepui, is where the borders of Brazil, Venezuela, and Guyana meet. There are also rock formations eroded by wind resembling a flying turtle, a Mexican hat, a monkey eating an ice-cream cone, and an elephant.
Kukenán-tepui
Also known as Matawi-tepui, Kukenán-tepui has a height of and was first climbed in 1963 on an expedition organized by Bangor University in Wales. The second ascent, in 1972, was by Stephen Platt, Ramon Blanco, Hans Swartz, and Ambrosio Perez. The Matawi-Tepui chain is part of the eastern tepuis of the Gran Sabana with the Yuruani-tepui. It is the location of Kukenan Falls, the world's tenth-highest waterfall, with of freefall.Other tepuis
Other tepuis are the Ilú-Tramén-Karaurín chain, the Wadaka-piapó and the Yuruaní, which are in the chain of seven eastern tepuis. They include the tepuis Iglú-tepui, Ptarí-tepui, Acopán-tepui and the Sororopán-tepui, which is tilted and can be climbed. Tramen Tepui, in the Ilú–Tramen Massif, was first climbed by Scharlie Wraight and Stephen Platt from the col between Ilu Tepui and Tramen Tepui on 24 November 1981.There are about 150 minor tepuis throughout Canaima National Park. Most tepuis reach heights of.
Climate
Temperature
Due to the Gran Sabana's elevation, about on average, it has an average annual temperature of . Due to cloud cover and rainfall, daily temperatures vary. Minimum temperatures rarely drop below, except on top of the tepuis. Maximum temperatures usually do not exceed.Precipitation
The rainy season lasts about 10 months, with a period of relative drought between January and March and an annual average of . The average varies along the savanna; in the south it is, in the north, and over in the south-east.Wind
The La Escalera area and the savanna experience strong winds. Altitude and winds determine climate, since the Gran Sabana's latitude is within the equatorial belt. The lower area further north is influenced by winds from the east and northeast, resulting in a rainy and dry season. The south and southeast are affected by winds from the Amazon rainforest, and receive heavy rain.Flora
The Gran Sabana has a variety of climatic and ecological conditions, ranging from hot lowlands to high, cold mountains, and has a number of plant species. The vegetation, particular to the region, is based on acidic soils derived from sandstone.Forests are along rivers and streams, and include trees, shrubs, guacos, epiphytes, and the Moriche Palm. Shrubs rarely exceed high. Leaves are primarily thick, probably due to soil acidity and lack of nutrients. The Gran Sabana has a variety of grasses, but the rocky, sandy soil makes them unsuitable for feeding livestock. The most important plant families are Theaceae, Humiriaceae, Ericaceae, Compositae, Aquifoliaceae, Burseraceae, and Sapotaceae. A wide variety of plants grow on the summits of the tepuis, ranging from to high.
In the rivers and waterfalls, plants on the rocks are green or tan; they are Spermatophyte plants of the family Podostemaceae. From above sea level, the submontane evergreen forests have a thick, well-developed understory. At on large tepui, low evergreen forests grow above. These form dense communities at medium-to-high altitudes, sometimes with a number of epiphytes. The summits of Auyantepui and the Massif Chimantá have several unique plants, such as the genera Brocchinia, Tepuia, Mallophyton, Coryphothamnus and Aphanocarpus, and Arimantaea and Achnopogon. Many of the rarest species are found on exposed sandstone formations. Endemic ferns of the genus Hymenophyllopsis and Pterozonium are found in shady and protected areas beneath rocks and in small cavities.
Carnivorous plant communities of the genera Heliamphora, Drosera, and Utricularia are found in the bedrock, where there is a thin layer of nutrient-deficient debris and dirt. This naturally-poor substrate has stimulated these genera to develop insectivorous habits.
Fauna
Despite the Gran Sabana's biodiversity, sightings of larger animals on the road between El Dorado and Santa Elena de Uairén are uncommon. The forest is open along that route; many animals are wary of people and hide in the forest, riparian zones, and in the deep jungle at the base of the tepuis. Many species can still be seen, however, including at least 25 mammal species:- Amazonian brown brocket deer
- Black-bearded saki
- Bush dog
- Capybara
- Collared peccary
- Colombian red howler
- Common red brocket deer
- Crab-eating fox
- Flat-faced fruit-eating bat
- Free-tailed bats
- Giant anteater
- Giant armadillo
- Giant otter
- Guyana red howler
- Jaguar
- Kinkajou
- Long-tailed weasel
- Margay
- Nine-banded armadillo
- Ocelot
- Prehensile-tailed porcupine
- Puma
- Red-rumped agouti
- Short-tailed bat
- South American coati
- South American tapir
- Southern naked-tailed armadillo
- Southern opossum
- Spotted paca
- Tamandua
- Tayra
- Tyler's mouse opossum
- Weeper capuchin
- White-faced saki