Map of Guyana

Geography

Mount Roraima is located in the Pacaraima Mountains in the eastern part of the Guiana Highlands, in northern South America. Its area is shared among three countries: Brazil to the east (5%), Guyana to the north (10%), and Venezuela to the south and west (85%). Access to Mount Roraima from the Venezuelan side is close to the road and relatively easy; however, for both Brazil and Guyana the area is completely isolated and can be reached only by a few days of forest hikes or small local airstrip.

Mount Roraima is a flat-topped mountain, typical of the Guyana Shield, with an elevation of about 1,200 m (3,900 ft) in the southeast and only about 600 m (2,000 ft) in the northwest.

Geology

Mount Roraima is composed of Proterozoic age sandstone formed about 1.7 to 2 billion years ago, and hence is amongst the oldest rocks on Earth. It contains a large amount of quartz deposits, 98% are silica particles, forming white or pink crystals several centimeters long. 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. The soil of the sandstone matrix is highly acidic, poor in nutrients, and very fine. Intense rainfall prevents the fixation of nutrients and particles, thereby preventing the formation of hilltop vegetation and soil.

Ecology

Due to the late exploration of this part of South America and the discovery of new species every year, the flora and fauna here are largely unknown. The currently identified species are strongly endemic, especially the fauna, which also puts them at a high risk of extinction. The bottom of the cliff at the foot of the mountain is an evergreen rainforest composed of trees 25–45 m (82–150 ft) high, and some can reach 60 m (200 ft). Vegetation is dominated by Arecaceae and Astragalus. The soils on the cliffs are sandier, the climate is cooler, and the vegetation consists of bromeliads very similar to the Andes. The vegetation on the plateau is still largely unknown and consists mainly of bare rocks, forests of trees and epiphytes, and wet and dry savannas in the form of swamps.

Geography

South America occupies the southern portion of the Americas. The continent is generally delimited on the northwest by the Darién watershed along the Colombia–Panama border, although some may consider the border instead to be the Panama Canal. Geopolitically and geographically, all of Panama – including the segment east of the Panama Canal in the isthmus – is typically included in North America alone and among the countries of Central America. Almost all of mainland South America sits on the South American Plate.

History

South America is thought to have been first inhabited by humans when people were crossing the Bering Land Bridge (now the Bering Strait) at least 15,000 years ago from the territory that is present-day Russia. They migrated south through North America, and eventually reached South America through the Isthmus of Panama.

Amongst the oldest evidence for human presence in South America is the Monte Verde II site in Chile, suggested to date to around 14,500 years ago. From around 13,000 years ago, the Fishtail projectile point style became widespread across South America, with its disappearance around 11,000 years ago coincident with the disappearance of South America's megafauna.

Economy

Since 1930, the continent has experienced growth and diversification in most economic sectors. Most agricultural and livestock products are destined for the domestic market and local consumption. However, the export of agricultural products is essential for the balance of trade in most countries.

The main agrarian crops are export crops, such as soy and wheat. The production of staple foods such as vegetables, corn or beans is large, but focused on domestic consumption. Livestock raising for meat exports is significant in Argentina, Paraguay, Uruguay and Colombia. In tropical regions the most important crops are coffee, cocoa and bananas, mainly in Brazil, Colombia and Ecuador.

Geology

The oldest rocks in the shield consist of Archean Imataca Complex, composed of a quartz-feldspar gneiss and subordinate mafic gneiss. The Guri Fault marks the southern boundary of the complex. South of that fault are Early Proterozoic rocks consisting of the metavolcanic Pastora Supergroup and the granitic plutonic Supamo Complex. The Cuchivero Group consists of ash flow tuff and granitic plutonic rocks. The Early to Middle Proterozoic Roraima Group consists of continental clastic sedimentary rocks. These Precambrian sediments include quartz sandstones, quartzites, and conglomerates presumed to be 1.8 to 1.4 Ga in age.

Ecology

The Guiana Shield is one of the world's most biodiverse regions, 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%). Diversity of invertebrates remains largely undocumented, but there are several species of endemic butterflies and dung beetles.

Plant life is equally rich and 13,367 species of vascular plants have been found, approximately 40% of which is considered endemic. The shield is overlain by the largest expanse of tropical forest on any Precambrian shield area in the world.