Most observers describe Venezuela in terms of four fairly well-defined regions: the Maracaibo lowlands in the northwest, the northern mountains extending in a broad east-west arc from the Colombian border along the Caribbean Sea, the wide Orinoco plains (llanos) in central Venezuela, and the highly dissected Guiana highlands in the southeast.

Maracaibo Basin

The Maracaibo lowlands form a large spoon-shaped oval bounded by mountains on three sides and open to the Caribbean on the north. The area is remarkably flat with only a gentle slope toward the center and away from the mountains that border the region.

Lake Maracaibo occupies much of the lower-lying territory. Areas around the southern part of Lake Maracaibo are swampy, and, despite the rich agricultural land and significant petroleum deposits, the area was still thinly populated in 1990.

The Maracaibo Basin in Western Venezuela is a prolific, oil-producing sedimentary basin. The basin is bounded on the north by the Oca Fault which separates it from the Caribbean Sea. The remaining sides of the basin are bounded by a branching in the northern Andes Mountains termed the Sierra de Perijá (to the west) and the Mérida Andes (to the south and east).

Topographic map of Venezuela

The city of Maracaibo, Venezuela is located in the northern central part of the basin on the shore of Lake Maracaibo, which occupies the central part of basin.

Oil was discovered in producible quantities in Venezuela in 1914 at the town of Mene Grande in the east central part of the basin. The site of the first well was near a surface oil seep.

Venezuela produces a mix of conventional heavy crude and nonconventional crude derrived from bitumen. This latter source, previously too expensive to produce in quantity, now makes up an increasing large percent of Venezuela’s oil exports—600,000 of Venezuelas’s three million barrels per day in 2006.

In the Maracaibo Basin, the balance of reserves is toward its conventional deposits, which make up half of the country’s exports. As the country continues shifting toward bitumen production due to its increasing profitability and decreases in conventional reserves, the level of Maracaibo Basin oil production will decrease, while that of the Orinoco Belt and its massive bitumen deposits will increase.

Llanos

The Llanos (The Plains) is a vast tropical grassland plain situated to the east of the Andes in Colombia and Venezuela, in northwestern South America. It is an ecoregion of the Flooded grasslands and savannas Biome.

The Llanos’ main river is the Orinoco, which forms part of the border between Colombia and Venezuela and is the major river system of Venezuela.

The climate change of the Llanos is extreme. During the rainy season from May to October, parts of the Llanos can flood up to a meter. This turns the woodlands and grassland into a temporary wetland, comparable to the Pantanal of central South America. This flooding also makes the area unique for its wildlife.

Vegetation map of Venezuela

The area supports around 70 species of water birds, including the Scarlet Ibis. A large portion of the distribution of the White-bearded Flycatcher is in the Llanos.

The flooding also makes the area unfit for most agriculture before the advent of modern, industrial farming technology. Therefore, during the Spanish colonial era, the prime economic activity of the area came from the herding of millions of heads of cattle.

The term llanero (“plainsman”) became synonymous with the cowhands that took care of the herds, and had some cultural similarities to the compare to the gauchos of the Pampas or the vaqueros of Spanish and Mexican Texas.

The area slopes gradually away from the highland areas that surround it; elevation above sea level in the llanos area never exceeds 200 meters.

Guiana Shield

The Guiana Shield is one of the three cratons of the South American Plate. It is a 1.7 billion year old Precambrian geological formation in northeast South America that forms a portion of the northern coast.

The higher elevations on the shield are called the Guiana Highlands, which is where the impressive and mysterious table-like mountains called tepuis are found. The Guiana Highlands are also the source of some of the world’s most spectacular waterfalls such as Angel Falls, Kaieteur Falls and Kuquenan Falls.

The Guiana Shield underlies Guyana (previously British Guiana), Suriname (previously Dutch Guiana) and French Guiana (or Guyane), as well as parts of Colombia, Venezuela and Brazil.

The rocks of the Guiana Shield consist of metasediments and metavolcanics (greenstones) overlain by quasi-horizontal layers of sandstones, quartzites, shales and conglomerates intruded by sills of younger mafic intrusives such as gabbros.