Atacama Desert

The Atacama Desert region is a sparsely populated, virtually rainless plateau, extending nearly 1,600 km (994 mi) and reaching a maximum width of 180 km (111 mi).

The original inhabitants of this area, the Diaguitas and Changos, valued its mineral wealth. As a result, the desert has rich deposits of copper and other minerals and the world's largest natural supply of sodium nitrate (Chile saltpeter), which was mined on a large scale until the early 1940s.

The Atacama border dispute over these resources between Chile and Bolivia began in the 19th century and resulted in the War of the Pacific. Since the 19th century, iron, copper, silver and gold have brought prosperity.

The desert is littered with about 170 abandoned nitrate (or "saltpeter") mining towns, almost all of which were shut down decades after the invention of synthetic nitrate in Germany in the first decade of the 20th century. The towns include Chacabuco, Humberstone, Santa Laura, Pedro de Valdivia, Puelma, María Elena, and Oficina Anita.

Today, most of the populated areas in the Atacama are located along the Pacific coast. However, in interior areas, oases and some valleys have been populated for millennia and were the location of Chile's most advanced pre-Columbian societies.

The Chinchorro culture developed in the Atacama Desert area from 7,000 to 1,500 BCE. These peoples were sedentary fishermen inhabiting primarily coastal regions.

Before the Inca empire and the Spanish's arrival, the highly arid interior was inhabited primarily by the Atacameño tribe. They are noted for building fortified towns called pucarás.

The coastal cities originated in the 16th, 17th, and 18th centuries during the Spanish Empire when they emerged as shipping ports for silver produced in Potosí and other mining centers. During the 19th century, the desert came under the control of Bolivia, Chile, and Peru.

With the discovery of sodium nitrate deposits and unclear borders, the area soon became a zone of conflict, resulting in the Pacific War. As a result, Chile annexed most of the desert, and cities along the coast developed into international ports, hosting many Chilean workers who migrated there.

With the guano and saltpeter booms of the 19th century, the population grew immensely, mainly due to immigration from central Chile.

In the 20th century, the nitrate industry declined, and at the same time, the predominantly male population of the desert became increasingly problematic for the Chilean state. As a result, miners and mining companies came into conflict and protests spread throughout the region.

San Pedro de Atacama, at about 2,400 m (8,000 ft) elevation, is like many small towns. The Spanish built the town's church in 1577—most people who tour the sites in the desert stay in San Pedro de Atacama.

The Atacama Desert is one of the top tourist destinations in Chile.

_{The area most commonly defined as the Atacama Desert is in yellow. In orange are the outlying arid regions.}

Atacama Desert Ecoregion

The Atacama Desert ecoregion is located in northern Chile between Argentina on the west and the Pacific Ocean on the east. Running east from the Pacific Ocean to the Andes Mountains — an extremely arid, almost barren landscape predominates — because rainfall has never been recorded in many areas.

Despite the aridity of this desert, some cacti (Eulychnia), perennials (Nolana) and mesquite (Prosopis) occur in basins where occasional water accumulation occurs.

Few animal species have adapted to this arid environment; therefore, faunal diversity and density are extremely low. Even bacteria are scarce, and insects and fungi are absent in many portions of the desert.

The intrinsic value of the Atacama Desert's plant and animal communities lies in the unique nature of their composition, the high levels of endemism and some species' remarkable adaptations for survival in some of the planet's most demanding conditions.

The Atacama Desert is one of the driest places in the world and the only true desert to receive less precipitation than the polar deserts. According to estimates, the Atacama Desert occupies 105,000 sq km (41,000 sq mi) or 128,000 sq km (49,000 sq mi) if the barren lower slopes of the Andes are included.

Although the almost total lack of precipitation is the most prominent characteristic of the Atacama Desert, exceptions may occur.

Most of the desert comprises stony terrain, salt lakes (salares), sand and felsic lava that flows toward the Andes. The desert owes its extreme aridity to a constant temperature inversion due to the cool north-flowing Humboldt Ocean current and the strong Pacific anticyclone.

The aridest region of the Atacama Desert is situated between two mountain chains (the Andes and the Chilean Coastal Range) of sufficient height to prevent moisture advection from either the Pacific or the Atlantic Oceans, a two-sided rain shadow.

The Atacama Desert may be the oldest desert on Earth and has experienced extreme hyper aridity for at least 3 million years, making it the oldest continuously arid region.

The Atacama is so arid that many mountains above 6,000 m (20,000 ft) are completely glacier-free. As a result, only the highest peaks (such as Ojos del Salado, Monte Pissis, and Llullaillaco) have some permanent snow coverage.

Flora and Fauna

Despite the geographic and climatic conditions of the desert, a wide variety of flora has evolved there. Over 500 species have been gathered within the border of this desert. These species are characterized by their extraordinary ability to adapt to this extreme environment.

The most common species are the herbs and flowers such as thyme, llareta and saltgrass (Distichlis spicata), and where humidity is sufficient, trees such as the chañar (Geoffroea decorticans), the pimiento tree, and the leafy algarrobo (Prosopis chilensis).

The desert is also home to cacti, succulents, and other plants that thrive in a dry climate. Cactus species here include the candelabra (Browningia candelaris) and cardon (Echinopsis atacamensis), which can reach a height of 7 m (23 ft) and a diameter of 70 cm (28 in).

The Atacama Desert, flowering Desierto Florido, can be seen from September to November in years with sufficient precipitation.

The climate of the Atacama Desert limits the number of animals living permanently in this extreme ecosystem. In addition, some parts of the desert are so arid no plant or animal life can survive.

Outside these extreme areas, sand-colored grasshoppers blend with pebbles on the desert floor, and beetles and their larvae provide a valuable food source in the Lomas (hills). In addition, desert wasps and butterflies can be found during the warm and humid season, especially on the Lomas. Red scorpions also live in the desert.

Birds are probably the largest animal group in the Atacama. Humboldt penguins live year-round along the coast, nesting in desert cliffs overlooking the ocean. Andean flamingos flock to eat algae on salt flats near the Pacific and inland.

Other birds (including species of hummingbirds and sparrows) visit the Lomas seasonally to feed on insects, nectar, seeds, and flowers. In addition, the Lomas help sustain several threatened species, such as the endangered Chilean woodstar.

Because of the desert's extreme aridity, only a few specially adapted mammal species live in the Atacama, such as Darwin's leaf-eared mouse. The less arid parts of the desert are inhabited by the South American gray fox and the viscacha (a relative of the chinchilla).

Larger animals, such as guanacos and vicuñas, graze in areas where grass grows, mainly because it is seasonally irrigated by melted snow. Vicuñas need to remain near a steady water supply, while guanacos can roam into more arid areas and survive longer without fresh water. Seals and sea lions often gather along the coast.