South America, known for its rainforests and mountains, also has significant desert regions. These arid landscapes range from hyper-arid coastal plains to cold, high-altitude steppes, showcasing the continent’s varied geography and climate.
Major Desert Regions
The Atacama Desert, primarily in northern Chile and parts of Peru, is one of the world’s driest non-polar deserts. This arid plateau stretches about 1,600 kilometers along the Pacific coast, covering 105,000 square kilometers. Some areas within the Atacama have recorded no rainfall for centuries.
Further south, primarily in Argentina, lies the Patagonian Desert, also known as the Patagonian Steppe. As the largest desert in Argentina and the eighth-largest globally, it spans approximately 673,000 square kilometers. This cold winter desert is characterized by vast gravel plains, tablelands, and massifs dissected by river valleys and canyons. Temperatures in this region rarely exceed 12°C, averaging around 3°C, with frost being common.
Along the northern coast of Colombia and Venezuela, the La Guajira Desert occupies most of the La Guajira Peninsula. This coastal desert meets the Caribbean Sea, featuring large sand dunes, salt flats, and xeric scrubland adapted to dry conditions.
The Sechura Desert is along Peru’s northwestern Pacific coast, extending inland to the Andes foothills. Though wetter than the Atacama, it is an arid environment influenced by coastal fogs. This desert covers approximately 50,000 square kilometers of plains, dunes, and rugged landscapes.
Factors Contributing to Aridity
South America’s deserts form due to distinct climatic and geographical mechanisms. The Andes Mountains play a role, creating a rain shadow effect. Moist air from the Amazon Basin rises over the Andes, releasing precipitation on the eastern slopes. The air then descends dry on the western side, contributing to the aridity of regions like the Atacama and Patagonian Deserts.
A major influence, particularly for coastal deserts such as the Atacama and Sechura, is the cold Humboldt Current, also known as the Peru Current. This ocean current flows northward along the western coast of South America, bringing cold water from the polar regions. The cold water cools the air above it, preventing moisture from evaporating and rising to form rain clouds. This results in stable atmospheric conditions and limited rainfall in adjacent coastal areas.
Atmospheric circulation patterns contribute to the continent’s dry zones. The South Pacific high-pressure cell generates dry, descending air. This stable air mass suppresses cloud formation and precipitation, especially along the western coast. The combination of these large-scale atmospheric patterns with local geographical features creates conditions for desert environments across South America.
Unique Characteristics and Biodiversity
South American deserts exhibit unique characteristics and host specialized biodiversity adapted to their harsh conditions.
The Atacama Desert, known for its hyper-arid core, is so dry that some areas have been used as simulation sites for Mars expeditions due to their similar terrain and climate. Despite this aridity, studies have identified microbial life surviving in its soils.
A feature in some coastal deserts, like parts of the Atacama and Sechura, are “fog oases” or lomas. These areas receive moisture from coastal fogs, locally known as “camanchaca” or “garúa,” which condense on mountain slopes near the sea. This fog drip supports unique plant communities, including specialized cacti and various shrub and herb species. Scientists have even developed fog catchers to collect this water, demonstrating adaptation to water scarcity.
The Patagonian Desert features geological formations shaped by wind and ancient glacial activity, including gravel plains, sandstone canyons, and clay formations. Its fauna includes species like guanacos, pumas, and a variety of birds such as lesser rheas and Patagonian mockingbirds. The unique conditions in these deserts have led to the evolution of flora and fauna with specific adaptations.