Geography of South America Great American Interchange. The Andes, likewise a comparatively young and seismically restless mountain range, runs down the western edge of the continent; the land to the east of the northern Andes is largely tropical rain forest, the vast Amazon River basin. The continent also contains drier regions such as eastern Patagonia and the extremely arid Atacama desert. The South American continent also includes various islands, most of which belong to countries on the continent. The Caribbean territories are grouped with North America. The South American nations that border the Caribbean Sea—including Colombia, Venezuela, Guyana, Suriname, and French Guiana—are also known
South American land mammal age the same stratigraphic horizon, then their age-range zones overlap. South America was an island continent for much of the Cenozoic, or the "Age of Mammals". As a result, its mammals evolved in their own unique directions, as Australia and Madagascar still have today. A simplified paleogeographic timeline of South America: South American land mammal age The South American land mammal ages (SALMA) establish a geologic timescale for prehistoric South American fauna beginning 64.5 Ma during the Paleocene and continuing through to the Late Pleistocene (0.011 Ma). These periods are referred to as ages, stages, or intervals and were established using