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Magellan Land Bridge: Cono del Sur and Antarctica

Magellan Land Bridge: Cono del Sur and Antarctica

(p.213) Six Magellan Land Bridge: Cono del Sur and Antarctica
Land Bridges
Alan Graham
University of Chicago Press

The Magellan Land Bridge is defined as the connection between southern South America and Antarctica although throughout its Cretaceous and Cenozoic history connections continued on into Australasia and other lands. Disruption in the region discussed here began in the Jurassic-Cretaceous (ca. 162-130 Ma) with opening of the Rochas Basin in southern Chile. In the Oligocene (35-30.5 Ma) the Powell Basin formed between Antarctica and South America, and the Drake Passage with a full-flowing Antarctic Circum-Current appeared in the Oligocene at 31-30 Ma. In the warmer Paleogene intervals Nipa, Araucaria, Podocarpaceae, Nothofagus and others grew on the continent and became established in South America and northward. The Paleocene-Early Eocene Climatic Optimum ended ca. 55 Ma and early glaciers began to form in the uplands. With the formation of the ACC in the Oligocene the continent was further isolated from warm waters to the north and glaciers spread into the lowlands. They expanded in the Neogene so that between ca. 22-17 Ma the Humboldt Current began transporting progressively colder water northward along the western coast of South America contributing to formation of the Atacama Desert and other dry zones.

Keywords:   definition, geology, climates, Humboldt Current, vegetation, Shackleton, Nothofagus, Araucaria

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