Andes Rose Rather Rapidly: Analyses of Sediments Suggest New Scenario Explaining South American Mountains' Height

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South America's Andes reached their staggering heights after a sudden growth spurt millions of years ago, new evidence suggests.

The central part of the Andes, one of the world's longest and tallest mountain chains, is home to some of the Earth's thickest crust: In spots, the crust extends to depths of 70 kilometers (SN: 1/15/05, p. 45). Previous studies have suggested that the slow, steady collision between the Nazca Plate, made of dense oceanic crust, and the South American plate, of lighter, continental crust, gradually lifted the Andes. But new analyses of South American sediments cast doubt on that steady-growth scenario, says John Eiler, a geochemist at Caltech in …