Abstract

The sedimentary succession in the Atacama Desert records deposition under an arid to semiarid climate from the late Jurassic (150 Ma) to the present day. Palaeomagnetic data indicate no significant latitudinal movement of this area since the late Jurassic. The present-day location of the Atacama within the dry subtropical climate belt is the principal cause of aridity. This situation is likely to have prevailed since the late Jurassic, supplemented by (1) the continentality effect (enhanced by the Gondwanan landmass), and (2) the presence offshore of a cold, upwelling current (from at least the early Cenozoic onwards and possibly earlier), resulting in conditions promoting climatic stability and desert development. Rapid and extreme climatic fluctuations during the Plio-Pleistocene were not sufficient to destabilize the climate within the Atacama. Comparison with other long-lived deserts (e.g. SW USA, Namib, Sahara and Australia) suggests that the Atacama is the oldest extant desert on Earth.

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