Earth Science

Old and Crusty

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Science  12 Mar 2004:
Vol. 303, Issue 5664, pp. 1585
DOI: 10.1126/science.303.5664.1585a

Some of the oldest rocks on Earth are found in the Davenport Range of central Australia, having crystallized in the Pre-Cambrian (>560 million years ago) or the Cambrian (about 560 to 530 million years ago). Cratons are the first continental land masses to form, and the remnants of the first landmasses make up the stable and thick crustal cores of several modern continents. Some of the earliest evidence for life in the rock record comes from the Australian craton.

Previous work has suggested that some of the outcrops in the outback have not been altered, making the landscape almost as old as the rocks. Belton et al. used apatite fission track thermochronology and Be-10 and Al-26 in situ cosmogenic radionuclide analyses to determine the rates of erosion. The rates vary from 0.4 to 4.0 m per million years to punctuated periods of erosion with rates as high as 17 m per million years. These rates suggest that the landscape has changed over 500 million years, experiencing multiple periods of burial and exhumation related to the northward migration of the Australian landmass and collisions with terrains in Asia. — LR

Earth Planet. Sci. Lett. 219, 21 (2004).

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