Article

Nature 410, 891-897 (19 April 2001) | doi:10.1038/35073504; Received 5 September 2000; Accepted 2 March 2001

Increased sedimentation rates and grain sizes 2–4 Myr ago due to the influence of climate change on erosion rates

Zhang Peizhen1, Peter Molnar2,3 & William R. Downs4

  1. Institute of Geology, State Seismology Bureau, Beijing, China
  2. Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
  3. Bilby Research Center, Northern Arizona University, Flagstaff, Arizona 86011-6013, USA
  4. Present address: Department of Geological Sciences, Cooperative Institute for Research in Environmental Science, Campus Box 399, University of Colorado, Boulder, Colorado 80309, USA.

Correspondence to: Peter Molnar2,3 Correspondence and requests for materials should be addressed to P.M. (e-mail: Email: molnar@terra.colorado.edu).

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Around the globe, and in a variety of settings including active and inactive mountain belts, increases in sedimentation rates as well as in grain sizes of sediments were recorded at approx2–4 Myr ago, implying increased erosion rates. A change in climate represents the only process that is globally synchronous and can potentially account for the widespread increase in erosion and sedimentation, but no single process—like a lowering of sea levels or expanded glaciation—can explain increases in sedimentation in all environments, encompassing continental margins and interiors, and tropical as well as higher latitudes. We suggest that climate affected erosion mainly by the transition from a period of climate stability, in which landscapes had attained equilibrium configurations, to a time of frequent and abrupt changes in temperature, precipitation and vegetation, which prevented fluvial and glacial systems from establishing equilibrium states.