Amazonian paleodunes provide evidence for drier climate phases during the Late Pleistocence-Holocene

Abstract

Recent studies on relict eolian dunes in the Rio Negro basin, northern Amazon, Brazil (00°35′N, 63°14′W), indicate a drier climate regime during the Late Pleistocene-Holocene transition that is different from the present humid climate. The eolian sands form long chains of linear dunes bordering the Rio Negro River and some tributaries. Here, we present thermoluminescence (TL) ages spanning the period 32,000-8000 yr B.P. The final dune stabilization took place after 8,000 yr B.P. and now the bases of the dunes are fixed by vegetation. Clustering of the TL dates suggests that the dry climate in the Amazon Basin occurred in distinct episodes and argues against current opinions that drastic ecological changes did not affect in the Amazon during the last global glaciation. © 2002 University of Washington.