Middle Holocene Drought on the Southern High Plains

Abstract

The climate of the Southern High Plains during the middle Holocene is indicated by data from a variety of sources. Stratigraphic, geomorphic, and pedologic research at six localities in draws, several dune sites, and one playa-lake basin show that widespread eolian erosion and sedimentation began in some areas by 9000 yr B.P. and culminated 6000-4500 yr B.P., probably because of warmer, drier conditions that reduced the vegetative cover. Archaeological investigations at three sites provide evidence for the excavation of wells at this time, apparently because of a declining water table. Studies of a few vertebrate and invertebrate faunas also indicate warming and drying in the middle Holocene. Climate models and very limited isotopic data from Bison bone suggest that summers in the middle Holocene were warmer than present, with reduced effective precipitation. All lines of evidence indicate that the Southern High Plains was subjected to prolonged drought in the middle Holocene with a maximum between 6500 and 4500 yr B.P., conforming climatically and chronologically to the Altithermal.