Paleoindian geoarchaeology and paleoenvironments of the western Killpecker Dunes, Wyoming, U.S.A.

AbstractThe Killpecker Dunes in southwestern Wyoming have long been known to contain evidence for Paleoindian occupation. This paper presents the results of geoarchaeological investigations in the western, dormant portion of the Killpecker Dunes. Five localities, including the Krmpotich Folsom and Finley Cody Complex sites, were examined in order to better understand the Paleoindian geochronology of the dune field, and to facilitate a late Quaternary paleoenvironmental reconstruction. Age control is provided by radiocarbon, optical, and artifact ages. Four late Quaternary eolian units, designated as strata 1–4, were recognized; strata 1 and 2 are relevant to the Paleoindian record. Aggradation of stratum 1 began by at least 14,690 cal yr (∼12,55014C yr B.P.), probably in the form of a sand sheet under cool, dry conditions. Redoximorphic features are ubiquitous in stratum 1, indicating a rise in the water table during the latest Pleistocene. A buried soil (Calcid) at the top of this unit indicates a period of stability between ca. 12,000 and 11,00014C yr B.P. and has the potential to yield Clovis (11,200–10,90014C yr B.P.) artifacts. Unconformably overlying stratum 1 is stratum 2, a latest Pleistocene to early Holocene sand containing Folsom (10,900–10,20014C yr B.P.) through Cody Complex (9000–850014C yr B.P.) occupations. A buried soil characterized by the accumulation of illuvial clay and sodium (Natrargid) occurs at the top of stratum 2 and probably formed in and around interdunal ponds. The association of Paleoindian material with the stratum 2 soil suggests the use of interdunal areas as natural traps for hunting extinct bison. The accumulation of soluble salts indicates increased rates of evaporation during the early Holocene, probably from an increase in summer insolation. Although conditions in the dune field during the early Holocene became increasingly dry, they were probably moister than at present. © 2003 Wiley Periodicals, Inc.