THE STABLE CARBON ISOTOPE SIGNATURE OF THE BIG EDDY SITE, SOUTHWEST MISSOURI: TOPOGRAPHIC AND TEMPORAL VARIATION IN D13C VALUES AT ONE OF THE OLDEST HUMAN OCCUPATION SITES IN NORTH AMERICA

The Big Eddy site in southwest Missouri contains a remarkably complete stratigraphic record that spans nearly all of North American prehistory.  Deposits of the Big Eddy site are contained within an extensive terrace sediment assemblage identified as the Rodgers Shelter Formation.  Organic-rich alluvium and stratigraphic integrity have provided ideal conditions for generating a high-resolution stable carbon isotope record that has been used to document changes in vegetation and reconstruct regional Holocene climate change.  However, to accurately interpret temporal shifts in isotopic composition, there must be a better understanding of across-landscape variability in d¹³C values.  Soil properties and the nature of the vegetation in a region can vary as a function of landscape position.  When this is the case, shifts in d¹³C values may be attributable to local microtopographical variation as opposed to climatic effects.  Soil samples from various paleotopographic positions on the early Holocene landsurface were collected and analyzed in order to assess the degree of spatial variability and determine how this influences our interpretation of the temporal d¹³C profile.