The Geoarchaeology of Source Bordering Sand Sheets on the Ceja Mesa Escarpment, New Mexico: Sand Sheet Dynamics and Site Formation

ABSTRACT Source bordering sand sheets form downwind of sandy stream beds on the Ceja Mesa escarpment in north-central New Mexico. Archaic archaeological sites are often buried in this type of deposit. A stratigraphic sequence from one site was examined using soil morphology, radiocarbon and optical dating, soil characterization, and stable isotope analyses of soil organic matter and carbonate. This geoarchaeological reconstruction documented a combination of rapid alluvial, eolian, and local hillslope sedimentation events that occurred between 4100 and 3200 years ago. These events coincided with changes in δ13C values that, in turn, reflect changes in local vegetation. Human occupation of the sand sheet occurred as early as 3700 years ago, and a sheetwash flooding event that altered the stratigraphic context of the site occurred sometime between 3700 and 3200 years ago. The effects of these rapid depositional and erosional processes on artifact stratigraphy and archaeological interpretations could be significant.