DUNE MIGRATION, PALEOSOLS AND PROJECTILE POINTS: NEW GEOARCHAEOLOGICAL INSIGHTS ON THE SOUTH TEXAS SAND SHEET

The South Texas Sand Sheet (STSS) spans ~7,000 km², and consists largely of sand sheet deposits, stabilized by vegetation, mostly under three meters thick, with active SE-NW longitudinal dune ridges near the coast. Evidence of human presence on the STSS in pre-Hispanic times is sparse. Archeological investigations are limited and have revealed a record characterized by low preservation of non-lithic remains, and overall very sparse cultural vestiges. Chronology of human occupation, subsistence strategies, and settlement patterns remain poorly known.

An isolated migrating dune at the center of the STSS, has exposed projectile points and abundant debitage, indicating human presence and perhaps a rich archaeological record buried beneath the sand. Preliminary findings from an ongoing investigation at this unique site include: 1) evidence of human occupation, dating back to the Early Archaic (Abasolo projectile points) and perhaps Paleoindian times, suggested by a single Golondrinas point. 2) the archaeological horizon sits on a well-developed paleosol, classified as an Oxysol, formed on a vegetated eolian deposit, indicative of a wetter climate and a stable landscape, and 3) a period of landscape instability between ~11,000 and ~4,000(?) years before present constrained by four optically stimulated luminescence ages from the buried dune. The lack of organic materials, which were likely lost to deflation, has precluded establishing an absolute ¹⁴C chronology for the time of human occupation.