Luminescence dating of burned clay objects from the Lodoso Site (41NU114), middle Texas Coast

The prehistoric cultural material at the Lodoso Site, a Middle Archaic to Late Prehistoric campsite near Driscoll, Texas, is dominated by irregularly shaped heat-hardened fragments of earth called burned clay objects (BCOs). These artifacts are a common component of coastal plain archaeology in Texas and elsewhere in the state. Many such sites, especially those situated in sandy soils, do not preserve charcoal well, which renders dating the occupations challenging. The clayey matrix of the Lodoso Site does preserve charcoal, which presents an opportunity to assess the suitability of luminescence dating of burned clay objects by thermoluminescence (TL) and optically stimulated luminescence (OSL), and directly compare those results with charcoal collected from the same excavation provenience, as well as OSL dating of the sedimentary matrix. The TL and OSL results generally track together well but are consistently slightly older than charcoal collected from the same level. The charcoal dates suggest the midden formed between approximately 1500 and 2300 years ago, whereas the luminescence ages suggest formation occurred between 2000 and 3000 years ago. Where the luminescence ages occur out of stratigraphic order, so do the paired charcoal samples, indicating that this is a result of pedoturbation. The results of both radiocarbon and luminescence dating indicate that the midden is a diachronic feature resulting from use over a prolonged period rather than the product of a single burning event.