Rock painting depicting re-incursion of Bison onto the South Texas plains: painted Indian Cave, Pedernales River, Blanco County, Texas

We extracted carbon from a sample removed from a small, non-descript, solid monochrome pictograph at Painted Indian Cave site on the Pedernales River, Blanco Count, Texas (41BC1). It contains red iron oxide pigment and is approximately 10-20 cm in size. The sample was taken with a surgical scalpel with a new blade. Plasma-chemistry was utilized to extract the organic carbon, without getting contamination from inorganic carbon-bearing minerals, calcite and calcium oxalate. Because the background of organic carbon in nearby unpainted rock (limestone) was negligible, the age should be reliable. Further, it is supported by archaeological inference. However, as always with only a single radio-carbon date, especially with minimal carbon extracted, caution is advised pending further study. Radio-carbon analysis at the Center for Accelerator Mass Spectrometry of the Lawrence Livermore National Laboratory indicated an age of 770 [+ or -]50 years BP. The age is consistent with the image of a bison within the small cave. The depiction of the bison probably corresponds with the earliest Late Prehistoric sightings of bison as they re-entered the south Plains of Texas in larger numbers. Keywords: rock painting; plasma-chemical extraction; radiocarbon dating; Late Prehistoric bison; central Texas Plains