Uranium-series and luminescence dating of volcanic lithic artefacts

U-series dating was used to determine the growth rate of a feldspar-to-clay weathering rind in a mid-Holocene Cascade-Olcott tradition andesite core, and luminescence dating (last exposure to sunlight) was used to date fine-grained feldspars scraped from the surfaces of similar buried artefacts from a C-14-sediment-dated archaeological site (45KI464) on the wet western slope of the Cascade Mountains of Washington. For U-series dating, we measured Ra-226 excess (Ra-226 excess = Ra-226 - Th-230) in five stratigrophic depth controlled rind scrapings. U-238, Th-232 and Th-230 were counted by alpha spectrometry, and Ra-226 and Pb-210 were counted by gamma spectrometry on each sub-sample.