Simple geoarchaeological techniques were used to study the distribution of prehistoric populations and to reconstruct behavior patterns at sites in the Colorado Desert region of southern California. Samples from two quarry-workshop sites, RIV-1814 and RIV-1819, at opposite ends of Chuckwalla Valley were systematically collected and micromapped, and knapping technology was reconstructed. Distribution patterns for the artifact forms and materials from these quarry workshops were determined by examining samples from other sites within and adjacent to Chuckwalla Valley. Hypotheses regarding the long duration of site utilization and late prehistoric and protohistoric occupation by Numic peoples were verified. Artifact production analysis, including refitting of flakes and cores, proved highly successful. One set of flakes from RIV-1819 near the Colorado river was refitted with a core from an occupation site 63 kilometers away, at the opposite end of the valley. Prehistoric quarry workshop sites are viewed as an underexplored resource with great potential for yielding important data on technology and demography.