Targeted explorations of Pleistocene-Holocene transition archaeology on the Colorado Plateau in southern Utah

The Pleistocene-Holocene transition (PHT) archaeological record on the Colorado Plateau has been interpreted as sparse, especially compared to the Great Basin to the west and the Rocky Mountains and Great Plains to the east. To explore whether this apparent sparsity is due to low PHT populations in the region, insufficient research targeting regional PHT archaeology, taphonomic processes, or cross-regional differences in lifeways, we surveyed ∼2400 acres of the San Rafael Desert on the Colorado Plateau in south-central Utah. Survey tracts were deemed likely to contain PHT archaeology by a random forest predictive model. We present the results of this survey, during which we encountered three sites and one isolate of likely PHT age, for a total of five diagnostic PHT points, including unfluted lanceolate points, a Scottsbluff point, a fluted point, and a stemmed point. In comparing the point types and PHT locality densities we recorded in the San Rafael Desert to those in areas of targeted PHT survey in surrounding regions, we conclude that while the San Rafael Desert's PHT record may be sparse, it demonstrates that the Colorado Plateau's PHT record is worthy of study given its potential to elucidate interaction between the Western Stemmed Tradition characteristic of the Great Basin and the fluted and lanceolate traditions characteristic of the Plains and Rockies.