QUANTIFYING THE PLAYA DISTRIBUTION SURROUNDING A PALEOINDIAN ROCKSHELTER LOCATED WITHIN THE HARNEY BASIN, SOUTHEASTERN OREGON (USA), USING GIS AND REMOTE SENSING METHODS

Playas are small, ephemeral depressions found in arid and semiarid regions of the world and are highly sensitive to climatic fluctuations, making them useful paleoenvironmental archives. Playas also have been important geomorphic features for human populations from prehistoric times to the present day as sources of water and minerals, making their layout and orientation of significance to archaeological studies. Playas are particularly ubiquitous in the Harney Basin of southeastern Oregon, with little known attention being paid to their distribution. Quantifying playa distribution within the Harney Basin can provide a platform for further geological and archaeological analyses and interpretations, as well as facilitate more focused hypotheses. In this exploratory study, we seek to understand the playa distribution within a small area of interest (27,821.38 ha) around Rimrock Draw Rockshelter (RDR; 35HA3855), a deeply stratified, multicomponent Paleoindian site located along the western margin of the Harney Basin.

Remote sensing and GIS methodologies were implemented to delineate playa distribution. The USDA Soil Survey provided training data to perform a more refined analysis which incorporated supervised image classification, cumulative cost mapping methods and USGS satellite imagery and DEMs. We have identified 47 playas within the area of interest, comprising 781.83 ha of the total calculated area. Playa size ranged significantly between 152.29 ha and 0.03 ha, with an average of 16.6 ha. Distance between playas averaged 628.74 m. The average distance between RDR and identified playas is 5841.34 m. The playa with the closest proximity to RDR is 582.52 m away, and is 1.21 ha in size. Our results demonstrate that RDR is centrally located within a cluster of the largest identified playas in the area of interest. Future archaeological applications will include visibility and least cost path analysis to potentially identify unknown settlements, resource availability, intra-site settlement movement, and migration patterns. Additionally, this study will be expanded to include the entire Harney Basin and integrate additional independent lines of evidence, such as refined hydrological analyses, other geomorphic classifications, and known archaeological sites.