DUNE SOILS AND PREHISTORIC AGRICULTURE IN THE PETRIFIED FOREST NATIONAL PARK, NORTHERN ARIZONA

Previous and current work in the Petrified Forest National Park in northern Arizona suggests that archaeological sites are frequently found in areas with extensive dunes. These include sites dating to the Basketmaker III through the Pueblo III periods (c. AD 500-1250). Many of these dunes show very weakly developed soils and are likely of Holocene age. Geoarchaeological methods were used to examine dune deposits in several areas of the park to determine periods of dune stability indicated by the presence of soils and weathering and to determine the potential for dry-farmed agriculture within the soils. Initial results from this pilot study show multiple periods of deposition within the dunes, with multiple buried soils in some locations. The dune deposits examined show stratified, weakly developed buried soils with low organic matter accumulation and low to moderate calcium carbonate accumulation. In addition, the dunes contain high clay content forming sandy loam textures, which results from a local geology of extensive claystone. Archaeological and ethnographic research has shown that dune agriculture on the Colorado Plateau requires alternating fine and coarse textured sediment to provide both permeable layers and capillary barriers conducive to plant growth. This suggests that the dune sediments which show stratified soils and loamy textures may have been conducive to retaining moisture needed for dry farming. Thus the dune environments in the area of Petrified Forest National Park may have been highly conducive to dune agriculture, and there is high potential for further investigations of dune agriculture as an important form of dry farming in the region.