PREHISTORIC LAND USE IN THE MT TRUMBULL REGION, NW ARIZONA USA

Remote sensing is used to estimate soil, vegetational, and geomorphical characteristics to determine the potential of landscape features to sustain productive prehistoric maize agriculture in the Mt Trumbull region of NW Arizona. Over 400 prehistoric archaeological sites have been recorded in the 4 USGS 7.5’ quadrangle area (~100,000 acres) of Mt Trumbull; in some areas site density is ~120 sites per square mile. Remote sensing (Landsat TM, ASTER, and digital elevation) data is used to estimate soil type, current vegetation cover, soil moisture, surface roughness, and proximity to known habitation sites. Existing images being examined includes: 18 ASTER images covering the period 2000-2008; one meter digital orthophoto quad data for the 4 central USGS 7.5’ quads; 10 m digital elevation data for the same quads; NRCS soil maps. New ASTER images along with complementary ground based IR camera images were acquired on May 2010. In the field, we measured depth of soil and slope, aspect, and soil moisture content. Adequate soil moisture during the germination and tasselling phases of maize growth is essential for a productive harvest. Data loggers have recorded air temperature at several locations allowing us to model length of growing seasons. Ancient maize is though to have required about 120 frost free days to produce adequate yields. Using 2 areas where archaeological survey is relatively complete, a crop/habitation model is being constructed showing optimal (and suboptimal) areas for maize agriculture. Important factors include high soils moisture to support germination and tasseling; specific soil associations; sufficient precipitation during the summer; and a plant community dominated by rabbit brush. We have determined where in the study area optimum soils and exposures were for effective maize agriculture. In future work we will conduct archeological survey in predicted optimum and other areas where we have hypothesized a high density of sites. Our model will provide some predictive capability in the region for prioritizing subsequent survey intensity. The research proposed here may also allow planners of the new Grand Canyon-Parashant National Monument (where the Mt Trumbull study area is located) to avoid particularly sensitive areas when designing recreation and other facilities for the National Monument.