USING REMOTE SENSING AND GIS TO IDENTIFY POTENTIAL CLAY SOURCES FOR TOPOC BUFF WARE, WILLOW BEACH, ARIZONA

Clay sourcing of prehistoric ceramics is important to archaeological investigations because it may provide information on where ceramic wares were produced. This information enables archaeologists to examine group relationships across space as well as discuss group mobility, interactions, and associations. Seymour and Rager (2002) performed preliminary ceramic petrology on Topoc Buff sherds from Willow Beach, Arizona. The results of that analysis indicated the pottery was probably locally produced (Rager, 2002, in preparation). However, clay sourcing of these ceramics is still of interest at this site as it will provide additional information on how the ceramics were produced (e.g., whether a particular clay source was selected over others). Clay sourcing entails performing laboratory analysis like X-Ray Diffraction or Neutron Activation Analysis (NAA) on sherds and comparing the results to similar analyses performed on fired clay samples from known localities.

In this study, the authors investigate the efficacy of using GIS and Remote Sensing to identify potential clay sources to collect clay samples on which future laboratory analyses may be performed. Clay minerals exhibit characteristic absorption features around 2.2 µ and 10 µ, wavelengths that are sensed by several satellite and airborne sensors. Image processing techniques including Spectral Angle Mapper (SAM), Decorrelation Stretch, and hyperspectral analyses are performed on MODIS/ASTER Airborne Simulator (MASTER) data to identify potential clay sources. Band ratios and Decorrelation Stretch are also performed on Landsat Enhanced Thematic Mapper (ETM+) scenes for the same purpose. Digital and hard-copy geologic and soil maps are used to interpret the image processing results and refine the potential clay source maps. Field visits are made to assess their accuracy.