31 Archaeological Geology (Posters)

Sunday, 27 October 2013
9:00 AM - 6:30 PM
Hall D

THERMAL PROPERTIES AND FUNCTIONAL ADVANTAGES OF OLIVINE-TEMPERED MOAPA WARE: A COMPARATIVE STUDY

Paper number: 31-2
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

  • Elizabeth Niespolo Presenting Author
    California Institute of Technology Geological and Planetary Sciences, Pasadena, CA
  • Jeanette Harlow
    California State University, Long Beach, Norwalk, CA
  • Carl Lipo
    California State University Long Beach, Long Beach, CA
  • Sachiko Sakai
    University of California Santa Barbara, Irvine, CA

Abstract

Mt. Trumbull is located on the Uinkaret Plateau in Northern Arizona and is among the most heavily occupied archaeological sites in the plateaus area. Pottery technology was developed during the Formative Period in this area by those known as the Anasazi or Ancestral Pueblo people. Moapa Gray Ware, a unique olivine-tempered pottery type seen widely in the Anasazi region, derives from Mt. Trumbull and is frequently found in surrounding areas. Like other ware types, it is considered a cookware; however, with other pottery type sources more proximate to many of the areas where it is found, this project explores why Moapa Ware could be considered functionally advantageous over other pottery types that would have been more easily obtained by people not directly local to Mt. Trumbull.

The use of thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) allowed for comparative analysis of the thermal characteristics of three Anasazi pottery types: the olivine-tempered Moapa Ware discussed; Shivwits Ware, which is tempered with Moapa Ware grog; and sand-tempered ware. All three ware types were analyzed using X-Ray Diffraction to confirm mineralogy of temper and eliminate the possibility of ceramic clay sourcing as a distinguishing characteristic of manufacture. TGA results proved that the samples tested from each ware type have a similar pyrotechnical manufacture, with firing temperatures between 950°C - 1000°C. Given the equivalent range of firing temperature for all three wares, the manufacturing technology of olivine temper in Moapa Gray Ware is eliminated as a distinguishing characteristic. DSC measures the change in heat flow over a sample with respect to temperature, indicating how different wares respond to heating at cooking temperatures and up to 1000°C. Preliminary results demonstrate potential functional differences between ware types. All ware types demonstrate peak exothermic reactions at approximately 500°C. Sand-tempered samples and Shivwits Ware samples demonstrate an inability to sustain exothermic reactions beyond 590°C, indicating that high temperature heating for these wares is inefficient. Moapa Ware samples show the highest exothermic reaction range of up to 648°C, indicating a possible high-heating functional capability of this ware type.