A Quantitative Analysis of Ceramic Thin Sections at Site 13LN323, Palisades-Dows State Preserve, Linn County, Iowa

April 6th, 2011

Thin sections, prepared from sherds that were collected during recent excavations at site 13LN323, were analyzed by point counting compositional elements, which included natural inclusions (sand and silt), non-natural inclusions (temper) and matrix (clay). Dominant temper lithologies are granite, gabbro and basalt. Temper was preferentially selected by different cultures, with earlier cultures preferring granite, and later ones selecting gabbro and basalt. Clustering of temper, sand/silt and clay percentages on trivariate plots indicates that pots were made from the same or similar material. The green color of hornblende observed in some thin sections indicates that firing temperatures of these pots did not exceed 700oC Sediment samples were collected from nearby sources, and the percentages of sand, silt and clay were calculated and compared to those from the thin sections.  Differences in composition indicate that none of the sediment sources sampled was used for making these pots.  Local availability of temper materials suggests that the inhabitants manufactured the pottery at or near the site. The source of the clay remains unknown.

Nicolas Slater, ’12
Milwaukee, WI
Majors: Environmental Studies, Geology

Sponsor: Paul Garvin

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