Colormod

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Introduction: Project background

This project involved a novel combination of techniques to investigate the ceramic tradition at ancient Urkesh. The correlation of macroscopic color analysis with X-ray imaging and element mapping offered a promising way to analyze large numbers of sherds, and thus contribute to a better understanding of chronological and stylistic variations on the site and beyond.

Each excavation season at Tell Mozan yielded between 40,000 and 60,000 pottery sherds and numerous whole vessels (more than 1000 from all seasons). The large body of ceramic data analyzed every season has been integrated into the Urkesh Global Record (see the Preface and Kelly-Buccellati 2016). The ceramic shape catalog was built up throughout the seasons and spans the city’s occupational history. A large and well-categorized reference collection of several thousand sherds allows ceramic analysts to match the paste, shape, and decoration of new sherds against the parameters set for each type. In this way full coherence within the system can be maintained, while avoiding the danger of gradual change in ware classifications over time. Macroscopic ceramic analysis has developed along the lines of descriptive statistics, distribution, function and context. [Ceramics Book, specific references?]

Building on this expansive and thoroughly documented corpus, a more intensive study of technological variation was initiated in 2003. The aim was twofold: First, to assess chronological changes in clay choice, tempering materials, and building and firing techniques within each ware. Second, to compare these parameters among different contemporary wares. This approach was expected to help contextualize measured variation in terms of time, space, technological and stylistic choice, and vessel use.

Traditional ceramic petrography involves finely polishing very thin slices of sherds (exactly 30 microns thick) and using a polarizing microscope to identify the silicate minerals present. Preparing and observing large numbers of samples, however, is expensive, time-consuming, and often impractical. In addition, this type of analysis usually ignores the ceramic matrix and any small non-silicate minerals (which are ordinarily all grouped together as “opaques”), omitting potentially valuable information. At Urkesh, we needed a different approach.

To this end, we combined image analysis with X-ray microanalysis and element mapping. Image analysis uses a flatbed scanner in the field to collect high-resolution images of sherd sections. Initially, in 2003–2005, Minna Hapaanen was responsible for the project; Marianna Nikolaidou took over in 2006, in collaboration with Marilyn Kelly-Buccellati. Our joint work took place during the field seasons of 2006–2007 and 2009, with subsequent analysis at the Mediterranean Laboratory of the UCLA Cotsen Institute of Archaeology (2010–2014, intermittently). In addition, a small portion of the scanned sherds was selected for electron microprobe analysis by Ellery Frahm, then at the University of Minnesota, in 2007–2008. Image analysis software correlated the two image sets.Urkesh Global Record (Frahm, Nikolaidou, and Kelly-Buccellati 2008; Kelly-Buccellati 2010, p. 263).