Tuesday, February 7, 2012

Ceramic Sourcing and Analysis: Plains

Hoard, Robert J., Danielle Montague-Judd and Elizabeth J. Miksa
2003 Ceramic Analysis The Plains Anthropologist 48(188):16-35

    In this article, the authors discuss the methods used for analysis of pottery samples found at the Stauffer site in Missouri. While they often use specific examples from the Stauffer site, it serves as a good explanation of common techniques.
    One of the first things done at the Stauffer site was that they ran the sherds through a 6 mm screen. Any pieces that fell through were too small to properly analyze. The authors do note, however, that “[i]n back sight, half-inch screen would have been preferable, as sherds below this size are of questionable analytic value” (16). Once they had all of the sherds that were big enough, about 18,500 out of an original total of 24,247, they sorted them based on shared attributes such as rim angle and coloration. One of the limitations of this method is that sherds from the same vessel can have different characteristics. This is especially relevant to the Stauffer site as the authors state that no intact vessels were found.
    The first analysis done was the analysis of ceramic attributes. By looking at attributes such as rim angle, lip shape, and temper, the tradition and style of the ceramics can be determined, which can be essential to sourcing. Although there are a few traditions that occur more often than others, this is easier said than done as it is often difficult to determine where one typology ends and another begins. Furthermore, in terms of temper, “it may be difficult to know if non-clay materials in a vessel’s clay body were intentionally added or were contaminants to the clay deposit that was used” (19).
    The other analysis detailed in the article is thin section analysis, which is a form of analysis used to gauge the grain size and composition of the temper. In their attribute analysis, they found that they had sherds both of limestone and of sand, so they made sure to do a thin section analysis on both types. What they found with the limestone sherds was that it was inconclusive whether the pottery was made from a layer of sedimentary limestone or if the limestone had been crushed. In the attribute analysis, they found that the ceramics showed a Woodlands influence, which is typical of the area at the time.

Philips, Scott C., Maury Morgenstein
2002 A plains ceramic clay source characterization by comparative geochemical and petrographic analyses: Results from the Calhan Paint Mines, Colorado, U.S.A. Geoarchaeology 17(6):579-599

    As the title suggests, this article focused on two methods of sourcing and analysis: geochemical and petrographic analysis. The site, the Calhan Paint Mines, has been a tourist attraction for much of the 20th century. The mines are filled with a multi-colored clay that geochemically matches the clay used in ceramics in the surrounding area, leading archaeologists to conclude that the site was a primary location for collecting materials for ceramics. However, the authors note that despite the similarities in geochemical analysis, there is no evidence of prehistoric quarrying. “This may be explained by the extent of historic activity in the area and by normal scarp erosion that both work as obliterating forces  on clay exposures that may have held evidence of earlier exploitation” (581).
    The article offered a bit of confusion by referring to the Woodland period as the Early Ceramic period when discussing the four sites that were examined around the Paint Mines. All four sites produced sherds that showed the same geochemical analysis as the Paint Mines. At three of the sites, the sherds were from the Early Ceramic period, but one of the sites had sherds from the Middle Ceramic period, which would indicate a later occupation. The sherds collected from each site were analyzed using optical petrography, x-ray diffraction, and neutron activation analysis. “The goal of these analyses was to determine the mineralogical and geochemical composition” of the area (582).
    Having completed analysis, the authors state that only geochemical analysis offered any conclusive answers, primarily due to a small sample size. However, they combined the geochemical and petrographic results to conclude that “the raw clays of the Calhan Paint Mines are consistent both geochemically and petrographically with clays used prehistorically in the ceramic sherds” (595).
    Throughout the article, the authors provide several examples of where these analytic methods have also been used, which indicates that these methods are at least somewhat common in ceramic sourcing and analysis.


  1. I find it really interesting that rim angle, lip shape, the tradition and style are so essential to sourcing ancient ceramics. I would have thought that the geochemical and petrographic analysis your second article talks about, would be much more significant in determining the source of specific sherds. Initially I thought that those qualities seemed to only be important in classifying typologies; as is discussed in the Firehole Basin article I posted. The more I think about it, the more it makes sense how determining what specific style a sherd fits into can assist in the sourcing of it.

    Middleton, Jessica L. Lubinski, Patrick M. Metcalf, Michael D.
    2007 Ceramics from the Firehole Basin Site and Firehole Phase in the Wyoming Basin. The Plains Anthropologist 52:29-41.

  2. I also find it interesting that some basic physical characteristics that might be demoted to being part of the 'bowl' or 'cup' shape can be used for sourcing. The vast number of variants on a simple shape could potentially make this problem incomprehensibly difficult. I would imagine it would be possible to apply a statistical model that reduces the vast number of ceramic possibilities down to a few variables in a series of equations, but my guess is that it would be nowhere near as accurate as the one found by Knight and Keyser in my article. Still, it's interesting that the authors of your article tried.

    Knight, George C., and James D. Keyser. 1983 A Mathematical Technique for Dating Projectile Points Common to the Northwestern Plains. The Plains Anthropologist 28(101):199-207.