30 Days of Tennessee Archaeology 2016, Day 7
Sierra M. Bow
Department of Anthropology, University of Tennessee, Knoxvillee
Since finding my first prehistoric artifact during a field school over a decade ago, I have been fascinated with exploring the interaction of past peoples with materials, the artifacts produced from those materials, and the environment that supported those developments. Each of these avenues enables us to more fully understand the physical, social, cultural, and ideological worlds in which those people functioned. Through recent years, my research endeavors have sought to integrate sophisticated analytical techniques with artifact analyses to make precise inferences about what artifacts are made from and how they made their way into the material culture of late-prehistoric societies in the Southeastern region.
These analytical techniques are often subsumed under the umbrella of Archaeometry, which refers to a broad range of applications such as archaeological dating, remote-sensing and geophysical survey techniques, and conservation in addition to artifact studies. My research is aimed at applying scientific techniques from other disciplines such as physics, chemistry, and geology to examine the physical properties of archaeological materials, specifically late-prehistoric paint.
Paint was a common material used throughout the Southeastern region during the Mississippian period (ca. AD 1000-1600) to decorate and even sanctify a variety of media. Paint, or color, has been identified in the form of rock art, both open air and cave art (Simek et al. 2013), mobilary art such as statuary (Smith and Miller 2009), ceramic wares, structures (Polhemus 1987), earthen mounds (Sherwood and Kidder 2011) and even the body. Despite their ubiquitous and varied use, very little attention has been directed towards understanding the technology of paint production itself and how it might reflect larger tenants of Mississippian society.
A variety of laboratory analytical instruments can be used to explore the physical constituents of artifacts, including prehistoric paints such as Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Instrumental Neutron Activation Analysis (INAA) just to name a few. Each of these techniques provides information on different aspects of material properties, and although very small sample sizes are typically required these techniques are inherently destructive to the artifact. Because of this, destructive analytical methods have rightly seen limited application in artifact studies. However, recent technological improvements have led to new portable equipment that can perform materials analysis in situ without sample preparation. These non-destructive analytical techniques have greatly expanded the potential for characterizing prehistoric paint production and use, and are imperative if we are to respect the relationship between indigenous peoples and their archaeological record.
My research uses two such non-destructive instruments, a portable X-Ray Fluorescence Spectrometer (PXRF) and a Fiber Optic Reflectance Spectrometer (FORS), to obtain both elemental and mineralogical data on Mississippian paint from different archaeological contexts in the Southeast.
Spectrometry in general is the study of light as a function of wavelength that has been emitted, reflected, or scattered from a solid, liquid, or gas. Both instruments collect information along the electromagnetic spectrum (EM), the difference is their detector capabilities and the EM radiation range. Types of EM radiation that make up the electromagnetic spectrum are gamma-rays, X-rays, ultraviolet light, visible light, infrared light, microwaves and radio waves. Therefore, the energy returned by a material can be broken into very fine divisions over a wavelength range much wider than that seen by the human eye. Both of these instruments are used to measure and study the properties of light and they gather data in two main areas of the EM spectrum—PXRF within the x-ray spectral range and reflectance spectroscopy in the ultraviolet, visible, and near-infrared range. Thus, PXRF produces spectra associated with atoms, giving the elemental composition of a material, while FORS produces spectra associated with compounds, i.e. mineralogy. The combination of this data provides a complete picture of the physical properties of a material.
Using these techniques, I have analyzed a variety of painted media. These include rock art from sites across the Southeastern region, cave art and ceramic wares from Tennessee, and even stone statuary. Paint colors characterized thus far include red, yellow, black, and white pigment recipes. Preliminary results indicate that paint recipes in certain context are very simple, consisting of a primary chromophore or colorant mixed with water to produce a liquid paint that is then applied to the media. The goal of this research is to determine if a consistent recipe was used to produce paints of different colors and motifs in different contexts, in order to reveal a more detailed picture of Mississippian belief systems for the region.
The ability to analyze archaeological specimens without destructive sample preparation is a significant advancement for archaeologists. While traditional, laboratory methods of compositional studies are still employed, the technological enhancements seen in the past decade and the application of such methods like PXRF and FORS are revolutionizing our ability to understand artifacts how prehistoric cultures are materially expressed. However, with this revolution, we must be cautious and not think of these techniques as “point and shoot” methods of obtaining information. As with any advances in analytical instruments and statistics, we must have a firm understanding of the analytical procedures and choose the techniques that are most appropriate for answering our research questions. As I continue to collect data, I look forward to revealing new information about how paint figured into Mississippian cultural constructs in the Southeast.
Polhemus, Richard R., Arthur E. Bogan, and Jefferson Chapman
1987 The Toqua Site 40MR6: A Late Mississippian, Dallas Phase Town. Report of Investigations, University of Tennessee, Knoxville no. 41. Publications in Anthropology, Tennessee Valley Authority no. 44.
Sherwood, Sarah and T.R. Kidder
2011 The DaVincis of Dirt: Geoarchaeological Perspectives on Native American Mound Building in the Mississippi River Basin. Journal of Anthropological Archaeology 30(1): 69-87.
Simek, Jan F., Alan Cressler, Nicholas P. Herrmann, and Sarah C. Sherwood
2013 Sacred Landscapes of the South-Eastern USA: Prehistoric Rock and Cave Art in Tennessee. Antiquity 87: 430-446.
Smith, Kevin E. and James V. Miller
2009 Speaking with the Ancestors: Mississippian Stone Statuary of the Tennessee-Cumberland Region. The University of Alabama Press, Tuscaloosa.