Identifying immigrants to Tikal, Guatemala: Defining local variability in strontium isotope ratios of human tooth enamel

As I have discussed in the last chapter, our goal here is not to elucidate XRF for the entire scientific community – this has been done admirably by others – but to translate the physics, mechanics, and art of XRF for those in archaeology and geoarchaeology who use it as one of the many tools to explain the human past in twenty-first century archaeology. While not a simple exercise, it has utility not only for those like us, who have struggled (and enjoyed) the vagaries of XRF applications to archaeological problems, but for a greater archaeology. First, we trace the basic history of X-rays used in science and the development of XRF for geological and archaeological applications, and the role some major research institutions have played in the science. Following this is an explanation of XRF that, in concert with the glossary, illuminates the technology.

An Introduction to X-Ray Fluorescence (XRF) Analysis in Archaeology

Comparison of XRF and PXRF for analysis of archaeological obsidian from southern Perú

A systematic approach to sample collection, chemical analysis, and statistical evaluation of obsidian sources is recommended before significant numbers of artifacts should be analyzed. Multivariate statistical methods based on Mahalanobis D 2 enable robust rejection of erroneous source assignments and lead to sourcing of artifacts with a very high degree of confidence. These multivariate procedures can also assist in identifying and evaluating abbreviated analytical methods that are more rapid and less expensive. Test cases based on obsidian data from sources in Mesoamerica are presented.

A Systematic Approach to Obsidian Source Characterization

In this article, we explore the typological distinction between primary and secondary states. We outline a methodology for exploring variability in the formation and organization of secondary states that integrates aspects of traditional neoevolutionary approaches, Marcus's “dynamic model,” Blanton et al.'s “dual-processual model,” and world-systems theory. We discuss the development of the Minoan and Mycenaean states of the Bronze Age Aegean and argue that they arose via different mechanisms of secondary state formation, through direct and indirect contact with neighboring societies in the Eastern Mediterranean, Near East, and Egypt. We argue that a model that measures state formation along several different theoretical dimensions encourages archaeological exploration of secondary states along varied historical trajectories, in different (pre)historic contexts.

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Secondary states in perspective: An integrated approach to state formation in the prehistoric Aegean

* Figure List * Foreword (Arthur A. Demarest) *1. Introduction: Reinterpreting Early Classic Interaction (Geoffrey E. Braswell) *2. Teotihuacan, Militarism, and Pacific Guatemala (Frederick J. Bove and Sonia Medrano Busto) *3. Dating Early Classic Interaction between Kaminaljuyu and Central Mexico (Geoffrey E. Braswell) *4. Understanding Early Classic Interaction between Kaminaljuyu and Central Mexico (Geoffrey E. Braswell) *5. Founding Events and Teotihuacan Connections at Copan, Honduras (Robert J. Sharer) *6. Problematical Deposits and the Problem of Interaction: The Material Culture of Tikal during the Early Classic Period (Maria Josefa Iglesias Ponce de Leon) *7. Architectural Aspects of Interaction between Tikal and Teotihuacan during the Early Classic Period (Juan Pedro Laporte) *8. Images of Power and the Power of Images: Early Classic Iconographic Programs of the Carved Monuments of Tikal (James Borowicz) *9. Teotihuacan at Altun Ha: Did It Make a Difference? (David M. Pendergast) *10. Teotihuacan and Oxkintok: New Perspectives from Yucatan (Carmen Varela Torrecilla and Geoffrey E. Braswell) *11. Tetitla and the Maya Presence at Teotihuacan (Karl A. Taube) *12. Teotihuacan and Early Classic Interaction: A Perspective from Outside the Maya Region (George L. Cowgill) *13. The Maya and Teotihuacan (Joyce Marcus) * Bibliography * Index

The Maya and Teotihuacan: Reinterpreting Early Classic Interaction

During the last four decades, mesoamerican archaeologists regularly have employed various chemical assay techniques to determine the geological sources of obsidian artifacts. In recent years, the reliability of these analytical procedures has increased and their costs have declined, encouraging the assay of ever larger samples. Nonetheless, several constraints make it unlikely that compositional data will be used routinely to attribute entire collections to their geological sources. This report describes a test of visual sourcing, a technique that for many sites in the Maya region is only slightly less accurate than compositional assay. We also propose sampling strategies that combine visual and compositional sourcing in ways that allow large collections to be accurately sourced at low costs. Finally, we suggest ways to develop the technique for use throughout Latin America.

Determining the Geological Provenance of Obsidian Artifacts from the Maya Region: A Test of the Efficacy of Visual Sourcing

The technique of obsidian-hydration dating contains great potentials for error, from both laboratory determinations of rate constants and measurements of egective hydration temperatures (EXTs) in the field. The rate constants used to determine these dates are of questionable validity and need to be independently verified. Significantly, no measurements of EXTs were taken at the site of Copan, Honduras, until the majority of the obsidianhydration dates were calculated. An error of but a few Kelvins in estimated EXT can lead to dates that are in error by several centuries. In view of the likelihood of large errors in the Copan obsidian dates, the assertion that the Late Classic Coner phase should be extended beyond A.D. 900 (Webster and Freter 1990a) is premature.

Obsidian-Hydration Dating, the Coner Phase, and Revisionist Chronology at Copan, Honduras

Compositional analyses have long been used to assign obsidian artifacts to particular source areas. In most cases, the chemical "fingerprint" of a particular source area has been determined through the assay of only a few geological specimens from one or two outcrops. As a result, the full range of intrasource compositional variation has rarely been noted, and its spatial patterning frequently has not been studied. This report describes the results of geoarchaeological survey at the important Guatemalan source area of San Martin Jilotepeque. Neutron activation analysis demonstrates the presence of seven distinct chemical "fingerprints" corresponding to spatially discrete subsources within the region. Ancient procurement and production are associated with only three of these subsources. Statistical procedures that can be used to assign artifacts to particular quarries or quarry systems are presented. Several minor Guatemalan source areas also are examined, and one (Media Cuesta) also can be characterized as consisting of two distinct subsources.

Geoffrey E. Braswell

Papers

A Systematic Approach to Obsidian Source Characterization

The Maya and Teotihuacan: Reinterpreting Early Classic Interaction

Determining the Geological Provenance of Obsidian Artifacts from the Maya Region: A Test of the Efficacy of Visual Sourcing

Obsidian-Hydration Dating, the Coner Phase, and Revisionist Chronology at Copan, Honduras

Interpreting Intrasource Variation in the Composition of Obsidian: The Geoarchaeology of San Martin Jilotepeque, Guatemala