Geochemical analysis of Late Classic and Post Classic Maya marketplace activities at the Plazas of Cobá, Mexico

Abstract

Lines of evidence for ancient exchange plazas may include trade routes and trade artifacts, urban open space near public structures, and rock alignments denoting market stalls, but regular patterns in soil chemical concentrations also point to marketplace use. We applied geochemical and geospatial analysis of the floors of the main Plaza of Group B and Plazas A, H, and J of Group D at Cobá, Mexico, to discover the chemical residues of phosphorus (P) and metals associated with the exchange of foodstuffs and mineral workshop items that may have been marketed there. The patterns of chemical residues in the floor of the Group B Plaza suggest ritual activities while the linear, parallel patterns of elevated Mehlich phosphorus and chelate extractable zinc concentrations in Plaza A support the hypothesis of market exchange at that location. Plaza H is associated with several Postclassic buildings, including the Pinturas Structure D-33. During the Postclassic period, Cobá had lost much of its population, though chemical residues from Plaza H are congruent with marketing. We argue that Plazas A and H were not permanent marketplaces but rather multi-purpose locations that also hosted large ceremonies.

Keywords:

• phosphorus (P)
• trace elements
• portable x-ray fluorescence (pXRF)
• Maya economy

Acknowledgments

This project was funded by NSF grant #BCS-0919833 and by Brigham Young University. The work was permitted by the National Institute of Archaeology and History in Mexico. Thanks go to Maria José Con for hosting us at the site of Cobá. Special thanks and acknowledgments to Bruce Dahlin whose vision, dedication, and enthusiasm made this project possible. Thanks go to Alex Norr and David Kotasek who assisted in sampling. Several BYU Environmental Science undergraduates assisted in the preparation and analysis of the samples.

Eric G. Coronel (M.S. 2011, Brigham Young University) is currently a graduate student of Agronomy at the University of Illinois.

Scott Hutson (Ph.D. 2004, University of California, Berkeley) is Associate Professor at the University of Kentucky. He is director of the Uci-Cansahcab Regional Integration Project.

Aline Magnoni (Ph.D. 2008, Tulane University) is Adjunct Assistant Professor at Tulane University. She is co-principal investigator of Collaborative Research: Geochemical Detection of Ancient Maya Exchange Environments and the co-director of the Proyecto de Interacción Pólitica en el Centro de Yucatán.

Chris Balzotti (Ph.D. 2014, University of Utah) is a research faculty member at Brigham Young University. His research focus is ecological modeling and remote sensing.

Austin Ulmer is a senior majoring in Environmental Science at Brigham Young University.

Richard E. Terry (Ph.D. 1976, Purdue University) is Professor of Soil Science at Brigham Young University. He is co-principal investigator of Collaborative Research: Geochemical Detection of Ancient Maya Exchange Environments. He has directed soil sampling and geochemical analysis research in activity areas and agricultural resources of the ancient Maya.