CHARACTERISTICS AND GENESIS OF EL SAUZ CHERT, AN IMPORTANT PREHISTORIC LITHIC RESOURCE IN SOUTH TEXAS

Abstract

Stone tools ranging in age from Early Archaic (3500–6000 B.C.) to Late Prehistoric (A.D. 700 to historic times), made of a distinctive light gray but sometimes colorful chert, have been identified in private collections in south Texas for at least 50 years. The source of this stone, known in the archeological literature as “El Sauz chert,” are two small bedrock outcrops in Starr County associated with altered rhyolitic ash of the Catahoula Formation. Physical characteristics, field evidence and major element chemical composition are used to infer an in situ origin of the chert associated with the devitrification of the volcanic ash and the remobilization of silica by ground and meteoric water. Distinctive characteristics of El Sauz chert include abundant vugs, opalized veins, smeared colorations, high aluminum content, and pale yellowish-green fluorescence under short-wave ultraviolet light. These geologically distinctive characteristics distinguish this material from other cherts and, as a result, have important implications for archaeologists interested in prehistoric exchange and resource procurement.

Keywords:

• Catahoula Formation
• chert chemistry
• stone artifacts
• silicification
• Starr County
• Lower Rio Grande Valley

Acknowledgments

The authors are grateful to J.M. Villarreal for granting us unrestricted access to his ranch in Starr County, where one of the outcrops and quarries is located. To Nick Morales for facilitating the ultraviolet light observations and for his assistance during fieldwork. To Wilson W. Crook, Gault School of Archeological Research, Texas State University for sharing his unpublished results on the geochemistry of the Edwards Plateau cherts. To Dr. Margaret A. Graham Associate Dean Department of Sociology and Anthropology, University of Texas-Pan American for her insightful comments on earlier drafts of this manuscript. To Roland Silva for drafting the figures. To John Boland, Paul Keller, Terry Kumpe and Danielle Sekula for the loan of their artifacts made from El Sauz chert.

Additional information

Notes on contributors

Juan L. GonzAlez

Juan González is an Assistant Professor at the Physics and Geology Department at the University of Texas Pan America. He has a Ph.D. in Geology from Tulane University. His research focuses on human transformation of the landscape in prehistory, Holocene paleoclimate and sea level change. Correspondence to: Department of Physics and Geology, University of Texas Pan American, 1201 W. University Drive, Edinburg, TX 78539–2999. Email: [email protected]

James R. Hinthorne

James Hinthorne is an Emeritus Professor of Geosciences (Central Washington U.) and currently a Lecturer in Physics and Geology, UTPA. He has a B.A., M.S., and Ph.D. in Geology (U. Calif., Santa Barbara). His research has centered on electron and ion microprobe and X-ray diffraction analyses of rock-forming minerals, lunar samples, ceramics, pigments, nanomaterials. Correspondence to: Department of Physics and Geology, University of Texas Pan American, 1201 W. University Drive, Edinburg, TX 78539-2999. Email: [email protected]

Russell K. Skowronek

Russell K. Skowronek is Professor of Anthropology & History at the University of Texas Pan America. He has a Ph.D. in Anthropology from Michigan State University and a M.A. in History from Florida State University. His research focuses on the archaeology and ethnohistory of prehistoric Texas and California, and the Spanish colonial empire. Correspondence to: Department of Sociology & Anthropology, University of Texas Pan American, 1201 W. University Drive, Edinburg, TX 78539-2999. Email: [email protected]

Thomas Eubanks

Thomas Eubanks is a lab coordinator at the Chemistry Department, The University of Texas Pan American. He earned a Masters degree in Biology from the University of Texas-Pan-American. He is responsible for running a number of analytical instruments including, Scanning Electron Microscope, Atomic Absorption, Gas Chromatograph Mass Spectrometer and High Pressure Liquid Chromatograph. Correspondence to: Department of Chemistry, University of Texas Pan American, 1201 W. University Drive, Edinburg, TX 78539-2999. Email: [email protected]

Don Kumpe

Don Kumpe is a vocational archaeologist who has identified hundreds of archaeological sites in south Texas and Mexico. A regular contributor to La Tierra and other archaeological venues, Kumpe has willingly shared his knowledge of El Sauz and other sites in south Texas with professional archaeologists for the past three decades. Correspondence to: 1101 Martin St. McAllen, TX 78504