Southwestern Archaeological Tree-Ring Dating

University Of Arizona, Tucson AZ

Investigators

Abstract

The Laboratory of Tree-Ring Research (LTRR) at the University of Arizona is the sole source of archaeological tree-ring dates in western North America. With continuing National Science Foundation support, LTRR operates a dating program for tree-ring samples collected by LTRR and other archaeologists from Alaska to Peru and from the Pacific Ocean to the Mississippi River. NSF support allows the program to keep pace with the growing demand for archaeological tree-ring dates, information, and assistance and to maintain high production levels and short turnaround times. On average, the program produces more than 1,000 tree-ring dates from 4,000+ archaeological tree-ring samples submitted annually. These data are integrated into relevant archaeological contexts to construct refined cultural sequences and examine important issues of past human behavior that cannot be addressed without accurate, high resolution temporal control. Among these topics are absolute site and regional chronologies, social organization, intergroup interaction, and cultural adaptation to physical and social environments. In addition, the program fosters the expansion of archaeological tree-ring dating into new regions such as the Southwestern deserts, Great Basin, Great Plains, Rocky Mountains, Alaska, and Mexico. The project's exact dating and chronology building are crucial to understanding human behavior, human-environment interactions, and processes of sociocultural stability, variation, change, and evolution. Either directly or indirectly (through tree-ring dated ceramics), tree-ring dating underlies the chronology of Southwestern prehistory and many aspects of the documented history of the region. The project also provides data for dendroclimatic reconstructions that are combined with reconstructions produced by other paleoenvironmental disciplines such as geology, pollen analysis, volcanology, and trace element studies. In addition to illuminating past environmental processes, these integrated reconstructions provide a solid empirical foundation for examining interrelationships between human behavior and environmental variability. Finally, the project's efforts to expand research into areas previously thought to be unsuitable for archaeological tree-ring dating are bearing fruit. Dates derived from samples acquired many years ago identify absolutely dated 'hinge points' for archaeological chronologies in the Sonoran and Chihuahuan Deserts. The program has a wide range of broader impacts. Its findings are integrated into undergraduate and graduate classes in anthropology, geosciences, and other disciplines at the University of Arizona and other academic institutions. In addition, the project interacts with K-12 programs, provides instruction for visiting scholars from around the world, and facilitates field training for governmental, Native American, and private archaeologists and resource managers. The LTRR tree-ring sample collection and data archives are unparalleled, easily accessed resources for archaeological research, and a developing digital database will enhance the research value of these collections. Increased understanding of long-term human adaptation to cultural and environmental variability and enhanced knowledge of environmental processes help develop and implement environmental and social policy. Project personnel have contributed directly to formulating policy for managing cultural and natural resources by federal, local, and tribal land management agencies.