Tree Ring Dating in Western North America

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Tree-ring dating is the most precise non-documentary method of dating archaeological materials from the past two thousand years in North America, and the Laboratory of Tree-Ring Research (LTRR) at the University of Arizona is the only source of archaeological tree-ring dates in the area. With National Science Foundation (NSF) support, the LTRR operates an analysis program for tree-ring samples collected by LTRR and other archaeologists from Alaska to Argentina and from the Pacific Ocean to the Mississippi River. NSF support will allow the program to keep pace with the ever growing demand for archaeological tree-ring dating, and to maintain high production levels and short turnaround times. On average, more than 750 dates from 1500+ archaeological tree-ring samples are produced 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, locality, and regional chronologies, social organization structure, intergroup interaction, and cultural adaptation to physical and social environments. The program actively promotes the expansion of archaeological tree-ring dating into new regions such as the Southwestern deserts, Great Basin, Great Plains, Rocky Mountains, Alaska, Mexico, and South America; it also supports student research both directly and indirectly. The project has a wide range of broader impacts. Its findings will be 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 and provides public tours of the facility to an estimated 12,000 visitors and students annually; it provides instruction for visiting scholars from around the world and facilitates field and laboratory training for non-profit, governmental, private sector, and Native American programs. Students will accrue particular benefits from the reduced cost of analysis, thus allowing them to conduct extensive research at lower costs. The LTRR tree-ring sample collections and archives are unparalleled, easily accessed resources for archaeological research, and an under-construction digital database will enhance the research value of these resources. Increased understanding of long-term human adaptation to cultural and environmental variability and enhanced knowledge of past environmental processes will help develop and implement environmental and social policy. Project personnel will contribute directly to formulating policy for managing cultural and natural resources by federal, local, and tribal land management agencies.The project has additional intellectual merits. Exact dating and chronology building are crucial to understanding human behavior, human-environment interactions, and processes of sociocultural stability, variation, change, and social 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 will also generate climatic 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 will provide a solid empirical foundation for examining the 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 provide absolutely dated "hinge points" for archaeological chronologies in the Sonoran Desert, the Great Basin, the western Great Plains, Alaska, northern Mexico, and South America.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.