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.
Submitted by Jeffrey S. Dean and Ronald H. Towner Tree-ring dates from archaeological wood and charcoal samples provide the highest quality dates available to archaeologists short of actual written records. Tree-ring dates are accurate to the calendar year, have no associated statistical uncertainty (±), and, under favorable circumstances, record the exact years in which trees were felled. These dates are applied to a wide range of past human activities including tree cutting, the construction, repair, and abandonment of individual structures, the establishment and history of communities, and interaction among the inhabitants of such communities. As an example, more than 60,000 dates from more than 6,000 sites underlie the archaeological chronology of the southwestern United States. 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 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 vigorously pursues the expansion of archaeological tree-ring dating into new areas. NSF Grant BCS 1006417, "Southwestern Archaeological Tree-Ring Dating," supported one technician to analyze archaeological tree-ring samples as part of LTRR’s archaeological dating program. This technical support provides the dating program with the stability necessary to maintain rapid turnaround in sample analysis and to afford archaeologists timely access to the service. During the year of support under this grant, the program as a whole derived 539 dates from the analysis of 1,675 samples representing 63 archaeological sites. Within the framework of these outcomes, notable achievements include (1) continued expansion of archaeological tree-ring dating into areas lacking in such dating including the Great Plains, Sonoran Desert, and northern Mexico; (2) reinvestigation of ancient living trees that were modified by prehistoric inhabitants of Mesa Verde Colorado in the thirteenth century; (3) the dating of fuelwood reserves in an attempt to assess the potential effects of dead wood use by past and present inhabitants of west-central Colorado and the use of the resultant ring chronologies to facilitate absolute dating of Ute-affiliated archaeological sites in the area; (4) the dating and analysis of historic period sites in New Mexico, which illuminates colonial and Dust Bowl period Spanish and Anglo population dynamics in the state; (5) the derivation of archaeological dates for sites in the Grand Canyon, a locality notoriously difficult for the application of tree-ring dating. The NSF sponsored technician contributes directly to the broader impacts of the LTRR dating program. Its findings are integrated into undergraduate and graduate classes in anthropology, geosciences, and other programs 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. 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.
