Through the creation and analysis of databases for radiocarbon, instrumental neutron activation analysis (INAA), and law, macro-level trends are exposed that form the framework of a broader research program aimed at advancing ideas of craft specialization and archaeological theory in the ancestral Caddo region of Southwest Arkansas, Northwest Louisiana, Northeast Texas, and Southeast Oklahoma. The findings of this investigation illustrate the research potential that remains buried within the context of cultural resource management (CRM) reports and legal databases (Westlaw and LexisNexis) that is awaiting consumption within regional research designs aimed at exploring the nuances and trends that appear through synthetic research. While more can—and should—be done to exploit these resources, this endeavor represents the first logical step toward a more general comprehension of Woodland and Caddo occupations in the region. As a testament to those projects that generated these data, the findings herein are representative of decades of work by numerous academic institutions, archaeological firms, undergraduate as well as graduate students, and avocational archaeologists alike; all of which have and continue to contribute to a more synthetic and dynamic understanding of the things, peoples, and cultures that lie underfoot.

The rate of atmospheric formation of radiocarbon (C-14) was long considered to be relatively constant over time during the Holocene and late Pleistocene epoch. Because living tissue fixes carbon derived from the atmosphere, the result is a fairly constant proportion of radioactive C-14 to stable C-12 in living plants and animals. Using the measured half-life of C-14 (5,730 years), the approximate age of plant and animal tissue containing C-14 extending back as far as 30,000 ybp can be calculated. However, the C-14 dating technique is not as accurate as was once believed because it has been discovered that the ratio of C-14 to C-12 in the atmosphere fluctuates with time.In an attempt to determine the degree of fluctuation in the C-14 to C-12 ratio, scientists have attempted to calibrate C-14 ages with the more reliable dendrochronological ages. Since a dendrochronological time scale has been verified by Becker (1993) for the last 11,000 ybp, the degree of fluctuation in the rate of C-14 production during the past 11,000 ybp is known. This has resulted in the compilation of C-14 calibration curves which reveal the presence of both a long-term and several short-term deviations in the C-14 to C-12 ratio of the atmosphere over the past 11,000 ybp. The difficulty scientists are still currently faced with, however, is how to interpret C-14 ages in the range of 11,000 to 30,000 ybp, beyond the dendrochronological time scale but within the present limit of C-14 dating methods. In an attempt to solve the dilemma of how to interpret C-14 ages in this age range, this paper offers: 1. A detailed summary of the dendrochronological, C-14 dating, and C-14 calibration via dendrochronological analysis methods; and 2. A complete extrapolation of an existing C-14 calibration curve out to 30,000 ybp.Using an extrapolation of both a best-fit straight line trend and a periodic oscillating trend (each with a C-14 deviation of + 100 C-14 years), a method of calibration for C-14 dates greater than 11,000 ybp is created by using both trends in conjunction with one another (Figure 3). This method, when applied to the existing calibration curve in Figure 1, shows a maximum increase in deviation of 335 dendrochronological years in addition to the 265 years produced at a C-14 age of 4,700 yr by by conventional analysis. In the range of extrapolation from 11,000 to 30,000 ybp, a maximum age difference between a best-fit straight line trend and periodic oscillating trend of ± 688 actual cal (calibrated) years is present at an approximate C-14 age of 23,000 yr by (Figure 2). At 30,000 years cal BP the two trends, however, differ by only ± 425 actual cal years which corresponds to a C-14 age of 26,500 yr bp. The 3,500 year difference between C-14 and dendrochronological age scales at 30,000 years cal BP results in part from the long and short-term deviations previously mentioned, and in part from a 3% short fall in using the Libby half-life (5,568 years used by Stuiver and Becker (1993) to make the calibration curve used in Figure 1 of this paper) instead of the more recently determined and more accurate half-life of 5,730 years.This method of extrapolation is in close accordance with the U-Th dating method used by Bard et. al. (1990). The maximum difference of approximately 3,500 years between C-14 and dendrochronological dates at 30,000 ybp equals the approximate 3,500 year maximum difference found between C-14 and U-Th ages at 20,000 ybp by Bard et. al. (1990). In addition, this correlation holds true even though these authors used the more accurate 5,730 year half-life in their extrapolation of C-14 instead of the Libby half-life used in Figure 1 of this paper. Therefore, the method of extrapolation presented here could be used as a reasonable first order check of approximate calendric age ranges for respective C-14 ages. This method of extrapolation would also be useful for checking the reasonableness of other C-14 calibration techniques in the range of 11,000 to 30,000 ybp. This analysis of extrapolating the calibration curve indicates that continued work on measuring the ratio of C-14 to dendrochronologically derived ages in materials older than 11,000 ybp is justified. / Department of Geology

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The Gulf of Mexico and Caribbean Sea comprise a sensitive and important region, both oceanographically and climatically. A better understanding of the history of climate and marine environmental conditions in this region provides valuable insight into the processes that affect climate globally. This dissertation furthers our understanding of these factors via investigations of the isotopes of corals and seawater, as well as coral growth. Results improve our understanding of how the isotope and coral growth records from the Gulf of Mexico and Caribbean Sea reflect recent environmental conditions, enhancing our ability to reconstruct the history of climate in this important region. Analysis of the relationship between salinity and oxygen isotopic composition of seawater from the Texas/Louisiana continental shelf and Flower Garden Banks yield improved understanding of the relative contribution of the fresh water sources into the northern Gulf of Mexico, and also the oxygen isotopic composition of open-ocean seawater in this region. Variations in the growth of long-lived coral cores from the Flower Garden Banks are compared to local and regional climate conditions, particularly winter air temperatures. During the latter half of the twentieth century, a close correlation has existed between slow coral growth and cold wintertime air temperatures along the Gulf Coast, which are due to a meridional orientation of the North American jet stream (associated with the Pacific/North American climate pattern). Existing long coral growth records are too limited to assess this relationship during earlier years. Knowledge of the marine radiocarbon (14C) reservoir age is important for understanding carbon cycling and calibrating the radiocarbon ages of marine samples. Radiocarbon concentrations in corals from the Flower Garden Banks, Veracruz, and the Cariaco Basin are measured and used to determine the surface ocean 14C reservoir ages for the Gulf of Mexico and Caribbean Sea. Results also indicate that the post-nuclear weapons testing Delta 14-C values of the Gulf of Mexico and Caribbean Sea differ. This difference is attributed to the advection of 14C-depleted surface water from the Southern Hemisphere into the Caribbean Sea. The results reported in this dissertation provide valuable information for understanding the marine environment when using carbonate proxies to study and reconstruct past climate and marine conditions in the Gulf of Mexico and Caribbean.

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Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1984. / Includes bibliographical references (leaves 64-68).

This project describes the Holocene environmental and pedogenic history of the Hiraethog Moors, particularly in relation to archaeological evidence. Ironpan stagnopodzol, brown podzolic and stagnohumic gley profiles have been studied from Aled Isaf together with cores from Cefn Mawr and Llyn y Foel-frech. Physical, chemical, clay mineralogical, micromorphological and palynological analyses have been undertaken and a time framework has been achieved by radiocarbon dating, including AMS 14C dating of ironpan and charcoal samples. A search for tephra has been undertaken and, although none was located, the presence of a biolith bloom in a core from Llyn Cororion on the Arfon Platform raises the possibility of a geochemical reconstitution of a low volume, fine-grained tephra fall. Parent material was reworked by periglacial processes during the Late-glacial resulting in an oriented fabric, cracked stones and a redistribution of clay and fine siltsized material. Until 6-7,000 years BP soils remained shallow and stony, with a clay mineralogy dominated by hydrous mica and chlorite. Between 6,000 and 4,000 years BP erosion led to deeper soil profiles on the lower slopes, burying flints and charcoal, and the woodland was periodically disturbed by humans. However, man was relatively inactive between 4,500 and 3,500 years BP. At 3,500 years BP woodland cover declined rapidly due to human activity with a subsequent change to a Gramineae- and then a Calluna-dominated vegetation community. In low lying sites the result was increased waterlogging, gleying, structural collapse and the build up of organic matter at the surface i. e. stagnohumic gley. In better drained sites podzolisation occurred to produce the Bs horizon, i.e. brown podzolic soil. In profiles most intensively leached, mor humus and then peat accumulated. This induced surface waterlogging resulting in a mobilisation of iron, structural collapse and the formation of an Eag horizon, within which chlorite was destroyed and hydrous mica weathered to vermiculite, and an ironpan i.e. ironpan stagnopodzol. Through the integration of soil and pollen analysis, 14C dating and archaeological information our understanding of soil development and human activity on Hiraethog has been increased.

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