Faculty of Humanities; School of Geography and Environmental Studies; PhD Thesis / The issues surrounding the nature and timing of the relations between users of the Zhizo and Leopard’s Kopje ceramic styles in the area of the Shashi-Limpopo confluence from AD 900 to 1300 are addressed. The results of archaeological investigations at five sites in the region are presented, as are the results of a re-analysis of the ceramic and radiocarbon material from the site Schroda. These results demonstrate that Leopard’s Kopje, Zhizo and Zhizo-derived ceramics co-occur in the region between around AD 1000 and 1200. These two ceramic styles are proposed to be the ceramic expressions of two separate, interacting, ethnic groups. It is proposed that interaction between these ethnic groups led, in part, to the development of more complex social and political institutions. The ceramic style called Zhizo is shown to change after around AD 1000 in reaction to this interaction. Zhizo ceramics after AD 1000 represent a new phase and facies of the Nkope Branch of the Urewe Tradition. This ceramic style is named “Leokwe” after the site at which it was identified, Leokwe Hill. The class-based social system in the area is hypothesised to have been the product of a prestige goods system. This prestige goods system involved the use of aggressive prestation whereby new social, economic, and political dependencies were created outside the traditional exchange system. The prestige goods system penetrated only to the upper tiers of society. Inclusion within this system, and thus within the new elite class, was not limited by ethnicity, and segments of both the Leokwe and Leopard’s Kopje ethnic groups participated within it. This new exchange system is proposed to have undermined the traditional exchange system, thereby encouraging a process of secularisation whereby exotic trade goods may have been seen as wealth items that potentially supplanted other, more traditional, exchange media. The continuing social and political status of Leokwe peoples after the Leopard’s Kopje entry into the region is posited to have been based upon the role of Leokwe ancestors as the owners of the land. The differential intra-site settlement patterns observed within the region, involving the removal of the central cattle byre from key centres, including Leokwe Hill, K2, and Mapungubwe Hill, are proposed to signal a rejection by Leopard’s Kopje elites of the traditional exchange system and its social, political, and religious underpinnings. This removal reflected a rejection of Leokwe peoples’ source of political standing and ritual authority. This shift is first seen at Leokwe Hill after around the mid-12th century AD. The implementation of the settlement pattern shift is proposed to mark a system of ethnic stratification which subordinated Leokwe peoples to Leopard’s Kopje elites; this shift paved the way for the submergence of the Leokwe style and the end of their ethnic identity in the region.

Thesis (Ph.D.) - Simon Fraser University, 2006. / Theses (Dept. of Archaeology) / Simon Fraser University. Includes bibliographical references (leaves 236-263). Also issued in digital format and available on the World Wide Web.

Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Applied Physics." Includes bibliographical references (p. 88-93).

Mollusk shells from Peruvian archaeological middens provide brief (< 5 yr per shell) records of past marine conditions. Marine radiocarbon age, R, is recorded in shell carbonate at the time of precipitation. R varies with changes in upwelling: when radiocarbon-depleted sub-thermocline water wells up, R is large; increased contribution from radiocarbon-enriched surface water (due to seasonal cycles or an El Niño event) reduces R. Are molluscan records of R a useful proxy for Peruvian upwelling? If so, does R from archaeological shells reveal mid-Holocene upwelling changes that constrain the Holocene history of El Niño-Southern Oscillation (ENSO)? Profiles of R along ontogeny from early 20th century Argopecten purpuratus (bay scallop) shells and mid-Holocene A. purpuratus, Mesodesma donacium (surf clam), and Trachycardium procerum (cockle) shells from eight coastal Peru locations show that R varies by up to 530 ± 200 ¹⁴C yr within individual shells. El Niño events are easily detectable in post-1950s shell carbonate due to increased radiocarbon contrast between sub- and super-thermocline water from “bomb carbon,” but R differences between El Niño and La Niña shells from the early 20th century are subtle. Decreasing precision in older shells due to ¹⁴C decay makes detecting El Niño events in the archaeological past using radiocarbon very difficult. Because of intrashell radiocarbon variation, caution is prudent when using marine material for chronometry in variable upwelling environments. Based on modeling, mollusks that grow seasonally rather than year-round can skew long-term average (> 1 yr) R reconstructions by nearly 200 ¹⁴C yr toward R of the preferred growth season. Coldloving M. donacium, for example, records older marine reservoir ages on average than A. purpuratus in the same water, because A. purpuratus grows in both warm and cold conditions. Comparisons of R between species with opposite seasonal growth habits can compound this effect. Because of intrashell R variation, seasonal growth biases, and measurement uncertainties, a change in R due to past ENSO changes would have to be hundreds of ¹⁴C yr or greater to be identifiable. Thus far, clear evidence for such a Holocene change in R has not been seen.

One of the most challenging questions surrounding the Clovis colonization of North America is the character and structure of terminal Pleistocene environments, including floral and faunal communities. A series of cores in the mouth of an arroyo revealed late Pleistocene - early Holocene wetland sediments buried 12 meters below surface, at the approximate elevation of the entrenched modern San Pedro River channel. A suite of ¹⁴C dates show that wetlands of the ancestral San Pedro River occupied portions of the inner valley coincident with the Younger Dryas (13,000 - 11,500 cal yr BP) and the early Holocene (10,000 - 9,500 cal yr BP). A lack of Sporormiella fungal spores indicates that mammoths were rare or absent when Clovis populations appeared in the valley around 12,800 cal yr BP. Palynological and stable carbon isotope analyses show that C₄ grasses increased at 9,940 cal yr BP, just prior to frequent burning after 9,510 cal yr BP and rapid erosion at 9,470 cal yr BP. δ ¹⁸O values from soil carbonates vary but do not record a systematic shift in precipitation source or temperature during the late Pleistocene - early Holocene transition. The establishment of C₄ grasslands in the inner valley correlates with widespread changes in the Chihuahuan Desert flora around 10,000 cal yr BP. A relatively dense accumulation of Clovis-mammoth associations in San Pedro Basin contrasts the lack of megaherbivores indicated at Palominas Arroyo. The upper San Pedro Basin of southeastern Arizona contains a minimum of four Clovis-mammoth associations, making it possibly one of the densest concentrations of human-proboscidean sites on earth in terms of time and space. I use the Younger Dryas-age stratum known as the "black mat" to compare the Clovis-age archaeofaunal record of the basin to its paleontological background in order to measure the level of human predation that created this remarkable record. This analysis indicates that Clovis people were affecting the last mammoth populations to a significant degree, a situation expected only in the presence of abundant mammoths. I argue that this condition was met in the San Pedro Basin, possibly in the form of a terminal Pleistocene refugium. If the refuge hypothesis indeed explains mammoth predation, then Clovis-mammoth associations should occur as clusters as they do in the San Pedro Basin rather than as isolates as they are known to occur elsewhere. The use of radiocarbon frequency distributions to reconstruct prehistoric human and animal populations must account for taphonomic loss and other factors that affect the archaeological and paleontological records. Surovell et al. (Journal of Archaeological Sciences, 36, 1715–1724) have recently proposed a volcanic-based correction factor for removing "taphonomic bias" from temporal frequency distributions. Analysis of 718 radiocarbon dates sampled from the alluvium of the San Pedro and Santa Cruz Rivers and their tributaries in southeastern Arizona shows that discovery and scientific biases play an equally important role in the creation of radiocarbon frequency distributions, and that "taphonomic bias" has not been systematic through time. The latter principle is further demonstrated using a sample of 123 Pliocene to Clovis-age proboscideans from the San Pedro Valley. We propose an alternative model that is based on the nature of the stratigraphic record, with discovery bias, scientific bias, taphonomic loss, and the shape of the calibration curve all operating to influence the temporal frequency distribution of prehistoric phenomena.

Accelerator mass spectrometry (AMS) has been used routinely for radiocarbon measurements for several years. During this period it has become evident neither the accuracy nor the range of the technique were as great as had originally been hoped. This thesis describes both theoretical work to understand the reasons for this and practical solutions to overcome some of the problems. The production and transport of the ions used in the measurements are found to be the most crucial stages in the process. The theories behind ion production by sputtering are discussed and applied to the specific case of carbon sputtered by caesium. Experimental evidence is also examined in relation to the theories. The phenomena of space charge and lens aberrations are discussed along with the interaction between ion beams and gas molecules in the vacuum. Computer programs for calculating phase space transformations are then described; these are designed to help investigations of the effects of space charge and aberrations on AMS measurements. Calculations using these programs are discussed in relation both to measured ion beam profiles in phase space and to the current dependent transmission of ions through the Oxford radiocarbon accelerator. Improvements have been made to this accelerator and these are discussed in the context of the calculations. There are many reasons for wishing to produce C^- ions directly from carbon dioxide. The most suitable type of source for achieving this is the Middleton High Intensity Sputter Source. Experiments to evaluate the performance of such a source are described and detailed design criteria established. An ion source designed and built specifically for radiocarbon measurements using carbon dioxide is described. Experiments to evaluate its performance and investigate the underlying physical processes are discussed. The source is found to have a high efficiency enabling small samples (<100 μg of carbon) to be measured. The cross contamination is measured to be low (<0.1%) and the background currents are small; the implications of these results are discussed.

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1982. / Includes bibliographical references (leaves 100-103).

Thesis (doctoral)--Rijksuniversiteit te Groningen, 1981. / "Stellingen" (2 p.) inserted. Includes bibliographical references (p. 103-114).

The region of Southern Mesopotamia, modern-day southern Iraq, saw a number of important socio-cultural transformations during the 4^th - 3^rd millennia BC, which led to the emergence of the world's first urban, literate civilisation. These crucial developments reverberated across the neighbouring regions and greatly contributed to the later Classical and Judaeo-Christian traditions. Despite the importance of this period, our understanding of its chronology is limited. The main aim of this thesis is to build a reliable absolute chronology for the Uruk, Early Dynastic, and Akkadian periods in Mesopotamia using radiocarbon (¹⁴C) dating. Radiocarbon dates published in the archaeological literature underwent a thorough evaluation in order to ensure that only reliable measurements were included in the analysis. New dates were produced for the periods and contexts most lacking in radiocarbon data. Archaeological and textual sources were used to create Bayesian models in order to produce even more precise time estimates. The resulting periodisation of Mesopotamia was compared to the contemporary cultural sequences of ancient Iran and the Syrian Jezirah. While corroborating the standard Middle Chronology model, the results highlighted a number of intricacies relevant to our understanding of the early history of the Mesopotamian civilisation. Most importantly, this thesis argues that the developmental process was one of long periods of cultural continuity punctuated by sudden changes and shorter phases of innovation and creativity.

Arsenic contamination of circum-Himalayan groundwater is leading to one of the greatest humanitarian disasters of modern times, poisoning at least 70 million people who are mostly poor and rural. The groundwater is hosted in Holocene aquifers consisting of Himalayan sediments deposited by the great Asian rivers in deltaic environments. Arsenic is released when organic material (OM) reacts with the iron-oxide minerals co-deposited in the sediments onto which arsenic is adsorbed. The source of OM is one of the most important questions facing researchers and policy makers. There are generally accepted to be three potential sources of OM: 1) sedimentary bound OM (SOM) co-deposited with sediments; 2) thermally mature petroleum upwelled from reservoirs below the aquifers; 3) dissolved organic carbon (DOC) some of which might be drawn in to the aquifer through modern pumping and irrigation. In this thesis the nature of organic material in the aquifer is researched and the processes and timescales which lead to arsenic release are studied. Here evidence for a new conceptual model of arsenic release is presented. Isotopic tracing combined with a new geochemical model and organic geochemical techniques, shows that OM driving arsenic release pre-dates agriculture in the region and was from natural grasslands in the early Holocene. The geochemical model utilises strontium isotopes to correct the radiocarbon age of dissolved inorganic carbon (DIC) to find only the age and isotopic signature of DIC from oxidation of organic material. This shows that DIC from oxidation of OM was from the early Holocene and had an isotopic signature consistent with the early Holocene SOM in this region. A study of the sediments in the region built upon a geomorphological history shows that the most oxidised SOM is from early Holocene sediments. Thus both techniques separately indicate that pre-agricultural organic material drove arsenic release. This conceptual model however reveals the "arsenic sand paradox", because whilst release is from early Holocene clays, today highest concentrations of arsenic are in younger sands. Explaining this paradox is the most important next step leading on from this research.