Historic records of arroyo formation have long been used as inferential tools for reconstructing paleoclimate in the American Southwest. These paleoclimatic reconstructions have attempted to demonstrate that synchronous incision of river valleys across the American Southwest was the result of large-scale (regional, global) climatic change. Projected to the past, the inferred chronological boundaries of certain climatic periods have been used by archaeologists as convenient boundaries for demarcating long-term changes in human settlement and subsistence. The rapid accumulation of new data on middle to late Holocene subsistence and settlement along the Santa Cruz River, and the application of new theoretical constructs in hunter-gatherer research require the use of higher resolution data in geoarchaeology. During the past ten years, advances have been made in our understanding of the hydroclimatological processes which cause channel changes on the Santa Cruz River and geologists are now better able to predict the circumstances under which desert streams become arroyos. Together with high-resolution geologic documentation of channel exposures, the prehistoric setting of human occupation along the Santa Cruz River can be addressed at a scale that is more relevant to the archaeological issues of today. The detail derived addresses specific geomorphic and paleoenvironmental variables that operate at the site or regional level and that have the most direct effect on human decision-making.

No description available.

The current study has evaluated shoreline dynamics and environmental change at St. Catherines Island, Georgia, with attention to the two major controls of barrier island formation and modification processes. These major controls include the increase in accommodation space, or the rate of sea level rise for the Georgia Bight which has remained constant in 20th and 21st century tide gauge data and dynamically changing rates of sediment supply based on anthropogenic modifications to land cover (Trimble, 1974) that are reflected in sediment transport (McCarney-Castle et al., 2010). Vibracoring and radiocarbon data provided valuable insights into the stratigraphy and development of St. Catherines Island. A stratigraphic model has been developed for the sediments associated with the Late Holocene accretional terrains where multiple small scale fluctuations in sea level have resulted in the formation of a sedimentary veneer punctuated with transgressive surfaces and regressive sequences. A working model for an interpolated Late Holocene sea level curve has been constructed using direct evidence from vibracore data as constraining points and indirect evidence from other regional sea level studies to provide additional structure. The relationship between the timing of the regressions versus periods of beach ridge formation and implications from the current shoreline dynamics study regarding the role of sediment supply complement each other. The ages of beach ridge formation strongly correlate to periods that are associated with regressions in sea level based on the sedimentary record and an evaluation of Late Holocene sea level conditions. The evaluation of anthropogenic modifications to the rate of sediment supply performed under the current study indicates that in spite of significant changes in sediment flux rates of +300% (pre-dam era) and -20% (post-dam era), shoreline retreat was continuous during the study period with an acceleration noted in the rates of shoreline retreat associated with spit and berm landforms during the post-dam or modern era. The two associations indicate strongly that the rate of sediment supply plays a secondary role to the major control of the rate of sea level rise in the formation and modification processes at St. Catherines Island.

The boreal forest region of Canada is climatically sensitive and may be impacted by anthropogenic-induced climatic changes. The results of this multi-proxy paleolimnological study contribute detailed information on changes to the boreal forest in northwestern (NW) Ontario, showing unequivocal changes in lake and forest structure due to climate during the warmer mid-Holocene. This study uses diatoms, pollen, and charcoal reconstructions to better understand the timing and extent of climate-related changes in Lake 239, Experimental Lakes Area (ELA), in NW Ontario throughout the Holocene with an emphasis on the warmer mid-Holocene. Diatom analysis revealed changes in water quality based on analysis of species assemblages and quantitative inferences of total phosphorus from a deep central core. Lake levels at least 8-m lower than today were inferred from a near-shore core and were concurrent with an increase in nutrient-rich diatom assemblages, an increase in diatom accumulation, and a decrease in chrysophytes relative to diatoms in the central core. A concurrent increase in pollen such as Cupressaceae and Ambrosia indicate more open boreal forest between ~4500-8000 cal yr BP. Pollen-based inferences of temperature suggest an increase on average of 1-2°C warmer than today with winter temperatures up to 4°C warmer. The pollen inferences also suggest enhanced precipitation, but with increased evaporation/evapotranspiration resulting in reduced moisture availability overall. A transect of cores surrounding ELA was synthesized using pollen-based reconstructions of temperature and precipitation to assess regional changes. All sites show shifts in pollen assemblages indicating a warmer mid-Holocene; prairie sites to the west show mid-Holocene decreases in precipitation relative to today, whereas sites near or east of ELA show consistent increases in precipitation, but with enhanced evaporation. Charcoal analysis shows an increase in charcoal accumulation during the mid-Holocene warm period compared to the early and late Holocene, suggesting a more active fire regime. Fire return intervals based on type-M charcoal show a pronounced decrease during the early-to-mid Holocene period and a corresponding increase in fire frequency, whereas fire frequency derived from total charcoal was virtually unchanged over the Holocene. This study helps fill a knowledge gap in NW Ontario noted by several large regional assessments. / Thesis (Ph.D, Biology) -- Queen's University, 2010-07-15 09:54:18.653

This research has examined the historical vegetation of two Eastern Otago sites below the regional treeline, with the aim of addressing questions about the distribution and spread of native tussock grasslands prior to human arrival in New Zealand c. 800 yr BP. Pollen and phytolith (plant opaline silicate) proxies have been extracted from peat cores at Swampy Summit and Clarks Junction to provide a record of vegetation spanning the Holocene. Using multiple proxies and two sample sites has allowed for comparisons of the record of vegetation from within sites and between sites. A record of the modern pollen rain was also gathered from localised moss polsters at Swampy Summit in order to reconcile modern pollen assemblages and transport patterns with historical findings. It became clear from the research that the record of vegetation inferred from phytoliths was not analogous to the pollen-based records, which supported the hypothesis that vegetation reconstructions based solely on pollen may be unreliable. Good pollen preservation in the sediments allowed for the identification of over 50 taxa, although only Chionochloid forms were identifiable to a family level in the phytolith records. Poaceae pollen was abundant throughout the Clarks Junction record, suggesting grassland had persisted at this site during the Holocene, while Poaceae pollen at Swampy Summit was minimal and sporadic. Phytoliths at Swampy Summit show grasses have persisted at the site thoughout the Holocene, at times in much greater proportions than the pollen record would suggest, while Chionochloid phytoliths only become common near the top of the record, possibly reflecting increasing dominance of this taxa after human disturbance. In contrast to Swampy Summit, the Clarks Junction phytolith record reflects a more stable presence of grasses throughout the Holocene, with Chionochloid forms present throughout. Phytoliths appear to be a more reliable proxy for local vegetation, with both sites indicating a Holocene presence of grasses below the regional treeline prior to human arrival in New Zealand. In comparison, the pollen record appears to indicate a more regional pattern of vegetation, with the grassland pollen record complicated by pollen dispersal and deposition factors.

No description available.

Records of stable oxygen isotope variations from a variety of proxies have been used in palaeoclimatic research since the 1950’s. Several studies have applied stable isotope analysis of lake sediments to reconstruct past climate changes in central and northern Sweden, including a study of Lake Blektjärnen in Jämtland, central Sweden, by Andersson (2010). In this study, sediments from that same lake were sampled for stable isotope analysis of bulk carbonates with the aim to improve the resolution of the isotopic record for the last two millennia. The results indicate a shift from relatively drier to wetter conditions between ~2,300–1,300 cal. years BP, generally wet conditions close to the Medieval Warm Period (~1,000–750 cal. years BP) and generally dry conditions during the Little Ice Age (~550–150 cal. years BP). These results are in agreement with previous palaeoclimatic reconstructions in the region. The isotopic record of Lake Blektjärnen was completed for the last ~2,350 years at a resolution of ~15 years per sample, three times higher than that of the previous study, displaying the advantages of bulk carbonate sampling for stable isotope analysis and providing a high-resolution dataset on humidity changes in central Sweden during the late Holocene.

The East Asian Summer Monsoon (EASM) is a major component in Asian climate. It is largely driven by climatic factors such as humidity, solar insolation and temperature. For at least 50 years the EASM has been studied extensively by scientists regarding its current strength. Models have been recreating past monsoon intensity as well as attempted to predict future intensity. As the monsoon undergoes changes, the climatic shifts responsible for them leave various traces behind; geochemical as well as biological, and these have been preserved and recorded in various locales on the planet. The most significant climatic change is the variation between glacial and interglacial periods which have been alternating for the last 2.6 million years and the EASM has changed in tune with the climate during this time. The EASM follows the δ18O-record in speleothems found in Eastern Asia as well as in ice cores from Greenland. Various geochemical and biological tracers seem to reflect these fluctuations in climate locally as well as globally over a 200 kyr period. The current intensity of the EASM seems to be one of decreasing strength, a phase that has persisted since the Holocene climatic optimum 8.5 kyr ago. Recently however a decrease in the East Asian Winter Monsoon has been confirmed, indicating an increase in EASM intensity. During the Holocene the EASM reached peak intensity during the Holocene climatic optimum but has fluctuated largely in tune with solar insolation. This is also true for the Eemian period although some events such as the mid-Eemian cooling show that factors other than solar insolation regulate monsoon intensity over large time periods. The future of the EASM seems to be one of increased strength due to climate change and models predict both increased wind speeds and an increasing occurrence of extreme precipitation despite decreasing solar insolation.

The topic of investigation of this thesis concerns a co-extensive analysis of Crete and Anatolia from the beginning of the Early Holocene (ca. 10,000 BCE) to the start of the Bronze Age (ca. 3000 BCE), with a select analysis of other locales in the Aegean, Levant, and eastern Mediterranean for comparative purposes. It has been long supposed in scholarship that the Neolithic on Crete (and, by extension, the Aegean) is of Anatolian extraction, but the claim has hitherto remained un-investigated systematically. Recent DNA studies have bolstered these suppositions, thus providing an appropriate opportunity for more detailed investigation via the archaeological evidence. / The aim of the thesis is two-fold. First, I aim to provide a systematic account of the archaeological evidence from various locales which has the potential to elucidate, materially, any affinities the Aegean and Anatolian locales may have shared throughout the aforementioned period of time. However, more detail will be devoted to phases in which Crete is supposed to have been subject to influx of settlers (early 7th millennium BCE, and late 4th millennium BCE). I shall examine elements such as pottery, chipped stone, settlement patterns, and hypothetical population movements in order to construct a picture of the dynamics in the respective periods. / The archaeological evidence will thus form a platform upon which I shall engage in a discussion using theoretical perspectives drawn from anthropological and sociological theory to answer questions about human comportment, and intentionality with regards to settlement patterns, material culture variation, and movement. Thus, I shall use the archaeological evidence to put forward a series of meaningful assumptions about social structures, people’s outlooks on the environments which they inhabited and experienced, and the motivations and reasons for particular changes. As a result, parts of the thesis will have a heuristic character, but it is hoped that such an approach will foster the capacity for debate in order to enhance the understanding of the dynamics spanning the geographies of the Aegean and Anatolia.

The topic of investigation of this thesis concerns a co-extensive analysis of Crete and Anatolia from the beginning of the Early Holocene (ca. 10,000 BCE) to the start of the Bronze Age (ca. 3000 BCE), with a select analysis of other locales in the Aegean, Levant, and eastern Mediterranean for comparative purposes. It has been long supposed in scholarship that the Neolithic on Crete (and, by extension, the Aegean) is of Anatolian extraction, but the claim has hitherto remained un-investigated systematically. Recent DNA studies have bolstered these suppositions, thus providing an appropriate opportunity for more detailed investigation via the archaeological evidence. / The aim of the thesis is two-fold. First, I aim to provide a systematic account of the archaeological evidence from various locales which has the potential to elucidate, materially, any affinities the Aegean and Anatolian locales may have shared throughout the aforementioned period of time. However, more detail will be devoted to phases in which Crete is supposed to have been subject to influx of settlers (early 7th millennium BCE, and late 4th millennium BCE). I shall examine elements such as pottery, chipped stone, settlement patterns, and hypothetical population movements in order to construct a picture of the dynamics in the respective periods. / The archaeological evidence will thus form a platform upon which I shall engage in a discussion using theoretical perspectives drawn from anthropological and sociological theory to answer questions about human comportment, and intentionality with regards to settlement patterns, material culture variation, and movement. Thus, I shall use the archaeological evidence to put forward a series of meaningful assumptions about social structures, people’s outlooks on the environments which they inhabited and experienced, and the motivations and reasons for particular changes. As a result, parts of the thesis will have a heuristic character, but it is hoped that such an approach will foster the capacity for debate in order to enhance the understanding of the dynamics spanning the geographies of the Aegean and Anatolia.