No description available.

The Elbow Sand Hills and the adjacent South Saskatchewan and QuAppelle River valleys in south-central Saskatchewan have long been recognized as the locus of extensive precontact Plains cultural settlement throughout the post-glacial period. The objectives of this geoarchaeological investigation are to identify the extent to which 1) Holocene environmental changes and landscape evolution impacted precontact settlement patterns and archaeological site preservation and visibility, and 2) to investigate the relationship between archaeological site location and the environmental elements on a Northern Plains landscape using a Geographical Information System (GIS). The lithostratigraphic record suggests that this region experienced significant Holocene climatic changes with repetitive alternations between arid and humid climatic conditions over the past 5,000 years. Holocene climatic conditions influenced settlement patterns as indicated by extensive occupations of the study area, particularly in the aeolian sand dunes, during prolonged humid climatic intervals that are recorded by paleosols. Precontact cultural groups departed the Elbow Sand Hills and the adjacent uplands for the nearby South Saskatchewan and QuAppelle River spillways during extended arid climatic intervals characterized by aeolian activity and sand dune development. <p>GIS analyses reveal that precontact cultural settlement patterns were focused on certain environmental characteristics according archaeological site distribution. Precontact cultural groups apparently concentrated their settlement activities within the glacial meltwater spillways and aeolian sand dunes, which are topographically complex and situated in close proximity to water resources where natural resources were abundant and diverse. The glaciofluvial plains and glaciolacustrine plains are topographically subdued landforms, and along with the hummocky moraine, are distal to permanent water resources. These landforms are characterized by a lower intensity of occupation because of a consequence of lower resource availability and diversity. Archaeological site visibility and preservation varies within the region with the hummocky moraine and glaciolacustrine plains displaying the greatest degree of site visibility and preservation. The aeolian sand dunes, meltwater spillways, and glaciofluvial plains were physiographic elements that exhibit the lowest site visibility and preservation potential. These landforms were more strongly influenced by post-glacial climatic conditions, geomorphic processes, and the recent formation of the Lake Diefenbaker reservoir.

The Elbow Sand Hills and the adjacent South Saskatchewan and QuAppelle River valleys in south-central Saskatchewan have long been recognized as the locus of extensive precontact Plains cultural settlement throughout the post-glacial period. The objectives of this geoarchaeological investigation are to identify the extent to which 1) Holocene environmental changes and landscape evolution impacted precontact settlement patterns and archaeological site preservation and visibility, and 2) to investigate the relationship between archaeological site location and the environmental elements on a Northern Plains landscape using a Geographical Information System (GIS). The lithostratigraphic record suggests that this region experienced significant Holocene climatic changes with repetitive alternations between arid and humid climatic conditions over the past 5,000 years. Holocene climatic conditions influenced settlement patterns as indicated by extensive occupations of the study area, particularly in the aeolian sand dunes, during prolonged humid climatic intervals that are recorded by paleosols. Precontact cultural groups departed the Elbow Sand Hills and the adjacent uplands for the nearby South Saskatchewan and QuAppelle River spillways during extended arid climatic intervals characterized by aeolian activity and sand dune development. <p>GIS analyses reveal that precontact cultural settlement patterns were focused on certain environmental characteristics according archaeological site distribution. Precontact cultural groups apparently concentrated their settlement activities within the glacial meltwater spillways and aeolian sand dunes, which are topographically complex and situated in close proximity to water resources where natural resources were abundant and diverse. The glaciofluvial plains and glaciolacustrine plains are topographically subdued landforms, and along with the hummocky moraine, are distal to permanent water resources. These landforms are characterized by a lower intensity of occupation because of a consequence of lower resource availability and diversity. Archaeological site visibility and preservation varies within the region with the hummocky moraine and glaciolacustrine plains displaying the greatest degree of site visibility and preservation. The aeolian sand dunes, meltwater spillways, and glaciofluvial plains were physiographic elements that exhibit the lowest site visibility and preservation potential. These landforms were more strongly influenced by post-glacial climatic conditions, geomorphic processes, and the recent formation of the Lake Diefenbaker reservoir.

A partir do padrão de distribuição das associações de foraminíferos ao longo de dois testemunhos e da sua correlação com características abióticas do sedimento, detectaram-se variações ambientais holocênicas ocorridas em dois embaiamentos marinhos rasos: as enseadas do Flamengo (Testemunho UB1) e da Fortaleza (Testemunho UB3), em Ubatuba, SP. Posteriormente, correlações foram estabelecidas entre as mudanças da composição faunística e curvas de variação do nível do mar existentes na literatura. O testemunho UB1 possui 222 cm de profundidade e foi coletado no Saco da Ribeira sob lâmina de água de 3,10 m. É constituído predominantemente por sedimentos sílticos que contêm fragmentos vegetais e biodetríticos. Camadas arenosas são encontradas em sua base, datada em 7290 + 40 anos A.P., e à profundidade compreendida entre 32 e 12 cm. O testemunho UB3 tem 342 cm de profundidade e foi coletado na Praia do Lázaro sob lâmina de água de 3,80 m. Seus sedimentos são predominantemente sílticos, contendo fragmentos vegetais, fragmentos vegetais oxidados e fragmentos biodetríticos. Seqüências arenosas e arenosiltosas são encontradas em sua base, datada em 7.530 + 40 anos A.P., e entre 32 e 12 cm de profundidade. Foram identificados 76 espécies e 40 gêneros de foraminíferos bentônicos e uma espécie de foraminífero planctônico nas 58 amostras analisadas, a cada 10 cm, ao longo dos dois testemunhos (23 amostras em UB1 e 35 em UB3). As associações observadas são típicas de ambiente marinho normal, de plataforma interna, com tendência redutora. Foraminíferos de testas hialinas predominam sobre foraminíferos de testas porcelanosas. Somente uma espécie de testa aglutinante foi encontrada em cinco amostras dispersas ao longo do testemunho UB3. As espécies bioindicadoras indicam ambientes com predominância da massa de Água Costeira, com energia de fundo moderada, alta acumulação de matéria orgânica e baixas concentrações de oxigênio, tanto para a Praia do Lázaro quanto para o Saco da Ribeira, nos últimos 7.500 anos A.P. Evidenciam, também, que a circulação de fundo no Saco da Ribeira se tornou cada vez mais restrita, enquanto na Praia do Lázaro a circulação hidrodinâmica não sofreu forte alteração. Os dados tafonômicos indicam que não houve processos post mortem capazes de alterar por completo as associações de foraminíferos analisadas ao longo de ambos os testemunhos. Todas as evidências microfaunísticas sugerem que houve, pelo menos, duas fases distintas de comportamento marinho para as duas enseadas ao longo dos últimos 7.500 anos A.P.: uma primeira, transgressiva, que teria durado até a, aproximadamente, 5.100 anos A.P., durante a qual as enseadas se encontravam conectadas; e outra de caráter geral regressivo, que se estendeu até a, pelo menos, 32 cm de profundidade em ambos os testemunhos, durante a qual teria surgido o Tômbolo do Saco da Ribeira, que passou a impedir a circulação entre a Praia do Lázaro e o Saco da Ribeira. / Variations in Holocene environments in the marine bays of Flamengo and Fortaleza at Ubatuba, State of São Paulo, southeast Brazil, were detected in cores UB1 and UB3, respectively, on the basis of the distribution pattern of foraminiferal associations and their correlation with abiotic characteristics of the sediments. Correlations were then established between changes in faunistic composition and existing sea-level variation curves. The UB1 Core measures 222 cm and was collected at Saco da Ribeira at a water depth of 3.1 m. This core is predominantly made up of silty sediments with biodetritus and plant fragments. Arenaceous layers at its base were dated by radiocarbon at 7.290 + 40 years B.P., and also occur between 32 and12 cm depth. The UB3 Core measures 342 cm and was collected at Praia do Lázaro at a water depth of 3.8 m. It is predominantly silty and contains fragments of plants, oxidized plants and biodetritus. Sandy and muddy sand layers were encountered at its base, with a radiocarbon age of 7.530 + 40 years B.P., and between 32 and 12 cm of depth. 76 species and 40 genera of benthic foraminifera and one species of planktonic foraminifera were identified in the cores. The observed associations are typical of normal marine, inner shelf environments, with low oxygen. Hyaline foraminifera predominate over porcelaneous species. Only one species of agglutinated test was found within the five samples of the UB3 Core. The bioindicator species indicate environments with a predominance of Coastal Water (CA), moderate hydrodynamic energy, high organic matter accumulation and low oxygen concentrations for both Praia do Lázaro and Saco da Ribeira since early on. They also show that the deep marine circulation in Saco da Ribeira has become ever more restricted from approximately 7.500 years B.P. until the present, while in Praia do Lázaro, deep circulation has not suffered any strong alteration. Taphonomical data suggest that there is no post mortem process capable of completely modifying the foraminiferal associations analyzed in the cores. All the microfaunistic evidence suggests at least two distinct phases of marine behavior for the two bays over the past 7.500 years: a former transgressive phase, that lasted until approximately 5.100 years B.P., during which the bays were connected; and a latter generally regressive phase, that would have extended itself until, at least, the depth of 32 cm in both cores, during which the appearance of the Tômbolo do Saco da Ribeira would have begun to hinder circulation between Praia do Lázaro and Saco da Ribeira.

A partir do padrão de distribuição das associações de foraminíferos ao longo de dois testemunhos e da sua correlação com características abióticas do sedimento, detectaram-se variações ambientais holocênicas ocorridas em dois embaiamentos marinhos rasos: as enseadas do Flamengo (Testemunho UB1) e da Fortaleza (Testemunho UB3), em Ubatuba, SP. Posteriormente, correlações foram estabelecidas entre as mudanças da composição faunística e curvas de variação do nível do mar existentes na literatura. O testemunho UB1 possui 222 cm de profundidade e foi coletado no Saco da Ribeira sob lâmina de água de 3,10 m. É constituído predominantemente por sedimentos sílticos que contêm fragmentos vegetais e biodetríticos. Camadas arenosas são encontradas em sua base, datada em 7290 + 40 anos A.P., e à profundidade compreendida entre 32 e 12 cm. O testemunho UB3 tem 342 cm de profundidade e foi coletado na Praia do Lázaro sob lâmina de água de 3,80 m. Seus sedimentos são predominantemente sílticos, contendo fragmentos vegetais, fragmentos vegetais oxidados e fragmentos biodetríticos. Seqüências arenosas e arenosiltosas são encontradas em sua base, datada em 7.530 + 40 anos A.P., e entre 32 e 12 cm de profundidade. Foram identificados 76 espécies e 40 gêneros de foraminíferos bentônicos e uma espécie de foraminífero planctônico nas 58 amostras analisadas, a cada 10 cm, ao longo dos dois testemunhos (23 amostras em UB1 e 35 em UB3). As associações observadas são típicas de ambiente marinho normal, de plataforma interna, com tendência redutora. Foraminíferos de testas hialinas predominam sobre foraminíferos de testas porcelanosas. Somente uma espécie de testa aglutinante foi encontrada em cinco amostras dispersas ao longo do testemunho UB3. As espécies bioindicadoras indicam ambientes com predominância da massa de Água Costeira, com energia de fundo moderada, alta acumulação de matéria orgânica e baixas concentrações de oxigênio, tanto para a Praia do Lázaro quanto para o Saco da Ribeira, nos últimos 7.500 anos A.P. Evidenciam, também, que a circulação de fundo no Saco da Ribeira se tornou cada vez mais restrita, enquanto na Praia do Lázaro a circulação hidrodinâmica não sofreu forte alteração. Os dados tafonômicos indicam que não houve processos post mortem capazes de alterar por completo as associações de foraminíferos analisadas ao longo de ambos os testemunhos. Todas as evidências microfaunísticas sugerem que houve, pelo menos, duas fases distintas de comportamento marinho para as duas enseadas ao longo dos últimos 7.500 anos A.P.: uma primeira, transgressiva, que teria durado até a, aproximadamente, 5.100 anos A.P., durante a qual as enseadas se encontravam conectadas; e outra de caráter geral regressivo, que se estendeu até a, pelo menos, 32 cm de profundidade em ambos os testemunhos, durante a qual teria surgido o Tômbolo do Saco da Ribeira, que passou a impedir a circulação entre a Praia do Lázaro e o Saco da Ribeira. / Variations in Holocene environments in the marine bays of Flamengo and Fortaleza at Ubatuba, State of São Paulo, southeast Brazil, were detected in cores UB1 and UB3, respectively, on the basis of the distribution pattern of foraminiferal associations and their correlation with abiotic characteristics of the sediments. Correlations were then established between changes in faunistic composition and existing sea-level variation curves. The UB1 Core measures 222 cm and was collected at Saco da Ribeira at a water depth of 3.1 m. This core is predominantly made up of silty sediments with biodetritus and plant fragments. Arenaceous layers at its base were dated by radiocarbon at 7.290 + 40 years B.P., and also occur between 32 and12 cm depth. The UB3 Core measures 342 cm and was collected at Praia do Lázaro at a water depth of 3.8 m. It is predominantly silty and contains fragments of plants, oxidized plants and biodetritus. Sandy and muddy sand layers were encountered at its base, with a radiocarbon age of 7.530 + 40 years B.P., and between 32 and 12 cm of depth. 76 species and 40 genera of benthic foraminifera and one species of planktonic foraminifera were identified in the cores. The observed associations are typical of normal marine, inner shelf environments, with low oxygen. Hyaline foraminifera predominate over porcelaneous species. Only one species of agglutinated test was found within the five samples of the UB3 Core. The bioindicator species indicate environments with a predominance of Coastal Water (CA), moderate hydrodynamic energy, high organic matter accumulation and low oxygen concentrations for both Praia do Lázaro and Saco da Ribeira since early on. They also show that the deep marine circulation in Saco da Ribeira has become ever more restricted from approximately 7.500 years B.P. until the present, while in Praia do Lázaro, deep circulation has not suffered any strong alteration. Taphonomical data suggest that there is no post mortem process capable of completely modifying the foraminiferal associations analyzed in the cores. All the microfaunistic evidence suggests at least two distinct phases of marine behavior for the two bays over the past 7.500 years: a former transgressive phase, that lasted until approximately 5.100 years B.P., during which the bays were connected; and a latter generally regressive phase, that would have extended itself until, at least, the depth of 32 cm in both cores, during which the appearance of the Tômbolo do Saco da Ribeira would have begun to hinder circulation between Praia do Lázaro and Saco da Ribeira.

The Devonian Taylor Group (the lower Beacon Supergroup), in the Taylor and Wright Valleys, southern Victoria Land (SVL), Antarctica, is separated from basement by a regional nonconformity, the Kukri Erosion Surface. Thereafter the Taylor Group sediments, observed in this thesis, are affected by two localized unconformities; the Windy Gully Erosion Surface, separating the Terra Cotta Siltstone Formation (TCzst) and older units from the younger overlying New Mountain Sandstone; and the Heimdall Erosion Surface (HES), separating the New Mountain Sandstone Formation (NMSst) and older units from the overlying Altar Mountain Formation. The depositional environments of the Windy Gully Sandstone, New Mountain Sandstone and Altar Mountain Formations have long been under debate. The Kukri Erosion Surface (KES) truncates the crystalline basement and separates the basement rock from the overlying Beacon Supergroup. Interpretation of the erosion surface characteristics and the directly overlying basal conglomerate lithofacies (WG-BCL) suggest a high relief rocky shore platform environment during a sustained and significant relative sea level fall. The environment has been suggested to be similar to what is currently seen on the West Coast, New Zealand today. The Windy Gully Sandstone Formation directly overlies the KES and consists of a basal conglomerate (WG-BCL) followed by moderately to well sorted tabular and trough cross bedded felds- to subfeldsarenites. At one location an interbedded siltstone and cross bedded sandstone lithofacies was observed and interpreted as a tidal flat. Overall interpretation of the WGSst suggests continued progradation from a rocky shore platform (WG-BCL) to a series low angle beach, to shallow marine, and back to low angle beach environments. This occurred during a relative sea level rise. Shallowing of the water column produced a gradational relationship with the Terra Cotta Siltstone Formation (TCzst).. The fine to very fine sandy mottled, well laminated siltstones moving to very fine fissile dark siltstones suggest a progression from sandy estuarine to a mud flat environment. The Terra Cotta Siltsone is truncated by the Windy Gully Erosion Surface The Windy Gully Erosion Surface is observed in the Handsley Valley by the presence of TCzst rip-up clasts in the directly overlying New Mountain Sandstone Formation. Elsewhere the horizon is either very sharp or has desiccation cracks present suggesting a cessation of deposition and subaerial exposure respectively. This suggests a small relative fall in sea level with only localized erosion. The New Mountain Sandstone Formation (NMSst) predominantly consists of a series of low angle tabular and higher angle trough cross beds. It has a subfeldsarenite base that progressively becomes a pure quartz arenites. Interpretation suggests an initial beach environment with rejuvenated sediments moving to quartzose shallow marine and back to beach environments. This represents a relative sea level rise with continued progradation The NMSst is truncated in the north by the HES forming a characteristic saw tooth pattern in the cross bedded sandstones; elsewhere the HES is represented by a feldspathic influx moving into the Altar Mountain Formation. The HES was formed due to a significant relative sea level fall leading to exposure and erosion of lithified NMSst cross beds in the north but continuation of deposition in the south. The Altar Mountain Formation consists of tabular and trough cross bedded subfields- to feldsarenites. The Odin Arkose Member directly overlying the HES is a granule to cobble conglomerate in the north where the HES is erosional and very coarse sand to granule feldsarenite in the south where the HES is conformable. This has been interpreted as a pebbly shore platform to coarse sandy to granular beach environment. The following Altar Mountain Formation is interpreted as a continuation of medium to coarse sandy beach environments with influxes of coarser sediments and possibly moving into shallow marine in places. Sequence stratigraphy identifies three stratigraphic sequences: S1, the Windy Gully Sandstone and Terra Cotta Siltstone Formations; S2, the New Mountain Sandstone Formation; and S3, the Altar Mountain Formation. The first two sequences (S1&S2) show a clear progression through transgression to a high stand systems tract through regression to a low stand systems tract. The Altar Mountain Formation follows a very similar trend but due to the lack of time and data the above measures have been speculated. Zircon age dating suggests the source of the sediments in the area come from the Neoproterozic Skelton Group and the DV2a Granite Harbour Intrusives, both directly underlying the sandstones but are exposed elsewhere in SVL. Laminated sandstone clasts within the New Mountain Basal Conglomerate Lithofacies (NM-BCL) are suggested to be sourced from recycled sediments directly below. Other exotic clasts are also observed in the lithofacies are of unknown origin.

Cette thèse porte sur l’étude des paléoenvironnements et des dynamiques morphologiques holocènes dans le bassin versant du Massengh et de ses confluences avec les oueds Sbiba et el Hathob (Tunisie du centre-ouest). Après l’étude du cadre physique de l’évolution des environnements holocènes et actuels, la thèse se concentre dans un premier temps, sur la chronostratigraphie des héritages et des archives sédimentaires. La reconstitution des paléoenvironnements et de la morphogenèse Holocène est tentée, dans un deuxième temps. En dernier lieu, la thèse fait porter l’analyse sur l’évolution morphodynamique actuelle du milieu fluvial à l’échelle de l’espace de confluences. / This thesis focuses on the study of paleoenvironmental and Holocene morphological dynamics in the watershed Massengh and its confluence with the wadis and Sbiba el Hathob (Tunisia's center-west). After studying the physical part of the evolution of Holocene and current environments, the thesis focusesinitiallyon chronostratigraphy inheritances and sedimentary archives. The reconstruction of paleoenvironmentaland morphogenesis Holocene is attempted, in a second step. To summarize, the thesis studies in depth the currentmorphodynamic evolution of the fluvial environment across the space of confluences.

No description available.

No description available.

Questions remain regarding the impacts of late-Holocene human activities and environmental change on landscapes of the Caribbean islands. This dissertation examined the long-term environmental history of two sites in the northern Caribbean primarily through the analysis of proxy data sources contained in sediment cores. At Laguna Alejandro, a coastal lagoon in the southwestern Dominican Republic, we interpreted, from sediment lithology and stable oxygen isotope data, at least ten storm events over the past 1,000 years, producing the first long record of storm activity from the island. During the Little Ice Age (1400−1800 CE), we interpreted an increased frequency of hurricane landfalls at the study site with longer ecosystem recovery times and decreased fire activity versus during earlier, more moist periods of the late-Holocene. At Freshwater Pond, an inland pond on Barbuda, we interpreted vegetation disturbance from presence of disturbance pollen taxa and biomass burning near the pond from abundance of macroscopic (>125 µm) charcoal from sediments representing ~150 BCE–1250 CE, with consistency of burning and human history on the island informed by the archaeological record suggesting fire activity was primarily due to Pre-Columbian inhabitants. Microscopic charcoal analysis indicated that extra-local burning, primarily island-wide, continued until ~1610 CE then declined, possibly reflecting a change in land-use practices by Europeans who entered the region in 1492 CE and established a permanent settlement on the island in the 1660s. My study on modern pollen from surface soils and sediments, the first from lowland seasonally-dry vegetation of the Greater Antilles, informed our ideas on vegetation-pollen representation in different plant communities, including tropical dry forest, thorn forest, mangrove, mudflat, and lagoon. My modern pollen results also aided in the interpretation of stratigraphic pollen in the study of nearby L. Alejandro’s sediments and revealed changes in floristic composition at the study site through time. Pollen of maize (Zea mays) and Prosopis juliflora in sediments representing ~1760 CE document human subsistence agriculture and disturbance to tropical dry forest in the watershed. / PHD