155 pages / In the stratigraphic record of Camp Creek are episodes of fluvial scour and fill thousands of years old. Radiocarbon dates and the Mazama tephra, which serves as a stratigraphic time line, temporally bracket episodes of vertical aggradation and incision. Before 9000 years B.P. the valley floor was scoured to the Tertiary bedrock. Aggradation dominated since that time. Large cut-and-fill structures indicate that two periods of erosion occurred prior to incision of the modern arroyo. The first occurred before 6800 yr B.P. and the second occurred approximately 3000 years ago. The modern arroyo-channel flows at or near the Tertiary bedrock, is entrenched as much as nine meters in the valley-fill alluvium and is thought to have originated during the late 19th century.

A baixa temperatura média anual (< 18ºC), a localização em zona de altitude elevada (> 1500 m) e a diversidade florística, bem representativa da parte sul da serra da Mantiqueira, tornam a região de Monte Verde (município de Camanducaia, sudeste do Estado de Minas Gerais), propícia para a investigação de mudanças climáticas ocorridas no Quaternário tardio, meta desta Dissertação. Para buscar esta meta, propõe-se como objetivo a análise e descrição da sucessão paleoflorística, integrada ao aporte sedimentar e às condições geoquímicas de deposição nesta região, com base de dados palinológicos, sedimentológicos (granulometria, concentração de matéria orgânica e teor e tipos de minerais pesados) e geocronológicos (datações 14C por espectrometria de aceleração de massa). A área amostrada foi a margem esquerda do Córrego dos Cadetes, afluente do rio Jaguari. Trata-se de um vale fluvial encaixado em alvéolo de relevo acidentado, onde se coletou testemunho raso (2,10m) contínuo, com equipamento vibrocorer (vibro-amostrador). Os depósitos sedimentares tertemunhados são argilo-arenosos orgânicos e turfosos. Sua análise sedimentológica demonstra a ocorrência de variações graduais e cíclicas relacionadas a mudanças no balanço entre aporte sedimentar terrígeno e biodretítico e/ou orgânico, controlado por alterações no tipo de processo deposicional, e, por extensão, na cobertura vegetal, esta possivelmente influenciada por oscilações climáticas do Quaternário Tardio. As cinco datações obtidas ficaram compreendidas no intervalo entre 20830-20370 anos 14C cal A.P. (100 cm de profundidade) e 2350?2150 anos 14C cal A.P. (10 cm). Os dados palinológicos permitem interpretar que durante todo esse período a região foi dominada por floresta, principalmente com a presença de Araucaria angustifolia, sob clima predominantemente frio e úmido, porém com possíveis oscilações de umidade. Para efeito de inferências paleoclimáticas, quatro fases principais foram identificadas, expressas a seguir em idades extrapoladas. A primeira fase corresponde ao intervalo de 17000 a 15000 anos A.P., no qual há oscilação da cobertura vegetal e aumento de erosão nas encostas, sob clima frio e úmido. Na segunda fase, de 15000 a 9000 anos A.P., detectou-se aumento de umidade acompanhado da redução do aporte trativo. A terceira fase, correspondente ao intervalo de 9000 a 8000 anos A.P., registra decréscimo na umidade e aumento da taxa de sedimentação. Nos últimos 8000 anos A.P., ocorre a manutenção da floresta de Araucaria em condições climáticas frias e úmidas. / Low annual average temperature (< 18ºC), the localization in a zone of high altitude (> 1500 m) and high floristic diversity, representative of the southern part of the Serra da Mantiqueira highlands, turn the Monte Verde region (city of Camanducaia, Southeast of the State of Minas Gerais), propitious for the inquiry of Late Quaternary climatic changes, the aim of this dissertation. The objective of the study is to analyze and describe the paleofloristic succession based on palynology, integrated with sedimentological (grain size and heavy mineral analysis), geochemical (quantification of organic matter) and geochronological (14C AMS dating) data. The sampled area is located at the left margin of the Cadetes stream, a tributary of the Jaguari River. A 2.10 m long sediment core was collected on the fluvial valley with a vibrocore equipment. The sandy-clay sediments show a high organic content and are similar in appearance to peatbog deposits. The sedimentological analysis demonstrate the occurrence of gradual and cyclic variations related to the change in incoming of terrigenous biodetrital/organic sediments, controlled by alterations in the type of depositional process, and, therefore, possibly by the vegetation cover. All these changes were possibly influenced by climatic oscillations of the Late Quaternary. The five 14C AMS dates obtained encompass the period between 20830-20370 14C cal. A.P. (100 cm of depth) and 2,350-2,150 years 14C cal. A.P. (10 cm). The palynological results indicate that in the last 20,000 years the landscape was characterized by Araucaria angustifolia forest under predominantly cold and humid climates, with minor oscillations of humidity. Four pollen phases had been identified, with extrapolated ages for paleoclimatic inferences. The first one corresponds to the interval between 17,000 and 15,000 years A.P. with oscillation of the forest cover under cold and humid climate. Between 15,000 and 9,000 years A.P., there is an increase of humidity and reduction of tractive sedimentary supply. The third interval corresponds to the period between 9,000 and 8,000 years A.P. with a decrease in humidity and increase of the sedimentation rate. In the last 8,000 years A.P. Araucaria forest was maintained under cold and humid climatic conditions, as it did during the Late Pleistocene.

This thesis is missing page 57, this page is not in any of the other copies. -Digitization Centre / Scientists believe that the global climate is undergoing significant changes due to anthropogenic increases of carbon dioxide (CO2) and other Greenhouse gases. The relationship between climate and vegetation is not fully understood. Knowledge of the response of vegetation to past climate change aids in the understanding of potential vegetation responses to climatic changes due to the Greenhouse effect. The objectives of this thesis were to determine if vegetation in the lower Lena River Region has changed in the past, what were the factors which caused the changes and over what time scales did the changes occur. To address the objectives, the pollen, stomate and sediment stratigraphy of a core from a medium size lake, located in north-central Siberia, were analysed. Radiocarbon dating indicates that the record spans the last 12310 yr BP, and possibly the last 15000 yr BP. The early part of the fossil record was characterised by short rapid changes in the vegetation. The initial shrub tundra was quickly replaced by herb tundra with sparse vegetation cover. This was followed by a reversion to shrub tundra conditions at ~12000 yr BP. A clear Younger Dryas signal is found in this record between 11000 and 10000 yr BP, characterised by a shift from shrub tundra to herb tundra dominated by taxa with arctic affinities. The warming at the close of the Younger Dryas signalled the first appreciable climatic amelioration at this site. Following 10000 yr BP, Alnus became abundant in the pollen record and likely on the landscape. The dominance of Alnus was short lived however. At ~8500 yr BP arboreal vegetation, dominated by Larix dahurica, became abundant in the pollen and stomate record. The expansion of forests was the result of changes in the orbital parameters of the earth as predicted by Milankovitch cycles. Arboreal vegetation persisted in this region until-3500 yr BP when the modem shrub tundra vegetation was established. The use of a new technique, stomate analysis, proved extremely useful. Stomates accurately recorded the expansion and retreat of treeline across this region. This study clearly indicates the usefulness of this technique, especially for investigating fluctuations of treeline. / Thesis / Master of Science (MS)

This dissertation presents results from a multi-year interdisciplinary study of the Late Quaternary geomorphic history of northwest Calvert Island, British Columbia, Canada. There is a considerable knowledge gap in the region pertaining to Cordilleran ice cover and extent as well as landscape response to a uniquely stable relative sea-level history. The objective of this study was to reconstruct this regional landscape response to deglaciation including post-LGM ice cover and extent, relative sea-level changes, coastal landform development, and climate and ecological variance. Methods used to inform this reconstruction included airborne lidar, aerial photography interpretation, sedimentary stratigraphy and detailed sedimentology of samples from shovel pits and lake cores, surficial geology and geomorphic mapping, palaeoecological examinations, and the development of a geochronology using radiocarbon and optical dating. To assist with landscape reconstruction, a new method was developed and used to differentiate littoral and aeolian sands in sediment samples that range in age from Mid to Late Holocene by using modern reference samples. The method utilized a standard optical microscope paired with freely available software (ImageJ) to characterize grain shape parameters. The method was tested on nearly 6,000 sand grains from samples of known and hypothesized depositional settings and was able to correctly identify the depositional setting for 76% of the samples. After testing, the method was used to differentiate littoral and aeolian sands in a number of shovel pit, exposure, and core sediment samples to give context to stratigraphic and geomorphic interpretations. A short-lived Late Pleistocene re-advance of Cordilleran ice occurred in the study area, with radiocarbon ages indicating ice advanced to, and then retreated from, the western edge of Calvert Island between 14.2 and 13.8 ka cal BP, respectively. Sedimentological and palaeoecological information that suggests a cold climate and advancing/retreating glacier as well as lidar remote sensing and field-based geomorphic mapping of moraines in the region provide evidence of the re-advance. After ice retreated from the area, a broad suite of geomorphic landforms developed, including flood plains, iv aeolian dunes, beaches, spits, marshes, and tombolos. Coastal reworking was extensive, with progradation rates greater than 1 m a-1 occurring in some locations during the Late Holocene. These data provide the first evidence of a re-advance of the retreating ice sheet margin on the central coast of British Columbia, contribute an important methodology to advance Quaternary reconstructions, and give a unique account of the geomorphic development of a Pacific Northwest coastline that experienced little relative sea-level change over the Late Pleistocene and Holocene. Results help fill a spatial and temporal gap in the landscape history of British Columbia and have implications for climate and sea-level reconstructions, early human migration patterns, and the palaeoenvironment of an understudied area of the Pacific Northwest coast of North America. / Graduate / 0368 / 0372 / 0426 / jeamer7@gmail.com

No description available.

This thesis investigates new late Quaternary vegetation records from four sites in the Craven District of the Yorkshire Dales. The chosen sites fall along an east-west transect broadly following the line of the south Craven Fault. The rationale for site selection was not based on conventional palynological considerations of potential for rich core samples, rather to provide a range of different locations within a distinct micro-region each existing in some specific proximity to known archaeological features. The logic was to attempt to get beyond broad 'natural' climatological and vegetational inferences to understand the nature and level of potential anthropogenically produced change at a local scale as a sub-set of natural change in a broader regional zone over time. The sites reveal varied vegetation histories from the Late Glacial period to the present day and all show signs of being influenced by changes in their arboreal structure at some time, although no two sites have exactly the same vegetation communities until around 5000 BP when the tree canopy is opened to allow an open grassland to dominate. The results indicate the possibility that Betula values, in particular, might indicate cooling events found in the Greenland ice cores for Greenland Interstadial 1 as well as the Pre-boreal Oscillation and the Holocene 9.3 ka BP Event. Closer chronological control of such values could help to determine whether vegetational dynamics were synchronous with fluctuations in temperature and the speed with which trees respond to severe temperature fluctuations. Various hiatuses identified during analysis of the cores may be caused by human influence on the wetlands, given that archaeological evidence from caves shows human occupation of the Craven area from the late Upper Palaeolithic onwards.

Considerada a maior ilha flúvio-marítima do mundo, com aproximadamente 48.000 km2, a Ilha de Marajó situa-se na zona equatorial brasileira, no litoral do Estado do Pará. Apresenta dois domínios distintos relacionados a geologia e vegetação. No setor oeste dominam solos desenvolvidos sobre os sedimentos Pós Barreiras (plio-pleistocênicos) recobertos pela Floresta Amazônica, enquanto no setor leste dominam sedimentos holocênicos derivados de ambiente fluvial/estuarino atualmente desativado. Neste setor encontram-se os extensos campos naturais marajoaras. O objetivo deste trabalho consistiu em aplicar os isótopos de carbono (12C, 13C e 14C) da matéria orgânica de solos e sedimentos com o intuito de avaliar possíveis modificações nos domínios da vegetação, em termos de plantas C3 e C4, durante o Quaternário Tardio e inferir sobre suas causas. Os resultados foram associados com observações de campo e análises petrográficas, sedimentológicas, químicas, de espículas de esponjas, isótopicas de nitrogênio e bibliográficas, sendo possível distinguir três mudanças ambientais relacionadas à geologia e vegetação, no setor leste da Ilha de Marajó durante o Pleistoceno Superior (aproximadamente 16.000 anos AP) ao Holoceno. No setor central da Ilha de Marajó foram obtidas as idades mais antigas da matéria orgânica em sedimentos de um paleocanal. Neste local, no intervalo Pleistoceno Superior-Holoceno Inferior, os dados isotópicos do carbono são característicos de plantas C3, com exceção de dois pontos correspondentes a 16.118 ± 60 anos AP e aproximadamente 13.000 anos AP, com valores de \'delta\' 13CPDB de -20,4 e -22,1 respectivamente. A relação entre os resultados isotópicos do carbono e nitrogênio indicam a presença de plantas terrestres (gramíneas C4) nesta região, atualmente ocupada por vegetação arbórea, provavelmente associada a clima mais seco. A presença de fragmentos vegetais carbonizados e minerais instáveis ao intemperismo químico como feldspato, hornblenda e biotita nos sedimentos, confirmam a hipótese. Nos demais pontos analisados, durante o Holoceno Médio/Superior (entre aproximadamente 5.000 a 3.000 anos AP) os dados isotópicos do carbono e de fragmentos vegetais carbonizados indicam que uma vegetação constituída por plantas C3 (arbóreas) no setor leste da ilha foi gradativamente substituída por gramíneas C4, iniciando a formação dos atuais campos na Ilha de Marajó, associados a um clima mais seco. Neste mesmo período os canais foram sendo abandonados, como indicado pela granodecrescência ascendente dos sedimentos de paleocanais e mudança da coloração (de cinza para marrom alaranjado) dos sedimentos argilosos da planície de inundação, associados à deposição em um ambiente redutor para um ambiente oxidante. No intervalo redutor, em alguns perfis houve a formação de pirita e jarosita. Estudos anteriores mostram que o processo de abandono de canais está associado a eventos de tectônica cenozóica na região. Os dados isotópicos de carbono mais enriquecidos observados no setor sudoeste da ilha, indicam no período de ~7000 a 3000 anos AP, uma abertura da vegetação arbórea e/ou a presença de plantas C4, associados a um período mais seco. Durante o Holoceno Superior os canais foram preenchidos e abandonados. O empobrecimento isotópico do carbono da matéria orgânica indica a implantação da vegetação arbórea sobre os mesmos, estabelecendo a condição atual observada no setor leste da Ilha com paleocanais com vegetação de cobertura arbórea (plantas C3) e planície de inundação com vegetação de campos (plantas C3 e C4). Aanálise de espículas de esponjas e isótopos de nitrogênio apontam o setor leste como um sistema deposicional transicional (estuarino) durante o Quaternário Tardio. / Considered the largest fluvial-marine island of the world, with approximately 48.000 km2, the Marajó Island is located in the Brazilian equatorial area, in the Pará State coast. It presents two different domains related to the geology and vegetation. In the west domain dominate soils developed on Pós Barreiras sediments (plio-pleistocenics) covered by the Amazonian Forest, while in the east domain dominate holocenic sediments derived of fluvial/estuarine environment, at present deactivated. In this sector are located the natural savanna. The objective of this work consisted of to apply the carbon isotopes (12C, 13C and 14C) of soil and sediment organic matter, in order to evaluate possible changes in the vegetation domains, in terms of C3 and C4 plants during the Late Quaternary, and inferences about their causes. The results were associated with field observations, petrographic, sedimentologic, chemical, sponge spicules and nitrogen isotope analyses and bibliography, being possible to distinguish three environmental changes related to the geology and vegetation in the eastern Marajó Island during Late Pleistocene (approximately 16.000 years BP) to the Holocene. In the central section of the Marajó Island were obtained the oldest ages of the sediment organic matter of a paleochannel. In this place, in the interval Late Pleistocene - Early Holocene, the carbon isotope data are characteristic of C3 plants, except for two points corresponding to 16.118 ± 60 years BP and approximately 13.000 years BP, with values of \'delta\' 13CPDB of -20,4 and -22,1 , respectively. The relation between the carbon and nitrogen isotopes data, indicate the presence of terrestrial plants (C4 grass) in this area, at present covered by arboreal vegetation, probably associated to a drier climate. The presence of charred wood fragments and unstable minerals to the chemical weathering as feldspar, hornblend and biotite in the sediments, confirm the hypothesis. In other points, during Middle/Late Holocene (between ~5.000 and 3.000 years BP) the carbon isotopes and charred wood fragments data, indicate that a vegetation constituted of C3 plants (trees) in the eastern sector of the island, was gradually substituted by C4 grasses, initiating the formation of savanna vegetation in the Marajó Island, associated to a drier climate. In this same period, the channels were abandoned, as indicated by the fining upward the paleochannel sediments and the color change (grey to brown orange) of the clayey sediments of the floodplain, associated to the deposition of a reducing environment to an oxidizing environment. In the reducing interval, in some profiles it was observed the formation of pirite and jarosite. Previous studies show that the channels abandonment processes is associated to tectonic Cenozoic events in the area. The more enriched isotope carbon data of soil organic matter observed in the Southwestern sector of the island, indicated in the period of ~7.000 and 3.000 years BP, an opening of the arboreal vegetation and/or the presence of C4 plants, probably associated to a drier climate. During the Late Holocene the channels were filled out and abandoned. More depleted carbon isotope data of the organic matter, indicates the implementation of the arboreal vegetation on the channels, establishing the modern conditions observed at the eastern section of the Island, with paleochannels covered by arboreal vegetation (C3 plants) and the floodplain covered by grassland vegetation (C3 and C4 plants). The sponge spicules and nitrogen isotope analysis, indicate the eastern section as a transitional deposition system (estuarine) during the Late Quaternary

Fossil Agamidae from Western Australia have been the subject of limited study. To aid in fossil agamid identification, Hocknull (2002) examined the maxilla and dentary of several extant species from Australia and determined diagnostic characters for various species groups. In the study here, fossil agamids from two localities in Western Australia, Hastings Cave and Horseshoe Cave, were examined, grouped, and identified to the lowest unambiguous taxonomic level. Morphometric analyses were conducted to compare morphotypes, and find additional diagnostic characters. From Hastings Cave there were two maxilla morphotypes and three dentary morphotypes. Based on identifications, taxa present at this locality were Pogona and Ctenophorus. Horseshoe Cave contained three maxilla morphotypes and two dentary morphotypes; taxa present were Pogona, Tympanocryptis, and Ctenophorus. Morphometric analyses showed separation between groups; however, the dentary morphotype separation was not as clear. Each morphotype identification matched a species in the respective localities today, but identifications are cautious.

A high-resolution record of organic-walled dinoflagellate cyst production in Guaymas Basin, Gulf of California (Mexico) reveals a complex paleoceanographic history over the last ~40 ka. Guaymas Basin is an excellent location to perform high resolution studies of changes in Late Quaternary climate and paleo-productivity because it is characterized by high primary productivity, high sedimentation rates, and low oxygen bottom waters. These factors contribute to the deposition and preservation of laminated sediments throughout large portions of the core MD02-2515. In this study we document dinoflagellate cyst production at a centennial to millennial scale throughout the Late Quaternary. Based on the cyst assemblages three major dinoflagellate cyst zones, with seven subzones were established. The most dominant dinoflagellate cyst taxa found throughout the core were Brigantedinium spp. and Operculodinium centrocarpum. Dansgaard-Oeschger events 5-8 are inferred in the dinoflagellate cyst records on the basis of increases in warm taxa, such as Spiniferites pachydermus. Preceding and during the Last Glacial Maximum cysts of Polykrikos cf. kofoidii increase in abundance, responding to oceanographic changes in the Gulf of California perhaps caused by a regression in sea-level. Other intervals of interest are the Younger Dryas where cooler conditions are not recorded, and the Holocene which is characterized by the consistent presence of warm water species Stelladinium reidii, Tuberculodinidum vancampoae, Bitectatodinium spongium and an increase in Quinquecuspis concreta. Changes in cyst assemblages, concentrations and species diversity, along with geochemical data reflect major millennial scale climatic and oceanographic changes. / Graduate

During the Late Quaternary, abrupt climate and cultural changes took place and made alternations to the past landscape. Climatic phenomena such as expand of ice masses,sea level rise, high and low temperatures, migration of humans, decline and increase of forest areas and more changes were the reason of changing the biodiversity of species and the formation of the land. Here cartographic maps with the use of GIS will be presented from reconstructions of the environment during the Late Quaternary, which then will be interpreted from coleopteran fossils for the whole of Europe. Furthermore, living and extinct species will be compared, in which the focus of the extinction will be in the British Isles. Each period will show a different abundance of species, the regional disappearance of the species will be depicted by the abrupt changes in the landscape during the past. Anthropogenic and natural factors will be discussed and be compared with the habitats of the species.