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Bullock, Michelle. „Holocene sediments and geological history, Woolley Lake, near Beachport, South Australia /“. Adelaide : Thesis (B. Sc.(Hons)) -- University of Adelaide, Dept. of Geology and Geophysics, 1994. http://web4.library.adelaide.edu.au/theses/09SB/09sbb938.pdf.
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Webb, Robert H. „Late Holocene flooding on the Escalante River, south-central Utah“. Diss., The University of Arizona, 1985. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1985_248_sip1_w.pdf&type=application/pdf.
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Huang, Guangqing. „Holocene record of storms in sediments of the Pearl River Estuary and vicinity /“. Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21687808.
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Burbidge, Susan M. (Susan Margot) Carleton University Dissertation Earth Sciences. „Holocene environmental history of lake Winnipeg; thecamoebians and stable lead isotopes“. Ottawa, 1997.
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Heine, Jan T. „Glacier advances at the Pleistocene/Holocene transition near Mount Rainier volcano, Cascade Range, USA /“. Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/6748.
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Selby, Katherine. „Late Devensian and Holocene relative sea level changes on the Isle of Skye, Scotland“. Thesis, Coventry University, 1997. http://curve.coventry.ac.uk/open/items/0e151cae-7151-0ae4-e4f3-99a45f12ce84/1.
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Five coastal sites have been studies on the Isle of Skye to investigate Late Devensian and Holocene relative sea level changes. In the field, detailed stratigraphical work, geomorphological mapping and levelling were undertaken and representatives cores were sampled. Detailed pollen and diatom analyses were undertaken in the laboratory and samples were submitted for radiocarbon assay where distinct pollen, diatom or lithostratigraphical changes were recorded. Loss on ignition analysis was also undertaken to ascertain the carbon content of the samples. The investigations have revealed that during the Late Devensian marine transgressions were experienced at two sites in southern Skye. These are thought to relate to readvances of the ice that arrested the isostatic recovery of the land, caused renewed isostatic depression and upon deglaciation, allowed marine waters to penetrate the sites. At Inver Aulavaig the transgression is thought to relate to the Wester Ross Readvance recorded in Wester Ross, Coll and Tiree and at Point of Sleat the transgression is thought to relate the Loch Lomond Readvance recorded extensively in Scotland. Relative sea level at Point of Sleat (southern Skye) then fell below an altitude of 4.13mOD at 10460+-50BP and remained low during the early Holocene until the Main Postglacial Transgression occurred. This transgression is recorded at three of the sites: at Inver Aulavaig (southern Skye) at 8850+-70BP where it had attained an altitude of at least 5.10mOD, at Peinchorran (eastern Skye) where it is thought to have been underway by 7980+-BP and attained an altitude of 4.49mOD and at Talisker Bay (western Skye) at 7790+-100BP where it had attained an altitude of -2.18mOD. At Ardmore Bay (northern Skye) it is thought that the Main Postglacial Transgression did not reach an altitude of 3.34mOD. It is possible that barrier formation at some of the sites accompanied the early states of the Mian Postglacial Transgression. It is thought that regression of the sea occurred between circa 6600 BP and circa 5400 BP and remained low until circa 4200 BP when a later rise in relative sea level took place at Peinchorran attaining a maximum altitude of 4.90mOD. A late Holocene transgression is also recorded at Point of Sleat at between circa 3800 BP and circa 2900 BP where it attained an altitude of greater than 4.13mOD and at Inver Aulavaig after circa 3200 BP where it attained an altitude of between 5.10-6.01mOD. It is unclear whether this episode of high relative sea level represents the diachronous nature of one late Holocene transgression or several fluctuations in relative sea level during the late Holocene. Following the late Holocene transgression, relative sea level fell until the present day. Comparison of the data obtained from Skye with the isobase maps and rheological models suggests that the isobases for the Main Lateglacial Shoreline (Firth et al., 1993) show a good fit in age and altitude but the rheological model of Lambeck (1993b) for 10500 BP requires modification. The isobases for the Main Postglacial Shoreline appear to lie circa 4m too high for the sites studied on Skye and the isobases produced for a late Holocene shoreline appear to be greatly in error (Firth et al., 1993). It is possible that the build up of ice during the Loch Lomond Stadial may have had a greater effect on crustal movements than previously thought and this may account for discrepancies identified in the isobase maps. The study of isolation basins and back-barrier environments has allowed an assessment of their potential in recording relative sea level changes. The use of isolation basins in areas devoid of estuarine sedimentation has been particualrly demonstrated. The vegetation reconstruction undertaken, suggests that variations do occur in coastal locations compared to sites further inland, although these are subtle. The dates obtained for the increase in taxa such as 'Corylus avellana' and 'Alnus' and the recording of anthropogenic indicators on the vegetation, agree with those previously obtained for Skye. The use of pollen analysis in verifying the radiocarbon dates obtained, particualrly for the Late Devensian, has been recognised and, combined with diatom analysis, has provided a comprehensive database from which to reconstruct past relative sea levels.
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McGinnis, Benjamin Adam. „Late Holocene evolution of a retrograding barrier : Hutaff Island, North Carolina /“. Electronic version (PDF), 2004. http://dl.uncw.edu/etd/2004/mcginnisb/benjaminmcginnis.pdf.
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Lee, Ting Jennifer. „Holocene evolution of a hypersaline lake Lagkor Tso, western Tibet /“. Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B39634140.
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Freeman, Andrea Kelly Lee. „Middle to late holocene stream dynamics of the Santa Cruz River, Tucson, Arizona : implications for human settlement, the transition to agriculture and archaeological site preservation“. Diss., The University of Arizona, 1997. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1997_349_sip1_w.pdf&type=application/pdf.
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Bridgeman, Jonathan G. „Understanding Mississippi Delta Subsidence through Stratigraphic and Geotechnical Analysis of a Continuous Holocene Core at a Subsidence Superstation“. Thesis, Tulane University School of Science and Engineering, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10789629.
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Land-surface subsidence can be a major contributor to the relative sea-level rise that is threatening many coastal communities. Loosely constrained subsidence rate estimates across the Mississippi Delta make it difficult to differentiate between subsidence mechanisms and complicate modeling efforts. New data from a nearly 40 m long, 12 cm diameter core taken during the installation of a subsidence monitoring superstation near the Mississippi River, southeast of New Orleans, provides insight into the stratigraphic and geotechnical properties of the Holocene succession at that site. Stratigraphically, the core can be grouped into four units. The top 12 m is dominated by clastic overbank sediment with interspersed organic-rich layers. The middle section, 12–35 m, consists predominately of mud, and the bottom section, 35–38.7 m, is marked by a transition into a Holocene-aged basal peat (~11.3 ka) which overlies densely packed Pleistocene sediment. Radiocarbon and OSL ages are used to calculate vertical displacement and averages subsidence rates as far back as ~3.5 ka, yielding values as high as 8.0 m of vertical displacement (up to 2.34 mm/yr) as obtained from a transition from mouth bar to overbank deposits. We infer that most of this was due to compaction of the thick, underlying mud package. The top ~80 cm of the core is a peat that represents the modern marsh surface and is inducing minimal surface loading. This is consistent with the negligible shallow subsidence rate as seen at a nearby rod-surface elevation table–marker horizon station. Future compaction scenarios for the superstation can be modeled from the stratigraphic and geotechnical properties of the core, including the loading from the planned Mid-Barataria sediment diversion which is expected to dramatically change the coastal landscape in this region.
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Callefo, Flávia 1983. „Análise tafonômica e paleoecológica de estruturas associadas a comunidades microbianas holocênicas e permianas“. [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287739.
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Orientador: Fresia Soledad Ricardi Torres BrancoDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências
Made available in DSpace on 2018-08-25T01:31:00Z (GMT). No. of bitstreams: 1 Callefo_Flavia_M.pdf: 11737292 bytes, checksum: 8072787b62f7e014cd2301d513fc4a17 (MD5) Previous issue date: 2014
Resumo: Esteiras microbianas são estruturas organossedimentares laminadas, desenvolvidas a partir do acréscimo de lâminas de sedimentos aprisionados através do metabolismo de microrganismos, que induzem a precipitação de carbonato. Microbialitos são depósitos organossedimentares formados pela interação de microrganismos com sedimentos detríticos, através dos processos de trapeamento e aglutinação dos grãos e minerais. Esta pesquisa apresenta os resultados obtidos com o estudo tafonômico e paleoecológico de estruturas desenvolvidas por atividade de microrganismos, como estromatólitos, microbialitos e esteiras microbianas, com o intuito de comparar os resultados e traçar similaridades e diferenças nas relações ecológicas e ambientes de formação . Foram utilizados modelos recentes (Holoceno), como a Lagoa Salgada e Lagoa Pitanguinha, RJ, para compreender modelos fósseis (Permiano), afloramentos em Taguaí e Santa Rosa do Viterbo, SP. A metodologia se constituiu em análise de sedimentos associados, petrografia, análises composicionais (como MEV/EDS e Espectroscopia Raman) e estudo de campo. Foram levados em consideração os aspectos ambientais e biota contemporânea ao crescimento e desenvolvimento dos microbiais. As principais conclusões obtidas foram que os ambientes apresentam similaridades com relação a biota desenvolvida, bem como as relações ecológicas que estas mantinham com as comunidades microbianas responsáveis pelo desenvolvimento dos microbialitos e esteiras microbianas. O ambientes de crescimento das estruturas eram marinhos de águas rasas e hipersalinas, com o clima quente e alta taxa de evaporação. A alternância de eventos de tempestades e águas calmas, com posterior período de calmaria no qual foi possível o desenvolvimento de esteiras microbianas foram evidenciados no afloramento de Taguaí e na Lagoa Pitanguinha. Os microbialitos recentes da Lagoa Salgada sofreram maior influência de atividade de predação e herbivoria por parte de invertebrados, o que pode ter sido um fator relevante para a limitação do crescimento destas estruturas em comparação com aquelas existentes em Santa Rosa do Viterbo
Abstract: Microbial mats can be defined as laminated organosedimentary structures developed from the addition of laminaes of sediments trapped trough microorganisms metabolism, which leads to carbonate precipitation. Microbialites are organosedimentary deposits generated by the interation between microorganisms and detritic sediments through trapping and agglutination of minerals and grains play a key role. This research present the results of taphonomic and paleoecological studies from of structures developed by the activity of microorganisms such as microbialites, stromatolites and microbial mats aiming to comparison between the results obtained and to map similarities and differences on the ecological relations and formation environments. Recent models such as Salgada Lagoon and Pitanguinha Lagoon (Holocene), both located on Rio de Janeiro, were used to understand permian fossils models, outcrops located in Taguaí and Santa Rosa do Viterbo/SP. The methodology was based on the analysis of associated sediments, petrography and compositional analysis (MEV/EDS and Raman Spectroscopy) besides field studies. Aspects such as recent environments and biotas were considered to the analysis. The main conclusions were that the environments present similarities based on the development of the biotas as well as the ecological relations which those developed within the microbial communities responsible for the development of the microbialites and microbial mats. The growth environments of the structures were classified as shallow marine hypersaline waters, with warm weather and high evaporation rates. There was an alternation between storm events and calm waters. The growth of microbial mats became possible when the waters were predominantly calm evidenced by the outcrops from Taguaí and Pitanguinha Lagoon. The recent microbialites from Salgada Lagoon had a greater influence by activities from predators and herbivorous organisms such as invertebrates, which may be a relevant factor for the limitation growth of these structures when compared with those founded at Santa Rosa do Viterbo
Mestrado
Geologia e Recursos Naturais
Mestra em Geociências
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Brown, Kendrick Jonathan. „Late quaternary vegetation, climate, fire history, and GIS mapping of Holocene climates on southern Vancouver Island, British Columbia, Canada“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ52755.pdf.
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Mok, Ka-man, und 莫嘉敏. „[Delta]¹³C as a palaeo-environmental indicator in a sediment core fromHong Kong“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B49770470.
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A study of marine palaeo-landscape development through a sediment core in the western Hong Kong waters has been carried out in this project as the sedimentation record could reflect the environmental changes during the Holocene period.
The objectives of this study was to reveal the influences of Holocene post-glacial sea-level fluctuations and the monsoonal freshwater discharge changes to the sedimentation processes in the mouth region of the Pearl River Estuary. These are the two important factors which shape the palaeo-landscape development.
Data has been obtained from a ground-truthing vibrocore to 35m below the seafloor at the south of the Shek Pik Reservoir, south Lantau Island. The sediment core was subsampled for elemental analysis to study the sources of the organic carbon by use of stable carbon isotope ratio (Ϭ13C) and for particle size analysis to reveal the energy state of the sedimentary environment. Shell fragments were chosen for radiocarbon analysis to construct the core chronology and marine seismic profiles were obtained to present the sub-bottom geological layers.
The data is presented in the form of graphs and tables in showing the sediment changes along the core in different period of time. The data has been interpreted in relation to the knowledge of post-glacial sea-level rise and the proposed model of the Pearl River Estuary evolution from previous studies. Comparison is also made with other sediment cores around the Lantau Island to reveal the regional palaeo-environmental changes in the Holocene period.
It is concluded that the sediment core has revealed four major phases of environmental change which is in general agreement with the previous studies except this data set has also shown a few localized climatic events in the mid-Holocene period. The sea-level low stand in the late Pleistocene had incised a network of drainage system on the exposed continental shelf which is the north South China Sea in present time. The rapid rising sea-level by Melt Water Pulse 1B filled the palaeo-valleys with alluvium deposits from 10600 to 9000 cal. yr BP at high sedimentation rate and the East Asian Monsoon was strengthened from 8800 to 5500 cal. yr BP as shown by the freshwater organic carbon deposited in the marine environment. Unconfined deposition occurred when the sediments spilled out of the palaeo-valleys and slowly covered the basin in stable sea-level and low hydrodynamic conditions.published_or_final_version
Applied Geosciences
Master
Master of Science
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Hornsby, Kristofer Tyler. „Constraining the Holocene Extent of the Northwest Meers Fault, Oklahoma Using High-Resolution Topography and Paleoseismic Trenching“. PDXScholar, 2017. https://pdxscholar.library.pdx.edu/open_access_etds/3890.
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The Meers Fault (Oklahoma) is one of few seismogenic structures with Holocene surface expression in the stable continental region of North America. Only the ~37 km-long southeastern section of the ~55 km long Meers Fault is interpreted to be Holocene-active. The ~17 km-long northwestern section is considered to be Quaternary-active (pre-Holocene); however, its low-relief geomorphic expression and anthropogenic alteration have presented difficulties in evaluating the fault length and style of Holocene deformation. We reevaluate surface expression and earthquake timing of the northwestern portion of the Meers Fault to improve fault characterization, earthquake rupture models, and seismic hazard evaluations based on fault length. We use a combination of airborne lidar (0.5--2 m-resolution), historical aerial photos, and new balloon-based photogrammetric (Structure from Motion) topography (0.25--0.5 m-resolution) collected in this study to analyze and characterize the fault scarp and local fault zone geomorphology. In the northwest, complex surface deformation includes fault splays, a left step, subtle monoclinal warping, and a minor change in fault strike. The fault is evident in the landscape as linear escarpments, incised channels on the up-thrown side of the scarp, and closed depressions on the downthrown side. I use topographic profiles, measured perpendicular to the fault scarp to show that the northwest scarp is characterized by decimeter surface offsets. Where the fault traverses the Post Oak Conglomerate the fault zone width rarely exceeds 25 m, in the Hennessey Shale I document an increase in fault zone width with deformation occurring over 20 m to 115 m. I further examined the northwest section of the fault in a paleoseismic excavation where weathered Permian Hennessey Shale and a ~1--2 m-thick veneer of Holocene alluvial deposits have been folded and warped during three surface-folding earthquakes. In an adjacent stream exposure these units are also faulted near the ground surface. Paleoearthquake age modeling (Oxcal) constrained by accelerated mass spectrometry (AMS) dating of detrital charcoal and optically stimulated luminescence (OSL) dating of sandy alluvial beds indicates two earthquakes occurred since ~6152-5550 cal. years BP and one possibly older event along the erosional unconformity along the Hennessey Shale bedrock. This analysis lengthens the Holocene extent of the Meers Fault by ~6 km, to ~43 km, and extends the paleoseismic record of the Meers Fault to ~9598 cal. years BP. These data will improve fault-rupture and earthquake recurrence models used for seismic hazard analysis of the Meers Fault.
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Bleakley, Nerida Lynn. „Late holocene palaeoecology of Taynaya Bay : the relationships between diatom assemblages and sediment composition in Antarctic coastal environments, and their response to regional climate change. Volume 1“. Monash University, School of Geography and Environmental Science, 2003. http://arrow.monash.edu.au/hdl/1959.1/5784.
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Gouw, Marc Jean Pierre. „Alluvial architecture of the Holocene Rhine-Meuse delta (The Netherlands) and the Lower Mississippi Valley (U.S.A.) /“. Utrecht : Koninklijk Nederlands Aardrijkskundig Genootschap [u.a.], 2007. http://www.loc.gov/catdir/toc/fy0803/2008400359.html.
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Gouw, Marc. „Alluvial architecture of the Holocene Rhine-Meuse delta (the Netherlands) and the Lower Mississippi Valley (U.S.A.) /“. Utrecht : Koninklijk Nederlands Aardrijkskundig Genootschap, Faculteit Geowetenschappen Universiteit Utrecht, 2007. http://www.loc.gov/catdir/toc/fy0803/2008400359.html.
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Lee, Ting Jennifer, und 李婷. „Holocene evolution of a hypersaline lake: Lagkor Tso, western Tibet“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B39634140.
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Gates, Edward Breed. „The Holocene Sedimentary Framework of the Lower Columbia River Gorge“. PDXScholar, 1994. https://pdxscholar.library.pdx.edu/open_access_etds/4801.
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The Columbia River is the largest fluvially dominated estuary in the Pacific Northwest, yet the Holocene transgressive fill of this system has not previously been studied. Nearly 1500 industry borehole and water well records in the lower Columbia River basin (LCRB) were analyzed. These records document the sedimentary infilling of the lower 120 miles of the drowned river valley that occurred during the Holocene marine transgression (10-0 ka) . Of particular importance is a key stratigraphic marker horizon of volcanic tephra that has been identified throughout the LCRB. INAA was used to determine the geochemical composition of the target tephra layer. The tephra geochemistry was then compared to geochemical data from potential Cascade source volcanos to determine whether the tephra layers are geochemically related, and the possible age and source of the tephra. The geochemical comparisons indicate that the suspect tephra horizon was derived from the climax eruption of Mount Mazama approximately 6845 years ago. Cross-sections have been constructed that record the lateral and longitudinal depositional development of the river basin. Sediment grain size distribution data have also been compiled and shows that grain size distribution does not change with respect to subsurface elevation within the LCRB. The results indicate that the LCRB has been dominated by fine sand deposition throughout the Holocene period, and silt and clay sized fractions were bypassed through the system to be deposited offshore. A total volume of 74.6 km3 of sediment has accumulated in the basin since the time of the catastrophic floods 12,700 years ago. Sediment volume analysis was used to predict past fluvial sediment supply rates and sediment retention. The volume of sediment deposition from early to late Holocene time has decreased by a factor of 2.4. Sedimentation rates in the basin are estimated from a basin isopach of the Holocene fill and from an extrapolated sediment sea-level curve. Basin sedimentation rates ranged from 12. 6 mm/yr-1 for the early Holocene to 2. 5 mm/yr-1 for the late Holocene period. This factor of 5 decrease in the sedimentation rate also indicates that the Columbia River bypassed much of its fine grained fraction through to the marine environment during the mid-late Holocene.
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Gudmundsson, Hjalti Johannes. „Holocene glacier fluctuations and tephrochronology of the Öræfi district, Iceland“. Thesis, University of Edinburgh, 1999. http://hdl.handle.net/1842/15756.
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The aims of this thesis are to refine the tephrochronology of the Öræfi district, SE Iceland and assess the Holocene glacier fluctuations of the Öræfajökull ice cap. The pattern and timing of glacier fluctuations are determined using glacial geomorphology and tephrochronology, and the implications for palaeoclimate are assessed. Iceland is important to the study of global and regional climatic change because it is located close to both the marine and atmospheric Polar Fronts widely regarded as the key factors in the climate of the North Atlantic region. Six outlet glaciers were studied: Svinafellsjökull, Virkisjökull, Kotárjökull and Kviárjökull originating from the Öræfajökull ice cap and Skaftafellsjökull and Morsárjökull originating from the Vatnajökull ice cap. A long history of glacier fluctuations were found with a similar temporal pattern of glacier oscillation between the outlets of Vatnajökull and Öræfajökull. A maximum of eight advances have been identified. The oldest advance is inferred to date from the maximum of the last Glaciation ca. 18000 yrs BP. The first advance in the Holocene occurred ca. 9700 BP during a still-stand of the last Termination. The onset of the Neoglaciation occurred between 6000 BP and 4600 BP with an expansion of all of the studied glaciers. Subsequent smaller advances have been dated to ca. 3200 BP, ca. 1800 BP, ca. 700 BP, ca. 200 BP and ca. 80 BP. The most significant movement of the Polar front during the Holocene is likely to have occurred around 5000 BP, and, as a consequence, an estimated temperature cooling of ca. 2.5°C took place in Iceland, perhaps the greatest cooling since the last Termination. Within the broad pattern of change, glaciers in the study area show variability which represents local precipitation patterns, contrasting topography and change in glacier process. In this thesis a total of 22 silicic tephra layers are identified from over 90 profiles in the study area. The majority of these layers are dated to the latter part of the Holocene. Three silicic tephras were deposited during historical time (post 900 AD) namely, Vö ca. 900AD,HI104 and Ö1362. The Vö ca. 900 AD and the H1104 tephras are located for the first time. Specific prehistoric (pre 900 AD) tephras identified include Hekla-Ö, Hekla-4 and Hekla-S. The tephrochronology of the Öræfi district is also used to assess the eruption history of the Öræfajökull stratovolcano during the Holocene. Prehistoric eruptions are dated to ca. 9200 BP, ca. 6500 BP(?), ca. 4700 BP, ca. 2800 BP and ca. 1500 BP. Jökulhlaups accompanied the eruptions of 1727 AD, 1362 AD and ca. 1500 BP and are likely to have followed older eruptions of the volcano. A strong relationship occurs between volcanic activity of the Öræfajökull stratovolcano and the pattern of glacier fluctuations. This is explained as a response to isostatic crustal adjustment during ice cap growth and decay, and indicates a general relationship between volcanic activity and climate change.
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Sloss, Craig R. „Holocene sea-level change and the aminostratigraphy of wave-dominated barriers estuaries on the southeast coast of Australia“. Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060306.154507/index.html.
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Schlichting, Robert B. „Establishing the Inundation Distance and Overtopping Height of Paleotsunami from the Late-Holocene Geologic Record at Open-Coastal Wetland Sites, Central Cascadia Margin“. PDXScholar, 2000. https://pdxscholar.library.pdx.edu/open_access_etds/3361.
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Mapping and stratigraphic investigations of back barrier, open-coastal plain sites have been used to establish minimum inundation distances and wave heights of tsunami produced by great subduction zone earthquakes in the central Cascadia margin. Cascadia tsunami deposits have been reported for many coseismic subsidence events in bay marsh settings where tidal-channel features focus tsunami energy. Variable magnitude (8.5±0.5 Mw), frequency (500±300 yr recurrence), and rupture geometry produce widely varying computer model outcomes for Casdcadia tsunami inundation. The results presented in this thesis provide specific quantitative data regarding tsunami inundation at the open coast.
Anomalous sand sheets that have been characterized consist of well-sorted beach sand that fine up-section. The thickness of the deposits vary from 45 em to 0.2 em, and thin in the landward direction. Many of the sand layers include detrital caps. One to three detritus and mud lamina are intra-layered in the deposits. Marine diatoms and bromine, a marine tracer, increase in concentration at each of the sand layers.
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Chiti, Bernardo. „Holocene fluvial and marine influences and settlement interactions in the lower Ribble Valley, Lancashire, U.K“. Thesis, University of Stirling, 2004. http://hdl.handle.net/1893/1805.
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The evolution of the lower course and estuary of the river Ribble (Lancashire, U.K.) during the Holocene is the object of study, along with the history of sediment fluxes in them and their influence on past human settlements. Investigation of the valley floor geomorphology and terrace fill stratigraphy and sedimentology, as well as palaeoecological analysis and a number of 14C essays, allowed the reconstruction of Late Pleistocene and Holocene alluvial history and chronology of a reach at the transition point between fluvial and estuarine influences; the archaeological evidence is evaluated in this context. Alluviation and incision cycles led to the formation of four river terraces. The oldest terrace, rich in coarse-grained materials, seems to be of Pleistocene age. 14C dating on the second terrace would point to an Earliest Holocene or Younger Dryas age; the fill, however, comprises abundant fine-grained overbank sediments. Large parts of the unit were reworked during a phase of lateral channel activity that occurred prior to ca. 8900 cal BP; between then and ca. 6900 cal BP the river underwent meander cut-offs, after which limited lateral activity occurred. New alluviation occurred around 4700 cal BP, possibly related to the aggradation of the third terrace, though its fill is only certainly known, from archaeological evidence, to be of pre-Roman age. Channel size increase occurred by the time the terrace was deposited. The fill features abundant clayey sediments; it was incised at or after the end of the Roman period. The last terrace was deposited in the late first millennium AD mainly as overbank silts, and has since been incised again. Fluvial response appears mainly related to climate changes, river activity corresponding to shifts to wetter, cooler climate. Human action likely enhanced fluvial response in the historical period, leading to post-Roman incision and deposition. There seems to be a good connection between sediment production in the catchment and deposition downstream. Local factors also show a major importance in determining river response. Early Holocene fluvial history finds no match in other Northern English rivers; a different response to the same climate changes is apparent, possibly related to differences in sediment supply conditions. No clear evidence is found supporting an influence of sea-level change on river processes. On the other hand, it appears plausible river sediment input has a driving influence in enhancing or causing minor regressions recorded on the estuary. The conditions existing in Roman times could have allowed access from the sea to the Roman sites at the upper end of the Ribble estuary and by its North shore; a relative sea-level minimum could have caused a shift of focus in naval traffic from the former to the latter site.
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Dewey, Felicity Joy. „The sedimentology and palaeoenvironmental significance of vlei sediments on the Winterberg range, South Africa“. Thesis, Rhodes University, 1989. http://hdl.handle.net/10962/d1001897.
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Palaeoenvironmental reconstruction of the late Pleistocene and Holocene geological periods for central and southern Africa has been hampered by the erratic distribution of suitable sites, incomplete and inaccurately dated sequences and the limited nature of published data. One geomorphological feature which has supplied valuable evidence for fluctuations in past environmental conditions, is the vlei or dambo. The type-site of these waterlogged features is in south central Africa, but similar features have been described on other continents. The clastic and organic sediments contained within these features are affected by, and therefore reflect to some degree, the environment under which they were formed. The characteristics of the sediments supply information as to their transport and mechanisms of deposition. From these processes, the environmental conditions at the time of vlei formation can be inferred. The environmental history of the Eastern Cape region has been considerably neglected, and is far less well understood than other countries such as Malawi, Zambia and Zimbabwe. A study site in the Winterberg Range (Eastern Cape) was selected which permitted the comparison of two vleis, the objective being to establish an accurate late Pleistocene sediment chronology for the entire plateau area. Radiocarbon dates from organic layers indicate that these sediments span the last 12 000 years BP, suggesting that organic accumulation at this site began at roughly the same time as at sites further afield. The vlei sediments are analysed in terms of their morphology, particle slze distribution, and other physical and chemical characteristics. These data facilitate the construction of detailed stratigraphic diagrams and a chronological summary of sediment accumulation, from which the period and governing processes of vlei development under changing environments may be described. It is found that the Winterberg vleis contain sediments which respond to changes in the prevailing environment. This makes these sediments useful indices from which to trace such changes during the late Pleistocene and Holocene times. These features are found to be similar in many respects to those described elsewhere in Southern Africa. The study attempts to provide greater understanding of contemporary vlei processes and emphasises the necessity of their preservation, as finite and valuable resources, by future generations
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Metcalfe, Elisabet Joan. „Late-glacial through Holocene Stratigraphy and Lake-level Record of Rangely Lake, Western Maine“. Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/MetcalfeEJ2007.pdf.
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Hazard, Colby. „Validity of Holocene Analogs for Ancient Carbonate Stratigraphic Successions: Insights from a Heterogeneous Pleistocene Carbonate Platform Deposit“. BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/5496.
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Observations of modern carbonate depositional environments and their accompanying depositional models have been used for decades in the reconstruction and interpretation of ancient carbonate depositional environments and stratigraphic successions. While these Holocene models are necessary for interpreting their more ancient counterparts, they inherently exclude important factors related to the erosion, diagenesis, and ultimate preservation of sediments and sedimentary structures that are ubiquitous in shallow marine carbonate environments. Andros Island, Bahamas is an ideal location to examine the validity of Holocene conceptual models, where geologically young (Late Pleistocene) limestones can be studied immediately adjacent to their well-documented modern equivalents. For this study, two 3D ground-penetrating radar (GPR) datasets (200 MHz and 400 MHz) were collected at a schoolyard in northwest Andros. These surveys reveal the geometries and internal characteristics of a peloidal-oolitic sand wave and tidal channel in unprecedented detail. These two prominent features are underlain by low-energy lagoonal wackestones and packstones, and are bordered laterally to the northwest by wackestones-packstones intermixed with thin sheets of peloidaloolitic grainstone. A deeper radar surface is observed at approximately 6 m depth dipping gently to the west, and is interpreted to be a karstified exposure surface delineating the base of a complete depositional sequence. Interpretation of the 3D radar volumes is enhanced and constrained by data from three cores drilled through the crest and toe of the sand wave, and through the tidal channel. This study is the first of its kind to capture the complex heterogeneity of a carbonate depositional package in three dimensions, where various depositional environments, sedimentary structures, and textures (mudstone to grainstone) have been preserved within a small volume.The results from this study suggest that the degree of vertical and lateral heterogeneity in preserved carbonate successions is often more complex than what can be observed in modern depositional environments, where sediments can generally only be observed in two dimensions, at an instant in time. Data from this study demonstrate the value of using two overlapping GPR datasets at differing resolutions to image the internal characteristics of a complete carbonate depositional package in three dimensions. From these datasets, a depositional model similar to other Holocene and Pleistocene carbonate depositional models is derived.
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Jones, Nadia Sittara. „Investigating the Holocene History of Eliot Glacier, Mount Hood, Oregon“. PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/618.
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This research documents the Holocene glacial history of Mount Hood, Cascade Mountains, Oregon by analyzing a set of three lateral moraines abutting Eliot Glacier, the largest glacier on the mountain. This study seeks to: 1) establish the relative ages of these lateral moraines and 2) determine if these features represent distinct glacial advances. The hypothesis is that the lateral moraines for Eliot Glacier represent three distinct periods of glacial advance based on their position relative to the current glacier and other diagnostic indicators. Soil profiles of three positions (shoulder, backslope, and footslope) on the distal side of each lateral moraine were described in the field and samples were taken from each horizon for laboratory analyses of pH and particle size. The results of the soil analysis show that the soils developing on the moraine closest to the current glacier are poorly developed and significantly younger than the other two features. The closest moraine likely dates to the Little Ice Age (600-150 YBP) and has soils with an A/C profile and a classification of Andic Cryopsamment. The soils on the middle and furthest moraines from the glacier are similar in the profile sequence (Andic Haplocryepts). Silt bulges were noted in the mid-slope pits. The furthest moraine has deeper horizons and more color development than the middle moraine. Ash layers were found in the backslope soil profile (36-51cm deep) on the middle moraine. Additional lab testing confirms the ash layers originated from Mount Hood, but no date can be assigned. The eruptive history of Mount Hood points to the Timberline eruptive period (1,500 YBP) as a likely candidate for one of the ash deposits. This evidence suggests the middle moraine was actively forming during this period and is intermediate in age between the furthest moraine and the Little Ice Age Moraine; hence, this sequence of moraines indicates three distinct periods of glacial advance in the Neoglacial.
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Crowe, Douglas E. „Stratigraphy and geologic history, Bunces Key, Pinellas County, Florida / by Douglas E. Crowe“. University of South Florida, 2003. http://purl.fcla.edu/fcla/etd/SFE0000022.
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Title from PDF of title page.Document formatted into pages; contains 113 pages.
Thesis (M.S.)--University of South Florida, 1983.
Includes bibliographical references.
Text (Electronic thesis) in PDF format.
ABSTRACT: Bunces Key, a narrow, linear, barrier island on the west-central coast of Florida, was formed in 1961. Its growth and development since that time is well documented by aerial photography. Cores taken from the Key and surrounding areas reveal a stratigraphic succession of facies reflecting rapid vertical aggradation. Sedimentation began on a gently sloping platform through the landward migration of large scale bedforms (sand waves) during fair weather periods. Migration of these bedforms ceased when emergence and lack of continued overwash precluded further movement.
Vertical accretion to supratidal levels resulted from the continued onshore transport of sediment and subsequent welding to the previously formed bars. Stratigraphically, the barrier exhibits a "layer-cake" type of stratigraphy, with nearshore sediments overlain by foreshore, backbeach, and dune deposits. The backbarrier generally exhibits muddy lagoon sediments intercalated with washover and channel margin sediments.Fining upward washover sequences reflect the unstable nature of the island.
Low pressure systems commonly cause overtopping of the barrier, with the subsequent formation of tidal inlets and washover fans. Aerial photographs document the formation of an initial barrier that was breached twice prior to 1973. A second barrier formed in late 1973 just seaward of the initial island and subsequently grew through littoral drift to a length of 1.8 km. A narrow inlet (30 m) formed through the northern end of the island in 1982.
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Dittmers, Klaus Hauke. „Late Weichselian to Holocene sedimentation in the inner Kara Sea : qualification and quantification of processes = Sedimentationsprozesse in der inneren Kara-See (Spät-Weichsel bis Holozän) /“. Bremerhaven : Alfred-Wegener-Inst. für Polar- und Meeresforschung, 2006. http://www.gbv.de/dms/goettingen/510037178.pdf.
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Campo, Bruno <1984>. „The Pleistocene-Holocene Transition in the Po Plain (Italy): Stratigraphic Architecture and Sequence Stratigraphy from a Highly-Subsiding Basin“. Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7540/1/Tesi_dottorato_XXVIII_ciclo_Bruno_Campo_Esame_Finale_2016.pdf.
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This work focuses on the Late Pleistocene-Holocene transition in the southern Po Basin. Five areas were investigated, with the aim of unraveling the role of different allogenic factors (climate, eustacy, sediment supply) on stratigraphic architecture in the last 45 ky. The study starts from the distal portion of the basin (the coastal plain deposits) and then moves towards increasingly internal areas: the alluvial sector characterized by the Po channel belt deposits, and the mud-prone interfluvial succession between the Apenninic margin and the Po channel belt. In the coastal sector, high-resolution facies analysis, along with a well-constrained chronostratigraphic framework, led to the accurate paleoenvironmental reconstruction of the last 45 ky BP depositional history along the 93 km-long transect. It is also provided a sequence stratigraphic interpretation for the whole sedimentary succession. In the Po channel belt sector, based on 28 radiocarbon dates, facies interpretation from high-quality core descriptions and freshly-drilled continuous cores, the contrasting stratigraphic architecture of Late Pleistocene and Holocene deposits was highlighted. Changes in lithofacies and channel stacking patterns reveal the vertical superposition of amalgamated fluvial-channel sands (Late Pleistocene) and mud-dominated deposits (Holocene), with isolated fluvial-channel bodies. We also attempted to establish the link between facies architecture, sea-level fluctuations and climate changes. The 3rd study area (interfuvial succession) was selected to test a new method for paleosol identification, on the basis of geotechnical properties generated from pocket penetrometer values.
Through the reconstruction of the Biferno coastal deposits (4th study area, located ca. 300 km south of the Po Plain) we had the opportunity to document two coeval (Late Pleistocene - Holocene) coastal sedimentary successions, diverging in terms of shelf gradient and proximity to the LGM-lowstand Po Delta. The 5th study area, broadly coincides with Ferrara, was selected to show how high-resolution stratigraphic studies can be used for aquifer protection.
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Campo, Bruno <1984>. „The Pleistocene-Holocene Transition in the Po Plain (Italy): Stratigraphic Architecture and Sequence Stratigraphy from a Highly-Subsiding Basin“. Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7540/.
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This work focuses on the Late Pleistocene-Holocene transition in the southern Po Basin. Five areas were investigated, with the aim of unraveling the role of different allogenic factors (climate, eustacy, sediment supply) on stratigraphic architecture in the last 45 ky. The study starts from the distal portion of the basin (the coastal plain deposits) and then moves towards increasingly internal areas: the alluvial sector characterized by the Po channel belt deposits, and the mud-prone interfluvial succession between the Apenninic margin and the Po channel belt. In the coastal sector, high-resolution facies analysis, along with a well-constrained chronostratigraphic framework, led to the accurate paleoenvironmental reconstruction of the last 45 ky BP depositional history along the 93 km-long transect. It is also provided a sequence stratigraphic interpretation for the whole sedimentary succession. In the Po channel belt sector, based on 28 radiocarbon dates, facies interpretation from high-quality core descriptions and freshly-drilled continuous cores, the contrasting stratigraphic architecture of Late Pleistocene and Holocene deposits was highlighted. Changes in lithofacies and channel stacking patterns reveal the vertical superposition of amalgamated fluvial-channel sands (Late Pleistocene) and mud-dominated deposits (Holocene), with isolated fluvial-channel bodies. We also attempted to establish the link between facies architecture, sea-level fluctuations and climate changes. The 3rd study area (interfuvial succession) was selected to test a new method for paleosol identification, on the basis of geotechnical properties generated from pocket penetrometer values.
Through the reconstruction of the Biferno coastal deposits (4th study area, located ca. 300 km south of the Po Plain) we had the opportunity to document two coeval (Late Pleistocene - Holocene) coastal sedimentary successions, diverging in terms of shelf gradient and proximity to the LGM-lowstand Po Delta. The 5th study area, broadly coincides with Ferrara, was selected to show how high-resolution stratigraphic studies can be used for aquifer protection.
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Stoneman, Rob. „Holocene palaeoclimates from peat stratigraphy : extending and refining the model“. Thesis, University of Southampton, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317945.
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Gonthier, Nicole. „Holocene stratigraphy and sedimentation off the Great Whale River entrance, southeastern Hudson Bay“. Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61215.
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The regional distribution of Holocene sediments of eastern Hudson Bay off the Great Whale River mouth was mapped using a grid of reflection seismic lines over 60 km long and covering an area of approximately 800 km$ sp2$ and data from eight piston cores. A larger data base and a greater area of study than that used in previous studies significantly increases our understanding of the sedimentation and deglaciation processes that have occurred in the area since the last deglaciation. Based on the seismic records and piston cores, four stratigraphic units overlying the Proterozoic bedrock (unit 1) were defined and interpreted: unit 2, glacial till deposited by a westward flowing ice sheet; unit 3, glaciolacustrine stratified muds deposited in glacial Lake Ojibway; unit 4, postglacial marine muds deposited in Tyrell Sea; unit 5, distal fluvio-deltaic sediments from the Great Whale River. Textural and geochemical analyses of individual laminae suggest that unit 3 rhythmites are true varves; dark "summer" laminae were deposited mainly by underflows during the open water season, and light "winter" laminae were deposited by overflows-interflows under a seasonal ice cover. Unit 5 covers approximately 400 km$ sp2$ and occurs as a deltaic constructional wedge which reaches 11 km offshore of the Great Whale River entrance. It was deposited between 3500 BP and 2800 BP from material supplied by the erosion of the Sakami Moraine and of glaciolacustrine and marine muds exposed along the river banks.
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Maike, Christopher A. „A Flood-Tidal Delta Complex, The Holocene/Pleistocene Boundary, and Seismic Stratigraphy in the Quaternary Section off the Southern Assateague Island Coast, Virginia, USA“. University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1408097363.
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Dal, Bo Patrick Francisco Fuhr. „Mecanismos deposicionais e processos pedogenéticos em lençóis de areia eólica = a Formação Marília, Neocretáceo da Bacia Bauru, Brasil, e La Salina, Holoceno da Bacia Tulum, Argentina“. [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287349.
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Orientador: Giorgio BasiliciTese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociências
Made available in DSpace on 2018-08-19T17:33:24Z (GMT). No. of bitstreams: 1 DalBo_PatrickFranciscoFuhr_D.pdf: 16255266 bytes, checksum: aeb871c6c13a2eecaa543a21baa19f06 (MD5) Previous issue date: 2011
Resumo: Lençóis de areia eólica são áreas morfodeposicionais caracterizadas por morfologias planas e ausência de dunas com faces de avalancha. Exemplos atuais e antigos de lençóis de areia eólica são conhecidos em todos os continentes e descritos na literatura desde o Paleoproterozóico. Em áreas em sedimentação, areias com marcas onduladas eólicas formam a feição sedimentar mais conspícua e a identificação de arenitos com estratificação cavalgante transladante permite o reconhecimento de sucessões sedimentares de lençóis de areia eólica. Apesar de inúmeros estudos centrados na organização faciológica e caracterização de fatores de controle à gênese e distribuição de depósitos eólicos nessas áreas, a inter-relação entre depósitos eólicos e solos foi pouco abordada na literatura. O estudo de dois exemplos de lençóis de areia eólica nesta tese, a Formação Marília, Neocretáceo da Bacia Bauru, Brasil, e La Salina, uma área em sedimentação na Bacia Tulum, Argentina, permitiu a elucidação dos principais processos e fatores ambientais que influenciam a sedimentação eólica e a pedogênese nessas áreas. Os processos eólicos e pedogênicos parecem ocorrer em intervalos temporais distintos e respondem a mudanças ambientais alogênicas ao sistema, principalmente climáticas, que governam diferentes fases de estabilidade e instabilidade da superfície morfodeposicional e podem conduzir à criação de um registro sedimentar marcado por alternâncias cíclicas verticais entre depósitos eólicos e paleossolos. O modelo de construção, acumulação e preservação do sistema eólico também é condicionado a diversas variáveis autogênicas e alogênicas ao sistema e é distinto nos dois casos estudados. A construção do sistema eólico na Formação Marília foi diferenciada em duas fases paleoclimáticas, caracterizadas por maiores ou menores índices pluviométricos, que controlaram o suprimento e a disponibilidade sedimentar, enquanto em La Salina, o processo de construção não parece ter sido determinado por variações climáticas. A acumulação dos corpos geológicos foi favorecida nos dois sistemas eólicos devido à presença de cobertura vegetal e outros fatores estabilizadores à superfície dos lençóis. A preservação em ambos os sistemas foi controlada por subsidência tectônica seguida de progressivo soterramento dos corpos geológicos
Abstract: Eolian sand sheets are morpho-depositional areas characterized by flat or gently undulated sandy surfaces covered predominantly with wind ripples and slipfaceless dunes. Ancient and modern eolian sand sheets are known to occur in all continents and ancient examples are described in the literature since the Paleoproterozoic, being largely recognized in the sedimentary record by inversely graded climbing translatent strata. Although many sedimentological studies have focused on characterization of eolian facies and environmental factors favorable for sand sheet development, studies on dynamic interactions between eolian deposits and soils in sand sheet areas are still lacking. The study of the Late Cretaceous Marília Formation and the modern La Salina eolian sand sheet has contributed to understand which environmental factors act to promote soil development and principally those that operate to withhold its development and favors eolian sedimentation in eolian sand sheets. The eolian sedimentation and pedogenesis seem to occur in different environmental phases, mainly controlled by climate, which are responsible for the stability and instability of the morpho-depositional surface. Eolian sedimentation prevails during the phase of instability and construction of the eolian sand sheet, whereas soil formation are dominant during the stable phase, when unavailability or bypassing of sediments, allied with the development of a vegetation covering, led to the absence of sedimentation and erosional processes. The constructional phase of the eolian system in the Marília Formation was subjected to paleoclimate variations, which controlled sediment supply and availability, whereas in the La Salina area, the construction has not been directly affected by climate. Accumulations of geological bodies were favored by vegetation covering and soil development in the Marília Formation and have been occurring through stabilization of the accumulation surface by vegetation, thin mud veneers, and surface cementation in the La Salina. The preservation of both eolian systems was controlled by tectonically induced subsidence and burial
Doutorado
Geologia e Recursos Naturais
Doutor em Ciências
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Summa, Michelle Carlene. „Geologic Mapping, Alluvial Stratigraphy, and Optically Stimulated Luminescence Dating of the Kanab Creek Area, Southern Utah“. DigitalCommons@USU, 2009. https://digitalcommons.usu.edu/etd/506.
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At the turn of the century, Kanab Creek incised 30-meters into its alluvium, leaving behind fluvial terraces and thick basin fill sediments exposed along arroyo walls. Research objectives were to determine the timing and causes of past valley-filling and arroyo-cutting episodes along a 20 km-long reach of Kanab Creek in southern Utah. Fluvial deposits were mapped at the 1:12,000 scale and sediments were described and dated using Optically Stimulated Luminescence (OSL) and radiocarbon dating. The Kanab Creek valley can be divided into a narrow, upper terraced reach and a broad lower basin fill reach near Kanab, Utah. The most prominent terrace in the upper reach is Quaternary alluvial terrace 4 (Qat4), followed by Qat3, Qat2/3, and Qat2 map units. These are composed of tabular-bedded, fine-grained sand, silt, and clay layers. The Qat2/3 map unit is a both a fill and fill-cut terrace underlain by Qa4, Qa3, and Qa2 alluvium and is used when the Qat3 fill-cut (fill-strath) terrace can not be differentiated from the Qat2 fill terrace due to their similar geomorphic position. The Qat3 fill-cut terrace upstream correlates to ~8 meters of aggradation downstream. The youngest terrace, Qat1, is a minor terrace, composed of coarse-grained channel facies. More recent channel and floodplain deposits were deposited over the last century following arroyo cutting. OSL and radiocarbon results suggest at least four cycles of fluvial cutting and filling: >6-3.5ka (Qa4), ~3->1ka (Qa3), 0.7-0.12ka (Qa2), and post-1880 AD (Qa1). Correlation to regional climate records suggests major periods of aggradation correlate to regionally cooler and wetter climatic intervals. Periods of arroyo cutting occurred at >6ka, ~3ka, 1-0.7ka, and during historic arroyo cutting (1882-1914 AD), and correlate to regionally warmer, drier intervals. These periods of aggradation and incision are roughly contemporaneous with regional drainages, except for the large aggradation seen in Kanab Creek 6-3.5ka (Qa4). Analysis of terrace longitudinal profiles indicates Qat4 has the lowest concavity suggesting that Qat4 aggraded during a period of greater sediment supply and/or reduced flood regime. Although OSL samples exhibited some degree of incomplete zeroing, calculated ages using a minimum age model are consistent with radiocarbon results.
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Griffiths, Ann Hilary. „A stratigraphical, sedimentological and palaeoenvironmental analysis of Holocene and present-day coastal sedimentation : Wigtown Bay, S.W. Scotland“. Thesis, University of Glasgow, 1988. http://theses.gla.ac.uk/1455/.
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Evidence of Holocene marine transgression and regression in South-West Scotland is exhibited in the stratigraphical record of present and former coastal deposits. Remnant areas of Holocene coastal (including marine) sediments are preserved at the head of marine inlets and estuaries along the northern shore of the Solway Firth and may extend up to 10km inland, indicating significant changes in coastal configuration as a result of marine transgression and regression during the last 10,000 years.At the head of Wigtown Bay, former Holocene coastal deposits are well exposed along the incised meanders of the upper Cree estuary and Palnure Burn. Referred to in the literature as `carse deposits', these sediments are products of several different environments.During late-Pleistocene times and very early in the Holocene Epoch, the upper Cree estuary area north of Creetown was a low lying boggy environment. The area was marginally marine in character. The exact position of the palaeo-Cree is uncertain but the river flowed in a general NW to SE direction and may have been braided. The marine waters of the Holocene marine transgression flooded northwards, penetrating the upper Cree estuary c . 7,900 years B.P., leading to the deposition of low to high tidal-flats. By 6,480107 years B.P. local regression had begun and seaward progradation of high upper tidal-flats and marsh had started. This environmental situation prevailed until 5,000 years B.P., when incision occurred and terrestrial conditions became dominant.In the lower Cree estuary, waters of the Holocene marine transgression initially flooded the lower courses of rivers and rose to flood the hollows in the uneven surface of the fluvio-glacial deposits flanking the estuary.Accumulation of low tidal-flat deposits gave way to upper tidal-flat and marsh deposits as the transgression diminished. The transgressive event was shortlived. Sediments were deposited at the `feather edge' of the transgression. North of Creetown and the Moneypool Burn, upper tidal-flat and marsh deposits rest directly on fluvio-glacial deposits. As regression occurred, seaward progradation and incision of the carse deposits proceeded.A pause in regression c . 2,000 years B.P. resulted in certain morphological features observed in the Cassencarie area. Stormy conditions resulted in the re-working of marginal fluvio-glacial deposits to form a spit, and to the south (between Cassencarie and Carsluith) coarse marine sands and gravels were transported landwards to form shore-parallel and oblique bars. At Carsluith, similarly-derived material forms a thinly-developed beach blanket. Recession of the sea has proceeded since 2,000 years B.P. to the present-day.
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Russell, Paul. „Tsunami Stratigraphy in a Salt Pond on St. Croix, US Virgin Islands“. The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524156328491204.
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Levesh, Jarrett Leigh. „Middle Miocene to Holocene History of the Delacroix Island Fault System“. ScholarWorks@UNO, 2019. https://scholarworks.uno.edu/td/2623.
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An in-depth field study of the Delacroix Island producing field illustrates the evolution of the east-trending Delacroix Island Fault during the last 13 My. Well log correlations and 3-D seismic interpretation of 22 subsurface bio-stratigraphic horizons across the fault reveal variable stratigraphic thicknesses and displacement. Wells, with well log curve data as shallow as 31 m (100 ft) below the surface, were used to calculate interval thicknesses, expansion indices, sediment accumulation rates, burial history and magnitudes of displacement. Through these analyses, a correlation was found between the positioning of ancient Miocene depocenters over Delacroix Island and a period of increased fault activity. Historic satellite imagery (last 34 yrs) of the field depicts a lineation on the modern marsh surface coincident with the upward projected fault plane. Continuous wetland loss on the downthrown side of the fault trace suggests that recent and continued fault movement may be contributing to marsh submergence.
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Partin, Judson Wiley. „Stalagmite reconstructions of western tropical pacific climate from the last glacial maximum to present“. Diss., Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22556.
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The West Pacific Warm Pool (WPWP) plays an important role in the global heat budget and global hydrologic cycle, so knowledge about its past variability would improve our understanding of global climate. Variations in WPWP precipitation are most notable during El Niño-Southern Oscillation events, when climate changes in the tropical Pacific impact rainfall not only in the WPWP, but around the globe. The stalagmite records presented in this dissertation provide centennial-to-millennial-scale constraints of WPWP precipitation during three distinct climatic periods: the Last Glacial Maximum (LGM), the last deglaciation, and the Holocene. In Chapter 2, the methodologies associated with the generation of U/Th-based absolute ages for the stalagmites are presented. In the final age models for the stalagmites, dates younger than 11,000 years have absolute errors of ±400 years or less, and dates older than 11,000 years have a relative error of ±2%. Stalagmite-specific 230Th/232Th ratios, calculated using isochrons, are used to correct for the presence of unsupported 230Th in a stalagmite at the time of formation. Hiatuses in the record are identified using a combination of optical properties, high 232Th concentrations, and extrapolation from adjacent U/Th dates. In Chapter 3, stalagmite oxygen isotopic composition (d18O) records from N. Borneo are presented which reveal millennial-scale rainfall changes that occurred in response to changes in global climate boundary conditions, radiative forcing, and abrupt climate changes. The stalagmite d18O records detect little change in inferred precipitation between the LGM and the present, although significant uncertainties are associated with the impact of the Sunda Shelf on rainfall d18O during the LGM. A millennial-scale drying in N. Borneo, inferred from an increase in stalagmite d18O, peaks at ~16.5ka coeval with timing of Heinrich event 1, possibly related to a southward movement of the Intertropical Convergence Zone (ITCZ). An inferred precipitation maximum (stalagmite d18O minimum) during the mid-Holocene in N. Borneo supports La Niña-like conditions and/or a southward migration of the ITCZ over the course of the Holocene as likely mechanisms for the observed millennial-scale trends. In Chapter 4, stalagmite Mg/Ca, Sr/Ca, and d13C records reflect hydrologic changes in the overlying karst system that are linked to a combination of rainfall variability and cave micro-environmental effects. Dripwater and stalagmite geochemistry suggest that prior calcite precipitation is a mechanism which alters dripwater geochemistry in slow, stalagmite-forming drips in N. Borneo. Stalagmite Mg/Ca ratios and d13C records suggest that the LGM climate in N. Borneo was drier and that ecosystem carbon cycling may have responded to the drier conditions. Large amplitude decadal- to centennial-scale variability in stalagmite Mg/Ca, Sr/Ca and d13C during the deglaciation may be linked to deglacial abrupt climate change events.
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Giacomelli, Serena <1974>. „The Remote Sensing-Stratigraphic Approach Applied to the Reconstruction of Holocene Sedimentary Evolution in Coastal Areas: Case Studies from Arno and Po Delta Plains (Italy)“. Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amsdottorato.unibo.it/8109/1/Giacomelli_Serena_tesi.pdf.
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The growing availability of open-access databases, made the RS data and analyses to be increasingly employed in several geological research areas, including Quaternary and Environmental Geology. Despite the frequent use of the RS in alluvial-coastal plains paleohydrographic reconstruction, especially to identify stagnant versus well-drained areas (i.e., past wetlands and paleochannels, respectively) by means of brightness contrasts on images, the relationship between surface RS-derived traces and shallow subsurface stratigraphy remains underexplored.
The present PhD thesis represents a contribution to this open issue, through the application of a multidisciplinary approach integrating RS (optical multi/hyperspectral images and DTM LiDAR) with sedimentologic and stratigraphic field data in the study of the Holocene evolution of paleodrainages from two coastal-deltaic areas: San Rossore site (SR-Arno plain) and Mezzano Valley (MV-Po plain).
The analyses of 27 scenes from Landsat, ASTER, Sentinel2a and Hyperion allowed to identify paleochannels traces in the two sites. Field surveys and soil sampling campaigns performed on selected traces to define their surface sedimentological and optical characteristics, invariabily highlighted silty-clayey composition. A cross-reference was performed between traces and the shallow subsurface (i.e., uppermost 10 m) through the collection of 26 auger and continuous core data on which facies analysis, 14C dating and stratigraphic correlations were performed that allow to identify buried (2-4m bgl) channels. Their surface visibility, connected to the soil moisture distribution, resulted to be influenced mainly by the distribution of organic-rich deposits and/or by the shallow subsurface stratigraphic architecture. The “stratigraphic calibrations” extendended along RS-detected traces suggested that during the early highstand (6000-3000 yr cal BP) the MV experienced a tidally-influenced lagoon phase with the development of 2 networks of “tidal-channels”, whose formation was favored by local factors (suh as low topographic gradient and continuous beachridges development) while, the Pisa lagoon, in the same time-interval, was gradually filled by distributary channels.
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Monjanel, Anne-Lise. „Les diatomées oligocènes à holocènes de l'Atlantique Nord et de la Méditerranée occidentale : biostratigraphie et paléoceanographie“. Brest, 1987. http://www.theses.fr/1987BRES2035.
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Etude de la flore des diatomees de forages oceaniques et de coupes situees a terre: site 647 de l'odp pour l'oligocene; formation des moronites et coupes de cobatillas en espagne, coupes de saint-laurent la vernede et d'uzes dans le gard, coupes du "tripoli di contignaco" en italie et forages dsdp des sites 116, 334, 335 et 545 pour le miocene; site 646 de l'odp pour le plio-pleistocene. L'interpretation biostratigraphique permet de mettre en evidence des hiatus de la sedimentation ,lies a la circulation oceanique profonde et a la presence d'upwellings cotiers
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Valentine, David W. „Late Holocene stratigraphy, Humboldt Bay, California evidence for late Holocene paleoseismicity of the southern Cascadia subduction zone /“. 1992. http://catalog.hathitrust.org/api/volumes/oclc/285528147.html.
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Oatney, Emily M. „Geology and paleoseismology of the Trans-Yamuna active fault system, Himalayan foothills of northwest India“. Thesis, 1998. http://hdl.handle.net/1957/33684.
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Satellite image interpretation, geologic mapping, and paleoseismic trenching are
used to investigate the Trans-Yamuna active fault system in the northwestern Doon Valley
of the Indian Himalayan foothills. This east-west fault system is subparallel to and crosses
the Main Boundary thrust near the structural transition from the Nahan salient to the
Dehra Dun reentrant. The Trans-Yamuna active fault system may terminate to the east at
a lateral ramp of the Main Boundary thrust. A south-side-up, relatively linear fault trace
with variable fault dips suggests that the fault system is high-angle reverse with a
component of strike-slip. It is subdivided into the Sirmurital, Dhamaun, and Bharli faults,
which probably connect at depth. The Dhamaun fault is exposed where it cuts the late
Holocene upper Bhatrog terrace deposit of the Giri River. A paleoseismic investigation of
the Sirmurital fault at another Giri River terrace did not expose the fault, but it suggests
that late Holocene terrace deposits there may be folded into a syncline parallel to fault
strike. The fold axis of the syncline continues into bedrock to the west. Earthquakes in
1905, 1803, or perhaps earlier may have been the source of folding of the fine-grained
sediments within this terrace deposit. The Trans-Yamuna active fault system is a
secondary hangingwall fault that may accommodate some strain release above the
decollement during large-magnitude earthquakes. Strike-slip motion may be related to the
lateral translation of the Karakoram fault block and east-west extension of the southern
Tibet block as a result of oblique convergence between the Indian and Eurasian plates in
the northwest Himalaya.Graduation date: 1999
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Higgs, Caldin Grant. „Geochemical insights into the influence of Holocene sea level change on the evolution of the Mkhuze River Delta, Lake St Lucia, northen KwaZulu- Natal“. Thesis, 2017. https://hdl.handle.net/10539/23745.
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Thesis submitted in fulfilment of the academic requirements for the degree of Master of
Science.
Department of Chemistry
University of Witwatersrand, Johannesburg April 2017.The Mkhuze River discharges into the most northern part of Lake St Lucia, via a contemporary bayhead delta. The delta formed in response to sea level rise during the last deglaciation and today exerts great influence on the functioning of Lake St Lucia, one of the largest estuarine systems in Africa and a globally important conservation area. A sediment core (11.5 m) was extracted from the distal end of the delta to examine the geomorphic evolution of the Mkhuze River Delta and links with variations in Holocene sea level and climate. Radiocarbon and optically-stimulated luminescence dating show that the core captured the entire Holocene infill and documents changes in sedimentation over the last ~13.8 kyr. Grain size and high resolution XRF analysis indicates that initiation of the modern delta occurred since ~7200 cal yr BP , when deglacial sea-level rise reached present-day level. Initial Holocene aged sediments are dominated by clay and silt material that was deposited when seawater intruded into Lake St Lucia via a palaeo-river connection to the ocean at Leven Point. The influx of silt and clay material was accompanied by the emergence of an onshore proto-barrier that created a sheltered lagoonal environment and promoted the accumulation of fine fluvial sediment. The presence of discrete, coarse-grained horizons enriched in zircon identifies a period of increased marine palaeostorm activity between 4700 and 2500 cal yr BP. This period is characterised by the presence of discrete shell fragment accumulations and is interpreted to reflect a strongly positive Indian Ocean dipole anomaly, which resulted in warmer sea surface temperatures and an increase in regional cyclone activity and frequency. The upper part of the core is characterized by generally fine silt and is marked by a decrease in sedimentation rate that corresponds to a phase of lateral delta progradation. The last ~1700 cal yr BP years of the record identify with subtle changes in grain size that can be attributed to a strengthening in El Niño–Southern Oscillation (ENSO) activity, which is known to be associated with prolonged drought and wind erosion in eastern South Africa. This study highlights the usefulness of coastal geochemical records in identifying environmental changes and related climate signals at a regional scale.
GR2018
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Krentz, Sarah. „Potentially tsunamigenic event layer in late Holocene Great South Bay, Long Island, New York constraints on origins, processes, and effects /“. Diss., 2009. http://etd.library.vanderbilt.edu/available/etd-07232009-175830/.
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Evans, Mary Yvonne. „The geology, sedimentology, geochronology and palaeo-environmental reconstruction of the Heelbo hillslope deposit, Free State Province, South Africa“. Thesis, 2016. http://hdl.handle.net/10539/19373.
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Thesis submitted in fulfillment of the requirements for the
Degree of Doctor of Philosophy
University of the Witwatersrand
South Africa
2015A multidisciplinary sedimentological, stratigraphic, mineralogical and geochronological analysis of a small, fossil-bearing, Holocene hillslope deposit, flanking a mesa, has enabled a reconstruction of the palaeo-environmental history of the region. The hillslope deposit, located on the farm Heelbo in the eastern Free State Povince, South Africa, overlies Jurassic mudrock and sandstone of the Elliot Formation, Karoo Supergroup. The deposit is located on a steep (~10°) slope and covers an area of ~7 km2 in two separate sections. It extends ~475 m downslope and reaches a maximum thickness of at least 6-8 m towards the base. Mineralogy indicates the deposit is sourced from the mesa but its fine grain size and location on a steep slope position Heelbo outside the scope of traditionally described alluvial fans or colluvial deposits. The hillslope deposit is described as an alluvial slope based on the morphology of the deposit and the grain size distribution against the slope gradient. The deposit comprises fine-sand to silt- grain size, but is found on a steep (~10°) slope. The source of the sediment is shown to be the sediment of the mesa, rather than input from an aeolian source. The grains are described as sub-angular and poorly sorted which also suggests a local provenance for the sediment. Microscopic and XRF analysis confirm the derivation of the sediment from the Elliot Formation, with the lithic fragments derived from subarkoses to arkoses of the underlying bedrock of the Upper Elliot Formation (UEF) in the Karoo Supergroup. Secondary calcite was visible in only two of the thin sections, thus it is likely due to a diagenetic overprint that is constrained by depth from the surface or time and not to specific layers. The deposit is cut by several mature and continuous gully networks with V-shaped profiles in the proximal slope, and combined V- and U-shaped profiles in the medial and distal sections. Gully formation is linked to both the sodium adsorption ratio (SARs), and high soil clay content, which facilitates swelling and shrinking. The Heelbo deposit comprises two palaeosols (BT1 and BT2) and four sediment (B1, B2, RB and TS) horizons. Through luminescence dating, the ages were found to be approximately 6390 ± 740 years BP for the oldest Brown (B1) horizon and 250 ± 170 years BP for the Red Brown (RB) horizon. The radiocarbon ages of the sediment were inconclusive, but the 14C ages of the fossil bones were in agreement with the luminescence ages. The multiple palaeosol horizons identified suggest two cycles of deposition, pedogenesis and erosion of the alluvial succession. The palaeosols and the presence of calcareous nodules and rhizocretions, and smectite and mixed-layer clay minerals, together with the total absence of illite and kaolinite, suggest protracted, dry periods with intermittent short periods of high rainfall. This is a similar climate regime to what the region experiences currently. Main findings: The Heelbo alluvial slope comprises locally derived sediment, rather than an aeolian source. Heelbo suggests that the hillslope deposits classification system needs to be re-evaluated and opens opportunities for wider study of Pleistocene-Holocene hillslope deposits in central / northern South Africa. This study also contributes to climate change debates in the Holocene.
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Mee, Aija C. „Origin, formation and environmental significance of sapropels in shallow Holocene coastal lakes of Southeastern Australia“. 2007. http://hdl.handle.net/2440/57295.
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Title page, contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library.The aims of this investigation on the Holocene carbonate successions of three shallow, ephemeral lakes from the Cooring coastal plain were: to determine the timing of the sapropel ’events’ in the three lakes; to determine the origin of the sapropelic organic matter and evaluate changes; to establish whether sapropel deposition in these shallow, coastal lakes primarily reflects increased organic matter delivery to the sediments during periods of enhanced terrestrial input and/or aquatic productivity, and; to relate sapropel deposition in these three lakes to both regional and global palaeoenvironment reconstructions. --p. 23-24.
http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1324064
Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2007
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Grossman, Eric E. „Holocene sea level history and reef development in Hawaii and the Central Pacific Ocean“. 2001. http://wwwlib.umi.com/dissertations/fullcit/3017398.
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Shulmeister, James. „Late Quaternary and Holocene environmental history of Groote Eylandt, Northern Australia“. Phd thesis, 1991. http://hdl.handle.net/1885/140901.
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