Дисертації з теми "Pleistocene sea level changes"
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1
Grant, Katharine M. "Sea-level change, monsoon variability, and eastern Mediterranean climate over the Late Pleistocene." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/362005/.
Повний текст джерелаАнотація:
A new, radiometrically constrained chronology is developed for a continuous, highresolution relative sea-level (RSL) record from the Red Sea that spans the past 500,000 years (500 ka BP). The method is based on indirect correlation of the RSL record with speleothem δ18O records from Soreq cave, Israel (for the period 0-150 ka BP), and from Sanbao Cave, China (for the period 150-500 ka BP). The new RSL record allows ice-volume (sea-level) phase relationships with key climate-system variables to be examined, without bias from icecore or orbital timescales. The effects of ice-volume changes on monsoon variability are also examined. In a separate development, the Soreq-synchronised interval of the RSL record is used to produce residual oxygen isotope (δ18O) records for the eastern Mediterranean; these represent regional environmental signals which are unbiased by ice-volume and sourcewater effects. Results suggest that, over the last glacial cycle, changes in polar climate and ice-volume were tightly coupled, with centennial-scale response times, and rates of sea-level rise reached at least 1.2 m per century during periods of significant ice-volume reduction. Results also suggest that, at the last five glacial terminations, ice-volume changes generally lagged insolation and atmospheric CO2 rises by ~2-7 kyr. This supports the Milankovitch theory of ice-age cycles, and disputes suggestions that CO2-driven feedback processes initiated glacial terminations. It is shown that ice-volume changes can partly explain East Asian monsoon (EAM) variability. In particular, rapid rates of ice-volume reduction at glacial terminations can account for rapid, millennial-scale variability in summer and winter EAM proxies. This observation is consistent with meltwater pulses into the North Atlantic at terminations leading to a delayed intensification of the summer EAM. Evidence also suggests that changes in different monsoon systems of the northern hemisphere were synchronous during periods of ice-volume minima. Regarding the East African summer monsoon (EAfSM), no systematic phasing is observed between precession minima and EAfSM maxima, and so the common use of a 3-kyr lag to date EAfSM records appears to be too generalised. The new palaeo-environmental reconstructions for the Mediterranean presented here suggest that local precipitation did not increase substantially during the deposition of sapropels S1, S3 and S4, whereas net moisture availability may have been elevated during the interval of sapropel S5 deposition, and within colder glacial periods of the last glacial cycle. The most climatically variable period of the last glacial cycle in the Mediterranean (~30-60 ka BP) coincides with marine isotope stage (MIS) 3.
2
Furze, Mark Fernley Alexander. "Late Pleistocene sea-level change in the Celtic Sea : radiocarbon dated macrofauna as palaeo-water-depth indicators." Thesis, Bangor University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367395.
Повний текст джерела
3
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.
Повний текст джерелаАнотація:
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.
4
Tobias, Amy E. "Effects of environmental change on species : Marvacrassatella lineage and the Plio-Pleistocene record of sea level change /." Thesis, This resource online, 1998. http://scholar.lib.vt.edu/theses/available/etd-07132007-143141/.
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5
au, rhoddell@central murdoch edu, and Richard James Hoddell. "A mtDNA study of aspects of the recent evolutionary history and phylogeographic structure of selected teleosts in coastal environments of south-western Australia." Murdoch University, 2003. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20070831.162328.
Повний текст джерелаАнотація:
At present, there is a general lack of information regarding the spatial genetic
architecture and genetic diversity of estuarine and coastal freshwater fish in
Australia or about the interacting intrinsic, extrinsic and historical influences
responsible for sculpting these patterns. This thesis represented the first
investigation of the phylogeographic structure and recent evolutionary histories
of teleost fishes from the coastal and estuarine environments of south-western
Australia, using the resolution afforded by mtDNA sequence data. Available
evidence indicated that, to different degrees, these species have limited
potential for dispersal amongst local assemblages from different water bodies.
As this theoretically reduces the confounding effects of recent gene flow on
extant genetic structure, these fishes were well suited to studying the
influences of historical factors. Historical influences were expected to be
particularly profound, given that these coastal environments underwent
massive modifications during Late Quaternary eustatic fluctuations.
The thesis consists of four major components, which explored different
aspects of interspecific and intraspecific phylogeny and p hylogeograp hy of
three teleost species, based on mtDNA control region and cytochrome b
fragments. First, the relationship between the endemic, 'strictly estuarine'
Leptatherina wallacei (Atherinidae) and the more widespread, 'estuarine &
marine' 6. presbyteroides was examined, with a view to establishing whether
6. wallacei represents a monophyletic or polyphyletic lineage and whether this
species was derived recently (i.e. in Holocene estuaries). Second, the
phylogeographic structure and genetic diversity of L. wallacei were investigated and compared with data from L. presbyteroides, with a view to
using this information to interpret the recent evolutionary histories of each
congener. Third, the divergence between assemblages of L. wallacei
inhabiting two isolated coastal lakes was used to estimate a maximal
substitution rate for the control region, which was then used to infer general
time frames for the divergence between the two Leptatherina species and
between the major phylogeographic partitions within each species. Fourth,
investigations were initiated into phylogeographic patterns and levels of
genetic diversity within and among assemblages of Pseudogobius olorum
(Gobiidae) from several coastal lakes and an estuary.
Phylogenetic analyses indicated that the two Leptatherina species were
characterised by exclusive and reciprocally-monophyletic lineages of
haplotypes from both mtDNA regions, supporting the monophyletic origins of
L. wallacei. Both 6. wallacei and 6. presbyteroides exhibited high levels of
genetic diversity and extensive overall subdivision (e.g. Qsr = 0.691 & 0.644
respectively for control region data). There was a profound phylogeographic
break in both species between all conspecific assemblages from the lower
west coast (LWC phylogroup) and all those from the south coast (SC
phylogroup), which suggested the influences of shared extrinsic and/or
historical factors. There was limited genetic structuring within the two major
phylogroups of either Leptatherina species, apparently reflecting recent
connectivity amongst local assemblages, with subsequent fragmentation and
insufficient time for lineage sorting. However, two major phylogeographic
breaks distinguished monophyletic control region phylogroups of L. wallacei from the isolated coastal Lake Clifton and Lake Walyungup, consistent with
their independent evolution following lacustrine entrapment during the
Holocene.
The divergence between these two isolated lacustrine assemblages of
Leptatherina wallaceiformed the basis for an estimate of the maximal
substitution rate of the control region. While these data were unable to
provide a precise estimate of the actual rate of molecular evolution, all the
evidence suggested that it was proceeding very rapidly. The maximal rate
estimate of 172.3% lineage-' MY-' was among the fastest ever reported.
Based on this rate, the two Leptatherina species diverged at least 1 SKya, thus
rejecting a Holocene origin for L. wallacei. The divergence between the LWC
and SC phylogroups of L. wallacei has been ongoing for at least GKya, while
the equivalent divergence in L. presbyteroides has been ongoing for at least
11 Kya. As the time frames of these divergences were consistent with periods
of massive environmental modifications associated with the end-Pleistocene
fall in sea level and the HMT, it was likely that these factors have played
important roles in sculpting the species' divergence and intra-specific genetic
structure. Although useful in temporally scaling genetic divergences within
and between the two Leptatherina species, wider application of this rate
estimate to questions regarding other taxa was limited. For example, evident
rate heterogeneity between the genera precluded its use with even the
relatively closely-related atherinid Atherinosoma elongafa.
Phylogeographic analyses identified high levels of genetic diversity and
extensive genetic subdivision (e.g. st = 0.652 for control region) amongst an
estuarine and several lacustrine assemblages of Pseudogobius olorum,
although phylogeographic structure was shallower than in either Leptatherina
species. There was increased divergence between three assemblages from
the lower west coast and two from the south coast, consistent with the
profound break evident in the Leptatherina. One lacustrine assemblage
appeared to represent a distinct lineage and a preliminary maximal rate
estimate (~61.4% lineage-1 MY-1) was calculated based on the minimum
divergence of this assemblage from its nearest conspecifics. Although slower
than the rate calculated for L. wallacei, this was still high for teleost fishes.
Overall, this study indicated that historical environmental factors, especially
those related to Quaternary eustatic changes, have played important roles in
sculpting the phylogeography and evolution of three teleost species from
south-western Australia. Moreover, as these species have differential
dependencies on estuarine environments (is. 'strictly estuarine' vs 'estuarine
& marine') and represented two different taxonomic groups (i.e. Atherinoidei &
Gobioidei), historical environmental factors may have exerted similar
influences on other coastal species in the region.
6
Pilaar, Birch Suzanne Elizabeth. "Human adaptations to climate change and sea level rise at the pleistocene-holocene transition in the Northeastern Adriatic." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607721.
Повний текст джерела
7
Alves, Daniel Pavani Vicente. "A evolução sedimentar do Canal de São Sebastião, no litoral norte do estado de São Paulo, estudada a partir de uma abordagem sismoestratigráfica." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/21/21136/tde-10122012-160544/.
Повний текст джерелаАнотація:
A sismoestratigrafia, em geral, não é utilizada em estudos de curto espaço de tempo geológico, como os de quinta e sexta ordem. Entretanto, o estudo da Baía do Araçá, no Canal de São Sebastião, no litoral norte do estado de São Paulo mostrou que este tipo de abordagem é possível para ciclos desta magnitude. Utilizando um sistema de aquisição de dados sísmicos, composto por uma fonte boomer, um pinger e um chirp, foi feito um levantamento da região, que resultou em cerca de 60 km de perfis sísmicos de alta resolução, foi possível reconhecer um conjunto de unidades sísmicas que pode ser entendida no conceito de tratos de sistema. Com a interpretação destes sismogramas, gerou-se um modelo evolutivo para a sedimentação no Araçá tendo sido encontrados tratos de sistemas de mar alto, de mar baixo e transgressivo muito bem definidos. Estes tratos foram relacionados com as curvas de variações eustáticas do Pleistoceno Superior e Holoceno conhecidas, possibilitando a proposição de duas hipóteses distintas: a primeira considerando um período de mar alto no Estágio Isotópico 5e e a segunda com um período de mar alto no Estágio Isotópico 3, em uma posição superior àquela considerada pela maioria dos autores, mas corroborada por outros. Além disso, foram encontradas evidências claras de tectônica Neoquaternária na região.It is not that common to use the seismic stratigraphy in studies of short geological time as those from fifth and sixth orders. However, the study of Araça\'s Bay, at São Sebastião Channel, at the north coast of São Paulo State, showed that this kind of approach is in fact possible for cycles of this magnitude. Using a seismic setup composed with one boomer seismic source, as well as one pinger and one chirp, a seismic survey was taken in the area, which resulted in about 60 km of seismic profiles of high resolution. Analyzing those seismograms, we propose an evolution model for the sedimentation at Araçá area, and we found records of highstand systems tract, lowstand systems tract and transgressive systems tract very well marked. These tracts were then related to the known sea level change curves for Late Pleistocene and Holocene, allowing a proposition of two distinct hypothesis: the first one considers a highstand period at Isotopic Stage 5e and the second one a highstand period at Isotopic Stage 3, in a higher position than that considered for most authors, but corroborated for some others. Also, it was found clear evidences of Neoquaternary tectonics at the area.
8
Caccamise, Dana J. "Sea and land level changes in Hawai'i." Thesis, University of Hawaii at Manoa, 2003. http://hdl.handle.net/10125/7023.
Повний текст джерелаАнотація:
An overall rise in sea level has been recorded by all Hawaii tide gauges over the last century; however, the rates vary considerably between islands. In particular, the sea level rise rate is higher at Hilo (3.3 mm/yr) on the island of Hawaii at the southeast end of the island chain, than at Honolulu (1.4 mm/yr) on the island of Oahu about 335 Ian to the northwest. This difference has been attributed to island subsidence associated with active volcanism at the southeast end of the Hawaiian ridge. Continuous GPS measurements collected over the past 5 years are used to examine the relative vertical movements of the main Hawaiian Islands in an attempt to reconcile the observed difference in sea level rates. The rates of vertical crustal motion are estimated in a reference frame realized using a network of 30 GPS stations spread across the Pacific region. Although absolute vertical motion rates are not yet obtainable, the differential rates of vertical crustal motion are determined to within approximately ± 0.5 mm/yr at the 95% confidence level. The geodetic measurements indicate that vertical velocities within the main Hawaiian Islands are similar. Hilo is subsiding relative to Honolulu, but the difference in rates is only 0.5 mm/yr, considerably less than the 1.9 mm/yr difference suggested by tide gauge observations. Historical hydrographic data suggest that steric sea level trends since 1945 vary considerably along the Hawaiian Ridge, with rates increasing from the northwest to the southeast. It is suggested that the difference in Hilo-Honolulu sea level rise rate is due in part to upper ocean thermal variations. The notion that oceanographic effects influence differential rates of sea level rise at Hawaii challenges previous interpretations based solely on variable crustal motion. The absolute rate of vertical crustal motion at Honolulu has been constrained by coral-age data to be less than 0.1 mm/yr since the last interglacial. A reanalysis of the age-depth relationship obtained from submerged Holocene corals recovered from the Hilo drill hole is consistent with an absolute rate of crustal subsidence anywhere between - 2.7 and 0 mm/yr. Given this wide range of velocities, the differential Holocene subsidence rates from coral data do not conflict with our reinterpretation of the tide gauge data.ix, 63 leaves
9
Knorr, Paul Octavius. "The case for high-order, pleistocene sea-level fluctuations in Southwest Florida." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001791.
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10
Botella, Albéric. "Past and Future Sea-Level Changes in French Polynesia." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/33392.
Повний текст джерелаАнотація:
Among the various adverse effects of climate change, sea-level rise is expected to increase the severity and frequency of flooding events impacting the vulnerable, low-lying islands of French Polynesia. It has long been understood that sea-level changes are not spatially uniform, yet this aspect is not taken into account in the decision-making. Notably, no projections of future sea level have been produced specifically for this region so far, partly because the processes driving sea-level changes remain poorly constrained. To approach the issue, we present a detailed reconstruction of sea-level changes for the mid-to-late Holocene, based on the observation of coral proxies. This dataset is then used to calibrate a sea-level model in order to estimate the contribution of glacial isostatic adjustment to regional sea-level changes and to infer past variations in global ice volume. Building upon this baseline and exploiting recent outputs of climate models, we project that in a “worst-case” scenario, sea level would rise 1.05 meters by 2100 in French Polynesia, exceeding the value adopted in the French adaptation strategy by 0.45 meters. We conclude that spatial variability of sea-level rise should be considered in future risk studies for this and other regions.
11
Hillier, Robert David. "Siliciclastic shelf margin sedimentology and relative sea-level changes." Thesis, University of Aberdeen, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386359.
Повний текст джерелаАнотація:
The effects of changes in relative sea-level on clastic shelf margins are examined utilizing two case studies, the passive Quaternary to Recent of Sable Island Bank, Nova Scotia, and the active Silurian shelf of Dyfed, southwest Wales. Within the overall transgressive systems tract of the Sable Island Sand and Gravel Formation, siliciclastic material is continually reworked in shallow water by modern storm-dominated, tidally-modulated flows in an attempt to reach equilibrium and textural grade with the bank-top hydrodynamics. Over the past 11,000 years marked transgressive marine ravinement of the bank-top has cannibalised considerable volumes of sediment into the dynamic realms of eustatically produced accommodation space. Sediment transport, together with bedform and grain-size variations reflect both progressive sorting and the depth dependent fluid power relationship. Bedload sediment transport is predominantly geostrophic, and is seen to be topographically steered at shelf-edge breaks in slope, a process related to the hydraulic fence concept. Through this process, sediment by-pass into deep water is hindered, and spatially significant upward coarsening/thickening sandbodies are developing, most notably at East Bar. Taken a stage further, shoal aggradation of this sediment supply dominated coastal system has enabled the emergence of the cuspate/elongate shelf-edge Sable Island. The effects of changes in relative sea-level on various scales is described from the Coralliferous and Gray Sandstone Groups of southwest Wales. Six Vailian sequences are recognised within a thick basinward prograding clastic wedge. During lowstands of relative sea-level, shelfal incision and sediment by-pass occurred, with sediment supplying deep water fan systems immediately to the north of the study area. Valley-fills vary in depositional environment from low sinuosity fluvial channels (Sequence I), estuarine tidal channels (Sequences II to V), and mixed estuarine/high sinuosity fluvial channels of Sequence VI.
12
Fernandez, Bilbao Roberto Alejandro. "Externally forced changes in ocean temperature and sea level." Thesis, University of Reading, 2017. http://centaur.reading.ac.uk/75154/.
Повний текст джерелаАнотація:
This thesis is concerned with the effects of climate change on ocean heat content in recent decades and the 21st century. We examine whether significant changes in ocean temperature can be detected in recent decades and attributed to anthropogenic or other factors, and we consider the recent and future pattern of sea level change due to ocean density change, which is dominated by temperature change. We compare ocean temperature change for 1960-2005 in four observational datasets and in historical simulations by atmosphere-ocean general circulation models (AOGCMs) from the Coupled Model Intercomparison Project phase 5 (CM1P5). Observations and CMIP5 models show that the upper 2000m have warmed and the signal gradually propagates to deeper layers over time with a defined geographical pattern determined by the regional processes of ocean heat uptake. Greenhouse gas forcing has contributed most to increase the temperature of the ocean which has been offset by anthropogenic aerosols, and volcanic eruptions cause episodic cooling. Using optimal fingerprinting, we show that observed changes may be attributed to greenhouse-gas, other anthropogenic and natural (mainly volcanic) forcings, with all three of these being detectable. Multi-model mean fingerprints are constructed using the time-depth structure of the warming by considering multiple depth levels, which decreases the uncertainty of the results. Limiting the observations and model fields to locations where there are observations benefits the detection of signals. By comparison of historical and pre-industrial control simulations using the AOGCMs of the CMIP5 project, we conclude that the observed geographical pattern for 1993-2012 of sea level change due to ocean dynamics and density changes is generally dominated by unforced (internal generated) variability, although some regions, especially in the Southern Ocean, may already show an externally forced response. Applying the method of pattern scaling to projections of sea level change we show that it gives accurate estimates of future local sea level change in response to anthropogenic forcing as simulated by the AOGCMs under RCP scenarios, and determine that the forced signal will be detectable above the noise of unforced internal variability within the next decade globally and may already be detectable in the tropical Atlantic. This work points to the need to continue developing AOGCMs in order to improve their simulations of past ocean temperature and sea level change and reduce their uncertainty in projections of the future.
13
Firoozfar, Alireza. "Caspian Sea level changes, seismicity assessment and beach evolution." Thesis, Kingston University, 2012. http://eprints.kingston.ac.uk/23704/.
Повний текст джерелаАнотація:
The Caspian Sea is the world's largest closed body of water, and it has a number of unique features, not least, the considerable fluctuations in water level during the 20th century. This water level dropped by 3 m from 1929 to 1977, increased rapidly by 2.6 m during thetwo decades following, and from 1995 a slow rate of change continues. It is likely that the underlying causes of these water level changes are the human activities in the Caspian Sea Basin but literature shows that climate change also had a significant effect. Moreover, these sea level changes occur in a region with a high intrinsic level of seismic activity due to its tectonic setting. Since the sea level fluctuations represent very large scale changes in the loading of the Earth's crust, it seems likely that they are responsible for aspects of the overall seismicity. This is analogous to the problem of Reservoir Induced Seismicity, although even the largest reservoirs are tiny compared to the Caspian Sea. The research reviews the available data to create a reliable database of seismic events in the desired timeframe and location. It was observed that there was a correlation between the Caspian Sea level fluctuations and changes in regional seismicity. Further analysis indicated changes in the b-value of the Gutenberg-Richter Relationship that had an inverse correlation with water level fluctuations, demonstrating that RIS effects are significant. Through statistical examination of the earthquakes listed in the catalogue, the research attempted to find events which could possibly be induced earthquakes. Another large scale effect of the Caspian Sea level changes is investigated on its coasts where the beach profiles were affected by these changes. This sea is a unique laboratory for studies related to sea level rise and several studies have been performed by other researchers on the northern and western Caspian Sea coast. The southern coast, however, has not been adequately explored, thus this research aimed to investigate this part of the coastline. Three field surveys were made along 700 km of the southern coast. In addition to shore sediment sampling, land forms were mapped. Also, deep sediments were sampled by divers along profiles at right angles to the coast at 5 depths up to a depth of 10 m, and hydrographic profiles were surveyed. Laboratory tests were performed on the collected sediment samples. Several classifications were generated based on different factors, and finally, the southern Caspian Sea coast was classified into four categories with respect to their behaviour in response to sea level change. This study investigates the cause and two large scale impacts of the changing water level in the Caspian Sea, and provides a database for future studies. The result can be applied to predict future problems if the water level of the Caspian Sea continues to show considerable changes.
14
Long, Antony. "Holocene sea-level changes in the East Kent Fens." Thesis, Durham University, 1991. http://etheses.dur.ac.uk/1487/.
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Amiruddin, Abd Muhaimin. "Sea-level changes over the last six decades in the South China Sea." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/415492/.
Повний текст джерелаАнотація:
Spatial and temporal changes in mean and extreme sea levels and their forcing mechanisms have been examined over the last six decades in the South China Sea (SCS). A total of 53 tide gauge records and 22 years of satellite altimetry observations, along with oceanographic and meteorological datasets, have been used. The first objective examined changes in mean sea level trends. It was found that the subregion basin sea level trends from altimetry for the period 1993-2014 varied between 2.9 ± 0.8 mm/yr in the northern SCS and 6.2 ± 5.7 mm/yr in the Celebes Sea. In the northern SCS, the halosteric variation significantly contributes to the observed altimetry trends, which are up to 3 mm/yr. The separation of the local sea level trends into various contributors involves high uncertainties especially due to vertical land motion (~3 mm/yr). The second objective assessed changes in inter-annual mean sea level variability. The inter-annual sea level variability is larger in the Celebes Sea and accounts for up to 70% of the monthly sea level variability. Changes in steric and wind stress contribute to more than half of inter-annual sea level variability in the Malacca Strait and the eastern basin of the SCS. The inter-annual sea level variability in these regions is associated with the El Niño Southern Oscillation (ENSO) and the monsoon. The third objective evaluated changes in the mean seasonal sea level cycle. It was found that the contribution of seasonal cycle is larger on the continental shelf of the Gulf of Thailand, accounting for up to 92% of monthly sea level variability. Wind forcing is dominant on the shelf areas of the SCS with the local winds showed annual amplitudes of up to 27 cm. In the deep basin regions and the shallow Malacca Strait, the steric component is the major contributor with the maximum annual amplitudes reaching 15 cm. Significant temporal variability of the annual and semi-annual harmonics is up to 63% and 45% of the maximum amplitude, 15 cm and 11 cm, respectively. The fourth objective explored changes in extreme sea level. Significant increases in extreme sea levels were observed at more than half of the stations analysed and were found to be mainly driven by changes in mean sea level. In the Malacca Strait, the inter-annual variability in extreme sea level is found to be associated with ENSO and the monsoon. Overall, this study provides improved understanding of changes in mean and extreme sea levels and their associate mechanisms that occurred over different timescales. Changes in these sea level components need to be taken into consideration for mean and extreme sea levels projections in this region.
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Hassan, Kamaludin bin. "Holocene sea level changes in Kelang and Kuantan, Peninsular Malaysia." Thesis, Durham University, 2001. http://etheses.dur.ac.uk/3786/.
Повний текст джерелаАнотація:
A proper methodological approach of investigating Holocene sea level changes is a prerequisite in order that the sea-level index points can be useful and significant. This requires the correct identification of the indicative meaning. The indicative meaning of the sea level indicator is defined as the altitudinal relationship of the local environment in which it accumulated to the contemporaneous reference tide level. This study identifies the index points using the litho-, bio-, and chrono-stratigraphic approach. The sea level indicator is derived from the regressive contact of the intercalated peat and marine clastic sequence, while the indicative meaning is estimated based upon the relationship with the contemporary samples. The study was carried out at two contrasting coastal locations, the fossil sites from Meru and Mardi in Kelang in the west and Penur (north and south transects) in Kuantan in the east, while the contemporary sites are from various ecological environments from both areas. Microfossil analysis of pollen and diatoms indicates that the former are more applicable, and defined the changing microfossil assemblages within the regressive contact of the sea level indicator samples. Seven sea level index points are identified. The finding agrees to the general assumptions of high mid-Holocene sea level history in peninsular Malaysia. A relative sea level difference between the west and east coast is indicated, but the significance, if any, is dealt with caution. The explanations of presumed differential crustal movement or sheer age/altitude variability of the index points are suggested.
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Jones, Sarah Louise. "Sea-level changes in south east England and northern France." Thesis, Queen Mary, University of London, 2002. http://qmro.qmul.ac.uk/xmlui/handle/123456789/28591.
Повний текст джерелаАнотація:
The aim of the research was to provide new sea-level index points,with the intention of identifying any cross-channel similarities and comparing the results to geophysical models of relative sea-level change. The research successfully provided new sea-level index points from the Pevensey levels, East Sussex; the Canche Estuary, Pas de Calais and the Somme Estuary, Picardie, which were validated using stratigraphic pollen,diatom,foraminiferal snd AMS radiocarbon dating analysis. The results pointed to the presence of a coastal barrier thoughout the mid-Holocene at Pevensey and the Somme which complicated the pattern of coastal sedimentation observed at these sites. A clear pattern of barrier de-stabilisation can be seen to take place either side of the Channel c.3000 years cal BP. A cross-channel comparison identified three similar transgressive events either side of the English Channel, c. 5500, 3000 and 2200 cal years BP. The observed results from each site were then compared to the predicted data( Lambeck pers.comm) .in order to determine whether the observational data could be used to validate the modelled data. The comparisons showed that for the sites in south east England the modelled data tended to over-predict sea-level rise for the mid-t o late- Holocene whereas the model tended to under-predict sea-level rise for the sites in northern France. The new observational data which the research provided could be used to further validate Lambeck's (1990,1997) geophysical model. The effects of local coastal processes, such as tidal range, crustal subsidence and barrier-dynamics were used to aid the comparisons between the pattern of sediment deposition and thus the sea-level signals. These findings suggested that reconstructions should be restricted to sites at an estuary-sized scale.
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Barnett, Robert Langdon. "Holocene relative sea-level changes in south Hinnøya, Arctic Norway." Thesis, University of Plymouth, 2013. http://hdl.handle.net/10026.1/2771.
Повний текст джерелаАнотація:
This study develops techniques for the preparation and counting of testate amoebae for Holocene sea-level reconstructions. In addition, this study provides a ~3000 year relative sea-level reconstruction for south Hinnøya in the Vesterålen islands off mainland Norway, adding new data to a poorly defined period of the Holocene sea-level history of north-western Norway. This is important to quantify rates of glacial-isostatic adjustment (GIA), to refine GIA models, and to establish baseline (pre-industrial) rates of relative sea-level change. Surface sediments from two salt marshes (Storosen and Svinøyosen) in south Hinnøya are used to assess the effects of using different preparation procedures and count totals when analysing for testate amoebae. Analytical efficiency can be improved upon by using a mild alkali, chemical disaggregant (5 % KOH) to break up fibrous salt-marsh sediment and concentrate tests prior to counting. A count total of 100 individuals, rather than 150, can be used to make time gains with little or no effects on assemblages. Training sets of salt-marsh surface testate amoebae, foraminifera and elevational data are established for the two field sites. For testate amoebae, species – elevation relationships are constructed using regression modelling and applied to downcore fossil samples using a transfer function to derive estimates of sea level for the past ~100 years. The greater water depths reconstructed between ~3000 and ~100 years ago are not covered by modern foraminiferal training sets and are therefore estimated qualitatively from the fossil foraminiferal assemblages supplemented by information derived from fossil molluscs. Chronology is based on a combination of AMS14C, 210Pb, 137Cs and a suite of geochemical markers. At south Hinnøya, sea level has been falling at a rate of ~0.5 mm yr-1 over the last 3000 years.
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Jones, Timothy Deryck. "A reconstruction of late Pleistocene and Holocene lake level changes at Ioannini, Northwest Greece." Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.535120.
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Newton, Thomas Lee. "Holocene sea-level changes in the Falkland Islands : new insights into accelerated sea-level rise in the 20th Century." Thesis, University of Plymouth, 2017. http://hdl.handle.net/10026.1/9650.
Повний текст джерелаАнотація:
This thesis investigates sea-level changes in order to test the hypothesis that the main contribution to early 20th century sea-level rise was Northern Hemisphere land-based ice melt. Multiproxy sea-level reconstructions were established for the Falkland Islands, a location where models suggest sea-level rise from Northern Hemisphere ice melt produces the largest signal. The Falklands reconstruction indicated sea levels in the early 20th century accelerated compared to the long-term rate, synchronous with accelerations observed globally. The magnitude of the acceleration in the Falklands reconstruction was greater than Northern Hemisphere rates, consistent with the spatial pattern from a Northern Hemisphere melt source, but likely less than in New Zealand and Australia. It is therefore not possible rule out other contributions to the observed sea-level acceleration. The Falklands reconstruction indicated a rapid sea-level jump around 8.4 ka BP, synchronous with a jump observed in the Northern Hemisphere, which has been attributed to the sudden drainage of Laurentide proglacial lake Agassiz-Ojibway associated with the 8.2 ka BP climatic downturn. A maximum estimate of 0.89 ± 0.22 m for this jump in the Falklands is considerably less than estimates from Northern Hemisphere records. This difference could indicate additional contributions from the Southern Hemisphere are being recorded in the Northern Hemisphere signal. This thesis also focused on developing testate amoebae as sea-level indicators. In the Falklands, testate amoebae transfer functions were able to reconstruct sea level with precision (±0.08 m) comparable to diatoms (±0.07 m). However, preservation issues were indicated in the fossil testate amoebae assemblages which limits their use as tools for sea-level reconstruction. In addition, contemporary distributions of salt-marsh testate amoebae were investigated over one annual cycle. Seasonal variations in the live assemblages were observed to be asynchronous between taxa. Variations in the death assemblages were also observed which were correlated with variations in the live assemblages. This observation suggests the commonly applied assumption in palaeoenvironmental studies that analysing the death population negates temporal bias is invalid. Further research is required to investigate the impact these observed variations have on reconstructive performance.
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Reid, Samuel B. "The Complex Architecture of New Providence Island (Bahamas) Built by Multiple Pleistocene Sea Level Highstands." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_theses/77.
Повний текст джерелаАнотація:
The present day Bahamian archipelago was deposited during sea level highstands when carbonate production was high enough to overfill accommodation space. This study unravels the complex stratigraphy and heterogeneity created by island accretion during and across the most recent Pleistocene highstands (MIS 5e, 9, and 11) using New Providence Island as a case study. Building upon the work of previous researchers, field based mapping was completed to understand the spatial relationships between ages, environments of deposition, and grainstone compositions across the island. Using the vertical and lateral relationships gained from detailed mapping, the depositional history of New Providence Island has been reconstructed for the Pleistocene MIS 5e, 9, and 11 sea level highstands. To map all of the environments of deposition, detailed criteria were created to recognize each environment observed on New Providence Island. Ages were estimated with field techniques and confirmed with dating done in previous studies and in this study, including both U-series techniques and amino acid racemization (AAR). Hand samples and short (< 1 m) cores were collected in the field and were used for petrographic analyses in the laboratory as well as whole rock AAR sampling for age determination. Detailed outcrop drawings were created, showing the lateral and vertical relationships of environments within outcrops. Meanwhile, maps and cross-sections were drafted to better understand island-wide relationships of environments, ages, and compositions. Based on age maps, New Providence formed by vertical and lateral accretion during the last three Pleistocene highstands (MIS 5e, 9, and 11), with a majority of deposition occurring during the most recent interglacial (MIS 5e, ~125 ka). Environment of deposition mapping revealed that island deposition occurred within shallow marine to eolian environments. Because of the abundance of MIS 5e deposits, the sedimentological complexity of an individual highstand (MIS 5e) reveals sub-orbital scale sea level changes. With mid-highstand sea level fluctuations apparent within the MIS 5e deposits on New Providence Island, a high level of lithofacies complexity could be expected within any individual sea level highstand. This study documents the complex vertical and lateral facies patterns associated with island building between and within sea level highstands.
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Kalniņa, Laimdota. "Middle and Late Pleistocene environmental changes recorded in the Latvian part of the Baltic Sea basin." Thesis, Department of Physical Geography and Quaternary Geology, Stockholm University, 2001. https://dspace.lu.lv/dspace/handle/7/364.
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Baron, Louise. "Sea level changes in the Oxfordian stage of Britain and France." Thesis, Imperial College London, 1997. http://hdl.handle.net/10044/1/7899.
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Morrow, Eric. "Estimates of Land Ice Changes from Sea Level and Gravity Observations." Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11385.
Повний текст джерелаАнотація:
Understanding how global ice volume on the Earth has changed is of significant importance to improving our understanding of the climate system. Fortunately, the geographically unique perturbations in sea level that result from rapid changes in the mass of, otherwise difficult to measure, land-ice reservoirs can be used to infer the sources and magnitude of melt water. We explore the history of land-ice mass changes through the effect that these mass fluxes have had on both global and regional gravity and sea-level fields.Earth and Planetary Sciences
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Brader, Martin David. "Postglacial relative sea-level changes and the deglaciation of northwest Iceland." Thesis, Durham University, 2015. http://etheses.dur.ac.uk/11317/.
Повний текст джерелаАнотація:
Iceland provides an important opportunity to investigate relative sea-level (RSL) changes and Last Glacial Maximum (LGM) glaciation in a sensitive area of the North Atlantic. This project employs new and existing RSL data, coupled with glacio-isostatic adjustment (GIA) modelling, to resolve the current debates surrounding the extent of the LGM Icelandic ice sheet (IIS). Robust understanding of the LGM IIS is important, because there are two markedly different maximum and minimum ice loading scenarios, with very different implications for global thermohaline circulation. Previous studies of glacial geomorphology and sedimentology have failed to differentiate between these scenarios. Reconstructing RSL changes in northwest Iceland can address this issue because the two LGM glaciation scenarios yield significantly contrasting RSL histories. Northwest Iceland is also an important location in which to determine Earth models for Iceland. In this study, a series of new sea-level index points (SLIPs) have been generated for northwest Iceland from isolation basin and coastal lowland sediment samples along two perpendicular transects. Diatom, tephrochronological and radiocarbon analyses have allowed the generation of new RSL curves for the region, showing higher marine limit elevations close to loading centres and differing influences of Younger Dryas ice re-advance. Mapping of the marine limit has shown differences in the pattern of deglaciation due to fjord width and morphology. The contrasting LGM glaciation scenarios have been tested using the GIA modelling, with the new and existing RSL dataset as a constraint. Both field data and GIA model outputs support the maximum glaciation hypothesis.
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Woodroffe, Sarah Alice. "Holocene relative sea-level changes in Cleveland Bay, north Queensland, Australia." Thesis, Durham University, 2006. http://etheses.dur.ac.uk/1293/.
Повний текст джерелаАнотація:
Full understanding of sea level, ice sheet and earth interactions during the Holocene, and the impact of current and future global sea-level rise requires observations of Holocene relative sea-level change from both near- and far-field locations. North Queensland is an ideal far-field location for testing models of mid/late Holocene global meltwater discharge and the viscosity structure of the solid earth, despite problems with indicators and gaps in its Holocene sea-level record. This thesis addresses inadequacies in the record of Holocene sea-level changes in North Queensland using for the first time a foraminifera-based transfer function, which employs vertically zoned modern intertidal and shallow subtidal calcareous foraminifera to reconstruct past water-level changes from fossil foraminiferal assemblages. This technique provides reconstructions which are of equal or greater vertical precision than reconstructions using mangrove mud or coral indicators on this coastline. AMS 14C dated calcareous foraminifera provide intra-site correlation of environmental and sealevel changes over the past 6000 calibrated years. This thesis also highlights problems which limit the applicability of the transfer function technique in this environment, including poor preservation of agglutinated foraminifera in fossil sediments and reworking of Holocene intertidal and shallow subtidal sediments which is not obvious from visual, bio- or litho-stratigraphical analysis. By creating new sea-level index points and re-calibrating existing ones from other indicators I infer the general form of the mid/late Holocene sea-level record in central North Queensland as sea level rising above its present value prior to 6700 cal years BP, with relatively stable sea level 1-2.3 m above present between 6700-5000 cal years BP, and between 1-2.8 m above present between 5000-3000 cal years BP. This is followed by sea-level fall to between 0.4-0.8 m above present until 1200 cal years BP and subsequent slow fall to present. This sea-level data supports theories suggested by geophysical models of a gradual end to global ice sheet melt, with melting ending after 5000 cal years BP.
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Dangendorf, Sönke [Verfasser]. "Sea level variability and its role for coastal flood risk in the southeastern North Sea : insights into past, present and future sea level changes / Sönke Dangendorf." Siegen : Universitätsbibliothek der Universität Siegen, 2015. http://d-nb.info/1075911648/34.
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Svensson, Jonas. "Beach processes and recent sea-level changes at Tönsneset, Kongsfjorden, northwestern Spitsbergen." Thesis, Stockholms universitet, Institutionen för naturgeografi och kvartärgeologi (INK), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-55573.
Повний текст джерелаАнотація:
Beaches occur throughout the coastal regions of the world. Ridges found on beachescan be used as indicators of past climatic and oceanographic conditions. Sea-levelchanges can also be extrapolated from these landforms, if the correct conditions occur, when the facies between eolian and intertidal sediments can be found. Groundpenetrating radar and fieldwork has been used to investigate the origins, processes, and the connection with sea-level fluctuations on a beach and the associated berm-ridge, located at Tönsneset in Kongsfjorden, northwestern Spitsbergen.The beach has a moderately simple internal structure, with the stratigraphy of the beachrevealing layers with a low gradient towards the sea on the foreshore, and overwashlayers with an inclination landwards on the backshore. Layers alternate mostly withsand and gravel, and a majority of them having low angle cross laminationcharacteristics. Previous datings, together with preliminary datings from this study, signify an origin from late Holocene for the berm-ridge. The berm-ridge at Tönsnesetdoes not indicate any clear-cut evidence of a former sea-level and it cannot be used asevidence for a suggested recent transgression.
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Lawrence, Thomas. "Reconstructing abrupt, high-magnitude sea-level changes from near-field coastal environments." Thesis, Durham University, 2016. http://etheses.dur.ac.uk/11655/.
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Abrupt, high-magnitude sea-level changes pose a major challenge to society and have, in the past, been significant drivers of coastal change. Traditionally, sea-level reconstructions from near-field regions - those close to or strongly influenced by current or former ice masses - depict long-term, millennial-scale sea-level changes associated with low-amplitude ice-sheet histories. Types of abrupt sea-level change, including meltwater pulses, tsunamis and storms, are not well studied in near-field regions, but such areas have potential to provide a suitable context for recording and identifying evidence of abrupt sea-level change. For example, unusually high sedimentation rates due to the presence of glaciers might promote the development of high-resolution records, while a dominant glacio-isostatic adjustment signal might facilitate improved registration and identification of globally significant episodes of abrupt sea-level rise. This thesis explores the efficacy of near-field regions in reconstructing abrupt sea-level change by using a combination of stratigraphic and dating methods at field sites in Scotland and Greenland. From southwest Scotland, a sub-centennially resolved, diatom-based sea-level reconstruction for the early Holocene constrains the timing and magnitude of three meltwater-induced sea-level accelerations in the c. 500 yrs prior to the 8.2 kyr BP event. Despite an inability of the 14C dating technique to confirm synchroneity of events, the three sea-level jumps overlap in age with other examples of abrupt change recorded in North Atlantic non-coastal and coastal archives, lending support to a three-event model of meltwater release from the Laurentide Ice Sheet as the driving mechanism responsible for the 8.2 kyr BP event. In Greenland, nearshore and freshwater stratigraphic records contain evidence of landslide- and iceberg-induced tsunami events in the mid and late Holocene. Field sites in Vaigat (Disko Bugt, West Greenland) preserve evidence of five tsunami events in the past 1500-2000 years, which is comparable to tsunami recurrence intervals described from sites on large subduction zone margins. A coastal lake at Innaarsuit also provides the first reported sedimentary evidence of an iceberg-generated tsunami in the mid Holocene. The thesis concludes by reflecting on the opportunities and challenges in reconstructing abrupt sea-level change from near-field settings.
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Massey, Anthony Carl. "Holocene sea-level changes along the Channel coast of south-west England." Thesis, University of Plymouth, 2004. http://hdl.handle.net/10026.1/476.
Повний текст джерелаАнотація:
A Holocene relative sea-level (RSL) history for the south Devon coast is reconstructed through an analysis of twelve cores extracted from the coastal back-barrier environments of Bantham Sands, North Sands, Slapton Sands and Blackpool Sands. Foraminifera preserved in the sediments are assigned an indicative meaning based on the vertical distribution of their modem counterparts from contemporary salt marsh and mudflat environments in the Erme and Salcombe-Kingsbridge estuaries. The contemporary data provide the first inter-tidal (-2.6 to +2.6 m MTL) foraminifera-based transfer function for south-west England from which sea-level changes can be predicted with good precision (RMSEP = ±0.29 m). Sea-level index points (SLIPs) from basal facies provide the longterm (103 yr) RSL history. SLIPs derived from non-basal minerogenic and peat sequences are subject to post-depositional consolidation and a vertical correction, using the Paul and Baffas (1998) method, was therefore applied to these index points. The vertical displacement of fine minerogenic sediments ranges from <0.1 m above basal facies to >1 m at minerogenic-peat contacts, increasing to >2 m in organic peat facies. The age of each SLIP is obtained by AMS 14C dating of bulk sediment or plant material. The electrical resistivity method of geophysical survey provides additional subsurface mapping information of the back-barrier sediments, and the lithostratigraphic results support the view that a complex barrier-lagoon system existed along the south Devon coastline during the early Holocene. Almost 13 m of RSL rise occurred along the south Devon coastline ca. 9000 to 4400 cal years BP. The rate of early Holocene RSL rise is -5.4 ± 2.1 m/ka and -1.1 ± 0.2 m/ka during the mid- to late Holocene. The pattern and rate of RSL rise is similar to other sea-level curves produced for the region. Lambeck's (1993a, b, 1995) geophysical model predictions fit the data well during the early Holocene but Peltier's (1998) model is the best overall fit of the robust data used to reconstruct the early to mid- Holocene RSL history. Rates of middle to late Holocene sea-level rise are generally faster than the models predict. The area is still undergoing glacio-isostatic adjustment (GIA) equating to a coastal land subsidence of -1.16 m/ka since ca. 4400 cal years BP. The dataset increases the current Holocene SLIP database for the south-west peninsula and southern Britain by 23% and for south Devon by almost fivefold.
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Rhodes, Guy. "Magnetostratigraphy of US Paleogene depositional sequences : implications for dating sea level changes." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294621.
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Bedlington, D. J. "Holocene sea-level changes anad crustal movements in North Wales and Wirral." Thesis, Durham University, 1994. http://etheses.dur.ac.uk/1029/.
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Punwong, Paramita. "Holocene mangrove dynamics and sea level changes : records from the Tanzanian coast." Thesis, University of York, 2013. http://etheses.whiterose.ac.uk/4035/.
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Tanzanian mangrove ecosystems have been, and are presently, influenced by changes in climate and sea level. Fluctuations in these environmental conditions lead to adaptations and changes in ecosystem structure and composition. In this thesis mangrove environments are investigated and used to unravel the Holocene environmental history of the Tanzanian coast. Palaeoecological data from sediments abstracted from three different mangrove locations (the Rufiji Delta, Makoba Bay and Unguja Ukuu) are analysed for fossil pollen and charcoal and combined with stratigraphical investigations and radiocarbon dating allow a detailed environmental reconstruction to be undertaken. The relationship between pollen in surface samples and the surrounding vegetation is used to interpret fossil pollen records. Changes in the relative proportions of mangrove pollen under different inundation regimes are used to reconstruct mangrove dynamics and provide estimates of past sea level changes and infer specific changes in sea level altitude. Palaeoecological records reveal that mangroves in the Rufiji Delta occurred at the central sites from at least ~5600 cal yr B.P. until the late Holocene when mangroves covered the landward site and were succeeded by terrestrial vegetation to the present day. The Zanzibar records reveal fluctuating mangrove compositions from ~8000 cal yr B.P. to the present day with noticeable changes in mangrove composition during the mid Holocene. A reconstructed sea level curve from the three sites document an early-mid to mid Holocene sea level rise from ~ 8000 cal yr B.P. to around 4600 cal yr B.P. with potential highstands at 5800 cal yr B.P. and 4700 cal yr B.P. Sea level fluctuations occurred in the last thousand years with a potential highstand at ~ 530 cal yr B.P. before falling to a lower than present level at ~140 cal yr B.P. The earliest intensive human interactions within the mangroves was recorded in Zanzibar after ~530 cal yr B.P; a time of increased settlements and overseas trade along the Swahili coast. The Rufiji Delta records also demonstrate the impacts of damming and the destruction of mangrove areas for rice cultivation during the last millennium. The palaecological data have helped unravel the environmental history of the Tanzanian coast and have the potential to assist in the development of policies and/or public awareness for the sustainable utilization and management of mangrove ecosystems under predicted future sea level and climate changes.
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Zong, Yongqiang. "Flandrian sea-level changes and impacts of projected sea-level rise on the coastal lowlands of Morecambe Bay and the Thames Estuary, U.K." Thesis, Durham University, 1993. http://etheses.dur.ac.uk/1190/.
Повний текст джерелаАнотація:
This thesis aims to reconstruct the Flandrian sea-level history of Morecambe Bay, from which, comparisons are made with the contrasting area - the Thames Estuary. This thesis also aims to assess the likely impacts of projected sea-level rise on the two coastal areas in the next century. A detailed investigation of Flandrian stratigraphy has been carried out in the area of Skelwith Pool, north of Morecambe Bay, by applying stratigraphic survey and pollen and diatom analyses. The results suggest that a rapid rise in sea level during 8300-7000 B. P. was followed by a rising and fluctuating sea-level during 7000-3500 B. P. The fluctuating sea-level resulted in alternative clastic and organic deposition. Regional and local isostatic components and palaeo-tidal variation are analyzed. The relationship between movements in sea level and changes in deposition are also explored. Attention is drawn to the uncertainties of the published sea-level scenarios. Two of the scenarios are adopted. Natural responses of coastal hydrology and sedimentation to the rising sea-level are explored. Effectiveness of the existing sea defence is assessed. Geographical Information Systems for the two coastal areas are established and the coastal lowlands subject to marine inundation are identified in terms of their altitudes and nature of landuse. Three pilot areas of different types of landuse and topography - Skelwith Pool, Heysham and Morecambe, and Canvey Island - are selected and impacts of sea-level rise in these areas are listed.
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Wells, James Michael. "Flandrian relative sea-level changes in the Cree Estuary region, south west Scotland." Thesis, Coventry University, 1997. http://curve.coventry.ac.uk/open/items/3ec3a56a-51bc-4841-a01f-96e30e5f164b/1.
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The northern shoreline of the Solway Firth (SW Scotland) is well established as being a region containing a wealth of evidence for changing sea-levels since the end of the last glaciation circa 10,000 years ago.
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Smith, Andrew David. "Late Quaternary tectonics, sedimentation and sea-level changes in the North Aegean region." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321021.
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Rosa, José Wilson Corrêa. "Global plate reconstructions, the area-age relationship, and global changes in sea level." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/60421.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1990.Archives copy lacks leaf 247.
15 folded maps in pocket.
Includes bibliographical references (leaves 120-140).
by José Wilson Corrêa Rosa.
Ph.D.
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Joshi, Neekita. "ASSESSING THE SIGNIFICANCE OF CLIMATE VARIABILITY ON GROUNDWATER RISE AND SEA LEVEL CHANGES." OpenSIUC, 2021. https://opensiuc.lib.siu.edu/dissertations/1908.
Повний текст джерелаАнотація:
Climate variability is important to understand as its effects on groundwater are complex than surface water. Climate association between Groundwater Storage (GWS) and sea level changes have been missing from the Intergovernmental Panel on Climate Change, demanding a requisite study of their linkage and responses. The current dissertation is primarily focused on the ongoing issues that have not been focused on the previous literatures. Firstly, the study evaluated the effects of short-term persistence and abrupt shifts in sea level records along the US coast by utilizing popular robust statistical techniques. Secondly, the study evaluated the variability in groundwater due to variability in hydroclimatic variables like sea surface temperature (SST), precipitation, sea level, and terrestrial water storage. Moreover, a lagged correlation was also analyzed to obtain their teleconnection patterns. Lastly, the relationship between the groundwater rise and one of the most common short-term climate variability, ENSO was obtained. To accomplish the research goals the current dissertation was subdivided into three research tasks.The first task attempted to answer a major question, Is sea level change affected by the presence of autocorrelation and abrupt shift? This question reflects the importance of trend and shift detection analysis in sea level. The primary factor driving the global sea level rise is often related to climate change. The current study investigates the changes in sea level along the US coast. The sea level records of 59 tide gauge data were used to evaluate the trend, shift, and persistence using non-parametric statistical tests. Mann-Kendall and Pettitt’s tests were utilized to estimate gradual trends and abrupt shifts, respectively. The study also assessed the presence of autocorrelation in sea level records and its effect on both trend and shift was examined along the US coast. The presence of short-term persistence was found in 57 stations and the trend significance of most stations was not changed at a 95% confidence level. Total of 25 stations showed increasing shift between 1990–2000 that was evaluated from annual sea level records. Results from the current study may contribute to understanding sea level variability across the contiguous US. The second task dealt with variability in the Hydrologic Unit Code—03 region. It is one of the major U.S. watersheds in the southeast in which most of the variability is caused by Sea Surface Temperature (SST) variability in the Pacific and Atlantic Ocean, was identified. Furthermore, the SST regions were identified to assess its relationship with GWS, sea level, precipitation, and terrestrial water storage. Temporal and spatial variability were obtained utilizing the singular value decomposition statistical method. A gridded GWS anomaly from the Gravity Recovery and Climate Experiment (GRACE) was used to understand the relationship with sea level and SST. The negative pockets of SST were negatively linked with GWS. The identification of teleconnections with groundwater may substantiate temporal patterns of groundwater variability. The results confirmed that the SST regions exhibited El Niño Southern Oscillation patterns, resulting in GWS changes. Moreover, a positive correlation between GWS and sea level was observed on the east coast in contrast to the southwestern United States. The findings highlight the importance of climate-driven changes in groundwater attributing changes in sea level. Therefore, SST could be a good predictor, possibly utilized for prior assessment of variabilities plus groundwater forecasting. The primary goal of the third task is to better understand the effects of ENSO climate patterns on GWS in the South Atlantic-Gulf region. Groundwater issues are complex and different studies focused on groundwater depletion while few emphasized, “groundwater rise”. The current research is designed to develop an outline for assessing how climate patterns can affect groundwater fluctuation, which might lead to groundwater rise. The study assessed the effect of ENSO phases on spatiotemporal variability of groundwater using Spearman Rank Correlation. A significant positive correlation between ENSO and GWS was observed. An increasing trend was detected in GWS where most grids were observed in Florida by utilizing the non-parametric Mann-Kendall. A positive magnitude of the trend was also detected by utilizing Theil-Sen’s Slope method with high magnitude in the mid-Florida region. The highest GWS anomalies were observed in the peak of El Niño events and the lowermost GWS was observed during La Niña events. Furthermore, most of the stations were above normal groundwater conditions. This study provides a better understanding of the research gap between groundwater rise and ENSO.
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Hein, Christopher. "Styles of coastal evolution in response to Holocene changes in sea level and sediment supply." Thesis, Boston University, 2012. https://hdl.handle.net/2144/32023.
Повний текст джерелаАнотація:
Thesis (Ph.D.)--Boston UniversityPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
This study employs a suite of geophysical, sedimentological, and chronostratigraphic tools to investigate the complex interactions among changes in sea level, climate, and sedimentation processes that have driven Holocene coastal evolution. These interrelationships were explored in investigations of three coastal sites with diverse sea-level and sedimentation histories: the Egyptian Red Sea (Wadi Gawasis), southern Brazil (Pinheira) and the Western Gulf of Maine (Plum Island). This study demonstrates the need to quantify the integrated impacts of spatially-diverse changes in global (sea level), regional (climate, sea level), and local (sedimentation) factors if we are to predict large-scale coastal evolution in response to the ongoing acceleration in sea-level rise. The mid-Holocene in both the Red Sea and southern Brazil was characterized by higher-than-present stands of sea level. Sedimentological, malachological, foraminiferal, and rheological studies at Wadi Gawasis reveal that this resulted in the formation of a shallow bay that reached its maximum extent prior to a 1.5-m highstand at 5 ka, demonstrating a dominance of sedimentation processes despite contrary sea-level change. Early bay closure was driven by sediment inputs enhanced by a wetter climate. Slowly falling sea level and coincidental climatic aridization allowed for the establishment of an Egyptian harbor 4 ka, followed by late-stage progradation dominated by sea-level fall. In southern Brazil, an abundant sediment supply and sea-level fall following the mid-Holocene highstand were responsible for the development of the 5-km wide Pinheira strandplain, composed of regular beach and dune ridges. Identification of anomalous barrier, lagoonal, and tidal fill deposits within this plain demonstrates the complex nature of the sedimentological response to a small-scale change in the rate of sea-level fall. By contrast, Plum Island formed in a regime of rapid sea-level rise that reworked shallow shelf and fluvial deposits. Geophysical and sedimentological studies reveal a complex barrier formation (aggradation, spit accretion and progradation), including evidence for inlet migration and closure. Time-transgressive backstripping of backbarrier facies shows that bay sedimentation in a regime of slowly rising sea level reduced tidal-prism and produced inlet closure. This is first study to demonstrate that the direct impact of backbarrier processes influencing barrier island development.
2031-01-02
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Solihuddin, Tubagus. "Holocene reef accretion of the inshore Kimberley Bioregion and response to sea-level changes." Thesis, Curtin University, 2016. http://hdl.handle.net/20.500.11937/2433.
Повний текст джерелаАнотація:
The Kimberley Bioregion of Northwest Australia is one of the world’s last great pristine marine environments and is broadly recognised as a “biodiversity hostspot” but is poorly known and studied. This project completed a comprehensive description of reef geomorphology and associated habitats, stratigraphy, palaeoecology, geochronology, accretion history along with shallow seismic profile. A combination of the data collected and interpreted provides the foundation for a scientifically based management plan of the Bioregion.
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Vanderslice, William Dale III. "Response of Cretaceous Marine Reptiles to Paleoceanographic Changes: Sea Level and Climate Changes as Drivers of Origination and Extinction." Bowling Green State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1542284081403242.
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Rennie, Alistair Flett. "The role of sediment supply and sea-level changes on a submerging coast past changes and future management implications /." Thesis, Connect to e-thesis, 2006. http://theses.gla.ac.uk/843/.
Повний текст джерелаАнотація:
Thesis (Ph.D.) - University of Glasgow, 2006.Ph.D. thesis submitted to the Department of Geographical and Earth Sciences, University of Glasgow, 2006. Includes bibliographical references. Print version also available.
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Chang, Biao. "Spatial analysis of sea level rise associated with climate change." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49062.
Повний текст джерелаАнотація:
Sea level rise (SLR) is one of the most damaging impacts associated with climate change. The objective of this study is to develop a comprehensive framework to identify the spatial patterns of sea level in the historical records, project regional mean sea levels in the future, and assess the corresponding impacts on the coastal communities. The first part of the study suggests a spatial pattern recognition methodology to characterize the spatial variations of sea level and to investigate the sea level footprints of climatic signals. A technique based on artificial neural network is proposed to reconstruct average sea levels for the characteristic regions identified. In the second part of the study, a spatial dynamic system model (DSM) is developed to simulate and project the changes in regional sea levels and sea surface temperatures (SST) under different development scenarios of the world. The highest sea levels are predicted under the scenario A1FI, ranging from 71 cm to 86 cm (relative to 1990 global mean sea level); the lowest predicted sea levels are under the scenario B1, ranging from 51 cm to 64 cm (relative to 1990 global mean sea level). Predicted sea levels and SST's of the Indian Ocean are significantly lower than those of the Pacific and the Atlantic Ocean under all six scenarios. The last part of this dissertation assesses the inundation impacts of projected regional SLR on three representative coastal U.S. states through a geographic information system (GIS) analysis. Critical issues in the inundation impact assessment process are identified and discussed.
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James, H. C. L. "Late Quaternary coastal landforms and associated sediments of west Cornwall." Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239536.
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Brouillette-Jacobson, Denise. "Analysis of coastal erosion on Martha's Vineyard, Massachusetts a paraglacial island /." Connect to this title, 2008. http://scholarworks.umass.edu/theses/176/.
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Albrecht, Frauke [Verfasser], and Hans Von [Akademischer Betreuer] Storch. "Regional Mean Sea Level Changes in the German Bight / Frauke Albrecht. Betreuer: Hans von Storch." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2013. http://d-nb.info/1037199642/34.
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Hamilton, Sarah Louise. "Late Holocene relative sea-level changes and earthquakes around the upper Cook Inlet, Alaska, USA." Thesis, Durham University, 2003. http://etheses.dur.ac.uk/4094/.
Повний текст джерелаАнотація:
The earthquake deformation cycle (EDC) produces a sequence of specific relative land- and sea-level movements associated with large (magnitude > 8) plate boundary earthquakes forming pre-seismic, co-seismic, post-seismic and inter-seismic periods. Measurements available for the 1964 Alaskan earthquake allow a comparison between late Holocene earthquakes and an event of known magnitude. This thesis analyses multiple late Holocene co-seismic events at three sites around the upper Cook Inlet, Alaska, including at least one complete EDC at each site, quantified using transfer function techniques. Results describe five definite co-seismic events at Girdwood and one each at Kenai and Kasilof, with further possible events at all three sites. These fall within six periods of co-seismic submergence, including 1964, spaced at irregular intervals over the last 4000 years. Quantitative reconstructions suggest that submergence resulting from most co-seismic events studied are of similar magnitude to the 1964 earthquake but it is not possible to identify whether pre-1964 events affected the same area. A key finding is the identification and quantification of pre-seismic relative sea-level (RSL) rise before all those events attributed to co-seismic submergence. The maximum magnitude of pre- seismic RSL rise is +0.21 ± 0.10 m and for the 1964 event starts approximately 10 years before the earthquake. This is strong evidence to suggest it represents a precursor to a large event and independent work elsewhere describes possible mechanisms for this phenomenon. Long-term patterns of RSL change show significant differences between sites around Turnagain Arm compared to Kenai and Kasilof. The latter show negligible permanent deformation over multiple EDC's but this is not the case at sites around Turnagain Arm. Before attributing this to only partial recovery between two earthquakes, other factors deserve further attention, especially sediment consolidation, tidal range change through time and improvements in GIA modelling taking into account local ice sheet reconstructions.
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Powell, Victoria Alicia. "Relative sea level change in the Forth and Tay Estuaries : past changes informing future trends." Thesis, University of Dundee, 2012. https://discovery.dundee.ac.uk/en/studentTheses/832abe7f-3917-48ad-a9e5-a66f5f57d583.
Повний текст джерелаАнотація:
This thesis introduces new relative sea level datasets from the Forth and Tay Estuaries dating between 1900 and 2010 and uses these to analyse sea level oscillations, surge components and to influence future sea level projections. Prior to this research, relative sea levels had not been analysed across this region. These datasets were collated and corrected using renowned methods and investigated using Shennan et al.’s (2012) GIA corrections, Torrence and Compo’s (1998) Morlet wavelet transform and Graff’s (1981) sea level maxima analysis. The relative sea level data were then used to support adaptations of two sea level projection models to 2100; the UK Climate Projections 2009 (UKCP09) probabilistic model and Vermeer and Rahmstorf’s (2009) temperature-sea level relationship projections model. These models were, in turn, used to project the impact of extreme relative sea levels on local infrastructure by 2100. This research revealed that relative sea level in the Forth and Tay Estuaries between 1900 and 2010 rose at a rate of 0.27 to 0.56 mm a-1, which is smaller than the global average of 1.7 mm a-1 (Church and White, 2011). Tidal residuals were commonly observed to be approximately 0.4 and 0.7 m at Leith and Dundee between 2003 and 2010, whilst the highest sea level maxima across 5 ports in the region ranged between 3.27 and 4.13 m above OD. Adaptions of the UKCP09 model reduced the original projections for 2100 of between 31.3 and 35.1 cm to between 24.3 and 27.5 cm above the 1990 mean. Similarly, adaptions of the Vermeer and Rahmstorf (2009) model reduced projections from 107.5 cm to between 50.9 and 54.2 cm above the 1990 mean. These adapted projections, when added to the extreme 2100 sea level calculations, suggests that the highest extreme sea level by 2100 could reach the present day quayside heights at selected locations in the Forth and Tay Estuaries. The approach and results are replicable across other regions, thereby refining projections made by previous authors.
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Chen, Xinping [Verfasser], and Thomas [Akademischer Betreuer] Pohlmann. "Investigation of temperature and sea level changes in the North Sea for the period 1948-2010 / Xinping Chen. Betreuer: Thomas Pohlmann." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2014. http://d-nb.info/1048626717/34.
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Turner, Jennifer 1979. "Investigating the effects of climate change and sea level rise on the coastal processes of the Beaufort Sea, Yukon Territory." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81448.
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High latitude areas have been identified in most GCMs as regions where global warming will appear earliest and be the greatest. Since much of Canada's north is underlain by permafrost, a warming of 3-5°C could cause widespread erosion and thermokarst. The Arctic coastal zone is particularly vulnerable, as it lies at the interface between terrestrial systems dominated by permafrost, and marine systems dominated by sea ice and wave action. This study aims at understanding some mechanisms of arctic coastal erosion, such as thermoerosional niches and block failure. The final goal of this research is to identify the areas of Herschel Island, Yukon Territory, which are likely to experience the greatest magnitude of change in the near future. This information is then coupled with a climate change scenario in order to predict future coastal erosion in the area.