No description available.

Thesis (M.S.) in Earth Sciences--University of Maine, 2008. / Includes vita. Includes bibliographical references (leaves 93-98).

Thesis (M.S.)--Brigham Young University. Dept. of Geology, 2005. / Includes bibliographical references (p. 37-40).

Thesis (doctoral)--Université de Rennes 1, 2005. / Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.E.)--University of Canterbury, 2007. / Typescript (photocopy). Includes bibliographical references (leaves 133-135). Also available via the World Wide Web.

The thesis aims to reconstruct the Holocene sea-level history in Bangladesh. Detailed litho-, bio-, and chrono-stratigraphic techniques have been applied to elucidate the nature of sedimentary sequences in association with the events of the Holocene marine transgressions and regressions. Samples have been collected from two separate sites, one at Panigati near Khulna and another at Matuail near Dhaka. The study shows evidence of five periods of marine transgression, each followed by a regression, during the Holocene. Each minerogenic sediment layer indicates a marine episode and these sediments were deposited under intertidal to estuarine conditions; each peat layer is in situ and indicates a retreat of the sea. It is difficult to separate the eustatic components contributing to these relative sea-level movements, although processes operating locally and regionally are clearly evident. Two separate sea-level curves, together with possible error ranges, have been proposed for Bangladesh; since the early mid-Holocene, an average relative sea-level rise of 1.07 mm. yr -1 has been estimated. The reconstructed sea-level curves show that during the early and mid-Holocene both sedimentation and subsidence rates were much lower than during the last millennium. Differential spatio-temporal progradation and coastline movements have also been evident. The Ganges and Brahmaputra rivers have provided a continuous sediment supply but their convergence is only of recent origin. A possible hypothesis of two separate estuarine systems for these two rivers has been put forward.

Thesis (Ph.D.)--Boston University / PLEASE 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. / 2999-01-01

No description available.

Sea level and the alongshore component of wind stress data at seven locations on the Pacific coast of Canada and the United States were analyzed. The effective data period was from August 1, 1973 to September 9, 1975. The seven locations were Tofino, British Columbia; Neah Bay and Toke Point, Washington; South beach (Newport) and Charleston, Oregon; and Crescent City and San Francisco, California. Sea level relative to the two year mean is higher at the northern locations during the winter months than it is at the southern stations. There appears to be an annual cycle in the sea level though the amplitudes are different for the two years. The monthly mean wind stress is northward during the winter months, and has a larger value at the northern locations. During the spring and summer the monthly mean wind stress is southward and has a larger value at the southern stations. Linear correlation analysis was performed on the sea level data and on the alongshore component of wind stress for the entire time period and seasonally. Auto-correlations and cross correlations were computed for the adjusted sea levels and wind stress. This analysis shows that the sea level and wind stress fluctuations among these seven locations are coherent. These show that the correlation is a function of location and that it has a seasonal variation. It also appears that by examining plots of correlation coefficients and of sea level slopes, that the region may be divided into two major regimes. This separation might be interpreted as the locale where the West Wind Drift impinges on the coast. / Graduation date: 1978

No description available.