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Thesis (doctoral)--Université de Rennes, 2004. / Includes bibliographical references (p. 197-209). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 325-351). Available also in a digital version from Dissertation Abstracts.

Thesis (M.S.)--University of North Carolina at Wilmington, 2005. / Includes bibliographical references (leaves: 47-48)

Heavy mineral compositions of sands from Oregon beaches, rivers and sea cliffs have been determined in order to examine the causes of marked along-coast variations in the beach-sand mineralogy. The study area extends southward from the Columbia River to the Coquille River in southern Oregon. The heavy-mineral compositions were determined by standard microscopic identification with additional verification by X-ray diffraction analyses. Initially the beach-sand samples were collected as single grab samples from the mid-beachface, but significant selective sorting of the important heavy minerals prevented reasonable interpretations of the results. Factor analysis of multiple samples from the same beach yielded distinct factors which correspond with known mineral sorting patterns. The effects of local sorting were reduced by the subsequent use of large composite samples, permitting interpretations of along-coast variations in sand compositions. Four principal beach-sand sources are identified by factor analysis: the Columbia River on the north, a Coastal Range volcanic source, sands from the Umpqua River on the south-Oregon coast, and a metamorphic source from the Klamath Mountains of southern Oregon and northern California. The end members identified by factor analysis of the beach sands correspond closely to river-source compositions, the proportions in a specific beach-sand sample depending on its north to south location with respect to those sources. During lowered sea levels of the Late Pleistocene, the Columbia River supplied sand which was dispersed both to the north and south, its content decreasing southward as it mixed with sands from other sources. The distributions of minerals originating in the Klamath Mountains indicate that the net littoral drift was to the north during lowered sea levels. With a rise in sea level the longshore movement of sand was interrupted by headlands such that the Columbia River presently supplies beach sand southward only to the first headland, Tillamook Head. At that headland there is a marked change in mineralogy and in grain rounding with angular, recently-supplied sands to the north and rounded sands to the south. The results of this study indicate that the present-day central Oregon coast Consists of a series of beaches separated by headlands, the beach-sand compositions in part being relict, reflecting the along-coast mixing at lower sea levels and subsequent isolation by onshore migration of the beaches under the Holocene sea-level transgression. This pattern of relict compositions has been modified during the past several thousand years by some addition of sand to the beaches by sea-cliff erosion and contributions from the rivers draining the nearby Coastal Range. / Graduation date: 1987

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Thesis (M.S.)--Oregon State University. / Part of illustrative matter in pocket. Includes bibliographical references (leaves 98-103). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 257-265). Available also in a digital version from Dissertation Abstracts.

This project studies the relation between the amount of sediment deposited in the Nile Submarine Cone (NSC) and the influence exerted by external controls such as climate change. A detailed calculation of sediment volumes was performed as well as a detailed estimation between intervals in order to assess sedimentation rates and dry mass per Ma for the NSC from the Late Oligocene to Recent. In contrast to previous studies, this project presents for the first time detailed calculations for ten intervals from Late Oligocene to Re- cent, including calculations for Pre-Messinian deposits since they also play an important role in the evolution of the NSC and in the history of erosion and deposition processes in the Nile province. The results of this project evidenced a connection between climate change and the amount of sediment carried by rivers as well as its final fate. Sedimenta- tion rate values obtained for each interval showed an increase in sediment supply during the Late Pliocene-Early Pleistocene, coincident with the i) final uplift of the Ethiopian and Somalian plateaus, ii) the drop in temperatures that took in the northern hemisphere as a consequence of the growth of the ice sheets, and iii) the increase in rainfall in the Ethiopian Highlands as a consequence of the African and Indian Monsoon that produced sapropel deposits and eroded sediments in north-eastern Africa. Pre-Messinian intervals showed low sedimentation rates values compared to Post-Messinian associated probably with an elevated evapo-transpiration cycle reducing the rainfall in the Ethiopian Highlands, des- pite the humid conditions that were present during certain ages (e.g. Zeit Wet Phase Late Miocene).