Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 177-180). Also available via the Internet

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2 v. : ill., maps ; 30 cm. + 5 fold. maps in end pocket of v.2 / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Economic Geology, 1976

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Thesis (Ph. D.)--University of Wisconsin--Madison, 1971. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 154-163).

Geomagnetic depth-sounding was carried out in a large-spaced profile across central British Columbia in order to map the conductivity structure of the crust and upper mantle in the central Canadian Cordillera. Geomagnetic variographs were set up from east of Jasper to Prince Rupert in two successive east-west profiles during the summer of 1969. Numerical analysis of geomagnetic storm activity indicates that the discontinuity in the attenuation of the vertical magnetic field, as first reported for south-eastern British Columbia by Hyndman (1963), is located in the area of the Rocky Mountain Trench. All stations to the west exhibit typical 'low Z' characteristics and no or little anomalous induction; stations to the east of the trench display a strong, high-frequency Z-variation content as well as anomalous field enhancement. Power spectral and polarization analyses show a first order agreement with the two-dimensional conductivity structure model proposed by Caner (1970) for south-western Canada. Second-order effects suggest a more complex model consisting of two conductivity discontinuities: One shallow structure strikes roughly NW-SE at a depth of 10 to 15 km. and may be associated with the 'edge' of a hydrated layer located at the western front of the Rocky Mountains; a second much deeper structure, trending approximately E-W, is located south of Kootenay Lake and is possibly associated with a strike-slip feature in the upper mantle (Lajoie and Caner, 1970). / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The purposes of this thesis were (1) to provide some knowledge of the herptiles and mammals of this area, (2) to clarify the distribution of many of these animals in this section of Texas, and (3) to provide additional ecological information about the area.

Estuaries have been identified as hotspots of microplastic pollution because they are transitional zones where coastal freshwater and oceans converge. Microplastics (MP) are transported through estuaries by a dynamic series of forces such as surface flow and tides, which influence MP abundances and trends. The eastern oyster, Crassostrea virginica, is an estuarine bivalve known to ingest MP, resulting in negative impacts on organism physiology. I investigated MP pollution as a threat to C. virginica in a dynamic Florida estuary, the Indian River Lagoon (IRL), and determined there are both regional and small-scale spatial and temporal fluctuations in MP abundance. Tributaries were identified sources of MP, while inlets flush them out of the system. The south IRL is a hotspot for MP, where the St Lucie Estuary is the primary tributary. Throughout the IRL, fibers dominated MP and polyethylene terephthalate (PET) was the most abundant polymer type ( > 50%). Overall, C. virginica had a mean of 2.2 MP/individual and lagoon water had 1.5 MP/L. An in-situ biodeposition experiment revealed C. virginica of all sizes were able to egest environmental MP at a rate of 1 MP per 1 hour through feces, and 1 MP per 2 hours through pseudofeces. Oysters had a mean MP egestion efficiency of 62.1%, and 32.1% of oysters were able to egest all MP from their tissues within 2 hours. Smaller C. virginica were more efficient at egesting MP, and egestion efficiency decreased by 0.8% for every 1-g increase in tissue weight. Overall, I provide an argument that MP are ubiquitous in this hydrologically dynamic estuary in both the water and in a keystone, filter-feeding invertebrate. I estimate there are currently ~1.4 trillion microplastics in the Indian River Lagoon.