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A depositional model for the Muncie Esker, East-Central IndianaTerrell, Mark A. January 1997 (has links)
The Muncie esker, a glaciofluvial ridged system, consists of three sharp-crested esker segments in the proximal and central sections, and a broad=crested, fan shaped distal segment. Grain size ranged from clay to boulders, although a larger presence of coarser material with high standard deviation values occurs in the proximal and central segments, while higher concentrations of finer sediment, primarily sand, exists in the distal segment. Field mapping and description included its geomorphic expression, stratigraphic relationships that consisted of facies identification, sedimentary structure , and paleocurrent direction. Sedimentological parameters, including downesker trends in grain size, sorting, a fractal analysis of grain size persistence, and clast roundness, was also investigated.The interpretation of the results provided us with detailed information allowing us to formulate a specific model of esker genesis. The depositional model consists primarily of nearly continuous, contemporaneous subglacial deposition that reulted in the formation of the proximal and central esker segments, and time-transgressive sedimentation, containing interlayered and randomly distributed ice rafted debris, in the form of a subaqueous delta that prograded beyond the ice-margin, forming the distal esker segment. Early stage deposition consisted of bed load transport from moderate flow velocities within a preglacial bedrock valley that served as an R-channel for preliminary subglacial meltwater drainage. Intermediate stage formation consisted of subglacial sedimentation from a hyperconcentrated deforming bed, induced by an outburst flood, and distal deltaic sedimentation as the subglacial flood discharged beyond the ice margin into an ice-marginal lake. Late stage deposition arises from bed load sedimentation of moderate fluvial activity reworking the upper portions of the hyperconcentrated flow deposits and upper deltaic facies. The finality of esker formation concluded with the ablation of the subglacial tunnel roof, sending a supraglacial debris flow that conformably covers the proximal and central esker segments in the form of a diamicton drape. / Department of Geology
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Impacts of past glaciation events on contemporary fish assemblages of the Ohio River basinJacquemin, Stephen J. January 2010 (has links)
I tested if spatial variation of Ohio River drainage basin fish assemblages, current habitat,
water quality, and hydrology were concordant with historic glaciation boundaries.
Assemblage analyses were organized using taxonomic and functional groups.
Multivariate analyses, principal components analysis (PCA) and indicator species
analyses, were used to test whether taxonomic and functional assemblages were distinct
among regions with varying glacial histories. Principal components analysis was used to
identify habitat and water quality as well as hydrologic gradients that could be discerned
by glacial region. I identified significant differences in both taxonomic and functional
fish assemblage structure and habitat variation among regions that had different
glaciation histories. Recently glaciated Wisconsinan sites were characterized by
assemblages of Cyprinidae and Catostomidae families, with high abundances of tolerant
fishes that tended to occur in habitats with reduced current velocity. Sites in the Pre-
Wisconsinan region were characterized by Cyprinidae, Catostomidae, Centrarchidae, and
Percidae families, with increased abundances of intolerant fishes that tended to occur in
habitats with coarser substrates and increased water velocity in streams of varying size.
Sites in the unglaciated region were dominated by Cyprinidae and Percidae families but
were not closely associated with any habitat-based functional group. Taxonomic and
functional analyses explained 25% and 40%, respectively, of the variance in assemblage
structure. Mean habitat PCA component scores in the unglaciated and Pre-Wisconsinan
sites were significantly different than Wisconsinan sites, which were characterized by
increased channel structure and reduced stream size. While a multitude of factors impact
the distribution of fishes, these results suggest that historical influences such as glaciation
may be used to further explain underlying mechanisms of spatial variation in fish
assemblages. / Department of Biology
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Occurrence and origins of streamlined forms in central British ColumbiaMcClenagan, Jerry Donald 03 May 2010 (has links)
The purpose of this research is to gain understanding of the occurrence and origin of streamlined forms in central British Columbia. More than 50,000 landforms, primarily drumlins and crag-and-tail ridges, were digitally mapped over an area covering five 1:250,000 NTS map sheets. Visual Basic programs were written to statistically analyze the streamlined forms database and to simulate site-scale, two-dimensional glacial erosion. Results show three principal ice and/or meltwater flow directions: southeast flows probably originating in the Skeena Mountains, northeast flows from the Coast Mountains and Quanchas Range, and west flows originating east of the Babine and Telkwa Ranges. Rat-tails and striae occur up to 1680 m elevation and record uphill flow to the west in these ranges.
Streamlined forms were investigated at outcrop scale (e.g. rat-tails), landform scale (e.g. drumlins) and landscape scale (as defined by closed contours). On bedrock outcrops, cross-cutting striae are common and they both parallel and cross-cut rat-tails. Small rat-tails occur on, and parallel to, larger rat-tails but they do not cross-cut, suggesting a different origin than striae. Rat-tails are interpreted as being formed by subglacial meltwater flows, an interpretation supported by the glacial erosion model. Lowland streamlined forms (e.g. drumlins and crag-and-tails) are interpreted as either glacially-formed ridges subsequently shaped by meltwater floods or as being formed entirely by meltwater floods. This interpretation is largely based on the common occurrence of interconnecting hairpin furrows around these streamlined forms and on the demonstrated association of hairpin furrows with fluvial erosion.
The results of topographic analysis indicate that an interconnecting system of valleys separates uplands that can be objectively defined by single (closed) contours. The aspect ratios of the uplands are highly correlated (L/W = 2.38, R2 = 0.89) with values that are similar to those reported for braid bars and erosional residuals thought to have been formed by glacial outburst floods. This upland/lowland landform assemblage may, in places, represent streamlined erosional residuals within braided channel networks formed, at least in part, by subglacial or glacial outburst floods.
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Land-cover mapping in an agriculture zone using simulated Sentinel-2 dataPryor, Logan S January 2012 (has links)
Remote sensing technologies are used to assist in the mapping and monitoring of land cover in space and time. The European Space Agency’s (ESA) upcoming Sentinel-2 MultiSpectral Instrument (MSI) to be launched in 2013 has improved spatial and spectral properties compared to the current large-swath medium-resolution satellite sensors. Prior to the deployment of future sensors it is important to simulate and test the sensor data to evaluate the sensor's potential performance in producing the existing data products and develop new algorithms. This study simulated Sentinel-2 MSI data from airborne hyperspectral data over an agriculture area in northern Alberta, Canada. The standard Sentinel-2 MSI land-cover product was evaluated by comparing it to one created from the standard Landsat 5 TM and SPOT 5 HRV data products. Furthermore the standard Sentinel-2 MSI water column content band configuration and algorithm was evaluated for atmospheric correction purposes. / xi, 90 leaves : col. ill. ; 29 cm
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A geomorphic investigation of retrogressive thaw slumps and active layer slides on Herschel Island, Yukon Territory /De krom, Valentina January 1990 (has links)
This thesis investigates the geomorphology of retrogressive thaw slumps and active layer slides on Herschel Island, northern Yukon Territory. In particular, it examines the formation and morphology of both landforms, and the ground ice characteristics of retrogressive thaw slumps. During 1988-1989 a number of retrogressive thaw slumps and active layer slides were surveyed and monitored. Field and laboratory investigations involved (1) documentation of landform distribution, setting and morphology, (2) examination of processes of landform formation, and (3) the examination of cryostratigraphy, ground ice characteristics and material properties. / Retrogressive thaw slumps developed in areas of low to moderate slopes underlain by a variety of sediments with ice contents up to 4500% (on a dry weight basis). Slump headwall retreat rates of up to 19.5 m/yr were recorded. By comparison, active layer slides developed on steeper slopes underlain mainly by marine silts and clays. The sediments exposed in the slide floors and headwalls displayed no visible ground ice, but moisture contents were between 15-35%. Retrogressive thaw slumps and active layer slides form by entirely different processes. However, they do occur in close association and are influenced by many of the same parameters.
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The restructuring of analogical reasoning in planetary science /Soare, Richard J. January 2004 (has links)
Despite its ubiquity in planetary science, analogue-based reasoning largely has remained unbounded by guidelines of use. Establishing analogical guidelines and putting them to the test is the main aim of the thesis. Towards this end, I discuss the philosophical foundations of analogical reasoning in planetary geomorphology and posit rules of use that facilitate the evaluation of analogical hypotheses. Subsequently, I present four hypotheses concerning aeolian, fluvial and periglacial processes on Mars. Each of these hypotheses is evaluated in terms of the analogical rules presented. The fourth hypothesis is original to this thesis and suggests that a periglacial landscape comprising pingos and small-scale polygonal ground exists in an impact crater located in northwest Utopia Planitia.
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Landscape evolution of the Umbum Creek Catchment, Western Lake Eyre, Central Australia.Waclawik, Victor G. January 2006 (has links)
Landscape evolution is important for mineral and petroleum exploration concepts, especially in dryland continental settings. This study seeks to understand the main issues and controls on landscape evolution that have produced the regolith and young sediments around the western side of Lake Eye, in the arid heart of Australia. Several methods were employed including satellite image analysis, geomorphometry, geological mapping, regolith mapping and surveying. Outcomes indicate that the underlying structural fabric of the basement has controlled the development of the surface morphology of the Umbum Creek Catchment. The arrangement of basement faults is reflected in the distribution of surface landforms and in the topography of the land surface. Significant deformation of the Etadunna and Eyre formations indicate tectonic activity occurred at the end of the Miocene and was probably related to movement in the Lake Eyre Fault Zone. Pleistocene faulting is expressed as minor blind faulting associated with pre - existing basement faults. These faults remain active and current seismic activity is driven by changes in hydrostatic pressure (hydroseismicity). The scale of Pleistocene faulting and modern seismic activity demonstrates that since the Pliocene tectonic activity has been subdued. Climate change caused landforms developed under wet conditions during the Palaeogene and Neogene to be preserved by the development of aridity in the Pleistocene. High erosion rates associated with tectonism and the onset of aridity in the Pleistocene led to topographic inversion of many features. Palaeo-Proterozoic inliers formed inselbergs, silcrete outcrops formed capstones, gypsum hardpans protected underlying sediment from erosion creating plateaux of gypsum patterned ground and palaeo-channels on the Neales Fan were eroded to make heavily armoured mounds and associated sand dunes and sand sheets. The dominant factor influencing the evolution of the landscape in the Umbum Creek Catchment was the deposition of sedimentary sulphides within the Bulldog Shale. The excess sulphur that this sediment supplied to the landscape over time created the necessary conditions for the formation of a range of landscape features that would not otherwise exist. Weathering, oxidation and leaching of the sedimentary sulphides led to the development of silcrete. Subsequent weathering and tectonic activity led to the breakdown of the silcrete and the distribution of silcrete pebbles widely across the landscape forming gibber plains. Sulphur from the Bulldog Shale continued to contribute to the landscape forming intra-formational gypsum and precipitating as gypsum hardpans. This study has implications for petroleum exploration in dryland continental settings as potential reservoirs may be affected by secondary diagenetic processes, such as the formation of gypsum or silcretes, that could act as baffles or result in reduced porosity within the reservoir. The broad-scale architecture of fluvial systems, like the Neales Fan, may not conform to traditional fan-shaped models being, instead, comprised of structurally rearranged channels. In terms of earthquake risk assessment, the identification of hydroseismicity active within the Lake Eye Basin allows for a new level of predictability of earthquake behaviour within Central Australia. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1260856 / Thesis (Ph.D.) -- School of Earth and Environmental Sciences, 2006
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Surface exposure dating of glacial deposits from the last glacial cycle : evidence from the Eastern Alps, the Bavarian Forest, the Southern Carpathians and the Altai Mountains /Reuther, Anne U. January 2007 (has links) (PDF)
Univ., Diss.--Regensburg, 2005.
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Late quaternary glacial and sea level history of the Bernier Bay area, northwestern Baffin Island, N.W.T. /Hooper, James Matthew, January 1990 (has links)
Thesis (M.Sc.) -- Memorial University of Newfoundland. / Restricted until October 1991. Typescript. Bibliography: leaves 92-97. Also available online.
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The late quaternary history of Terra Nova National Park and vicinity, Northeast Newfoundland /Sommerville, Anne A., January 1997 (has links)
Thesis (M.Sc.)--Memorial University of Newfoundland, 1997. / Restricted until November 1998. Bibliography: leaves 237-261. Also available online.
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