Thesis (Ph. D.)--University of California, Los Angeles-Geology. / Includes abstract and vita. Description based on print version record. Bibliography: leaves 403-426.

Thesis (M.S. in Applied Science (Physical Oceanography))--Naval Postgraduate School, June 2005. / Thesis Advisor(s): Thomas H.C. Herbers. Includes bibliographical references (p. 45). Also available online.

Thesis (Ph. D.)--Montana State University--Bozeman, 2005. / Typescript. Chairperson, Graduate Committee: John C. Priscu. Includes bibliographical references (leaves 181-201).

No description available.

Image and Imagination: Creative Photography and the South Wales Valleys, explores the development of practices within photography undertaken in and about the South Wales Valleys during the second half of the twentieth century. Central to this study is an examination of the work of the American photographer W. Eugene Smith, who photographed in the Valleys in 1950, and how his practice influenced the wider development of 'creative photography'. The term 'creative photography' is applied here as a description of photography during a period of its transition, moving beyond a recognised position as a pragmatic communicative medium, toward its wider acknowledgement as a significant form of artistic expression. This study considers a range of processes through which photography largely achieved this acceptance. Particular consideration is given to the development of Smith's career, and how his work moved between ever shifting photo-journalistic and photo-art contexts. Photographers working in the Valleys subsequent to Smith are also examined, including those engaged in the Valleys Project' undertaken during the I980's. This study reveals how social, economic and political factors not only shaped Smith's work, but also shaped the increasingly varied modes of photographic representation seen in the latter part of the twentieth century. The study initially considers the South Wales of the mid-twentieth century and how both cinematic and photographic imagery of the region in the decades prior to 1950 engendered particular photographic responses from later visitors. The national and international contexts for the developments in photographic practice such as magazine and book publishing, along with the growing institutional advocacy for exhibiting photography are also examined. The study concludes with an evaluation of the current status of photographic practice relating to the Valleys of South Wales.

The nature of the inter-relationship of valley-side slopes and the streams at their base is regarded as being of fundamental significance in the study of landscape morphology. One aspect of this relationship, the problem of the development of valley-side asymmetry in east-trending valleys under the joint influence of microclimatic and stream controls, is investigated in two areas of uniform, flat-lying beds, using the approach and techniques of experimental design. Valleys in both study areas have been formed during the last 12,000 years, so that the importance of fossil slope forms is minimal. The variation in lithology between the two areas is held to be of less consequence than the difference in climatic regimes, as far as the type of asymmetry developed. The moister of the two areas, S.W. Manitoba, shows the typical, valley-wide asymmetry regarded as characteristic of non-periglaclal regions, with north-facing slopes significantly steepened by 3.1°, on average: the effects of basal steepening by meandering streams are additive with the microclimatic differences. In the drier area, S.E. Wyoming, the effects of the two controls are non-additive, and asymmetry is a purely localised development created by the over-steepening of shaded, north-facing undercut slopes. The moisture availability in this environment is probably increased by the formation of snowdrifts in the winter months. Asymmetry resulting from differences in aspect is statistically insignificant both in east-trending valleys without defined stream channels and in south-trending valleys with meandering streams. The absolute maximum angle is found to be an excellent indicator both of local changes in slope form and of the nature of the profiles as a whole. The degree of organisation of all profiles studied, in relation to the maximum angle, is high, with the exception of the south-facing slopes in those east-trending valleys in Wyoming which lack defined channels. In general, the maximum angle appears more directly related to the other geometric features of the profile than to the characteristics of soil, vegetation or nearby stream channel. A consideration of all available data on multiply-controlled asymmetry in non-periglacial areas leads to the conclusion that differences in steepness of slopes with northern and southern aspects are more likely to develop in regions of comparatively low humidity and that the valley-wide asymmetry found in Manitoba is the most common form. The strictly localised asymmetry developed in the Wyoming valleys appears to be a specialized phenomenon confined to a narrow area of semi-arid climate. It is suggested that the local conditions of moisture availability are the prime controls of multiply-controlled valley asymmetry, in that they will determine the relative importance of slope and channel processes and hence the nature of the valley-side development. / Arts, Faculty of / Geography, Department of / Graduate

In the McMurdo Dry Valleys, Victoria Land, East Antarctica, melting of glacial ice is the primary source of water to streams, lakes, and associated ecosystems. To better understand meltwater production, three hypotheses are tested: 1) that small changes in the surface energy balance on these glaciers will result in large changes in melt, 2) that subsurface melt does not contribute significantly to runoff, and 3) that melt from 25-m high terminal cliffs is the dominant source of baseflow during cold periods. These hypotheses were investigated using a surface energy balance model applied to the glaciers of Taylor Valley using 14 years of meteorological data and calibrated to ablation measurements. Inclusion of transmission of solar radiation into the ice through a source term in a one-dimensional heat transfer equation was necessary to accurately model summer ablation and ice temperatures. Results showed good correspondence between calculated and measured ablation and ice temperatures over the 14 years using both daily and hourly time steps, but an hourly time step allowed resolution of short duration melt events and melt within the upper 15 cm of the ice. Resolution of short duration melt events was not important for properly resolving seasonal ablation totals. Across the smooth surfaces of the glaciers, ablation was dominated by sublimation and melting was rare. Above freezing air temperatures did not necessarily result in melt, and low wind speed was important for melt initiation. According to the model, subsurface melt between 5 and 15 cm depth was extensive and lasted for up to six weeks in some summers. The model was better able to predict ablation if some subsurface melt was assumed to drain, lowering ice density, consistent with observations of a low density weathering crust that forms over the course of the summer on Dry Valley glaciers. In extreme summers, drainage of subsurface melt may have contributed up to half of the observed surface lowering through reduction of ice density and possibly through collapse of highly weathered ice. When applied spatially, the model successfully predicted proglacial streamflow at seasonal and daily time scales. This was despite omitting a routing scheme, and instead assuming that all melt generated exits the glacier on the same day, suggesting refreezing is not substantial. Including subsurface melt as runoff improved predictions of runoff volume and timing, particularly for the recession of large flood peaks. Because overland flow was rarely observed over much of these glaciers, these model results suggest that runoff may be predominantly transported beneath the surface in a partially melted permeable layer of weathered ice. According to the model, topographic basins, particularly the low albedo basin floors, played a prominent role in runoff production. Smooth glacier surfaces exhibited low melt rates, but were important during high melt conditions due to their large surface area. Estimated runoff contributions from cliffs and cryoconite holes was somewhat smaller than suggested in previous studies. Spatial and temporal variability in albedo due to snow and debris played a dominant role in flow variations between streams and seasons. In general, the model supported the existing assumption that snowmelt is insignificant, but in extreme melt years snowmelt in the accumulation area may contribute significantly to runoff in some locations.

This thesis evaluates the nature, provenance, geometry and morphology of incised valley fills to test assumptions made by valley models using ancient examples from well exposed outcrops, in the late Turonian Ferron Sandstone Member of the Mancos Shale Formation in southeastern Utah. The relevance of this work will have particular significance to long wavelength cycles of fluvial landscapes and valley morphology, non-marine reservoir characterization and significant implications for non-marine response to high frequency allogenic cycles such as climate change and changes in relative sea-level. This study illustrates the stratigraphic complexity of valley fill deposits at three levels of spatial resolution. At channel scale within the lower backwater, facies architecture and paleohydraulic analysis are used to predict the degree of shale drape coverage of point bars in a tidally-influenced incised channel. At channel belt scale the study documents a tidally incised, mudstone prone trunk-tributary valley fill and overlying highstand fluvial succession within a stratigraphic framework of fluvial aggragation cycles. 3D photogrammetry models and a high resolution GPS survey are used to restore the morphology of a trunk-tributary valley floor, revealing a surface of tidal ravinement and tidal drainage morphology. At a regional scale, this study radically revises the paleogeographic mapping of the Ferron trunk system, spanning over 1,600 km2. Provenance analysis reveals Ferron Notom trunk valleys were filled at times by sediment from the Mogollon Highlands of Arizona to the southwest, and alternately by sediment from the Sevier Thrust Front to the northwest. Evidence shows the Ferron trunk rivers, previously hypothesized to be an avulsive axial drainage, to be more analogous to Quaternary examples. / Thesis / Doctor of Philosophy (PhD)

The Devonian Taylor Group, in the Olympus Range area, southern Victoria Land (SVL), Antarctica, is separated from the basement by a regional nonconformity (Kukri Erosion Surface). A second localized unconformity within the Taylor Group called the Heimdall Erosion Surface separates the New Mountain Sandstone and older units from the younger Altar Mountain Formation. The depositional environment of the New Mountain Sandstone has long been under contention. The New Mountain Sandstone Formation is a predominantly quartzose cross-bedded sandstone. Its newly defined Mt Jason Member is a coarse arkosic small scale cross-bedded pebbly sandstone that grades up section into the rest of the quartzose New Mountain Sandstone with large scale cross beds. The New Mountain Sandstone has been divided into five lithofacies including the Basal Conglomerate Lithofacies, Pebbly Sandstone Lithofacies, Granule Cross-bedded Lithofacies, Pinstripe Cross-bedded Lithofacies and Cross-bedded Sandstone Lithofacies. Deposition was in a shoreface environment with minor coastal aeolian deposition. The environment changed from upper shoreface to lower shoreface up section, forming transgressive to highstand systems tracts. The Heimdall Erosion Surface truncates the Cross-bedded Sandstone Lithofacies and the Pinstripe Cross-bedded Lithofacies and was formed due to relative sea level fall leading to exposure and erosion of underlying sedimentary and basement rocks. It forms a type 1 sequence boundary. The New Mountain Sandstone was partially or totally lithified before erosion as shown by the jagged morphology of the eroded cross beds on the surface. It is not known when cementation of the NMS took place or how much of the formation has been eroded. The Heimdall Erosion Surface and Kukri Erosion Surface converge locally due to erosion on the Heimdall Erosion Surface and relief on the Kukri Erosion Surface. The Heimdall Erosion Surface became a shore platform and the site of deposition as relative sea level rose. The Altar Mountain Formation with its Odin Member is a cross-bedded, massive and bedded feldspathic and quartzose sandstone that fines up section and is deposited on the erosion surface. The Altar Mountain Formation is divided into four lithofacies including the Conglomerate Lithofacies, Trough Cross-bedded Lithofacies, Cross-bedded Bioturbated Lithofacies and Bedded Fine Lithofacies. Deposition was in a shoreface environment, changing up section to an inner shelf environment with minor estuarine/tidal influence near the top of the section forming transgressive to highstand to regressive system tracts. The sedimentary rocks are derived mainly from the Granite Harbour Intrusives and Koettlitz Group, which underlie the sandstones, but were exposed elsewhere in SVL. The sandstone clasts within the Conglomerate Lithofacies could be derived from underlying older Taylor Group rocks or exotic sources from outside the field area. Correlation with data from adjacent areas suggests deposition of the New Mountain Sandstone occurred in a shallow sea that existed from the Olympus Range, southwards into the Asgard Range and included Vashka Crag. The area around Sponsors Peak and to the north was exposed and supplying feldspathic and quartzose sediment and pebbles into the depositional basin. As relative sea level fell due to either tectonic uplift or eustatic processes a large area of southern Victoria Land was exposed including the Olympus and Asgard Ranges and Bull Pass-St Johns Range area. This lead to erosion of the New Mountain Formation and basement rocks. Deposition of the New Mountain Sandstone continued further south shown by the gradational contact between it and the overlying Altar Mountain Formation. Relative sea level rise led to deposition of the Altar Mountain Formation. Shallow seas once more dominated the southern Victoria Land with deltas in the east (in the Bull Pass-St Johns Range area) feeding feldspathic sediment into the depositional basin (Odin Member). Further sea level rise drowned the delta region and a shallow marine to inner shelf environment led to deposition of the rest of the Altar Mountain Formation.

The inland region of the McMurdo Dry Valleys (MDV) of Antarctica represents a subzero, hyper-arid endmember for physical weathering, and is Earth’s closest terrestrial analog to the Martian surface. In order to document the style and rate of rock breakdown in this region, I conducted field-based, experimental, and numerical modeling studies of supraglacial debris (Mullins till) on Mullins Glacier. These investigations were designed to (1) quantify the rate and processes of physical breakdown of surface rocks on Mullins till, particularly of Ferrar Dolerite, (2) determine the efficacy of thermal stress weathering as an agent in rock erosion, and (3) examine the role of physical weathering in altering the sublimation of buried glacial ice. Results from morphometric field surveys characterizing changes in rock shape, strength, and small-scale surface features, coupled with an iterative cosmogenic nuclide-based age model for Mullins Glacier, show that total erosion rates for clasts of Ferrar Dolerite on Mullins till range from 1.1 to 15 cm Myr-1. In situ field measurements of rock surface temperatures and local ambient conditions recorded at 15-second intervals, combined with a numerical finite element model elucidating changes in internal rock temperatures and associated strain, show that thermal stress weathering is sufficient to induce spalling by propagating existing microcracks of ≥1.1 cm that typically occur at the base of thin, mm-scale alteration rinds. The implication is that thermal stress weathering, previously undocumented in this region, may account for >80% of the total estimated erosion of Ferrar Dolerite. Furthermore, the spalled fragments (up to 5% of Mullins till) provide a negative feedback that slows the rate of subsurface ice sublimation and internal vapor diffusion. Experimental analyses in a controlled environmental chamber set with Mullins till and driven by local meteorological conditions measured in the field yields an average effective diffusivity of 4.5 x 10-6 m2 s-1 for Mullins till and annual rates of buried ice loss of <0.068 mm (assuming Fickian diffusion); these values are consistent with theoretical estimates, demonstrate the importance of physical weathering in modifying supraglacial deposits, and support arguments for persistent cold-desert conditions in the MDV for the last several million years.