Thesis (B.A.Hons.) from the Department of Geography, University of Adelaide, 1977. / Includes bibliographical references (p. i-iii).

Thesis (M.A.)--University of Wyoming, 2008. / Title from PDF title page (viewed on Sept. 3, 2009). Includes bibliographical references (p. 43-50).

Thesis (M.S.)--University of California, Santa Cruz, 1995. / Typescript. Includes bibliographical references (leaves 143-147).

<p>South-central Alaska is home to many tectonic structures and mountain ranges that have experienced active uplift and deformation within the past 5 to 10 Ma. The Talkeetna Mountains are located above the area of flat-slab subduction of the Yakutat microplate. I hypothesize that the Talkeetna Mountains have been uplifted as a result of this underlying flat-slab subduction and that areas of the Talkeetna Mountains are neotectonically active. The Talkeetna Mountains are deforming heterogeneously across four different structural domains defined by differences in geomorphic patterns, seismicity, dominant fault types, and the orientation of horizontal maximum stress (SHmax). A strain partitioning structure divides the northern and southern domains, and is observed by a change in SHmax orientation from E-W in southern domains to NW-SE in the northern domain. The strain partition is accommodated by a crustal break along the Talkeetna thrust fault, which is expressed at the surface as a wide zone of deformation. Apatite fission-track analysis suggests two distinct periods of uplift: one dated from 45 to 30 Ma and another from approximately 10 Ma to present, with uplift rates of 0.14 mm/yr and 0.24 mm/yr, respectively. The first phase of uplift coincides with a time of significant plate reorganization in the north Pacific which resulted in translation of terranes northwestward. The second phase of uplift correlates with Neogene accretion of the Yakutat microplate. I propose that the majority of Neogene deformation and uplift in the Talkeetna Mountains is due to far-field deformation in the upper plate above the subducting slab. Variations in both composition of the crust and depth to the downgoing slab resulted in strain partitioning and northwest-directed compression in the northern Talkeetna Mountains and northwest compression and warping in the southern Talkeetna Mountains.

No description available.

This study presents an integrated approach to estimating the risk of flash floods in arid wadis. Flash floods impact seriously on the infrastructure and development of Egyptian desert towns, such as Marsa Alam, and their surrounding areas. The study developed a method using the example of the wadi El-Alam, which has an area of approximately 407 km2. The method has three stages. First, the construction of a Digital Elevation Model from which morphometric properties of the brain were calculated. In particular, representing the flat areas and the sharp junctions between badland slopes and the adjacent wadi system (which generally characterised arid landscapes), were among the major issues facing this study. Second, the derivation of land cover from satellite remote sensing data which were rigorously pre-processed with the aid of aerial photographs and fieldwork measurements. Third, the application of a hydrological model, incorporating the basin morphometry and land cover data, to transform rainfall into runoff and route the floodwater through the sub-catchments of the wadi. The hydrological model system (HMS) was run to simulate discharge at the main wadi outlet (where the town of Marsa Alam is located) and at each sub-basin intersecting the Idfu-Alam highway that runs through the wadi. From these results, sites vulnerable to flash flood and their risk classes were identified. The sites judged to have the highest flood hazard along the highway were exactly the sites damaged in the 1991 flash flood. Thus, as an outcome of this study, the first digital database that includes information on land cover, geomorphology and hydrology of wadi El-Alam was developed. This database can be used to highlight regions vulnerable to flood damage.

No description available.

No description available.

The subglacial settings of glaciers and continental ice sheets serve as a fundamental, long term control on the dynamics of the ice but are also obscured by the great thickness of the ice. Integrated analysis of geophysical datasets is a fundamental tool for understanding a glacier's underpinnings. Using a combination of gravity, magnetic, radar and surface elevation data, we examine the relationship between the ice and its subglacial setting in three chapters that address the question on varying scales. The first explores the Gamburtsev Subglacial Mountains, a region of high topography in the center of East Antarctica. This range is thought to be the nucleation site of the East Antarctic Ice Sheet despite the lack of evidence to constrain its age. The geophysical data suggest a crustal architecture which, when compared with global mountain ranges, provides insight to the age and origin of the Gamburtsev Subglacial Mountains. We conclude that the mountains are over crust that was thickened in the Precambrian but have been been reactivated, creating their high modern relief. In the second chapter, we explore the Recovery Ice Stream in East Antarctica. Here the onset of fast flow is more than 500 km in the ice sheet interior and is thought to be linked to periodic drainages from four large Recovery Lakes. Using new aerogeophysical data in the region, we uncover two tectonic boundaries that each play a key role in the dynamics of the ice stream. The inland boundary limits the catchment of the lakes and their potential for frequent flood events. The second boundary is a transition from rugged bedrock to smooth, low-lying sediments. We conclude that the basal sediments facilitate fast flow independent of water input from the large Recovery Lakes. In the third and final chapter, we examine Jakobshavn Isbrae, West Greenland, the fastest moving non-surge glacier. Since the loss of its floating ice tongue beginning in 1998, this glacier has accelerated and now maintains fast flow speeds throughout the year. The glacier has a known subglacial trough and high driving stresses but even these optimal conditions cannot explain the late summer velocities. We find that the geophysical signals in the Jakobshavn Isbrae region require more geophysical contrasts than the coastal outcrops suggest. Specifically, we interpret a trough-centered gravity low as evidence of sediments underlying the radar-detected trough. These sediments facilitate fast flow by reducing basal resistance. Though Jakobshavn Isbrae is a glaciological endmember, its fate is linked to the underlying geology and best demonstrates the need for continued aerogeophysical survey to constrain subglacial settings. Understanding conditions at the bed is fundamental to understanding the state and fate of the planet's ice.

No description available.