Thesis (M.S.) in Quaternary and Climate Studies--University of Maine, 2004. / Includes vita. Includes bibliographical references (leaves 67-71).

Thesis (Ph. D.)--Lehigh University, 2000. / Includes bibliographical references and vita.

No description available.

Thesis (M.Sc.)--Memorial University of Newfoundland, 1982. / Bibliography : leaves 128-143. Also available online.

One of the profound realizations in Earth science during the last several decades has been that the solid earth and climate system interact through mountain belt evolution. Tectonic forces generate topography, and erosion, driven largely by the climate, destroys topography. Perturbations to the competition between these processes may, for example, have driven the transition from greenhouse to icehouse climate during the Cenozoic. Erosion is the ultimate connection between the climate and solid earth system, and because landscapes are shaped by erosion, they hold in their form information about climatic and tectonic forcings. Reading climatic and tectonic processes from the landscape requires an understanding of how these processes drive erosion. One way that climate influences erosion is by setting the elevation at which glaciation occurs. It has been thought for over a century that erosion by glaciers can limit the height of cold, heavily glaciated mountains. In this thesis, I argue that the prevalence of this phenomenon is underappreciated, and that glacial erosion has imposed an upper limit on the growth of warm, tropical mountains. The argument is premised on a combination of field observations from two (sub)tropical mountain ranges in Costa Rica and Taiwan (including 10Be and 3He surface exposure ages), a new method of topographic analysis that identifies previously unrecognized patterns of landscape rearrangement introduced by high elevation glaciation, and a study of ten tropical mountain ranges that reveals a widespread glacial control on their height. The results of this thesis demonstrate the efficacy of glacial erosion even in the warmest mountains, and challenge the hypothesis that quickly uplifting and eroding landscapes have approached a steady state balance between rock uplift and fluvial erosion during the Pleistocene.

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 99-111).

Thesis (M.S.)--Oregon State University, 2006. / Printout. Includes bibliographical references (leaves 45-49). Also available via the World Wide Web.

Deformation in southern Alaska is controlled by the accretion and partial subduction of the Yakutat terrane as margin-parallel motion transitions to subduction. Recent studies have shown that deformation in the St. Elias orogen, at the northern end of the terrane, accommodates a large portion of convergence, but deformation at the eastern and southern margins remains more poorly constrained. Rapid recent sedimentation (> 1cm/yr) and glacio-isostatic uplift rates (> 3 cm/yr) in the Fairweather corridor highlight short-term vertical deformation at the eastern margin; however, the relationship between these rates and long-term deformation is less well known. New low-temperature cooling ages are reported along the eastern flank of the St. Elias orogen, placing constraints on vertical deformation over the past few million years. Young cooling ages (< 3 Ma) occur in a broad zone, extending along the onshore length of the strike-slip Fairweather fault. These ages indicate that protracted convergence has been accommodated in the Fairweather corridor. Average (~1 mm/yr) and peak (~3 mm/yr) late Cenozoic exhumation rates are similar to rates to the north, and suggest that the orogen is actually boomerang-shaped in map view. If ~1 mm/yr exhumation has been steady, the onset of rapid exhumation is constrained to post-12 Ma, but likely occurred at 5 Ma with changes in climate and plate obliquity. Although cooling ages reveal no coherent regional pattern relative to known structures, they indicate the margin accommodates a significant component of pure shear and is slip-partitioned. The resolved magnitude of convergence in the Fairweather corridor also indicates that Yakutat terrane motion is rotated from Pacific plate motion, and likely requires significant slip on the Transition fault at the southern edge of the Yakutat terrane. Although million-year exhumation rates are rapid, they are slower than short-term rates related to deglaciation. / Master of Science

The influence of erosion on uplifting orogens has been demonstrated to be a primary force in landscape development. An understanding of fluvial erosion in mountain belts is fairly well documented, but the impact of glacial erosion is yet to be fully recognized. The uplift of the Chugach-St. Elias Mountains over the last 5-6 Ma under the influence of intense glaciation provides a unique setting to study the impact of glacial erosion on landscape development. The range has been built by rapid convergence (~5 cm/yr) of the Yakutat terrane with North America. Climatic forcing of northward-driven storms has created a disproportionate glacier distribution across strike, where extensive piedmont glaciers (low equilibrium line altitudes) cover the windward side of the range and small isolated glaciers (high equilibrium line altitudes) occupy the leeward side. If glacial erosion is greatest at the equilibrium line altitude, then glaciers will act as "buzzsaws" there to limit topographic development. Exhumation would therefore be expected to increase towards the coast. If glacial erosion is not dominant, exhumation would be expected to increase away from the coast towards the core of the range, where fault dip angles are high and deep crustal rocks are exposed. To determine the impact of long-term glacial erosion on exhumation of the Chugach-St. Elias Mountains, samples were collected along and across the strike of the range and analyzed by the apatite radiogenic helium (AHE) technique. Samples previously dated using the apatite fission track (AFT) method and located adjacent to our field area were also included in the analyses. The low-temperature sensitivity of these thermochronometers allows exhumation rates to be determined for shallow crustal depths. Both glacial and tectonic processes have influenced exhumation of the range. Exhumation rates increase to the south and east towards the collision zone, but coastal rates (0.36-2.5 mm/yr) are significantly higher than inland samples (0.038-0.24 mm/yr). These rates indicate that coastal glaciation plays a dominant role in landscape development and suggest that short-term erosion rates inferred from sediment yields are exaggerated. Although the exhumation rates are lower than expected, the correlation of exhumation patterns, glacier distribution, and equilibrium line altitude supports the "glacial buzzsaw hypothesis". / Master of Science

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