Geomorphology of the deglaciated Eglinton Valley, Fiordland : new insights into the origin of hummocky terrain : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Geography at Massey University, Manawatu, New Zealand
Open Access Location
The distribution and types of landforms within deglaciated valleys provide information on past processes and indicate the potential for future changes and associated hazards. This study is the rst to characterise the landform assemblages within Eglinton Valley, Fiordland, New Zealand, and develop a model for the post-glacial evolution of the valley. In particular, it assesses the origins of hummocky topography on the valley oor which, like in many other parts of the world, have previously been interpreted to be glacial in origin. Geomorphic eld mapping, GPR, sedimentology (clast and agglomerate identi cation), and a novel terrestrial cosmogenic nuclide dating (TCND) method of extracting meteoric 10Be from pyroxene minerals were utilised to reconstruct the geomorphology of the valley during the Holocene. Glacial deposits were con rmed at Knobs Flat and Eglinton Flat while RA deposits were conclusively found at Knobs Flat, Deer Flat, and adjacent to Lake Malvora. Eglinton Valley has been completely blocked on (a minimum of) three separate occasions, forming a large lake each time, with only Lake Gunn and a few minor swamps and lakes (e.g. Lake Malvora) remaining today. Relative age dating evidence suggests the rst lake was formed by the large Deer Flat RA, the next formed due to the extensiveWesney Creek alluvial fan, and the youngest, Lake Gunn, as a result of the Lake Gunn Landslide ~7.6 kyrs BP. TCND was uncompleted due to lab contamination at the nal step, however, the methods attempted here appeared to yield promising results. The Eglinton Valley has been sculpted by glacial, mass movement, and uvial processes. This work advances the knowledge of the processes responsible for the hummocky terrain found throughout Eglinton Valley, and adds to the currently limited pool of research into the reinterpretation of hummocky deposits within deglaciated valleys in a global and New Zealand context.
Geomorphology, Glacial landforms, Fiordland, New Zealand, Research Subject Categories::NATURAL SCIENCES::Earth sciences::Exogenous earth sciences