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    Quantifying hillslope response to glacier retreat : landslide mechanics, processes and impacts : a dissertation presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Physical Geography at Massey University, Palmerston North, New Zealand
    (Massey University, 2022) Cody, Emma
    Landslides are a natural hazard experienced in all countries around the world. Their formation is heavily influenced by internal and external processes including geology, earthworks, rainfall and in some instances glacier ice. This thesis investigates the response of alpine hillslopes to glacier retreat through the utilisation of movement monitoring techniques, subsurface investigations and geotechnical slope stability analysis. Three objectives are proposed and guide the research outcomes of this thesis. The first objective is to investigate the underlying preconditions, preparatory factors and triggers which control and enhance paraglacial rock slope failures through the study of the Mueller Rockslide in New Zealand’s South Island. Preconditioning and progressive weakening of the rockslide began over 8000 years prior to current glacier retreat, with the rockslide forming ~7500 years ago. Movement monitoring shows the rockslide to accelerate gradually over its history, culminating in maximum movement rates of ~6 m per year. Movement is constrained along structurally conditioned discontinuities, identified through a novel ground investigation combining geophysical and geotechnical techniques. Glacier debuttressing is considered a primary trigger of controlled slope failure, with increased displacement in spring attributed to snow melt and rainfall. Step-path failure of the rockslide is ongoing with tensile stress accumulating in the landslide body leading to segmentation of the rockslide into four zones. Ongoing progressive failure will likely lead to block sliding of the rockslide. The second objective of this thesis was to identify drivers of movement in paraglacial sediment slopes. A novel suite of monitoring techniques was used at Fox Glacier which showed clear correlation between hillslope failure and glacier retreat and downwasting. Unlike previous studies, this thesis found debuttressing to be the primary trigger of slope failure with rainfall acting as an accelerant. Debris flows, once thought to be a dominant process in sediment slope adjustment did not begin until debuttressing was completed. Finally, this thesis investigated the potential impacts of paraglacial landsliding on the broader environment. Both the rock and sediment slope failures in this study have deformed their supporting glaciers and a combination of monitoring techniques have uncovered to how sediment is delivered to the proglacial zone. Due to both sites being located within a high seismic hazard zone, catastrophic failure of both sites is possible. Continued failure of the Mueller Rockslide will likely result in a landslide dam and will also lead to continued retrogression of the headscarp and weakening of the surrounding hillslope. Continued failure of the sediment slopes at Fox Glacier will contribute large volumes of sediment to the proglacial zone, allowing for remobilisation of sediment in flood conditions. Both landslides have apparently created morphological change in their supporting glaciers. A unique combination of monitoring methodologies was used to provide insight into landslide movement and evolution, but their usage should not be limited only to studies of landslides. The methodologies used in this thesis provided context across a range of spatial and temporal scales.
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    Structural glaciology, dynamics and evolution of Te Moeka o Tuawe Fox Glacier, New Zealand : thesis submitted in partial fulfilment of the degree of Doctor of Philosophy in Geography at Massey University, Palmerston North, New Zealand
    (Massey University, 2012) Appleby, John Richard
    The aim of this thesis is to investigate and identify relationships between glacier structure, dynamics and debris transport at Te Moeka o Tuawe Fox Glacier; a temperate, maritime glacier in South Westland, New Zealand. Structural analyses of steep, exceptionally dynamic alpine glaciers that respond rapidly to changes in mass balance are rare. In particular, an appreciable dearth of New Zealand-focussed investigations into structural glaciology and glacial dynamics is found in the literature. Structural glaciology of Fox Glacier is determined by field observations, analysis of remotely sensed images, and ground-penetrating radar (GPR). Dynamics are investigated and quantified by the measurement of ice flow velocity and surface deformation. Debris transport processes occurring at Fox Glacier are investigated using field and laboratory analysis of grain size and clast morphology. The structures identified on Fox Glacier during this study display similar patterns to structural features of temperate valley glaciers reported in other studies. Strain-rates measured on the surface of Fox Glacier are higher than those reported for both cold-based glaciers and warm-based alpine-style glaciers in the European Alps. However, strain rates are lower than values typically reported for surging glaciers during surge phases. Unequivocal relationships between measured strain-rates and structures are not evident from this research. This may be because many structures are undergoing passive transport down-glacier, and do not reflect the prevailing local stress regime. Or, some structures, such as crevasse traces, may be close to crevassing, without crevasses actually forming. Results and findings from this study are a useful addition to the accumulating body of work that has emerged over the last decade on the South Westland glaciers. The vast majority of that research has typically focused on glacier fluctuations in response to climate, or has attempted to link late-glacial moraine-forming events to glacier dynamics. In contrast, the present study has attempted for the first time in New Zealand, to characterise and explain the spatial pattern of structures within a valley glacier in its entirety from the névé to the snout.
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    Strain and structure of a temperate, maritime glacier : Te Moeka o Tuawe / Fox Glacier, South Westland, New Zealand : thesis submitted in fulfilment of the degree of Master of Science in Physical Geography, at Massey University, Palmerston North, New Zealand
    (Massey University, 2007) Appleby, John Richard
    The study of glaciers has an immense significance for understanding and predicting global environmental change. The Earth is a dynamic system, consisting of individual units such as the cryosphere, an understanding of which may provide the basis for predicting future environmental change on a global scale. The dynamics of a glacier, a major indicator of the climatic and environmental situation is often presented as supraglacial structures, which reflect glacier formation, deformation and flow. Although structural attributes such as folds, faults, crevasse traces and foliation are commonly described in glaciers, the origin and significance of many of these structures remains unclear. This research project mapped the surface structures of Fox Glacier, using remote sensing in the form of aerial photographs and field observations, to produce a structural glaciological interpretation of the glacier surface, structural field maps of individual structures, and a schematic structural evolution of Fox Glacier. In addition, cumulative strain, and strain rates were calculated for three different areas of the lower Fox Glacier. The relationship between the observed structures and the measured strain rates has also been considered. Fox Glacier is located in the South Westland region of the South Island of New Zealand. From the Main Divide of the Southern Alps up to 3000m altitude, Fox Glacier flows for 13 km, terminating at an altitude of 270 metres in temperate rainforest, 17 km from the present coastline. The steep gradient allows for relatively rapid ice flow. Despite being a very dynamic glacier, very little research has been carried out on Fox Glacier in recent years with most research in the area being concentrated on its neighbour the Franz Josef, and even more so on the glaciers of the Eastern side of the Main Divide (e.g. the Tasman and Mueller glaciers). There is a high level of spatial variability in structural types observed, and the cumulative strain and strain rates measured on the surface of the Fox Glacier, with the variations being linked to valley topography including long-profile gradient and valley width. Strain rates of 208.78 y-1 and -162.06 y-1 were recorded on Fox Glacier. A relationship can be determined between observed glaciological structural features and measured strain rates, suggesting strain rate has an influence on the type, magnitude, location and frequency of these features, however, the study is only a ‘snap-shot’ of the strain conditions experienced in the most dynamically active time, during the summer ablation season. Developing predictive models of the structural evolution of glaciers may help further understanding of how glaciers respond to a change in climatic input, especially climatic warming. This is particularly important for larger ice sheet outlet glaciers whose structure and flow appear to reflect and control dynamics of the ice sheet behind
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    Reconstructing debris transport pathways on constructional ridges : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Quaternary Science at Massey University, Palmerston North, New Zealand
    (Massey University, 2007) Mandolla, Stephanie
    It is generally accepted that Mt Ruapehu, Tongariro National Park, New Zealand, was heavily glaciated during the Pleistocene. Eight small glaciers can still be found on the summit of this active volcano. However, the glaciers have been retreating at a fast rate during the last few centuries. The scientific community has placed its main focus on the volcanic aspects of the region. Although most authors refer to the landforms that appear to be of glacial origin as ‘moraines’, no actual glacial studies have been undertaken so far to provide the necessary evidence that is needed to support this hypothesis. The aim of this study is to use established field techniques in glacial geomorphology to (1) identify the extent of glacial deposits using diagnostic criteria and (2) to reconstruct the transport pathways of the Wahianoa Glacier. Four main diagnostic criteria have been used: clast morphology, macrofabrics, grain size distribution and the surface texture of grains. The Wahianoa valley has a very pronounced U-shape and is likely to be of glacial origin. The valley consists of two elongate debris ridges that are made out of unconsolidated, poorly sorted diamict of varying lithologies. This study has identified that the activity and the composition of the volcano has lead to complex glacial processes. Glacial ice has advanced over a deformable bed and the glacier itself was probably extensively covered by supraglacial debris. The area has been identified as a pre-historic pathway for lahars and the volcano erupts frequently to produce fresh volcanic deposits. As the active vent has changed its position during the eruptive history of the volcano, the quantity and the location of the source rock that fed the glacier has varied greatly. This study is an initial attempt at unfolding the glacial history of Mt Ruapehu. This is based on field analysis of glacigenic sediments, rather than topographic and aerial photo analysis. The results show great complexity and the potential for further studies of other moraine systems on Mt Ruapehu.
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    Relative age dating of the Wahianoa moraines, Mount Ruapehu, New Zealand : thesis submitted in partial fulfilment of the degree of Master of Science in Quaternary Science at Massey University, Palmerston North, New Zealand
    (Massey University, 2008) Nolan, Erin
    This study attempts to determine a relative age of the Wahianoa moraines, Mt Ruapehu using three relative age dating techniques: Lichenometry, Schmidt hammer and Boulder roundness. There were three study areas used, termed the Wahianoa ‘A’, ‘B’ and ‘C’ moraines. Upon determining a relative age for these moraines, their timing of their formation was placed within New Zealand’s glacial timescale. This is the first study of its kind conducted on Mt Ruapehu and has left the door open for more research in this field. The species of lichens measured on the Wahianoa moraines were Rhizocarpon subgenus, which the largest diameters were measured using callipers. A total of 606 lichens were measured in the Wahianoa Valley and were processed using the growth curve and size frequency methods. A lichenometric growth curve was constructed from lichens growing in the Ohakune cemetery. The dates derived from both methods placed the formation of the Wahianoa moraines during the Little Ice Age. An L-type Schmidt hammer was used on the boulders in the Wahianoa Valley. A total of 280 measurements were taken off the boulders on the Wahianoa moraines. The results of this method, when compared to Winkler’s (2005) study in the South Island placed the formation of the Wahianoa moraines pre-Little Ice Age. Although no definitive ages could be derived from this comparison due to differences in lithology between the two studies, it provided an idea as to where the formation of these moraines could belong. This is the first time that the Boulder roundness method has been used in New Zealand, having only been developed by Kirkbride (2005). This method was used to determine which of the ridges in the Wahianoa Valley were older. It was found that the Wahianoa ‘A’ moraines were the oldest in the valley followed by Wahianoa ‘B’ and ‘C’ respectively. A climate reconstruction was also conducted for the Wahianoa Valley to see what conditions may have been in existence during the formation of the Wahianoa moraines. The paleo-ELA for the Wahianoa Glacier was estimated using the Accumulation-Area Ratio (AAR), Terminus to Headwall Ratio (THAR), Maximum Elevation of the Lateral Moraines (MELM) and Extrapolation methods. The current ELA was estimated using the AAR, THAR and Extrapolation methods. The difference between these estimates was used to determine what temperature decrease would have caused the formation of the Wahianoa moraines. The average paleo-ELA was found to be c. 1715m, while the current ELA was found to be 2475m which lead to a 4.5°C decrease. This temperature decrease correlates well with that of the Last Glacial Maximum. This study found significant differences in relative age of the Wahianoa moraines. There are a number of factors that can affect the growth of lichens such as micro-environmentalconditions and the fact that a growth curve was constructed off site. Factors such aspetrography can affect the Schmidt hammer results and the Boulder roundness measurements. In addition, precipitation can affect the ELA values which can then cause the wrong placement within a glacial event. Further research lies in the use of the Schmidt hammer on a known age surface such as the Mangatepopo moraines which will aide in a better correlation of relative age. Also, further research using climate reconstructions on Mt Ruapehu and the effect of precipitation will also aide in a better correlation with a glacial event.