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This thesis examines the role of rock avalanches in tectonically active terrains including the effects of the deposits on glacier behaviour and their contribution to moraine formation. The chronologies of mountain glacier fluctuations, based on moraine ages, are widely used to infer regional climate change and are often correlated globally. In actively uplifting mountain ranges rock avalanches that travel onto the ablation zone of a glacier can reduce ice-surface melting by insulating the ice. This can cause buried ice to thicken due to slower ablation and can significantly alter the overall glacier mass balance. This glacier response to supraglacial rock avalanche deposits can confound apparent climatic signals extracted from moraine chronologies. This thesis investigates the processes through which rock avalanche deposits may affect glaciers and develops a new technique to identify the presence of rock avalanche debris in glacial moraines. From laboratory experiments on the effects of debris on ice ablation it is demonstrated that the rate of underlying ice ablation is controlled by diurnal cyclicity and is amplified at high altitude and in lower latitudes. The relatively low permeability of rock avalanche sediment in comparison with non-rock avalanche supraglacial debris cover contributes to the suppression of ablation, at least partly because it greatly reduces the advection of heat from rain water to the underlying ice. The laboratory findings are supplemented by field investigations of two recent rock avalanche deposits on glaciers in the Southern Alps of New Zealand. This work demonstrates that the rock avalanche deposits are very thick (10 m at Aoraki/Mt. Cook and 7m at Mt. Beatrice) and almost stopped the ablation of the overlying ice. This resulted in the formation of an ice-platform more than 30 m high. This led to a reduction of the existing negative mass balance of the affected Tasman and Hooker Glaciers. There was little noticeable alteration of the overall glacial regime due to the small scale of the debris covered area (4 and 1% of the ablation zones for the Tasman and Hooker Glaciers, respectively) but there is a significant contribution to supraglacial debris, which is passively transported toward the terminus. A conceptual model of the response of mountain valley glaciers to emplacement of extensive rock avalanche debris on the ablation zone has been proposed for the effect of this type of debris on terminal moraine formation based on enhanced ‘dumping’ of supraglacial sediments. A new technique has been developed to distinguish rock-avalanche-derived sediment from sediment of glacial origin, based on the sedimentary characteristics of the finest fraction. Examination of rock avalanche sediment under the Scanning Electron Microscope showed that finer particles tend to form strong clumps, which comprise many smaller (down to nanometre-scale) clasts, named here ‘agglomerates’. These agglomerates are present in the fine fraction of all examined rock avalanche deposits and absent in known non-rock-avalanche-derived glacial sediments. The agglomerates are characteristics of sediment produced under the high-stress conditions of rock avalanche emplacement and contrast with lower-stress process sub- and en-glacial environments. It is demonstrated that these agglomerates are present in some moraines in the Southern Alps of New Zealand that have been attributed to climate fluctuation. Consequently, this technique has the potential to resolve long-standing arguments about the role of rock avalanches in moraine formation, and to enhance the use of moraines in palaeoclimatological studies.

<p>Dams that comprise broadly and widely graded glacial materials, such as moraines, have been found to be susceptible to internal erosion, perhaps more than dams of other soil types. Internal erosion washes out fine-grained particles from the filling material; the erosion occurs within the material itself or at an interface to another dam zone, depending on the mode of initiation. Whether or not internal erosion proceeds depend on the adequacy of the filter material. If internal erosion is allowed, it may manifest itself as sinkholes on the crest, increased leakage and muddy seepage once it surfaces, which here is called surfacing internal erosion (i.e. internal erosion in the excessive erosion or continuation phase). In spite of significant developments since the 1980s in the field of internal erosion assessment, the validity of methods developed by others on broadly graded materials are still less clear because most available criteria are based on tests of narrowly graded granular soils. This thesis specifically addresses dams that are composed of broadly graded glacial soils and investigates typical indicators, signs and behaviors of internal erosion prone dams. Based on a review of 90+ existing moraine core dams, which are located mainly in Scandinavia as well as North America and Australia/New Zealand, this thesis will show that not only the filter’s coarseness needs to be reviewed when assessing the potential for internal erosion to surface (i.e., erosion in the excessive or continuing phase); in addition, the grading stability of the filter and the core material as well as non-homogeneities that are caused by filter segregation need to be studied. Cross-referencing between these aspects improves the assessment of potential for internal erosion in dams of broadly graded soils and furthermore it provides aid-to-judgment.</p> / QC 20100715

Recent work suggests an emerging new paradigm for the Scandinavian ice sheet (SIS); one of a dynamically fluctuating ice sheet. This doctoral research project explicitly examines the history and dynamics of the SIS at four sites within Sweden and Norway, and provides results covering different time periods of glacial history. Two relatively new dating techniques are used to constrain the ice sheet history: the optically stimulated luminescence (OSL) dating technique and the terrestrial cosmogenic nuclide (TCN) exposure dating technique. OSL dating of interstadial sediments in central Sweden and central Norway indicate ice-free conditions during times when it was previously inferred the sites were occupied by the SIS. Specifically, the SIS was absent or restricted to the mountains for at least part of Marine Isotope Stage 3 around 52 to 36 kyr ago. Inland portions of Norway were ice-free during part of the Last Glacial Maximum around 25 to 20 kyr ago. Consistent TCN exposure ages of boulders from the Vimmerby moraine in southern Sweden, and their compatibility with previous estimates for the timing of deglaciation based on radiocarbon dating and varve chronology, indicate that the southern margin of the SIS was at the Vimmerby moraine ~14 kyr ago. In central Sweden, consistent TCN ages for boulders on the summit of Mt. Åreskutan and for the earlier deglaciated highest elevation moraine related to the SIS in Sweden agree with previous estimates for the timing of deglaciation around 10 ka ago. These results indicate rapid decay of the SIS during deglaciation. Unusually old radiocarbon ages of tree remains previously studied from Mt. Åreskutan are rejected on the basis of incompatibility with consistent TCN ages for deglaciation, and incompatibility with established paleoecological and paleoglaciological reconstructions. Altogether this research conducted in different areas, covering different time periods, and using comparative geochronological methods demonstrates that the SIS was highly dynamic and sensitive to environmental change. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Manuscript.

Accessibility to consistent subsurface hydrostratigraphic information is crucial for the development of robust groundwater flow and contaminant transport models. However, full three-dimensional understanding of the subsurface geology is often the missing link. Construction of watershed-scale hydrostratigraphic models continues to be limited by the quality and density of borehole data which often lack detailed geologic information. This can become a serious problem where rapid sediment facies changes and intricate sediment architecture occur. This research is motivated by the idea that if we can understand more about the distribution of sediments and structures of complex deposits, we learn more about depositional processes and how they affect the internal geometry of a deposit and the distribution of hydraulic properties. One approach is to study surficial excavations (e.g. sand and gravel pits) that often punctuate shallow aquifers. The purpose of this study is to develop and test a method of integrating high-resolution georeferenced stratigraphic and sedimentologic information from sand and gravel pits as a means to better document sedimentologic data and improve understanding of the depositional environments. The study area is located within the Waterloo Moraine, in southwestern Ontario, and is an unconsolidated shallow aquifer system with a complex internal architecture and sediment heterogeneity. The method involves the integration of high-resolution field data with borehole and geophysical information in a computer-based 3D environment. A total of fourteen virtual sedimentary sections were constructed by georegistering digital photographs within a framework of georeferenced positions collected using a reflectorless total station and GPS. Fourteen sediment facies have been described in the field. These include crudely stratified gravel beds, planar and cross-laminated sandy strata (ripple and dune scales), along with laminated and massive silty and clayey beds. Calculated hydraulic conductivities span over seven orders of magnitude. The analysis of a single excavation has shown contrasting sediment assemblages from one end of the pit to the other, highlighting the complexity of the Waterloo Moraine. The heterogeneous and deformed layers of gravel, sand, and mud may be the product of an ice-contact to ice-proximal environment, whereas the extensive sandy assemblages may reflect an intermediate subaqueous fan region. The results also suggest that the borehole database overestimates the amount of fine-grained material in the study area. Finally, this research demonstrates that it is possible to build in a timely manner a 3D virtual sedimentologic database. New emerging technologies will lead to increased resolution and accuracy, and will help streamline the process even further. The possibility of expanding the 3D geodatabase to other excavations across the region in a timely manner is likely to lead to improved hydrostratigraphic models and, by extension, to more efficient strategies in water resources planning, management and protection.

Accessibility to consistent subsurface hydrostratigraphic information is crucial for the development of robust groundwater flow and contaminant transport models. However, full three-dimensional understanding of the subsurface geology is often the missing link. Construction of watershed-scale hydrostratigraphic models continues to be limited by the quality and density of borehole data which often lack detailed geologic information. This can become a serious problem where rapid sediment facies changes and intricate sediment architecture occur. This research is motivated by the idea that if we can understand more about the distribution of sediments and structures of complex deposits, we learn more about depositional processes and how they affect the internal geometry of a deposit and the distribution of hydraulic properties. One approach is to study surficial excavations (e.g. sand and gravel pits) that often punctuate shallow aquifers. The purpose of this study is to develop and test a method of integrating high-resolution georeferenced stratigraphic and sedimentologic information from sand and gravel pits as a means to better document sedimentologic data and improve understanding of the depositional environments. The study area is located within the Waterloo Moraine, in southwestern Ontario, and is an unconsolidated shallow aquifer system with a complex internal architecture and sediment heterogeneity. The method involves the integration of high-resolution field data with borehole and geophysical information in a computer-based 3D environment. A total of fourteen virtual sedimentary sections were constructed by georegistering digital photographs within a framework of georeferenced positions collected using a reflectorless total station and GPS. Fourteen sediment facies have been described in the field. These include crudely stratified gravel beds, planar and cross-laminated sandy strata (ripple and dune scales), along with laminated and massive silty and clayey beds. Calculated hydraulic conductivities span over seven orders of magnitude. The analysis of a single excavation has shown contrasting sediment assemblages from one end of the pit to the other, highlighting the complexity of the Waterloo Moraine. The heterogeneous and deformed layers of gravel, sand, and mud may be the product of an ice-contact to ice-proximal environment, whereas the extensive sandy assemblages may reflect an intermediate subaqueous fan region. The results also suggest that the borehole database overestimates the amount of fine-grained material in the study area. Finally, this research demonstrates that it is possible to build in a timely manner a 3D virtual sedimentologic database. New emerging technologies will lead to increased resolution and accuracy, and will help streamline the process even further. The possibility of expanding the 3D geodatabase to other excavations across the region in a timely manner is likely to lead to improved hydrostratigraphic models and, by extension, to more efficient strategies in water resources planning, management and protection.

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The thesis deals with hydrological conditions in a proglacial environment, focusing on the development of glacial lakes and the assessment of their susceptibility to outburst. The study site is the Adygine glacier-moraine complex located in the north-facing valley of the Kyrgyz Ridge, northern Tien Shan, Kyrgyzstan, at an altitude of 3400-4200 m a.s.l. In the past 50 years, the receding glacier allowed formation of several lakes, which form a three-level cascade and are fed by glacier meltwater. Below the glacier, there is a complex of several generations of moraines, through which the glacier meltwater is routed downstream. The aims of the work were to evaluate the development of individual lakes, their susceptibility to sudden outburst and possible triggers, to estimate the probable development of the site in the future, to analyse the hydrological regime of the lakes and to obtain basic information on the subsurface flow of water from the site to the stream. For the purposes of assessing the development of the lakes, the data obtained in the field (geodetic surveying of a shore line, bathymetric measurements), as well as satellite and aerial images were used. Fluctuation of lake water level was monitored by pressure sensors and the processing of this data allowed to analyse the hydrological...

Dams that comprise broadly and widely graded glacial materials, such as moraines, have been found to be susceptible to internal erosion, perhaps more than dams of other soil types. Internal erosion washes out fine-grained particles from the filling material; the erosion occurs within the material itself or at an interface to another dam zone, depending on the mode of initiation. Whether or not internal erosion proceeds depend on the adequacy of the filter material. If internal erosion is allowed, it may manifest itself as sinkholes on the crest, increased leakage and muddy seepage once it surfaces, which here is called surfacing internal erosion (i.e. internal erosion in the excessive erosion or continuation phase). In spite of significant developments since the 1980s in the field of internal erosion assessment, the validity of methods developed by others on broadly graded materials are still less clear because most available criteria are based on tests of narrowly graded granular soils. This thesis specifically addresses dams that are composed of broadly graded glacial soils and investigates typical indicators, signs and behaviors of internal erosion prone dams. Based on a review of 90+ existing moraine core dams, which are located mainly in Scandinavia as well as North America and Australia/New Zealand, this thesis will show that not only the filter’s coarseness needs to be reviewed when assessing the potential for internal erosion to surface (i.e., erosion in the excessive or continuing phase); in addition, the grading stability of the filter and the core material as well as non-homogeneities that are caused by filter segregation need to be studied. Cross-referencing between these aspects improves the assessment of potential for internal erosion in dams of broadly graded soils and furthermore it provides aid-to-judgment. / QC 20100715

Many growing southern Ontario communities, including Guelph, rely on fractured bedrock aquifers for drinking water. Contamination and overexploitation pose a threat to these water resources, necessitating characterization of vulnerability, risks, and recharge areas. Quaternary sediments southeast of the City of Guelph, including the Paris Moraine, were investigated in order to delineate hydrostratigraphy. This was achieved through study of 9 cored-holes, as well as existing MOE, GRCA, and University of Guelph data. Falling head permeameter measurements and empirical grain-size distribution measurements and analysis were employed for determination of 𝐾𝑠𝑎𝑡 values, which were used to construct a hydrostratigraphy. Of 19 methods evaluated, The Kozeny-Carman empirical grain-size method for determining 𝐾𝑠𝑎𝑡 was found to be more representative of measured values for the study area. The area is dominated by a conductivity regime of 2.72x10-7 – 1.40x10-6 m/s with local heterogeneity present on the scale of 10’s to 100’s of meters. The Paris Moraine, particularly its backslope, is at higher risk due to its relatively high conductivity, greater occurrence of aquifer units, as well as prevalence of small-scale topographic (hummocky topography), and bedrock topographic lows. / Thesis / Master of Science (MSc)