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1
O'Malley, Dana Jean. "Glacial warm." Thesis, University of Iowa, 2016. https://ir.uiowa.edu/etd/3154.
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Glacial Warm investigates romantic, human relationships and our collective commitment to the environment we inhabit. A couple travels and settles into polar and tropical landscapes, gathering, taking shelter, and finding sustenance together. They build their climate, adapting to continuous change. Through glaciers melting, volcanoes hissing, whales breaching, and nude bodies touching and holding, I develop a painted mythology.
Partnership is embodied through separate entities working together. Everyday tasks become intimate gestures. The tenderness of these gestures is rooted in their separation as individuals. Paint application is direct. What melts, drips. What freezes is preserved in cloudy impasto. A kiss is an oily smudge.
2
Butts, Eric Clark. "Models of glacial flow /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487262825076709.
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Yu, Jaehyung. "Investigation of glacial dynamics in lambert glacial basin using satellite remote sensing techniques." Texas A&M University, 2005. http://hdl.handle.net/1969.1/3123.
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The Antarctic ice sheet mass budget is a very important factor for global sea level. An
understanding of the glacial dynamics of the Antarctic ice sheet are essential for mass
budget estimation. Utilizing a surface velocity field derived from Radarsat three-pass
SAR interferometry, this study has investigated the strain rate, grounding line, balance
velocity, and the mass balance of the entire Lambert Glacier  Amery Ice Shelf system,
East Antarctica.
The surface velocity increases abruptly from 350 m/year to 800 m/year at the
main grounding line. It decreases as the main ice stream is floating, and increases to
1200 to 1500 m/year in the ice shelf front. The strain rate distribution defines the shear
margins of ice flows. The major ice streams and their confluence area experience the
most severe ice deformation. The width of the shear margin decreases as it flows
downstream except for the convergent areas with tributary glaciers. The grounding line
for the main ice stream and the boundary of Amery Ice Shelf and surrounding tributary
glaciers is delineated. The total basal melting is estimated to be 87.82 ± 3.78 Gt/year for the entire
Amery Ice Shelf. Compared with the ice flux (16.35 ± 3.11 Gt/year) at the ice shelf
front, basal melting is apparently the dominant discharging process of the system. The
melting rate for the Amery Ice Shelf decreases rapidly from the grounding zone (21.64 ±
2.17 m/year) to the ice shelf front (-0.95 ± 0.14 m/year).
The Lambert Glacial Basin contributes the total ice mass of 95.64 ± 2.89 Gt/year
to the ocean, which is equivalent to increasing the global sea level by 0.24 mm/year.
Considering 90.54 ± 1.55 Gt/year of snow accumulation, the entire Lambert Glacier Â
Amery Ice Shelf system is slightly negatively imbalanced at -5.09 ± 3.46 Gt/year.
Although the entire system is estimated to have a slight negative mass balance, three
sub-glacial systems have a net positive mass balance due to a relatively high snow
accumulation rate or relatively slow ice motion. Considering the large mass loss in West
Antarctica, it is believed that the overall mass budget in Antarctica is negative based on
this research.
4
Hyatt, Olivia Marie. "Insights into New Zealand Glacial Processes from studies of glacial geomorphology and sedimentology in Rakaia and other South Island Valleys." Thesis, University of Canterbury. Geological Sciences, 2010. http://hdl.handle.net/10092/3699.
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This thesis investigates the assertion by many early and more recent New Zealand glacial workers, that the high catchment rainfall and low seasonality in New Zealand create unique glacial sedimentary and geomorphic processes. Specifically the thesis examines the nature of glacial sedimentology and geomorphology in South Island, New Zealand focussing on the Rakaia Valley, as most of the early studies that suggested a distinct New Zealand process environment were based on South Island, East Coast glacial valleys. The thesis provides insights into glacial processes operating at glacial termini of late Quaternary glaciers in this region. The primary findings are as follows: Glacial terminus landforms (moraines) and sediments are described in two eastern (Rakaia and Ashburton Lakes) and one western (Waiho) valley of South Island. There are three main types of landforms 1) outwash head, 2) push moraines and 3) ice-contact fans. Outwash heads and push moraines have been identified before in New Zealand, but ice-contact fans have not. The spatial relationships between the three landforms can be complex especially where there is a fluctuating glacier terminus. Outwash heads are the dominant landform, with ice-contact fans deposited at a stationary terminus with channelised meltwater and push moraines preserved during retreat accompanied with outwash head incision. Both ice-contact fans and push moraines are prone to reworking into the outwash head. Supraglacial material comprises a small cap on the moraines and is usually insignificant in this system. The nature of past glacier termini can be gained from detailed study of these three landform relationships and their sediment record. The dominance of glacifluvial processes at the glacier terminus is a reflection of the low seasonality, abundant catchment rainfall, coupled with a large sediment supply. Preservation and deposition of the push moraines and ice-contact fans are controlled by glacifluvial processes on an outwash head, which in turn are controlled by the mass balance of the glacier. Sedimentology, stratigraphy and facies architecture were examined in the lower Rakaia Valley and elsewhere. The main environments recorded by these sediments are largely proglacial lacustrine and fluvial including 1) outwash gravels, with deposition of a sequence of glacier-fed, Gilbert-type deltas deposited over buried ice at Bayfield Cliff, 2) lacustrine silts and sands, 3) sub-aqueous ice-contact fans, 4) sub-aqueous mass flow deposits, and 5) supraglacial melt out material. These glacilacustrine facies are widespread during both retreats and advances. Sub-aqueous deltas are the primary ice terminus form, in this mid-valley lacustrine setting, which record termini advance and retreats. Syn- and postdepositional deformation of lacustine facies are also common as a result of pushing and overriding from the fluctuating glacier termini. Buried ice is also widespread and many of these deposits display evidence of disruption of sedimentation by its meltout. This implies that stagnant tongues of ice were often buried by outwash and lacustrine sediments. From the sediments and geomorphology described in this thesis, two main glacier terminus settings in New Zealand valleys are apparent A) when the glacier terminus is on or abutting its outwash fan-head, or B) when the glacier terminus is within its trough. Both the geomorphic and edimentological findings allow a better understanding of New Zealand glacial chronologies. Firstly, the sedimentology permits the identification of many more advances and retreats than are recorded in surface sediments. At Rakaia Valley, facies record six significant advances and retreats and many more small oscillations over the last 200 000 years. The geomorphic understanding and high resolution mapping has identified many more ice termini in the valleys than were previously recognised and allow the insights into ice margin behaviour through time. This includes the changing location of outwash heads and glacial troughs, with a migration up-valley since the OIS 6 advance/s, in the Rakaia Valley. The glacier overran its outwash head to reach its LGM position, and subsequently retreated slowly over about 10,000 years, back to its outwash head. It then changed to a calving margin and continued retreating but with no terminal moraines preserved, only lateral features. The research in this thesis has contributed to greater understanding of the New Zealand glacial system. Although low seasonality and large volumes of meltwater do play a role, and equally important control in New Zealand valleys is that of tectonics in terms of delivering huge sediment supply. This sediment supply enables large outwash head and fans to accumulate, which allow large stable lakes to form during glacier recession. The data and interpretations from this thesis will underpin the development of a New Zealand glacial land system, of which other valleys such as the Himalayas have. This land system development is important for understanding the temperate, high sediment yield glacial environment end member.
5
Evatt, Geoffey William. "Jokulhlaups and sub-glacial floods." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496870.
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Hindmarsh, R. C. A. "Modelling glacial erosional landform development." Thesis, Durham University, 1985. http://etheses.dur.ac.uk/7235/.
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Glacial erosional systems exhibit a complex, highly scaledependent phenomenology. Some aspects of modelling the development of glacial erosional landforms in response to glacial erosional processes acting over a wide range of scales are considered. The physics of ice at the glacier sole is discussed. A simple ice-water mixture theory is proposed. A method for finding the solution of the equations of motion of ice at the glacier sole based on the finite element velocities-pressure formulation is shown, which includes novel formulations for the sliding boundary condition, compression of ice and flow of water between ice and bedrock. These finite element formulations are used to simulate flows at the ice-rock interface. The use of the Laplace equation in simulating uni-axial flow is also considered, and further simulations are carried out using this equation. The results from these finite element simulations are used to consider erosional processes occurring at the glacier bed. The processes of abrasion are considered, and previous models are shown to be physically inconsistent. Cavitation, transiency and heterogeneity are shown to have an effect on clast-bed contact forces, and the local viscosity of ice is identified as being a further controlling variable on abrasion. These results are used to consider the likely development of hummocks of bedrock. A mass-balance analysis of basal debris is carried out and shown to have an important effect on erosional patterns. The equations describing the movement of a surface normal to itself are considered. Various solution techniques for these equations are tested, and requirements for the persistence of form under lowering are given. The modelling strategy used in this thesis is a nested hierarchy, with the various hierarchical levels corresponding to different scales. The effect of this hierarchisation on the modelling is discussed with respect to the generic properties of the systems, explanation and testability.
7
Jackson, Rebecca H. (Rebecca Harding). "Dynamics of Greenland's glacial fjords." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104586.
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Thesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 165-172).
Glacial fjords form conduits between glaciers of the Greenland Ice Sheet and the North Atlantic. They are the gateways for importing oceanic heat to melt ice and for exporting meltwater into the ocean. Submarine melting in fjords has been implicated as a driver of recent glacier acceleration; however, there are no direct measurements of this melting, and little is known about the fjord processes that modulate melt rates. Combining observations, theory, and modeling, this thesis investigates the circulation, heat transport, and meltwater export in glacial fjords. While most recent studies focus on glacial buoyancy forcing, there are other drivers - e.g. tides, local wind, shelf variability - that can be important for fjord circulation. Using moored records from two major Greenlandic fjords, shelf forcing (from shelf density fluctuations) is found to dominate the fjord circulation, driving rapid exchange with the shelf and large heat content variability near the glacier. Contrary to the conventional paradigm, these flows mask any glacier-driven circulation in the non-summer months. During the summer, when shelf forcing is reduced and freshwater forcing peaks, a mean exchange flow transports warm Atlantic-origin water towards the glacier and exports glacial meltwater. Many recent studies have inferred submarine melt rates from oceanic heat transport, but the fjord budgets that underlie this method have been overlooked. Building on estuarine studies of salt fluxes, this thesis presents a new framework for assessing glacial fjord budgets and revised equations for inferring meltwater fluxes. Two different seasonal regimes are found in the heat/salt budgets for Sermilik Fjord, and the results provide the first time-series of submarine meltwater and subglacial discharge fluxes into a glacial fjord. Finally, building on the observations, ROMS numerical simulations and two analytical models are used to investigate the dynamics of shelf-driven flows and their importance relative to local wind forcing across the parameter space of Greenland's fjords. The fjord response is found to vary primarily with the width relative to the deformation radius and the fjord adjustment timescale relative to the forcing timescale. Understanding these modes of circulation is a step towards accurate modeling of ocean-glacier interactions.
by Rebecca H. Jackson.
Ph. D.
8
Allen, Robert. "Reconstructing the last glacial maximum climate of Europe and Russia using the glacial-geological record." Thesis, University of Bristol, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439675.
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Miller, Helen. "Lake bed environments, modern sedimentation and the glacial and post-glacial history of Windermere, UK." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/365472/.
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Windermere, the largest natural lake in England, is a glacial ribbon lake located in the southeast of the Lake District. High resolution geophysical datasets, combined with sediment analysis, geomorphological mapping and historical research have been used to investigate the lake bed environments, recent sediment record of pollution and glacial and post-glacial history of the lake and surrounding catchment. The data are used to generate a present-day landscape map of Windermere, revealing a complex landform record characterised by nine sub-basins, separated by steps, ridges and isolated topographic highs related to the retreat of the British and Irish Ice Sheet (BIIS). Debris flows and anthropogenic features are superimposed on the general bathymetric framework formed since the Last Glacial Maximum. Analysis of sediment cores and correlation with existing seismic data have revealed key stratigraphic facies extend across the lake basin, and consist of a drape of Holocene gyttja overlying glaciolacustrine and lacustrine sediment fill relating to retreat of the BIIS. Analysis of geophysical core properties have identified a peak in magnetic susceptibility and iron which possibly represents a change in relative input from different ice masses. Onshore mapping of Troutbeck Valley identifies a series of depositional environments, including recessional moraines formed by still-stands or small readvances of an outlet glacier. Following deglaciation through disintegration into a number of independent ice caps, major sediment redistribution led to formation of a large fan delta via paraglacial and post-glacial sedimentation. The sedimentology of Windermere is characterised by five distinct lake bed facies showing a dominance of gyttja, representing recent Holocene sedimentation derived from the catchment over the last 10,000 years. Coarser sediments (gravel and fine sand) are found in lake-marginal shallow water. High resolution geochemical data, radiochronology and isotopic analysis have revealed significant increases in lead, zinc and copper in recent lake sediments. The principal sources of anthropogenic lead contamination are gasoline lead, Carboniferous coal (most likely source is coal fired steam ships) and lead derived from Carboniferous Pb-Zn mineralisation (mining activities). A number of up-system sediment traps have limited the amount of mining related heavy metals entering Windermere. As a result, many peaks in heavy metals do not correlate with periods of metal workings, but recent increases are possibly due to flood-induced metal inwash. Elevated concentrations of zinc and filamentous growths on the lake bed are attributed to sewage inputs. Geophysical, physical and visual surveys of twelve demonstrated or putative spawning grounds of Arctic charr (Salvelinus alpinus) suggest suitable spawning habitat in Windermere is limited and siltation by fine sediments has occurred over the past 50 years. The integrated approach used in this study has shown that a catchment analysis, using several datasets and techniques, can be used to inform wider regional and ice sheet wide glacial reconstructions. This approach, which can be applied to other lacustrine environments, is capable of determining modern lake bed habitats and the sediment record of pollution, and further demonstrates the value of lake sediments as a high resolution record of local and regional environmental change.
10
Rowan, Ann Victoria. "Braided river response to glacial-drainage capture and climate variations through the last glacial maximum." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/braided-river-response-to-glacialdrainage-capture-and-climate-variations-through-the-last-glacial-maximum(5ad78c4e-f5b6-4d53-9221-193e7ed75573).html.
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Glacial-interglacial cycles drive changes in the discharge and sediment flux from the headwaters of glaciated basins, which are recorded by proglacial fluvial sediments. Linking braided river stratigraphy to the Quaternary climate record could indicate the control of climate-driven variations in discharge and sediment flux on fluvial processes, and the magnitude and frequency of past climate variations. New Zealand is a key location for investigating terrestrial records of Southern Hemisphere climate change. The Late Quaternary braided river deposits on the Canterbury Plains, South Island, New Zealand have formed over the last 400 ka. The coastal cliff marking the southeastern margin of the Canterbury Plains provides excellent exposure of fluvial sediments deposited during the last glacial period, from ~40 ka until the end of the Last Glacial Maximum (LGM) (~18 ka).Deposition at the modern coastline of the Canterbury Plains is interpreted in the context of the climate event stratigraphy for New Zealand, which requires a precise geochronology. This thesis demonstrates the first successful application of optically stimulated luminescence (OSL) dating to glaciofluvial sediments on South Island: a technique that was previously considered unsuitable for this region. Ages produced for the coastal stratigraphy range from 36.7 ± 2.9 to 18.2 ± 1.3 ka, indicating that deposition took place during the last glacial, with little or no postglacial aggradation. Three adjacent catchments on the southern Canterbury Plains - the Rakaia, Ashburton and Rangitata - have undergone glacial-drainage capture during the period represented by the coastal stratigraphy. During glacials, transfluent ice reversed the flow direction in several key tributaries, resulting in dramatic variations in effective drainage area of the Ashburton and Rangitata, and variations in discharge and sediment flux which are recorded in the stratigraphy of these catchments. The magnitude, timing and duration of drainage capture were quantified using the Plummer and Phillips (2003) glacier model. The Ashburton catchment increased to 160% of the modern effective drainage area when temperature change relative to modern conditions exceeded -6°C during the LGM. Meanwhile, the effective drainage area of the Rangitata decreased to 63%, and the Rakaia to 93%, reducing discharge from these catchments. Furthermore, glaciation dramatically affects the seasonality of the annual hydrograph. At four coastal sites, the fluvial stratigraphy was surveyed to investigate possible variations in depositional architecture, due to both climate variations, and glacial-drainage capture in the Ashburton and Rangitata. Unexpectedly, little vertical variation in depositional architecture was found, indicating that the deposits created by the braided rivers represent sediment transport during a similar set of flow (and by inference, climate) conditions. Laterally extensive erosional surfaces separating storeys of one or two flow depths in thickness, in combination with the OSL geochronology, suggest that the gravel-bed braided river stratigraphy primarily records a response to climate variations within glacial maxima, rather than on the scale of the glacial-interglacial cycle.
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Foster, Stephen W. "The late glacial and post glacial history of the Vale of Pickering and northern Yorkshire Wolds." Thesis, University of Hull, 1985. http://hydra.hull.ac.uk/resources/hull:5039.
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This thesis is an attempt to combine a number of different approaches as part of a wider attempt to re-interpret the late Quaternary history of the Vale of Pickering and Northern Wolds in Yorkshire. This involved the critical analysis of part evidence together with the collation and interpretation of data from a variety of sources, some published, some unpublished but mostly from field work.The course of the research followed a number of different lines. The first of these was to study the sedimentary data from glacial and pro-glacial deposits in the Vale of Pickering to assess their age and environment of deposition. The sediments were mapped in the field and analysed in the laboratory. A glacial outwash rather than lake-beach origin was proved for an important group of these sediments. The sedimentary data from the Vale of Pickering showed that ice had undoubtedly advanced further into the area than had been envisaged by Kendall at the turn of the century. - this was supported independently by geomorphological evidence and more sedimentary data from the northern Yorkshire Wolds escarpment. In the western end of the Vale, a thicker lobe of ice than that supposed by Kendall seems to have advanced into the area from the Vale of York, but its furthest limits cannot be shown from data available at the moment.On the Yorkshire Wolds an attempt was made to delineate the advance of the Late Quaternary ice, but unfortunately the data was so poor that no firm limits could be drawn. Glacial outwash sediments were found at several scattered sites and compared with those found in the Vale, some similarity was proved, suggesting that meltwater from late Quaternary glaciers had flowed across the Wolds and that ice from the Vale had overtopped the Wolds scarp along much of its length. The soils were analysed and found to have a higher blown sand content than suspected previously. The blown sand content increased towards the northwest, suggesting a probable glacial outwash source.The dry valleys were studied and new light shed on the processes which may have contributed to their formation. In addition evidence of periglacial evidence from the whole region was collected, described and assessed. Finally it was found that the structural lines of disturbance which traverse the chalk of the northern Wolds could easily be mapped from aerial photographs. These were mapped and included in the thesis as a small contribution to the solid geology of the area, even though they only impinge indirectly upon the main scope of this study.
12
Kenneally, James Patrick. "Crevassing and Calving of Glacial Ice." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/KenneallyJP2003.pdf.
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Barber, Jonathan Mark. "Pleistocene glacial history of West Yorkshire." Thesis, University of Leeds, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432295.
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Moore, Edwin Neville. "Glacial geology and geomorphology of Weardale." Thesis, Durham University, 1994. http://etheses.dur.ac.uk/1625/.
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van, der Vegt Paul. "Glacial systems sedimentation and tunnel valleys." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610766.
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Burley, Jonathan Mark Anderson. "Magmatism and glacial cycles : coupled oscillations?" Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:c55a6d98-d222-46de-8500-1ad44d05be75.
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The Earth's climate system is driven by varying insolation from the Sun. The dominant variations in insolation are at 23 and 40 thousand year periods, yet for the past million years the Earth's climate has glacial cycles at approximately 100 kyr periodicity. These cycles are a coupled variation in temperature, ice volume, and atmospheric CO2. Somehow the Earth system's collective response to 23 and 40 kyr insolation forcing produces 100 kyr glacial-interglacial cycles. Generally it has been assumed that the causative mechanisms are a combination of ice dynamics (high ice reflectivity controlling temperature) and ocean circulation (changing carbon partitioning between the deep ocean and the atmosphere, and heat transport to the poles). However, these proposed mechanisms have not yet resulted in a compelling theory for all three variations, particularly CO2. This thesis explores the role of volcanic CO2 emissions in glacial cycles. I calculate that glacial-driven sea level change alters the pressure on mid-ocean ridges (MORs), changing their CO2 emissions by approximately 10%. This occurs because pressure affects the thermodynamics of melt generation. The delay between sea level change and the consequent change in MOR CO2 emissions is several tens-of-thousands-of-years, conceptually consistent with a coupled non-linear oscillation that could disrupt glacial cycles from a 40 kyr mode to a multiple of that period. I develop an Earth system model to investigate this possibility, running for approximately one million years and explicitly calculating global temperatures, ice sheet configuration, and CO2 concentration in the atmosphere. The model is driven by insolation, with all other components varying in response (and according to their own interactions). This model calculates that volcanism is capable of causing a transition to ̃100 kyr glacial cycles, however the required average volcanic CO2 emissions are barely within the 95% confidence interval. Therefore it is possible for volcanic systems and glacial cycles to form a 100 kyr coupled oscillation.
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Deaney, Emily. "Abrupt climate change and glacial terminations." Thesis, Cardiff University, 2015. http://orca.cf.ac.uk/88993/.
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The Earth’s system has witnessed abrupt climate changes throughout its history. It is widely understood that the pacing of the large-scale glacial-interglacial cycles (tens to hundreds of thousands of years) of the Pleistocene Epoch (~2 million years) are not simply the result of changes in the incoming solar insolation (orbital forcing) alone and as such, this large-scale variability calls upon feedback mechanisms in order to explain the magnitude of such changes. This thesis investigates the shorter millennial scale events (thousands of years) and their role in determining the magnitude of glacial-interglacial cyclicity. In order to investigate this, in this thesis three sediment cores will be used, ODP Site 1063 and ODP Site 983 in the North Atlantic and ODP Site 1089 in the South Atlantic. Datasets from these core locations provide insights in to the magnitude and duration of millennial scale variability across terminations 1, 2 and 5. The two regions studied here (North and South Atlantic) are important regions for recording changes in ocean circulation, specifically the Atlantic Meridional Overturning Circulation. Upper water column reconstructions from the North and South Atlantic based on both planktonic foraminiferal faunal assemblage reconstructions and paired δ18O and Mg/Ca analysis provide insight into the abrupt changes in ocean dynamics across glacial cycles. Additionally with the use of neodymium isotope analysis, changes in the deep North Atlantic, likely the result of changes in the Meridional Overturning Circulation, have also been identified. Importantly, this data provides evidence that the timing of the resumption of the Atlantic Meridional Overturning Circulation following glacial conditions is integral in determining the extent of deglacial CO2 release. The work presented here suggests that rather than it being the magnitude of millennial scale events determining the magnitude of glacial-interglacial climate variability, instead, it is the relative timing of the millennial scale events that plays a role in controlling the magnitude of glacial-interglacial cyclicity.
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Geiger, Alessa J. "Patagonian glacial reconstructions at 49°S." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6404/.
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Patagonia has one of the most extensive and well preserved glacial geomorphic records of anywhere else in the world. This study provides empirical constraints of Patagonian Ice Sheet (PIS) configuration and dynamics during the last two glacial cycles and the Holocene at 49°S. In particular a chronology of palaeo-ice surface elevations, thickness changes and ice-thinning rates is developed. Cosmogenic surface exposure dating across eight mountain transects at Hielo Patagonico Sur (HPS) outlet glaciers' Viedma and Chico, and from eastern facing mountain valley glaciers, is utilised to reconstruct PIS ice-surface elevation changes through time. The earliest dated glacier ice thickness marker falls into MIS6 (Marine Isotope Stage). The last glacial cycle is characterised by continuous ice-surface elevation lowering from a maximum at MIS5a to the Antarctic Cold Reversal (ACR). Large scale PIS cover occurred between ca. 40-47 kyrs, in both the HPS outlet glaciers and the eastern mountain valleys. This regional ice-cover considerably pre-dates the global Last Glacial Maximum (gLGM). A gLGM vertical ice surface expression is absent from the study area. A minor re-advance and/or stillstand at ca. 18 kyrs is recorded by the valley glaciers, but is not evident at the HPS outlet glaciers. Glacier Viedma records a prominent ice elevation during the ACR with rapid thinning at the end of the climate perturbation. Ice-surface lowering from the ACR limit continues with acceleration toward the late-Holocene. The PIS palaeo-ice elevation and thinning record presented here is sensitive to internal PIS dynamics, local and global climate forcing acting on different timescales, with glacier response to climate perturbation strongly linked to glacier catchment size and distance from the main source of precipitation at 49°S.
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Perondi, Cleiva. "Análise da eolução do ambiente proglacial das geleiras Ecology, Sphinks, Baranowski, Tower e Windy, Ilha Rei George, Antártica." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/180993.
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Esta dissertação objetiva investigar a evolução geomorfológica dos ambientes proglaciais (geleiras Ecology, Sphinx, Baranowski, Tower e Windy) da margem leste do campo de gelo Warszawa (62°12’0” S - 58°30’0” W) na Ilha Rei George, Antártica, entre 1956 - 2017. Dados obtidos por sensores remotos, como Aster GDEM2, imagens Sentinel-2 (2017) e WorldView-2 (2014), possibilitaram o mapeamento geomorfológico das formas de relevo de mesoescala proglaciais. A variação frontal e de área total das geleiras foi estimada e mapeada com dados de imagens de satélite (Sentinel-2 de 2017 e WorldView-2 de 2014) e vetores de variação frontal de 1956, 1979, 1988 e 2000. Evidenciou-se um contínuo processo de retração nas geleiras Ecology, Sphinx, Baranowski, Tower e Windy, com perda total de área de 33%, 25%, 37%, 71% e 30%, respectivamente, no período. A geleira Windy apresentou mudanças recentes em seu término de maré para terrestre, formando uma área proglacial com a exposição de formas de relevo deposicionais glaciais. Estimou-se um aumento das áreas livres de gelo de 6,3km² no período entre 1956-2017. Em resposta ao processo de retração glacial, há exposição de formas de relevo nos ambientes livres de gelo na área de estudo com a formação da rede de drenagem fluvioglacial e glaciolacustre e a formação de ambientes proglaciais com exposição de morainas laterais, frontais, latero-frontais e eskers. As áreas livres de gelo recentes são suscetíveis a processos de retrabalhamento por ação gravitacional, eólica e pluvial. Foram determinados três estágios de evolução do ambiente proglacial das geleiras associadas às feições geomorfológicas geradas em cada fase. Como mudança ambiental detectada está a sucessão de ambientes proglaciais, paraglaciais e periglaciais.This dissertation aims to investigate the proglacial geomorphological evolution (Ecology, Sphinx, Baranowski, Tower and Windy glaciers) in the western sector of Warszawa Ice Cap (62°12’0” S 58° 30’ 0” W), Admiralty Bay coast, King George Island, Antarctica between 1956 and 2017. Data obtained by remote sensors, such as Aster GDEM2, Sentinel-2 (2017) and WorldView-2 (2014) images, were applied in geomorphological mapping of the proglacial mesoscale landforms. Glacial retreat and fluctuations of glaciers areas were estimated (using Sentinel-2 images, acquired in 2017, WorldView-2 data, acquired in 2014, and outline data of the 1956, 1979, 1988 and 2000). The results evidenced the continuous retreat processes in period for Ecology, Sphinx, Baranowski, Tower and Windy glaciers, with of 33%, 25%, 37%, 71% and 30% of the area lost, respectively. The Windy glacier changed of outlet glacier for land terminus conditions in latest decades, with a recent proglacial environment development. In response to glacial retreat processes there is a glacial landforms exposition in new ice-free environments in the study area. Was recorded an increase of the 6.3km² in ice-free land areas between 1956 and 2017 in in the western sector of Warszawa Ice Cap. As response the retreat processes there are the development of the glacio-fluvial drainage network, glacio-lacustrine landforms and the formation of proglacial ice marginal environments with lateral moraines, lateral-frontal moraines, frontal moraines, eskers. Recent ice-free areas are susceptible to gravitational, wind and pluvial reworking process. Three stages of evolution of the proglacial environments of the glaciers associated with the geomorphological features formed in each phase and environmental changes in response the glacier retreat was determined. Was detected the succession of proglacial for paraglacial and periglacial environments as evidence of the environmental change.
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Cuffey, Kurt. "Glaciological investigations beneath an active polar glacier /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/6848.
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Petrenko, Vasilii Victorovich. "A study of carbon-14 of paleoatmospheric methane for the last glacial termination from ancient glacial ice." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3291947.
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Thesis (Ph. D.)--University of California, San Diego, 2008.Title from first page of PDF file (viewed March 18, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Riger-Kusk, Mette. "Ice dynamics of the Darwin-Hatherton glacial system, Transantarctic Mountains, Antarctica." Thesis, University of Canterbury. Geography, 2011. http://hdl.handle.net/10092/6602.
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The Darwin-Hatherton glacial system (DHGS) drains from the East Antarctic Ice Sheet (EAIS) and through the Transantarctic Mountains (TAM) before entering the Ross Embayment. Large ice-free areas covered in glacial sediments surround the DHGS, and at least five glacial drift sheets mark the limits of previous ice extent. The glacier belongs to a group of slow-moving EAIS outlet glaciers which are poorly understood. Despite this, an extrapolation of a glacial drift sheet boundary has been used to determine the thickness of the EAIS and the advanced West Antarctic Ice Sheet (WAIS) during the Last Glacial Maximum (LGM). In order to accurately determine the past and present contributions of the Antarctic ice sheets to sea level changes, these uncertainties should be reduced. This study aims to examine the present and LGM ice dynamics of the DHGS by combining newly acquired field measurements with a 3-D numerical ice sheet-shelf model. The fieldwork included a ground penetrating radar survey of ice thickness and surface velocity measurements by GPS. In addition, an extensive dataset of airborne radar measurements and meteorological recordings from automatic weather stations were made available. The model setup involved nesting a high-resolution (1 km) model of the DHGS within a lower resolution (20 km) all-Antarctic simulation. The nested 3-D modelling procedure enables an examination of the impact of changes of the EAIS and WAIS on the DHGS behaviour, and accounts for a complex glacier morphology and surface mass balance within the glacial system.
The findings of this study illustrate the difference in ice dynamics between the Darwin and Hatherton Glaciers. The Darwin Glacier is up to 1500 m thick, partially warm-based, has high driving stresses (~150 kPa), and measured ice velocities increase from 20-30 m yr⁻¹ in the upper parts to ~180 m yr⁻¹ in the lowermost steepest regions, where modelled flow velocities peak at 330 m yr⁻¹. In comparison, the Hatherton Glacier is relatively thin (<900 m), completely cold-based, has low driving stresses (~85 kPa), and is likely to flow with velocities <10 m yr⁻¹ in most regions. It is inferred that the slow velocities with which the DHGS flows are a result of high subglacial mountains restricting ice flow from the EAIS, large regions of frozen basal conditions, low SMB and undulating bedrock topography. The model simulation of LGM ice conditions within the DHGS implies that the ice thickness of the WAIS has been significantly overestimated in previous reconstructions. Results show that the surface of the WAIS and EAIS away from the TAM would have been elevated 600-750 and 0-80 m above present-day levels, respectively, for the DHGS to reach what was inferred to represent the LGM drift sheet limit. Ultimately, this research contributes towards a better understanding of the dynamic behaviour of slow moving TAM outlet glaciers, and provides new insight into past changes of the EAIS and WAIS. This will facilitate more accurate quantifications of contributions of the WAIS and EAIS to changes in global sea level.
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Hope, Pandora. "The weather and climate of Australia at the Last Glacial Maximum." Connect to thesis, 2005. http://repository.unimelb.edu.au/10187/2884.
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The global climate has experienced four glacial cycles in the last 420,000 years, with each cycle characterised by a prolonged period of cooling culminating in maximal glaciation followed by a brief warm period. The most recent period of maximal glaciation is termed the Last Glacial Maximum (LGM) and occurred about 21,000 years ago. We currently live in one of the warm periods. The global climate is changing, and it is becoming more important to understand the extremes of the climate system and how well our modelling capability can capture those extremes.There has been a modelling intercomparison project established to examine how global general circulation models compare in simulating past climates, including the LGM. Analysis and comparison of these model results has been presented for many parts of the globe, but there has not been a comparison of the different model results over the Australian region. This thesis aims to fill that gap and explore the simulated LGM weather and climate of Australia and its drivers in more detail. Comparison with proxy evidence is also undertaken, and inconsistencies seen in the literature addressed.
The Australian climate at the LGM was believed to be generally cooler, drier and possibly windier from proxy evidence in the literature. In the comparison done here the mean temperature and precipitation fields from most models show cooler and drier conditions, with some seasonal variability, but there are some strong outliers. It was found that the differences were not dependent on model resolution, but that the surface parameterisations were highly important for these fields.
The shifts in the circulation were examined both in the model results and with a study of the non-linear link between the wind, surface moisture and dunes, which are a proxy for past winds. All the models simulate a southward shift in the westerlies in the Australian region. This is strongly driven byte prescribed sea-surface temperatures. Australia's current wind regime is conducive to dune building. However, the binding effect of soil moisture (or vegetation) is strong enough to limit present day movement, whereas in the drier climate at the LGM there was a capacity for sand movement. The analysis of dune orientations did not produce conclusive evidence for how the westerlies might have shifted at the LGM.
An apparent enigma in the proxy evidence at the LGM is the high lake levels in Australia’s south east, while most inland lakes were dry. Previous authors believed that the precipitation was still low, but the high lake levels were driven by lowered potential evaporation. The hydrological cycle was generally depressed in the LGM simulations, but the potential for evaporation remained high. Thus an alternative hypothesis is posed based on increased run off due to a known shift in the vegetation types and a lag in the timing of the run off due to snowmelt.
The analysis here shows that our capacity to simulate climates quite different from the present is still developing, but that model results can help explain apparent inconsistencies in the reconstruction of past climates from proxies.
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O'Neal, Michael Aaron. "Late Little Ice Age glacier fluctuations in the Cascade Range of Washington and northern Oregon /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/6727.
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Smith, Colby A. "A comparison of glacial chronologies between the Eastern and Western Cordilleras, Bolivia." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1211995355.
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Araujo-Cabarcas, Juan Carlos. "Numerical methods for glacial isostatic adjustment models." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-193856.
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Nordic countries experience post-glacial rebound, a movement where geographical contours slowly change elevation with respect to the mean sea level. The glacial isostatic adjustment (GIA) model aims to explain the phenomena, which combined with seismic data allows geoscientists to reconstruct elastic coefficients and viscosities of the Earth's lithosphere and upper mantle. The use of standard commercial codes are not adequate for GIA simulations and result in significant errors in the displacement field. This negative outcome suggests the development of GIA codes that include advection of pre-stress in the model. The problem set up consists on a solid 2D elastic layer under a flat Earth approximation, described by three different models suggested by current studies in geophysics. For space discretization the mixed finite element method (mFEM) is used and efficient preconditioners are built for the resulting algebraic system in saddle point form. A three level GMRES iterative solution strategy is proposed, based on Schur Complement preconditioners coupled with Multigrid techniques. The implementation is presented as a ready-to-use toolbox that easily deals with problem parameters, geometries, compressible and fully incompressible materials and provides higher accuracy for the displacement field compared with the previously existent codes. It also can be easily extended to 3D geometries and allows the implementation of a viscoelastic mantle. The code is written in C++ using the deal.II library designed for FEM, permitting the use of readily-made software packages, such as Trilinos that are straightforwardly parallelizable.
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Mueller, Derek. "A bipolar comparison of glacial cryoconite ecosystems /." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33017.
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This thesis compares the habitat and community ecology of cylindrical meltholes from the surface of two polar glaciers. These holes (termed cryoconite holes) are formed when wind-blown dust gathers in small depressions in the ice causing vertical melting by absorption of more radiation than the surrounding ice. The communities are complex microbial consortia of heterotrophic bacteria, cyanobacteria, eukaryotic algae, and protists. Samples were taken from cryoconite holes on Canada Glacier, Taylor Valley, Antarctica (77°37'S, 162°55'E) and on White Glacier, Axel Heiberg Island, Nunavut Territory, Canada (79°27'N, 90°40'W). Water from Canada Glacier cryoconite holes contained significantly higher concentrations of nutrients and had higher pH values and conductivities, relative to the White Glacier meltwater. Cryoconite communities on the Canada Glacier were dominated by cyanobacteria, either coccoid or filamentous, while the White Glacier cryoconite holes showed an abundance of either saccoderm desmids or filamentous cyanobacteria. Canada Glacier communities were found to be associated with environmental gradients whereas White Glacier cryoconite ecosystems were not.
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McCuaig, Shirley J. "Glacial history of the Nass River region." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ51898.pdf.
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Cheesbrough, Kyle S. "Glacial recession in Wyoming's Wind River Range." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1445046281&sid=2&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Smith, Graeme. "Late glacial palaeomagnetic secular variations from France." Thesis, University of Edinburgh, 1985. http://hdl.handle.net/1842/11404.
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Elvidge, Elizabeth Mary. "Aspects of glacial geomorphology of northern Scotland." Thesis, University of East Anglia, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261199.
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Cuthbert, Mark. "Hydraulic processes controlling recharge through glacial drift." Thesis, University of Birmingham, 2005. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.762417.
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Möne, Cecilia. "Glacial lake deposits in Kerlingarfjöll, Central Iceland." Thesis, Uppsala universitet, Institutionen för geovetenskap, 1997. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-393047.
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The extent of glacial lake sediments found north of the Kerlingarfjöll mountains in central Iceland has been determined and their formation in an ice dammed lake is suggested. The damming ice moved from an ice divide in the south-east highlands and was divided into two ice lobes by the Kerlingarfjöll mountains. In an early stage the lake was dammed between the two ice lobes but as they retreated the glacial lake was enlarged in the eastern part where it in the later stage was dammed by topography. The ice dammed lake was almost filled with sediments before it drained to the west when the western ice lobe retreated. The ice dammed lake was contemporaneous with the Hvítárvatn ice dammed lake which was dammed between the western ice lobe and the hills below the Langjökull glacier.Utbredningen hos glaciolakustrina sediment som påträffas norr om fjällklasen Kerlingarfjöll på centrala Island har fastställts och det föreslås att de avsatts i en isdämd sjö. Inlandsisen rörde sig från en isdelare i sydost och flödet delades i två lober vid Kerlingarfjöll. I ett tidigt stadium dämdes sjön upp mellan dessa lober, men när isranden drog sig tillbaka utvidgades sjön i den östra delen och dämdes där av ett topografiskt hinder. Issjön var praktiskt taget fylld med sediment innan den dränerades när den västra isloben drog sig tillbaka. Issjön i Kerlingarfjöll var samtida med Hvítárvatn-issjön som dämdes upp mellan den västra isloben och sluttningarna upp mot glaciären Langjökull.
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Biddle, Louise. "Identifying glacial meltwater in the Amundsen Sea." Thesis, University of East Anglia, 2016. https://ueaeprints.uea.ac.uk/59385/.
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Pine Island Ice Shelf (PIIS), in the Amundsen Sea, is losing mass due to warm ocean waters melting the ice from below. The glacial meltwater appears as a warmer and more saline water mass (with lower O2 concentration) than theWinterWater. Tracing meltwater pathways from ice shelves is important for identifying the regions most affected by the increased input of this water type. Water mass characteristics (temperature, salinity, O2 concentration) are used to calculate glacial meltwater fractions (MW). The observations from the Amundsen Sea show a plume of MW travelling away from PIIS along ¾ = 27.7 kg m¡3, out to the continental shelf edge. We investigate the reliability of the interpretation of the observations as a signature of MW. Physical and biological processes can affect the calculated apparentMWby causing variations in the water mass characteristics. In theWeddell Sea, iceberg meltwater was found to enhance biological productivity. In the Amundsen Sea, the biological productivity was seen to artificially decrease the apparentMWsignature. We analyse the effects of these processes on the reliability of the calculated meltwater fractions using a modified one-dimensional ocean model. The model simulates the effects of an increase in sea ice production and an influx of Lower CDW, as well as biological activity. These processes are found to result in an observation that can conventionally be interpreted as a meltwater signature, similar to the plume observed at the continental shelf edge. Recommendations are made to improve the reliability of MW calculations, including the identification of a ‘pseudo’-CDW endpoint and to increase the uncertainty associated with the O2 concentrations. A meltwater pathway leading to the west of PIIS, along the coastline, is observed. This has implications for water mass characteristics further to the west and ultimately AABW formation in the Ross Sea.
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Cromack, Marianne. "A glacial sedimentary system in northwest Spitzbergen." Thesis, University of Cambridge, 1991. https://www.repository.cam.ac.uk/handle/1810/268051.
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The record of climate change in Signedalen and Krossfjorden, northwest Spitsbergen, since the Late Weichselian glacial maximum, has been constructed using an integrated analysis of lacustrine, terrestrial and marine sediments. Thirty-four piston cores were taken from two series of linked lakes in Signedalen, fed by three small cirque glaciers. Six further cores were taken from the fjord inlet, Signehamna, into which meltwater from the linked glacier-fed lakes and a further two glaciers drain. Signehamna drains into Lilliehookfjorden, which with Mollerfjorden, combines to form Krossfjorden, from which 16 .cores were made available. Cores were analysed for moisture content, loss-on-ignition, bulk density, grain size, magnetic susceptibility, infra-red stimulated luminescence, by X-radiography and by radioisotopic dating methods, 210Pb and 14C. Bathymetric maps were constructed following echo sounding survey of the lakes. Seventy-two water samples from the linked lakes were used to assess contemporary environmental conditions, and to aid interpretation of sedimentary structures within core sediments. Results of lichenometric survey of moraine ridges and pro-talus deposits in and around Signedalen were analysed using discriminant analysis, and compared with Werner's (1988) lichen growth curve in order to establish a chronology of moraine stabilisation. Seismic records of Krossfjorden have revealed evidence of glacier advance at least as far as the sill separating Krossfjorden from the outer parts of the fjord and shelf associated with the Late Weichselian glacial maximum (Sexton et al., in press). Overlying the basal unit of a possible till , or sediments associated with rapid glacier retreat, is a blanket of homogeneous sediment formed by ice-distal deposition during the Holocene. There is no evidence of Younger Dryas glacier expansion preserved in the marine sediments, or in terrestrial moraines. Denudation rates calculated from lacustrine sediment accumulation infer the presence of smaller glaciers in Signedalen during the Younger Dryas than at present. The early to mid Holocene appears to have been characterised by relatively warm conditions, with much reduced glacier presence in Signedalen. Evidence of Neoglacial cooling, between approximately 3,000 yr BP and 1,500 yr BP, is found in lichenometric recorckof talus deposits, although precise dating of the inception, and duration of this cooling is problematic. No moraine sediments are recorded from this period. The Little Ice Age maximum, dated by licheno~etry to AD 1890, was the most extensive glacier advance to have affected the cirque glaciers of Signedalen and the tidewater glaciers of Krossfjorden, and is associated with the highest denudation rates recorded in the lacustrine sediments. It also appears to have been responsible for the formation of rock glaciers within the protalus deposits of Signedalen. Since this date, a general retreat of glaciers has been interrupted periodically by still-stands or slight readvances when climatic conditions deteriorated.
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Ordenes, Cocio Sergio Antonio. "Inestabilidad Interna en Materiales de Origen Glacial." Tesis, Universidad de Chile, 2008. http://www.repositorio.uchile.cl/handle/2250/101963.
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La inestabilidad interna en suelos de amplio rango de partículas se produce por el arrastre del material más fino cuando el suelo es sometido a fuerzas de percolación. La inestabilidad depende principalmente del tipo de suelo y las condiciones hidrodinámicas del flujo. Fallas observadas en embalses construidos con estos materiales indican que este fenómeno adquiere gran importancia en la inestabilidad potencial de dichas obras.
Los materiales de origen morrénico constituyen un ejemplo de estos suelos que han sido extensamente utilizados en presas chilenas. Para evaluar su potencial de inestabilidad se realizó un estudio experimental de su comportamiento en laboratorio y los resultados fueron posteriormente analizados a la luz del estado del arte.
Para cuantificar y evaluar los principales factores que controlan este fenómeno, se diseñó un equipo especial que permite ensayar muestras de 30 cm de diámetro y hasta 80 cm de largo, con mediciones de la distribución de tensiones verticales y gradientes hidráulicos a lo largo de la muestra.
Las condiciones de saturación, tensión y filtración de una presa, se estudian aplicando el procedimiento de ensayo propuesto en esta investigación, que permite reconocer el proceso de inestabilidad a través de dos umbrales: el primero visual, relacionado con la turbidez del agua drenante, y el segundo detectando el inicio de la variación brusca del gradiente hidráulico previo al colapso. Comparando las curvas granulométricas pre y post ensayo, se cuantifica la magnitud del proceso de erosión interna.
Para evaluar el potencial de inestabilidad a partir de la curva granulométrica original, se utilizan dos criterios empíricos, que demuestran ser eficaces para predecir el comportamiento inestable de este tipo de suelo.
Los resultados de esta investigación confirman que el material morrénico estudiado es inestable. Se definen además las condiciones de gradiente hidráulico y tensión efectiva necesarios para iniciar el fenómeno de inestabilidad observado a través de los umbrales anteriormente mencionados. Se constata que a mayor tensión vertical, mayor es el gradiente hidráulico requerido para dar inicio a este fenómeno, lo que resulta concordante con estudios internacionales recientes.
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Gilbert, Adrien. "Modélisation du régime thermique des glaciers : applications à l’étude du risque glaciaire et à la quantification des changements climatiques à haute altitude." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENU029/document.
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Ces travaux de thèse se focalisent sur la modélisation numérique de la réponse thermique des glaciers froids aux variations climatiques. La prise en compte du forçage climatique par la modification des conditions de surface des glaciers est l'un des points clefs de cette étude. On montre l'importance des processus de fusion/regel en zone d'accumulation froide ainsi que de l'épaisseur de la couverture de neige et névé autour de la ligne d'équilibre. Les modèles développés dans cette thèse s'appliquent à des cas concrets sur trois glaciers du massif du Mont Blanc (Alpes françaises). Ces études permettent d'analyser des situations à risque et de reconstituer le climat passé à haute altitude. Le jeu de données très complet acquis sur le site du Col du Dôme (4250 m) comprend des mesures profondes de températures et de densités ainsi que des mesures d'accumulation et de vitesses de surface. Il a permis de valider et développer un modèle à trois dimensions de régime thermique couplé à un modèle d'écoulement et forcé par des données climatiques. Ce modèle permet d'étudier en détail la réponse thermique des zones d'accumulation froides aux changements climatiques. Il peut aussi être utilisé pour la prédiction du réchauffement futur des glaciers suspendus présentant un risque comme le glacier de Taconnaz dont une analyse préliminaire est effectuée ici. Le réchauffement basal jusqu'au point de fusion pourrait conduire à la déstabilisation de ce type de glacier. Le site du glacier de Tête Rousse ( environ 3200 m) a permis d'établir clairement l'influence de la couverture de neige et de névé sur le régime thermique des glaciers autour de la ligne d'équilibre. Les résultats obtenus à partir du couplage d'un modèle de neige (CROCUS) avec un modèle de régime thermique sont en excellent accord avec les observations de températures réalisées dans le glacier. On explique ainsi les causes de la structure thermique particulière du glacier de Tête Rousse responsable de la formation d'une poche présentant un risque pour la commune à l'aval. Dans le futur, les simulations indiquent que le glacier va continuer de se refroidir, limitant ainsi le risque de formation de poche d'eau. Dans le dernier chapitre, nous avons développé une nouvelle méthode inverse pour reconstituer les températures du passé à partir de profils de températures observées dans la glace. Elle est basée sur l'inversion simultanée de plusieurs profils de températures provenant de différents sites de forage ayant subi le même forçage climatique. La méthode permet de s'affranchir de l'impact des processus de fonte/regel en surface pour reconstruire les variations passées des températures de l'air. Les résultats obtenus sur le Col du Dôme montrent que le réchauffement climatique sur le site à 4250 m est similaire à celui observé à basse altitude. Ces résultats tendent à montrer que le réchauffement climatique n'est pas amplifié avec l'altitudeThis thesis focuses on the numerical modeling of the thermal response of glaciers to climate changes. The change in surface conditions related to climate forcing is one of the key point of this study. We point out the crucial role of the meltwater refreezing in cold accumulation zone and the thickness of the snow and firn cover around the equilibrium line. The models are developed from the study of specific cases of three glaciers in Mont Blanc range ( French Alps). These studies allow us to analyze the risk related to hanging glaciers and to reconstruct the past temperaures at high altitude from observede nglacial temperatures. The very extensive dataset obtained at the site of the Col du Dôme (4250 m) includes measurements of deep temperatures and density profiles as well as measurements of snow accumulation and surface velocities. These observations allow us to develop and validate a three-dimensional thermal regime model coupled with a flow model and forced by meteorological data. This model is used to perform a thorough study of the thermal response of cold accumulation zone to climate change. It can also be used for the prediction of future glacial hazard related to hanging glaciers warming. A preliminary analysis has been carried out on the hanging glacier of Taconnaz. The warming could have a major impact on the stability of this kind of glaciers frozen to their beds if the melting point is reached. The study performed on Tête Rousse glacier (about 3200 m) shows clearly the influence of the snowpack and firn cover on the thermal regime of glaciers around the equilibrium line. The results obtained from coupling of a snow model (CROCUS) with a model of thermal regime reveal a very good agreement with the observed ice temperatures. This study provides insights into the thermal processes responsible for water storage inside a small almost static glacier, which can lead to catastrophic outburst floods. In the future, according to atmospheric temperature increase scenarios for the coming century, most of the glacier will become cold which will reduce the risk of water filled cavity formation. Finally, a new inverse method has been developed to reconstruct temperatures in the past from observed englacial temperatures. The method is based on the simultaneous inversion of several temperature profiles coming from different drilling sites with the same climate forcing. The method overcomes the impact of refreezing meltwater to reconstruct past air temperatures variations. This is similar to the observed regional low altitude trend. The results obtained on the Col du Dome shows that climate warming on the site at 4250 m is similar to the observed regional low altitude trend in the northwestern Alps, suggesting that air temperature trends are not altitude dependent
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Tschetter, Timothy J. "Seasonal evolution of a glacial hydrologic system observations of borehole water levels from the Bench Glacier, Alaska /." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1594501731&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Kruszynski, Glen A. "Variations in the relation between suspended sediment and solute delivery in glacial meltwaters, Maxwell Glacier, Yukon Territory." Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6638.
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The purpose of this thesis is to investigate the interactions between meltwaters and sedimentary material at the base of an alpine glacier which are indicated by intra- and interseasonal variations of discharge, solute and sediment outflow from the terminus. During the 1989 and 1990 ablation seasons, discharge, suspended sediment concentration and dissolved solids draining from Maxwell Glacier, St. Elias Mountains, Yukon Territory, were obtained at hourly intervals. The discharge time series of Maxwell Creek reveals that flow varies at a period of one to two weeks, at a diurnal level and over one to three hours. Over all three time scales, electrical conductivity is inversely proportional to discharge suggesting that during high during high diurnal flows, outwash water is derived primarily from surface melt while at low nocturnal discharge, water originates from subglacial and englacial stores. In spring, when supraglacial meltwater begins to access the subglacial drainage system the basal water pressure is raised. Large areas previously hydraulically isolated are integrated releasing stored basal sediment. During periods of increasing discharge in the early summer hydroglacial events resulting from gradual expansion and/or isolation of subglacial cavities, temporary blockage of subglacial conduits or from input from adjacent gravity deposits occur. As flow increases, conduit diameters increase and water gradually spreads out over the glacier bed as a diffuse network of linked cavities. Throughout the ablation season, different areas of the sole are integrated with flow. Towards the end of the ablation season, meltwater supply declines resulting in the reduction of flow in subglacial passageway and reduced sediment and solute supply. (Abstract shortened by UMI.)
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Donovan, Laurance S. "A floristic and phytogeographic study of Glacial Mountain and vicinity, northwestern British Columbia." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26247.
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Botanical exploration in northern British Columbia has lagged behind that of adjacent Alaska and the Yukon Territories. This is particularly true of alpine and sub-alpine areas. For the most part, limited accessibility has restricted plant collecting to within a short distance of the few available roadways.
During the course of the present study, botanical field work was conducted in an alpine, sub-alpine area in the Three Sisters Range of the Cassiar Mountains (northwestern British Columbia). Over 1000 vascular plant collections were idenified from the study area. A total of 239 Taxa were recognized representing 116 genera and 44 families.
Taxonomic keys to the local flora and an annotated species list are provided. The annotated species list includes : habitat information for each taxon, a list of associated species and, where applicable, a discussion of noteworthy features of the taxon in question. Approximately 13% of the flora examined is listed as rare in British Columbia in Straley et al. (1985).
Virtually all of northern British Columbia was overridden by the Cordilleran Ice Sheet during the last major Wisconsin advance (approximately 22,000-15,000 yrs. b.p.). Potential Refugia from which taxa now present in the study area may have migrated post-glacially are discussed. Worldwide distributions of each taxon were examined and seven phytogeographic elements are recognized in the flora.Science, Faculty of
Botany, Department of
Graduate
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Rathburn, Sara L. "Pleistocene glacial outburst flooding along the Big Lost River, east-central Idaho." Thesis, The University of Arizona, 1989. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0127_sip1_w.pdf&type=application/pdf.
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Scherler, Dirk. "Climate variability and glacial dynamics in the Himalaya." Phd thesis, Universität Potsdam, 2010. http://opus.kobv.de/ubp/volltexte/2011/4987/.
Full textAbstract:
In den Hochgebirgen Asiens bedecken Gletscher eine Fläche von ungefähr 115,000 km² und ergeben damit, neben Grönland und der Antarktis, eine der größten Eisakkumulationen der Erde. Die Sensibilität der Gletscher gegenüber Klimaschwankungen macht sie zu wertvollen paläoklimatischen Archiven in Hochgebirgen, aber gleichzeitig auch anfällig gegenüber rezenter und zukünftiger globaler Erwärmung. Dies kann vor allem in dicht besiedelten Gebieten Süd-, Ost- und Zentralasiens zu großen Problem führen, in denen Gletscher- und Schnee-Schmelzwässer eine wichtige Ressource für Landwirtschaft und Stromerzeugung darstellen. Eine erfolgreiche Prognose des Gletscherverhaltens in Reaktion auf den Klimawandel und die Minderung der sozioökonomischen Auswirkungen erfordert fundierte Kenntnisse der klimatischen Steuerungsfaktoren und der Dynamik asiatischer Gletscher. Aufgrund ihrer Abgeschiedenheit und dem erschwerten Zugang gibt es nur wenige glaziologische Geländestudien, die zudem räumlich und zeitlich sehr begrenzt sind. Daher fehlen bisher grundlegende Informationen über die Mehrzahl asiatischer Gletscher.
In dieser Arbeit benutze ich verschiedene Methoden, um die Dynamik asiatischer Gletscher auf mehreren Zeitskalen zu untersuchen. Erstens teste ich eine Methode zur präzisen satelliten-gestützten Messung von Gletscheroberflächen-Geschwindigkeiten. Darauf aufbauend habe ich eine umfassende regionale Erhebung der Fliessgeschwindigkeiten und Frontdynamik asiatischer Gletscher für die Jahre 2000 bis 2008 durchgeführt. Der gewonnene Datensatz erlaubt einmalige Einblicke in die topographischen und klimatischen Steuerungsfaktoren der Gletscherfließgeschwindigkeiten in den Gebirgsregionen Hochasiens. Insbesondere dokumentieren die Daten rezent ungleiches Verhalten der Gletscher im Karakorum und im Himalaja, welches ich auf die konkurrierenden klimatischen Einflüsse der Westwinddrift im Winter und des Indischen Monsuns im Sommer zurückführe.
Zweitens untersuche ich, ob klimatisch bedingte Ost-West Unterschiede im Gletscherverhalten auch auf längeren Zeitskalen eine Rolle spielen und gegebenenfalls für dokumentierte regional asynchrone Gletschervorstöße relevant sind. Dazu habe ich mittels kosmogener Nuklide Oberflächenalter von erratischen Blöcken auf Moränen ermittelt und eine glaziale Chronologie für das obere Tons Tal, in den Quellgebieten des Ganges, erstellt. Dieses Gebiet befindet sich in der Übergangszone von monsunaler zu Westwind beeinflusster Feuchtigkeitszufuhr und ist damit ideal gelegen, um die Auswirkungen dieser beiden atmosphärischen Zirkulationssysteme auf Gletschervorstöße zu untersuchen. Die ermittelte glaziale Chronologie dokumentiert mehrere Gletscherschwankungen während des Endstadiums der letzten Pleistozänen Vereisung und während des Holzäns. Diese weisen darauf hin, dass Gletscherschwankungen im westlichen Himalaja weitestgehend synchron waren und auf graduelle glaziale-interglaziale Temperaturveränderungen, überlagert von monsunalen Niederschlagsschwankungen höherer Frequenz, zurück zu führen sind.
In einem dritten Schritt kombiniere ich Satelliten-Klimadaten mit Eisfluss-Abschätzungen und topographischen Analysen, um den Einfluss der Gletscher Hochasiens auf die Reliefentwicklung im Hochgebirge zu untersuchen. Die Ergebnisse dokumentieren ausgeprägte meridionale Unterschiede im Grad und im Stil der Vergletscherung und glazialen Erosion in Abhängigkeit von topographischen und klimatischen Faktoren. Gegensätzlich zu bisherigen Annahmen deuten die Daten darauf hin, dass das monsunale Klima im zentralen Himalaja die glaziale Erosion schwächt und durch den Erhalt einer steilen orographischen Barriere das Tibet Plateau vor lateraler Zerschneidung bewahrt.
Die Ergebnisse dieser Arbeit dokumentieren, wie klimatische und topographische Gradienten die Gletscherdynamik in den Hochgebirgen Asiens auf Zeitskalen von 10^0 bis 10^6 Jahren beeinflussen. Die Reaktionszeit der Gletscher auf Klimaveränderungen sind eng an Eigenschaften wie Schuttbedeckung und Neigung gekoppelt, welche ihrerseits von den topographischen Verhältnissen bedingt sind. Derartige Einflussfaktoren müssen bei paläoklimatischen Rekonstruktion und Vorhersagen über die Entwicklung asiatischer Gletscher berücksichtigt werden. Desweiteren gehen die regionalen topographischen Unterschiede der vergletscherten Gebiete Asiens teilweise auf klimatische Gradienten und den langfristigen Einfluss der Gletscher auf die topographische Entwicklung des Gebirgssystems zurück.In the high mountains of Asia, glaciers cover an area of approximately 115,000 km² and constitute one of the largest continental ice accumulations outside Greenland and Antarctica. Their sensitivity to climate change makes them valuable palaeoclimate archives, but also vulnerable to current and predicted Global Warming. This is a pressing problem as snow and glacial melt waters are important sources for agriculture and power supply of densely populated regions in south, east, and central Asia. Successful prediction of the glacial response to climate change in Asia and mitigation of the socioeconomic impacts requires profound knowledge of the climatic controls and the dynamics of Asian glaciers. However, due to their remoteness and difficult accessibility, ground-based studies are rare, as well as temporally and spatially limited. We therefore lack basic information on the vast majority of these glaciers. In this thesis, I employ different methods to assess the dynamics of Asian glaciers on multiple time scales. First, I tested a method for precise satellite-based measurement of glacier-surface velocities and conducted a comprehensive and regional survey of glacial flow and terminus dynamics of Asian glaciers between 2000 and 2008. This novel and unprecedented dataset provides unique insights into the contrasting topographic and climatic controls of glacial flow velocities across the Asian highlands. The data document disparate recent glacial behavior between the Karakoram and the Himalaya, which I attribute to the competing influence of the mid-latitude westerlies during winter and the Indian monsoon during summer. Second, I tested whether such climate-related longitudinal differences in glacial behavior also prevail on longer time scales, and potentially account for observed regionally asynchronous glacial advances. I used cosmogenic nuclide surface exposure dating of erratic boulders on moraines to obtain a glacial chronology for the upper Tons Valley, situated in the headwaters of the Ganges River. This area is located in the transition zone from monsoonal to westerly moisture supply and therefore ideal to examine the influence of these two atmospheric circulation regimes on glacial advances. The new glacial chronology documents multiple glacial oscillations during the last glacial termination and during the Holocene, suggesting largely synchronous glacial changes in the western Himalayan region that are related to gradual glacial-interglacial temperature oscillations with superimposed monsoonal precipitation changes of higher frequency. In a third step, I combine results from short-term satellite-based climate records and surface velocity-derived ice-flux estimates, with topographic analyses to deduce the erosional impact of glaciations on long-term landscape evolution in the Himalayan-Tibetan realm. The results provide evidence for the long-term effects of pronounced east-west differences in glaciation and glacial erosion, depending on climatic and topographic factors. Contrary to common belief the data suggest that monsoonal climate in the central Himalaya weakens glacial erosion at high elevations, helping to maintain a steep southern orographic barrier that protects the Tibetan Plateau from lateral destruction. The results of this thesis highlight how climatic and topographic gradients across the high mountains of Asia affect glacier dynamics on time scales ranging from 10^0 to 10^6 years. Glacial response times to climate changes are tightly linked to properties such as debris cover and surface slope, which are controlled by the topographic setting, and which need to be taken into account when reconstructing mountainous palaeoclimate from glacial histories or assessing the future evolution of Asian glaciers. Conversely, the regional topographic differences of glacial landscapes in Asia are partly controlled by climatic gradients and the long-term influence of glaciers on the topographic evolution of the orogenic system.
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Wolff, Christian. "East African monsoon variability since the last glacial." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2012/5807/.
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The impact of global warming on human water resources is attracting increasing attention. No other region in this world is so strongly affected by changes in water supply than the tropics. Especially in Africa, the availability and access to water is more crucial to existence (basic livelihoods and economic growth) than anywhere else on Earth. In East Africa, rainfall is mainly influenced by the migration of the Inter-Tropical Convergence Zone (ITCZ) and by the El Niño Southern Oscillation (ENSO) with more rain and floods during El Niño and severe droughts during La Niña. The forecasting of East African rainfall in a warming world requires a better understanding of the response of ENSO-driven variability to mean climate.
Unfortunately, existing meteorological data sets are too short or incomplete to establish a precise evaluation of future climate. From Lake Challa near Mount Kilimanjaro, we report records from a laminated lake sediment core spanning the last 25,000 years. Analyzing a monthly cleared sediment trap confirms the annual origin of the laminations and demonstrates that the varve-thicknesses are strongly linked to the duration and strength of the windy season. Given the modern control of seasonal ITCZ location on wind and rain in this region and the inverse relation between the two, thicker varves represent windier and thus drier years. El Niño (La Niña) events are associated with wetter (drier) conditions in east Africa and decreased (increased) surface wind speeds.
Based on this fact, the thickness of the varves can be used as a tool to reconstruct a) annual rainfall b) wind season strength, and c) ENSO variability. Within this thesis, I found evidence for centennialscale changes in ENSO-related rainfall variability during the last three millennia, abrupt changes in variability during the Medieval Climate Anomaly and the Little Ice Age, and an overall reduction in East African rainfall and its variability during the Last Glacial period. Climate model simulations support forward extrapolation from these lake-sediment data, indicating that a future Indian Ocean warming will enhance East Africa’s hydrological cycle and its interannual variability in rainfall. Furthermore, I compared geochemical analyses from the sediment trap samples with a broad range of limnological, meteorological, and geological parameters to characterize the impact of sedimentation processes from the in-situ rocks to the deposited sediments. As a result an excellent calibration for existing μXRF data from Lake Challa over the entire 25,000 year long profile was provided.
The climate development during the last 25,000 years as reconstructed from the Lake Challa sediments is in good agreement with other studies and highlights the complex interactions between long-term orbital forcing, atmosphere, ocean and land surface conditions. My findings help to understand how abrupt climate changes occur and how these changes correlate with climate changes elsewhere on Earth.Änderungen des Klimas in einer sich erwärmenden Erde haben große Auswirkungen auf den globalen und lokalen Wasserhaushalt und rücken anhand starker Extremereignisse immer häufiger in den Fokus der Öffentlichkeit. Besonders die Regionen der Tropen sind von derartigen Einschnitten stark gefährdet. Der jährliche Niederschlag in Ostafrika ist stark mit der saisonalen Wanderung der ITCZ (Innertropischen Konvergenzzone) sowie mit dem El Niño/Southern Oscillation (ENSO) Phänomen verbunden. Extreme Regenfälle und Überschwemmungen während El Niño Jahren stehen Trockenheit und Dürren in La Niña Jahren gegenüber. Prognosen über zukünftige Veränderungen der ostafrikanischen Niederschläge erfordern ein verbessertes Verständnis der ENSO antreibenden Faktoren. Unglücklicherweise sind die vorhandenen meteorologischen Datenreihen nicht lang genug oder besitzen nicht die benötigte Homogenität. Einen hilfreichen Beitrag können jährlich geschichtete Seesedimente des am Fuße des Kilimandscharo gelegenen Lake Challa leisten. Anhand einer monatlich aufgelösten Sedimentfalle konnte ich nachweisen, dass die rund 25.000 Jahre zurückreichenden Sedimente eine jährliche Struktur besitzen sowie die Dicke dieser jährlichen Schichtung (Warve) stark mit der Dauer und Intensität der saisonal windreichen/trockenen Jahreszeit verbunden ist. Dickere Warven repräsentieren windige/trockene Jahre, wohingegen dünnere Warven für windschwache und feuchte Jahre stehen. Stärkere Winde und kaum Niederschläge treten oft im Zusammenhang mit einem La Niña Ereignis in Ostafrika auf, wohingegen während eines El Niño Ereignisses häufig extreme Niederschläge mit wenig Wind zu beobachten sind. Anhand der Vermessung der Warven kann man verschiedene Klimaparameter rekonstruieren: a) den jährlichen Niederschlag b) jährliche Windgeschwindigkeiten und ihre Intensitäten sowie c) ENSO Variabilitäten. Die in meiner Arbeit gewonnenen klimatischen Informationen zeigen starke Änderungen der ENSO Variabilität innerhalb der letzten 3.000 Jahre mit starken Unterschieden während der Kleinen Eiszeit und während der Mittelalterlichen Warmzeit sowie deutlich trockene und windige Bedingungen mit sehr geringen ENSO Aktivitäten im glazialem Zeitraum (18.500 und 21.000 Jahren). Modellberechnungen unterstützen diese Ergebnisse einer Zunahme von Extremereignissen und feuchteren Bedingungen im Zuge einer Erwärmung des Indischen Ozeans. Mittels geochemischer Analysen der Sedimentfallenproben sowie die daraus resultierende Verknüpfung mit limnologischen und meteorologischen Parametern, konnte ich einen entscheidenden Beitrag zur erfolgreichen Interpretation der existierenden 25.000 Jahre langen μXRF Datensätze leisten. Der Anteil an allochthonem und autochthonem Eintrag kann so genau klassifiziert werden. Das dadurch gewonnene Bild der Klimaentwicklung der letzten 25.000 Jahre deckt sich hervorragend mit anderen Studien und ermöglicht Einblicke in das komplexe Zusammenspiel zwischen Ozean-Atmosphäre und Umwelt auf dem afrikanischen Kontinent. Besonders die für die Ostafrikaforschung extrem hohe Auflösung der Daten wird helfen, die abrupten Klimawechsel und Interaktionen besser verstehen zu können.
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Milne, Glenn Antony. "Refining models of the glacial isostatic adjustment process." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0011/NQ35251.pdf.
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Wright, Janet S. "Non-glacial origins of loess-sized quartz silt." Thesis, Queen's University Belfast, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333850.
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Ridgwell, Andy J. "Glacial-interglacial perturbations in the global carbon cycle." Thesis, University of East Anglia, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365134.
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Jomier, Hugo. "Sediment dynamics of the pro-glacial Tarfalajaure, Kebnekaise." Thesis, Stockholms universitet, Institutionen för naturgeografi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-160486.
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The sensitive response of glaciers to climate change can be recorded in sediments, in glacier fed lakes. By studying sediments from pro-glacial lakes it is possible to determine how glaciers have reacted to past climate change and variability. Therefore, proglacial lake sediments cores can be used as proxy archives for climate and glacier activity reconstructions. The aim of this study is to detect any glacier signal in the lacustrine sediment cores from Tarfalajaure and seek for correlation with glacier processes and variations recorded in the past literature. Sediment cores were retrieved from the deepest part (52 m) of Tarfalajaure (65°55’25”,18°35’23”) in September 2016. Tarfalajaure is situated within the Swedish part of the Scandinavian Caledonides, in the Kebnekaise Mountains, northern Sweden. There are four glaciers draining into Tarfalajaure, Kebnepakteglaciären (the closest and largest one), Sydöstra Kaskasatjåkkaglaciären, Sydöstra Kaskasapakteglaciären and SydvästraKaskasatjåkkaglaciären. It is assumed that the variations of the minerogenic input and sediment characteristics in the cores over time reflect variations in glacier activity or changes in the proglacial environment. XRF measurements (Ti, Si, K, Fe, Ca, Mn/Fe, Zr/Rb, Ca/Ti,Fe/Ti, Si/Ti, K/Ca and K/Ti), magnetic susceptibility, grain-size analysis and radiocarbon dating have been used to detect variations in the sediment core. Comparisons have been made with results from other studies of glacier activity in northern Scandinavia, and with reconstructions of temperature variation during the last millennia. The results indicate several periods of glacieradvances which were also identified in other studies. These advances occurred around 25 cal BP, between 300 and 375, 1000 and 1150 cal BP, and around 700 – 800, 1900, and 2200 –2275 cal BP.
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Ramsdale, Jason. "Studies of glacial and periglacial environments on Mars." Thesis, Open University, 2017. http://oro.open.ac.uk/49751/.
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This thesis presents the development and application of a grid-based mapping approach that provides an efficient solution to the problems of mapping small landforms over large areas. The approach allows the cataloguing of landform classes, of multiple sizes, efficiently in a single pass. The speed at which the data could be recorded allowed for the first continuous, full resolution mapping of decametre-scale landforms in CTX images on hemispherical-scale maps. The discrete, tabular nature of grid mapping opens up the possibility of citizen science meaning the grid mapping approach could have considerable future use and impact. The main scientific goal of this thesis was to determine the distribution and origins of ice-related landforms in the northern plains, and provide insight as to whether these landforms are related to distinct geological or geomorphological units. To accomplish this, I used the grid mapping approach to explore a large tract covering the Arcadia Planitia region of the northern plains of Mars. In addition, I was able to compare these results to two other sister studies performed in the Utopia and Acidalia Planitia regions of Mars. To explore possible sources of ice I performed a detailed study of the Rahway Vallis system. This found an assemblage of terraces, channels and sinuous ridges in Rahway Vallis that are topographically and morphologically consistent with either a draining lake, or a melting, once liquid, ice-body, and is indicative of a flow of volatiles into the northern plains and large scale shifts in ground ice stability. Overall, this thesis demonstrates the dominant effects of the deposition and sublimation of the Latitude Dependent Mantle in shaping recent landscapes on the northern plains of Mars. There was little evidence for thaw-related landforms, and evidence for a fluvial origin for ice in the near surface is circumstantial, or has been erased or covered.
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LeNoir, James. "Post-Glacial Sedimentation in Ossipee Lake, New Hampshire:." Thesis, Boston College, 2019. http://hdl.handle.net/2345/bc-ir:108650.
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Thesis advisor: Noah P. SnyderLand cover and climate changes, attributed to natural and anthropogenic forcings, cause deviations in geomorphic processes that act to deliver sediment from watersheds to lakes. In New England, contradictory evidence exists as to the influence of deforestation associated with EuroAmerican settlement and major flood events on watershed erosion rates over the past ~250 years. Through combining sediment core analysis from Ossipee Lake, New Hampshire with geomorphic analysis of the Ossipee Lake watershed, this study quantifies Holocene through Anthropocene watershed erosion rates, and assesses variations in rates in relation to short-term historic events such as major storm events or deforestation, and long-term variations related to natural climate variability and post-glacial landscape evolution. An 8.63 m core was collected and spans the entire period from deglaciation to present. Bulk composition and age-depth modeling, utilizing both short-lived radioisotopes and radiocarbon dating, are used to quantify changes in deposition and inferred erosion rates over time. Additional insight on sedimentary processes is provided by measurements of magnetic susceptibility and bulk geochemistry. Lake-sediment data suggests clastic sediment mass accumulation rates vary between 0.0032 to 0.5870 g/cm2/yr, with deposits of increased terrestrially derived sediment focused between ~8500 to 7800, ~6500 to 2500, and 1600 cal yr BP to present. Geomorphic analysis is used to identify regions within the watershed that act to deliver sediment to Ossipee Lake. Potential sources of sediment supply include loose, unconsolidated proglacial deposits near Ossipee Lake that transition to primarily till in upland areas. Calculated bed shear stress along rivers highlights areas in the watershed capable of transporting sediment and areas that can serve as traps thus limiting sediment delivery to Ossipee Lake
Thesis (MS) — Boston College, 2019
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Earth and Environmental Sciences
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Walkling, Adrian Paul. "Coleopteran records from the last interglacial-glacial transition." Thesis, Royal Holloway, University of London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302622.
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