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  • 1
    Online Resource
    Online Resource
    Cambridge :Cambridge University Press,
    Keywords: Glaciers. ; Electronic books.
    Description / Table of Contents: This 2005 edition of a successful textbook is intended to give upper-level students the tools they need to understand modern glaciology. Practising geologists and glaciologists will also find it useful as a reference book. Relatively simple concepts are introduced first, followed by mathematically more sophisticated chapters. Student exercises are included.
    Type of Medium: Online Resource
    Pages: 1 online resource (449 pages)
    Edition: 2nd ed.
    ISBN: 9780511196881
    DDC: 333.917
    Language: English
    Note: Cover -- Half-title -- Ttile -- Copyright -- Dedication -- Contents -- Preface to the first edition -- Preface to the second edition -- Physical constants relevant to ice -- Derived SI units and conversion factors -- Chapter 1 Why study glaciers? -- Chapter 2 Some basic concepts -- A note on units and coordinate axes -- Glacier size, shape, and temperature -- The condition of incompressibility -- Stresses, strains, and strain rates -- Notation -- Tensors -- Strains and strain rates -- Yield stress -- Deviatoric stresses -- Effective and octahedral shear stresses and strain rates -- Principal stresses and strain rates -- The flow law -- Chapter 3 Mass balance -- The transformation of snow to ice -- Snow stratigraphy -- Dating ice using preserved snow stratigraphy -- Mass balance principles -- Climatic causes of mass balance fluctuations -- The budget gradient -- Other modes of ice loss from valley glaciers -- Calving -- Bottom melting -- Mass balance of polar ice sheets -- Calving of ice shelves -- Bottom melting -- Effect of atmospheric circulation patterns on mass balance -- ENSO and Decadal Oscillations -- Global mass balance -- Summary -- Chapter 4 Flow and fracture of a crystalline material -- Crystal structure of ice -- Dislocations -- Rate-limiting processes -- Drag as the rate-limiting process -- Climb as the rate-limiting process -- Slip on other crystallographic planes -- Inhomogeneous strain -- Internal stresses -- Recrystallization -- Development of fabrics with preferred orientations of c-axes -- Summary -- Deformation mechanism maps -- A flow law for glacier ice -- Fracture -- Summary -- Chapter 5 The velocity field in a glacier -- Measurement of velocity -- Balance velocity -- Shear stress distribution -- Horizontal velocity at depth in an ice sheet -- Horizontal velocity in a valley glacier -- Comparison with measurements. , Mean horizontal velocity and ice flux -- Vertical velocity -- Submergence and emergence velocities -- Flow field -- Transverse profiles of surface elevation on a valley glacier -- Radar stratigraphy -- Effect of drifting snow on the velocity field -- Ice streams -- Summary -- Chapter 6 Temperature distribution in polar ice sheets -- Energy balance in an ice sheet -- Advection -- Conduction -- Strain heating -- The generalized energy balance equation -- Dependence of K on temperature -- The steady-state temperature profile at the center of an ice sheet -- Simplifying assumptions -- The first integration -- The basal boundary condition -- The second integration -- The boundary condition at the surface -- Melting and freezing at the bed -- Character of the temperature profile -- Error introduced by the assumed vertical velocity distribution -- Temperature profiles in the ablation zone -- Temperature profiles near the surface of an ice sheet -- Temperature distributions far from a divide -- The Column model -- Englacial and basal temperatures along a flowline calculated using the Column model -- A problem with high uAlphaLambda warming rates in the Column model -- Basal temperatures in Antarctica - comparison of solutions using the Column model and a numerical model -- Geomorphic implications -- Summary -- Chapter 7 The coupling between a glacier and its bed -- Sliding -- Regelation -- Plastic flow -- Sliding speed -- Roughness in the Nye-Kamb theory -- Tests of sliding theories -- Weaknesses of present sliding theory -- Rheology of basal ice -- The role of normal pressure -- Cavities and the effect of water pressure -- Deformation of subglacial till -- Cohesion -- Consolidation -- Angle of internal friction -- Void ratio -- Grain fracture and the granulometry of deforming subglacial till -- Strain rates in subglacial till. , Till rheology - the Coulomb plastic model -- Till rheology - the viscous model -- Sliding of ice over till -- Ploughing -- Depth of deformation in a subglacial till -- Stability of ice streams -- Effect of a frozen bed -- Summary -- Chapter 8 Water flow in and under glaciers: geomorphic implications -- The upper part of the englacial hydraulic system -- Veins and the initial development of passages -- Connections to the surface -- Equipotential surfaces in a glacier -- Alternative derivation of equipotential-plane dip -- Melt rates in conduits -- Water pressures in subglacial conduits on hard beds -- Shapes of subglacial conduits -- Types of subglacial drainage system -- The linked-cavity system -- Transitions between conduit and linked-cavity systems -- Multi-branched arborescent system -- Conduits on deforming till -- Temporal and spatial distribution of drainage system types -- Surges -- Subglacial drainage paths and the formation of eskers -- Sediment supply to eskers -- Size and location of water conduits on eskers -- Ramp structures and esker nets -- Tunnel valleys -- Water pressure and glacier quarrying -- Origin of cirques and overdeepenings -- Summary -- Chapter 9 Stress and deformation -- Stress -- General equations for transformation of stress in two dimensions -- Principal stresses -- Mohr's circle -- Invariants of a tensor -- Extension to three dimensions and introduction of deviatoric stresses -- A yield criterion -- The invariants in plane strain -- Momentum balance -- Deformation -- Logarithmic strain -- General equations for transformation of strain in two dimensions -- Condition that principal axes of stress and strain rate coincide -- Summary -- Chapter 10 Stress and velocity distribution in an idealized glacier -- Solutions for stresses and velocities in plane strain -- Stress solutions in a perfectly plastic medium. , Velocity solutions in a perfectly plastic medium -- Stress and velocity solutions for a nonlinear material -- Comparison with real glaciers -- Summary -- Chapter 11 Numerical modeling -- Goals of modeling -- Numerical integration -- Finite-difference models -- Implicit methods -- Alternating direction schemes -- Backward, forward, and centered differences -- Non-dimensionalization -- Shallow ice approximation -- Finite-element models -- Initial conditions and forcing -- Validation -- Intercomparison of models -- Sensitivity testing and tuning -- Coupling thermal and mechanical models -- Examples -- Calving -- Role of permafrost in ice sheet dynamics and landform evolution -- Three-dimensional models of ice sheets -- Summary -- Chapter 12 Applications of stress and deformation principles to classical problems -- Collapse of a cylindrical hole -- Tunnel and borehole closure -- Subglacial water conduits -- Calculating basal shear stresses using a force balance -- Creep of floating ice shelves -- Analysis of borehole-deformation data -- Summary -- Chapter 13 Finite strain and the origin of foliation -- The strain ellipse -- Simple and pure shear -- Parameters describing cumulative deformation -- Calculating cumulative strain -- Components of foliation -- Foliation in the marginal zone -- Recumbent folds in basal ice -- Summary -- Chapter 14 Response of glaciers to changes in mass balance -- Positive feedback processes -- Response of a temperate glacier -- Elementary kinematic wave theory -- Analysis of the effect of a small change in mass balance using a perturbation approach -- Solution for a small part of a glacier with uniform longitudinal strain rate and without diffusion -- Effect of diffusion -- The problem at the terminus -- Further study of the response time -- Numerical modeling of glacier responses -- Comparison with observation. , Nisqually Glacier -- South Cascade Glacier -- Summary -- Appendix Problems -- Chapter 3 -- Chapter 4 -- Chapter 5 -- Chapter 6 -- Chapter 8 -- Chapter 9 -- Chapter 10 -- Chapter 11 -- Chapter 12 -- Chapter 13 -- Chapter 14 -- References -- Index.
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  • 2
    Publication Date: 2019-01-02
    Description: Subglacial hydrology plays a key role in many glaciological processes, including ice dynamics via the modulation of basal sliding. Owing to the lack of an overarching theory, however, a variety of model approximations exist to represent the subglacial drainage system. The Subglacial Hydrology Model Intercomparison Project (SHMIP) provides a set of synthetic experiments to compare existing and future models. We present the results from 13 participating models with a focus on effective pressure and discharge. For many applications (e.g. steady states and annual variations, low input scenarios) a simple model, such as an inefficient-system-only model, a flowline or lumped model, or a porous-layer model provides results comparable to those of more complex models. However, when studying short term (e.g. diurnal) variations of the water pressure, the use of a two-dimensional model incorporating physical representations of both efficient and inefficient drainage systems yields results that are significantly different from those of simpler models and should be preferentially applied. The results also emphasise the role of water storage in the response of water pressure to transient recharge. Finally, we find that the localisation of moulins has a limited impact except in regions of sparse moulin density.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 3
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    PANGAEA
    In:  Supplement to: Elverhoi, Anders; Svendsen, John Inge; Solheim, Anders; Andersen, Espen Sletten; Milliman, John; Mangerud, Jan; Hooke, Roger LeB (1995): Late Quaternary sediment yield from high Arctic Svalbard area. The Journal of Geology, 103, 1-17, https://doi.org/10.1086/629718
    Publication Date: 2023-06-27
    Description: Late Quaternary sediment yields from the Isfjorden drainage area (7327 km**2), a high arctic region on Svalbard characterized by an alpine landscape, have been reconstructed by using seismic stratigraphy supported by sediment core analysis. The sediments that accumulated in the fjord during and since deglaciation can be divided into three stratigraphic units. The volumes of these units were determined and converted into sediment yield rates averaged over the drainage basin. During deglaciation, 13 to 10 ka, the sediment yield was ~860 tons(t)/km**2/yr. In the early Holocene it decreased to 190 t/km**2/yr, and then increased to 390t/km**2/yr during the late Holocene Little Ice Age. When normalized to the approximate glacierized area, these rates correspond to a sediment yield of ~800 t/km**2/yr . Sediment yield from non-glacierized parts of the drainage is estimated to be 35 t/km**2/yr. At times when ice advanced to the shelf edge, sediment was scoured from the fjord and deposited on the outer shelf and in a well-defined deep sea fan. Between 200 ka and 13 ka, 328 km**3 of sediment accumulated here, corresponding to a mean sediment yield rate of 335 t/km**2/yr. This is broadly consistent with calculations based on the above rates of sediment yield in glacierized and non-glacierized areas, and on estimates, based on glacial geology, of the temporal variation in degree of glacierization over the past 200 kyr. These figures indicate that much of the glacigenic sediment on the shelf and slope was eroded from the uplands of Svalbard by small glaciers during interstadials and interglacials. The sediments were temporarily stored in the fjord prior to redeposition on the shelf and slope during ice sheet advance. Taken into consideration, such redisposition of pre-eroded material will reduce estimates of primary ice sheet erosion rate.
    Keywords: 88-PCM-2; 90-01-GC1; 90-03-PC1; GC; Gravity corer; PC; Piston corer; Quaternary Environment of the Eurasian North; QUEEN; QUEEN_Exped
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 4
    Publication Date: 2023-06-27
    Keywords: 90-03-PC1; Age, 14C milieu/reservoir corrected; Age, dated; Age, dated material; Age, dated standard deviation; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; PC; Piston corer; Quaternary Environment of the Eurasian North; QUEEN; QUEEN_Exped; Sample code/label
    Type: Dataset
    Format: text/tab-separated-values, 36 data points
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  • 5
    Publication Date: 2023-06-27
    Keywords: 90-01-GC1; Age, 14C milieu/reservoir corrected; Age, dated; Age, dated material; Age, dated standard deviation; DEPTH, sediment/rock; GC; Gravity corer; Quaternary Environment of the Eurasian North; QUEEN; QUEEN_Exped; Sample code/label
    Type: Dataset
    Format: text/tab-separated-values, 40 data points
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  • 6
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    PANGAEA
    In:  Supplement to: Elverhoi, Anders; Hooke, Roger LeB; Solheim, Anders (1998): Late Cenozoic erosion and sediment yield from the Svalbard-Barents Sea region: implications for understanding erosion of glacierized basin. Quaternary Science Reviews, 17(1-3), https://doi.org/10.1016/S0277-3791(97)00070-X
    Publication Date: 2024-01-09
    Description: Data on glacial erosion have been compiled and synthesised using a wide range of sediment budget and sediment yield studies from the Svalbard-Barents Sea region. The data include studies ranging in timescale from 1 to 10**6 yr, and in size of drainage basin from 101 to 105 km**2. They show a clear dependence of sediment yield on the mode of glacierization. Polar glaciers erode at rates comparable to those found in Arctic fluvial basins, or about 40 t/km**-2/ yr or 0.02 mm/yr. In contrast, rates of erosion by polythermal glaciers are 800-1000 t/km**2/ yr (or ca 0.3-0.4 mm/yr), while rates from fast-flowing glaciers are slightly more than twice this: 2100 t/km**2/yr (or 1 mm/yr). Similar rates are also found for large glacierized basins like those in the southwestern parts of the Barents Sea. In contrast to the situation in fluvial basins, in which sediment yield typically decreases with increasing basin size, the tendency in glacierized basins is for erosion to be independent of basin size. In studies of sediment yield from glaciers it is sometimes difficult to distinguish between material actually dislodged from the bedrock by glaciers and material dislodged by other processes in interglacial times and simply transported to a depocenter by a glacier. Our data suggest that pulses of sediment resulting from advance of a glacier over previously-dislodged material last on the order of 10**3 yr, and result in inferred erosion rates that are approximately 25% higher than long-term average rates of glacial erosion. The maximum sediment fluxes from the large Storfjorden and Bear Island drainage basins occurred in mid-Pleistocene. The onset of this period of high sediment yield coincided with the onset of the 100 kyr glacial cycle. We presume that this was the beginning of a period of increased glacial activity, but one in which glaciers still advanced and retreated frequently. During the last two to four 100 kyr cycles, however, sediment yields appear to have decreased. This decrease may be the result of the submergence of the Barents Sea. Glacier erosion would be much higher for a subaerial Barents Sea setting than it would be for a present day subsea Barents Sea. A classical question in Quaternary Geology is whether glaciers are more erosive than rivers. We surmise that if factors such as the lithology and the available potential energy (mgh) of the precipitation falling at a given altitude, whether in liquid or solid form, are held constant, then glaciers are vastly more effective agents of erosion than rivers.
    Keywords: Age, 14C milieu/reservoir corrected (-440 yr); Age, dated; Age, dated material; Age, dated standard deviation; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; DSDP/ODP/IODP sample designation; GC; Gravity corer; NP90-52; Ocean Drilling Program; ODP; Sample code/label
    Type: Dataset
    Format: text/tab-separated-values, 48 data points
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