Subglacial Origin of Till
نویسندگان
چکیده
منابع مشابه
Subglacial till formation: Microscale processes within the subglacial shear zone
This was a study of subglacial deformation till genesis from a modern temperate glacier, at Sk alafellsj€ okull, Iceland. Detailed microscale properties of till samples (from Scanning Electron Microscope [SEM] and thin section analysis) were examined from a glacial site with in situ subglacial process monitoring and an exposed subglacial surface in the foreland. Two lithofacies were examined, a...
متن کاملCreep closure of channels in deforming subglacial till
We examine theoretically the creep closure of subglacial tunnels cut into basal till, generalizing Nye's classical analysis of tunnel closure in glacier ice to rheologies in which the creep rate depends on effective pressure (the difference between total pressure and pore-water pressure). The solutions depend critically on a dimensionless permeability parameter. For the appealingly simple Boult...
متن کاملSpontaneous generation of pure ice streams via flow instability: Role of longitudinal shear stresses and subglacial till
[1] A significant portion of the ice discharge in ice sheets is drained through ice streams, with subglacial sediment (till) acting as a lubricant. The known importance of horizontal friction in shear margins to ice stream dynamics suggests a critical role of longitudinal stresses. The effects of subglacial till and longitudinal stresses on the stability of an ice sheet flow are studied by line...
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The existence of both water and sediment at the bed of ice streams is well documented, but there is a lack of fundamental understanding about the mechanisms of ice, water and sediment interaction. We pose a model to describe subglacial water flow below ice sheets, in the presence of a deformable sediment layer. Water flows in a rough-bedded film; the ice is supported by larger clasts, but there...
متن کاملDynamics of subglacial floods
The Nye model of jökulhlaups is able to explain both their periodicity and even the detailed shape of the flood hydrograph. In this paper, we show how the model can be used to predict the shape of the hydrographs from the subglacial lake Grı́msvötn beneath Vatnajökull in Iceland, and we comment on three particular issues that have proved contentious in the application of the Nye model: the role ...
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ژورنال
عنوان ژورنال: Geological Magazine
سال: 1878
ISSN: 0016-7568,1469-5081
DOI: 10.1017/s0016756800150605