Andrew Evans Andrew Evans
The project aims to use the spatially extensive paleo-deposits of the last ice age to elucidate the basal conditions of 'the last great ice sheets'. Suites of subglacial deformation structures are being examined on a range of scales from micro (m) to macro (10's km) scale to determine the processes at work in varying glacial regimes. This study is being complemented by a series of controlled deformation / hydrological experiments on sediments in the triaxial deformation system at Aberystwyth. These experiments will allow the vital relationships between the processes of dilation, consolidation and water throughflow to be linked to sediment structure. Such relationships will enable sediment structures seen in the field to be interpreted in terms of their development and importance in the subglacial deformation of each area. This process is being made quantifiable through the production of a model of the changing permeability of the lab deformed sediments on a microstructural scale. This permeability model will be applied to glacial deposits in thin section. The relevance of these subglacial processes will be discussed in particular in reference to the dynamics of the 'fast flow' (?) ice lobe that occupied the East coast of Britain in Oxygen Isotope Stage Two.
Initial results have focused on model development, the distinguishing of basal conditions from microstructures, and micro/mesoscale interactions between basal melting and sediment deformation and lodgement. In further elucidating the connections between water throughflow, subglacial hydrology and sediment deformation on all scales it is hoped the project will cast light on basal processes under the mid to high latitude ice sheets which left the great till plains. This information the will aid in reconstructing the dynamics of these ice masses.
Includes work on Microstructures associated with clast lodgement. from Criccieth on the Llyn Peninsular
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