EGS Seminar: Tuesday, 6th December 2011

Tuesday 06th December, E34, John Dalton East Building, from 1.00-2.00 pm.

Sandwiches, coffee and tea are available from 12.30 pm in room E402.
If you would like to chat informally with the speaker before the seminar, please contact this week’s host, Cathy Delaney.

Glacial Sediments under the Microscope: A Small Method for Big Questions


Dr Simon Carr


Queen Mary, University of London

In the past 30 years, it has become evident that deformable materials beneath glaciers and ice sheets have exerted a fundamental control over their extent, behaviour and dynamics. Within a wider context in which we increasingly view glaciers as an unstable and highly sensitive component of the global climate system, the deformable bed model has defined a paradigm in which glaciers are seen as complex, rapidly evolving systems. Although the deforming bed model of glacier dynamics has been generally accepted, and often invoked to explain key glacier flow and dynamic behaviour, the evidence used to illustrate processes operating at the glacier bed is incredibly sparse and ambiguous. This is because many of the sediments deformed and deposited beneath glaciers look structureless at the macroscopic scale. As such, application of the deforming bed model of glacier dynamics is often built on speculative and somewhat tenuous interpretations of limited sediment data.
Whilst many glacial sediments look structureless at a macroscopic scale, when examined at relatively low magnifications using optical or electron microscopes, they preserve a wide range of structures and characteristics. These structures reflect that all subglacially-transported sediments preserve a host of evidence of different forms of deformation. In this seminar, I will demonstrate the way in which micro-scale approaches have been applied to understand the nature and significance of glacial sediments in two and three (and perhaps even four) dimensions. I will argue that micro-scale methods such as these are currently the only way in which key questions of the stability and sensitivity of glaciers to climate change may be adequately answered.