Ice dynamics and sediment movement : last glacial cycle, Clyde Basin, Scotland

Finlayson, Andrew G.. 2012 Ice dynamics and sediment movement : last glacial cycle, Clyde Basin, Scotland. Journal of Glaciology, 58 (209). 487-500. 10.3189/2012JoG11J207

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The nature and behaviour of sediment beneath glaciers influences how they flow and respond to changing environmental conditions. The difficulty of accessing the bed of current glaciers is a key constraint to studying the processes involved. This paper explores an alternative approach by relating sediments under the beds of former mid-latitude ice sheets to changing ice behaviour during a glacial cycle. The paper focuses on the partly marine-based Pleistocene British-Irish ice sheet in the Clyde basin, Scotland. A three-dimensional computation of subsurface glacial sediment distribution is derived from 1260 borehole logs. Sediment distribution is linked to an empirically based reconstruction of ice-sheet evolution, permitting identification of distinctive phases of sedimentation. Maximum sediment mobilization and till deposition (∼0.04 m a-1) occurred during ice advance into the basin from adjacent uplands. Transport distances were generally short. Subglacial processes were influenced locally by the relative stiffness of pre-existing sediments, the permeability of the sub-till lithology, and topography; the resulting mean till thickness is 7.7 m with a high standard deviation of 7.0 m. In places, focused till deposition sealed pre-existing permeable substrates, promoting lower effective pressures. Sediment remobilization by meltwater was a key process as ice margins retreated through the basin.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.3189/2012JoG11J207
Programmes: BGS Programmes 2010 > Geology and Landscape (Scotland)
ISSN: 0022-1430
Date made live: 23 Jul 2012 10:57

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