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Geophysical surveys of the sediments of Loch Ness, Scotland : implications for the deglaciation of the Moray Firth Ice Stream, British-Irish Ice Sheet.

Turner, A.J. and Woodward, J. and Dunning, S.A. and Shine, A.J. and Stokes, C.R. and O'Cofaigh, C. (2012) 'Geophysical surveys of the sediments of Loch Ness, Scotland : implications for the deglaciation of the Moray Firth Ice Stream, British-Irish Ice Sheet.', Journal of quaternary science., 27 (2). pp. 221-232.

Abstract

We present results from three geophysical campaigns using high-resolution sub-bottom profiling to image sediments deposited in Loch Ness, Scotland. Sonar profiles show distinct packages of sediment, providing insight into the loch's deglacial history. A recessional moraine complex in the north of the loch indicates initial punctuated retreat. Subsequent retreat was rapid before stabilisation at Foyers Rise formed a large stillstand moraine. Here, the calving margin produced significant volumes of laminated sediments in a proglacial fjord-like environment. Subsequent to this, ice retreated rapidly to the southern end of the loch, where it again deposited a sequence of proglacial laminated sediments. Sediment sequences were then disturbed by the deposition of a thick gravel layer and a large turbidite deposit as a result of a jökulhlaup from the Spean/Roy ice-dammed lake. These sediments are overlain by a Holocene sheet drape. Data indicate: (i) a former tributary of the Moray Firth Ice Stream migrated back into Loch Ness as a major outlet glacier with a calving margin in a fjord-like setting; (ii) there was significant sediment supply to the terminus of this outlet glacier in Loch Ness; and (iii) that jökulhlaups are important for sediment supply into proglacial fjord/lake environments and may compose >20% of proglacial sedimentary sequences.

Item Type:Article
Keywords:Loch Ness, Geophysical surveys, Jökulhlaup, Deglaciation, Proglacial.
Full text:Full text not available from this repository.
Publisher Web site:http://dx.doi.org/10.1002/jqs.1538
Date accepted:No date available
Date deposited:No date available
Date of first online publication:February 2012
Date first made open access:No date available

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