Morphological characteristics, formation and glaciological significance of Rogen moraine in northern Scotland



Finlayson A & Bradwell T (2008) Morphological characteristics, formation and glaciological significance of Rogen moraine in northern Scotland. Geomorphology, 101 (4), pp. 607-617.

Rogen moraine are enigmatic landforms whose exact origin is still debated. We use NEXTMap digital surface models and aerial photographs to map the distribution of previously unreported fields of Rogen moraine in the vicinity of Loch Shin, northern Scotland. Existing models of formation are tested against detailed morphological Rogen moraine characteristics obtained from the remote sensing data and field observations. Detailed morphometric analyses combined with their geographical setting lead us to postulate a likely mechanism of formation. Rogen moraine appear to have formed in areas where there were strong basal ice-flow velocity gradients. Thrusting by compression, or fracturing by extension of preexisting partially frozen sediment probably occurred in these areas, resulting in Rogen moraine formation. A general down-ice increase in ridge crest spacing suggests that the latter process may have been dominant, and is consistent with the location of Rogen moraine in the lee of topographic obstructions, in areas that experienced overall extensional ice flow. We also suggest that at least one field of Rogen moraine formed where lateral basal ice-flow velocity gradients were strongest — possibly in a subglacial shear margin setting. Given their location, the landforms may be consistent with formation during headward scavenging of the Moray Firth palaeo-ice stream into a shrinking core of cold-based ice.

Digital surface models; Transverse ridges; Ice-flow velocity; Ice stream

Geomorphology: Volume 101, Issue 4

Publication date30/11/2008
Publication date online13/03/2008
Date accepted by journal29/02/2008

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Dr Tom Bradwell

Dr Tom Bradwell

Senior Lecturer, Biological and Environmental Sciences