Morphological analysis and mapping of Loch Lomond Stadial moraines using digital photogrammetry and geographical information systems
Morphological analysis and mapping of Loch Lomond Stadial moraines at five key sites, Torridon, Rannoch Moor, Tyndrum and Strath Fillan, the upper Forth Valley and the east Loch Lomond basin has allowed the genetic interpretation and inferences of climatic significance to made. Hummocky moraine is found at three of these sties, Torridon, Rannoch Moor and Tyndrum, where they are interpreted as polygenetic in origin. The spatial organisation and morphology of hummocky features investigated in Torridon allows the differentiation of cross-valley orientated marginal moraines and the more numerous streamlined features with a down-valley orientation interpreted as flutings. As the flutings are superimposed on the cross-valley moraines they are thought to post-date moraine formation. The spatial organisation of glacial landforms in Torridon therefore represents a palimpsest landscape. Mapping of moraines in the Rannoch Moor basin suggests that this was a major centre of ice convergence rather than accumulation during the Loch Lomond Stadial. Ice mainly accumulated in the corries in the mountains to the west of moor from where it flowed to coalesce as an upland icefield. Ice is thought to have reached a sufficient volume in the Rannoch Moor basin to flow down valleys as outlet glaciers. Hummocky features found at Tyndrum and Strath Fillan have a polygenetic origin and include the remnants of eskers, hummocks produced by local ice stagnation, marginal moraines, and lateral moraines which have been modified by paraglacial debris flow. Large terraces at this sites are interpreted as kame terraces with pitted and channelled surfaces. Local ice stagnation is thought to have occurred during a regional pattern of active deglaciation.