The glacial geomorphology of part of the Western Grampians of Scotland, with especial reference to the limits of the Loch Lomond Advance

Thorp, Peter William (1984) The glacial geomorphology of part of the Western Grampians of Scotland, with especial reference to the limits of the Loch Lomond Advance. Doctoral thesis, City of London Polytechnic.


The limits of a large ice mass that built up in the western Grampians during the Loch Lomond Stadial were mapped using O.S. maps to scales of 1 : 10,000 and 1 : 25,000. The main forms of mapped glacial evidence comprised moraines, thick till, fluvioglacial landforms, erratics, boulder spreads, ice-moulded bedforms, striae and friction cracks. Outside the glacial limits the main types of mapped periglacial evidence included frost-riven bedrock, thick fossil screes, smooth debris-strewn slopes, tors, and solifluction lobes, terraces and sheets. 199 mapped trimlines, based on various forms of contrasting glacial and periglacial evidence, enabled the upper limits and form of the glaciers to be reconstructed, to varying degrees of accuracy, especially in the accumulation areas of the former glaciers. This information was supplemented by the evidence on 64 cols. The reconstructed form of the main ice mass indicates that it covered an area in excess of 2,000km (to the power of 2), that its total volume was ca. 460km (to the power of 3), and that maximum ice-shed altitudes of ca 700 - 750m O.D. were attained in the Glen Nevis-Rannoch Moor-Glen-Lyon areas.

Equilibrium rim lines calculated for the main ice mass and for 17 independent corrie, valley and plateau glaciers indicate that firn lines rose from ca. 400m O.D. in the SW to +900m O.D. in the NE part of the study area. Trend surface analysis of corrie-floor altitudes, the spatial distribution of amounts of precipitation at the present time t and the equilibrium rim lines of the former Loch Lomond Advance glaciers, indicates a broad correspondence between these factors. Amounts of precipitation during the stadial on the mountains are estimated to have ranged from 3000 - 4000mm yr-1 in the SW to less than 1000mm yr-1 in the NE.

Glacial evidence outside the limits of the Loch Lomond Advance suggest that the pattern of build-up and directions of ice-flow in ice-sheet times were very similar to those that occurred in the stadial. This implies that the climatic parameters that operated during the stadial were broadly similar to those that operated in earlier glacial periods.

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