Paraglacial and periglacial slope adjustment of a degraded lateral moraine in Glen Torridon

Abstract

Introduction The importance of paraglacial processes – those which operate immediately following deglaciation–in modifying glacial landforms and sediment associations in mountainous areas has been established for some time ([Ryder 1971 a ][1],[ b ][2]; [Church and Ryder 1972][3]). Of particular importance is the development of large alluvial fans and valley fills, often associated with the redistribution of sediment via large debris flows ([Jackson et al. 1982][4]; [Claque 1986][5]; [Eyles and Kocsis 1988][6]; [Eyles et al 1988][7]; [Owen 1989][8]). On a slightly smaller scale is the development of thick deposits of head due to the reworking of glacial sediments on steep slopes (e.g. [Wright 1983][9]; [Owen 1991][10]; [Harrison 1993][11]; [Ballantyne and Harris 1994][12]; [Benn and Ballantyne 1994][13]). In the Scottish Highlands the significance of periglacial processes and Holocene debris flows in reworking valley side sediments has frequently been described (e.g. [Brazier and Ballantyne 1989][14]; [Ballantyne and Harris 1994][15]). In contrast, paraglacial processes have received relatively little attention, yet these also had the potential to modify the land-form and sediment assemblages in many Highland valleys. Given that recent work on these assemblages has emphasised their complexity (e.g. [Benn 1992][16]; [Bennett and Boulton 1993 a ][17]; [Bennett 1994][18]) the effects and products of paraglacial activity perhaps deserve greater attention within Scotland. This communication records observations made in a road-side cutting, above Loch Torridon (Fig. 1), within a thick, valley-side, sediment accumulation and suggests that this is the product of both paraglacial and periglacial modification of a now indistinct lateral moraine. Geomorphology and sedimentology The section is in a road-side . . . [1]: #ref-20 [2]: #ref-21 [3]: #ref-12 [4]: #ref-17 [5]: #ref-13 [6]: #ref-15 [7]: #ref-14 [8]: #ref-18 [9]: #ref-23 [10]: #ref-19 [11]: #ref-16 [12]: #ref-1 [13]: #ref-5 [14]: #ref-11 [15]: #ref-2 [16]: #ref-3 [17]: #ref-8 [18]: #ref-7