Scottish Landform Examples: The Cairngorms – A Pre-glacial Upland Granite Landscape

Unequal ice-sheet erosional impacts across low-relief shield terrain in northern Fennoscandia

“…greatest along valleys where glacier ice was thick, fast moving and warm-based and least on the high elevation, low relief surfaces in between valleys where ice was thin, slow-moving and locally cold-based (Sugden, 1968;Kleman, 2008;Hall et al, 2013a,c). This is the case for glaciated passive margins such as the Cairngorms (Sugden, 1968;Hall, 1991;Hall et al, 2013c), Greenland , the northern Scandes in northern Sweden Goodfellow, 2007;Ebert et al, 2011), southern Norway (Bonow et al, 2003;Hall et al, 2013a), the coastal mountains of Marie Byrd land, Antarctica (Sugden et al, 2005), the Torngat mountains in north-east Canada (Staiger et al, 2005) and Baffin Island (Sugden, 1978;Refsnider and Miller, 2013).…”

Fracture controls on valley persistence: the Cairngorm Granite pluton, Scotland

“…7). These surviving pre-glacial valley elements indicate that, before Pleistocene glaciation, narrow river valleys with steep long profiles extended towards the core of the massif (Hall et al 2013). The differences in elevation between glen floors and neighbouring summits indicate persistence of these valley floors through >700 m of vertical erosion.…”

“…Spatial variations in grain size and the degree to which phenocrysts of feldspar are developed make it possible to divide the pluton internally (Fig. 2); the distribution of texturally distinct elements in the pluton shows no relationship to landscape features, and it is clear that granite texture has not been an important control on geomorphology (Thomas et al 2004;Hall et al 2013). The country rocks to the Cairngorm pluton are mainly Dalradian psammite, with minor quartzite and semipelite.…”

“…Warm-based, convergent ice flow, however, led to significant modification of valley forms (Hall and Glasser 2003). Pre-glacial river valleys were deepened by several hundred metres in places (Hall et al 2013). Several large glacial breaches developed as ice flowed through cols (Linton 1949), and glacial erosion also led to major drainage diversions ( Fig.…”

Early and Middle Pleistocene environments, landforms and sediments in Scotland

“…Depths of cumulative glacial erosion can be estimated by using non-glacial landforms and landsurfaces as reference points and surfaces for erosion. Glacial forms, mainly cnoc-and-lochain terrain, rock basins, valleys and corries, are cut into pre-glacial landsurfaces and so, along with any glacial lowering of hilltops and interfluves, represent total glacial erosion through the Pleistocene (Hall et al, 2013b). Minor non-glacial forms and weathering mantles -such as many tors (Hall & Sugden, 2007) and blockfields (Ballantyne, 2010b) and some shallow saprolites (Wright, 1997) -are of Early to Middle Pleistocene age and indicate little or no glacial erosion through later glacial cycles.…”