The far northwest: Sutherland, Assynt and Coigach

Tom Bradwell*, Colin K. Ballantyne

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

The far northwest of mainland Scotland is renowned for its scenery, structural complexity and geodiversity, and is designated as a UNESCO Global Geopark. The region is bisected by the Moine Thrust Zone (MTZ), west of which a foreland of undeformed Archaean gneiss supports inselbergs of Neoproterozoic and Palaeozoic rocks, and east of which are thrust-stacked, deformed metasedimentary rocks of the Neoproterozoic Moine Supergroup. The MTZ forms a north–south belt within which rocks were extensively thrust and folded during the Caledonian Orogeny. Successive Pleistocene glaciations have resulted in an array of erosional landforms: troughs, rock basins, cirques, glacially steepened inselbergs, extensive areas of knock-and-lochan terrain and clusters of glacial megagrooves. During the last and earlier ice-sheet glaciations, the region sourced northwestward-flowing ice feeding the Minch Ice Stream, which extended far across the adjacent shelf, but by ~15 ka the last ice sheet had retreated to its mountain heartland. The Loch Lomond Stade (~12.9 to 11.7 ka) witnessed reoccupation of the main mountain axis by a substantial (~350 km2) icefield, and cirque glaciers formed on peripheral mountains; the extent of the former is mainly delimited by multiple recessional moraines, the latter by end-moraine belts. Lateglacial and Holocene landforms include outwash or delta terraces at fjord heads, sea stacks, beaches backed by sand dunes, rock-slope failures, relict talus accumulations, and active periglacial and aeolian features on high ground. Karst terrain developed on dolostones comprises sinkholes, resurgences and extensive cave networks formed by water-table lowering due to Middle and Late Pleistocene valley deepening.

Original languageEnglish
Title of host publicationLandscapes and landforms of Scotland
EditorsColin K. Ballantyne, John E. Gordon
Place of PublicationCham
PublisherSpringer Science and Business Media B.V.
Chapter12
Pages233-250
Number of pages18
ISBN (Electronic)9783030712464
ISBN (Print)9783030712457, 9783030712488
DOIs
Publication statusPublished - 25 Aug 2021

Publication series

NameWorld geomorphological landscapes
ISSN (Print)2213-2090
ISSN (Electronic)2213-2104

Keywords

  • Caves
  • Cirques
  • Coastal landforms
  • Glacial landsystems
  • Glacial megagrooves
  • Glacial troughs
  • Hummocky recessional moraines
  • Inselbergs
  • Karst
  • Knock-and-lochan topography
  • Landslides
  • Moine Thrust Zone
  • Periglacial features
  • Stable foreland

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