Editing Scottish Highlands (section)

== Geology ==
[[File:Liathach from Beinn Eighe.jpg|thumb|[[Liathach]] seen from [[Beinn Eighe]]. With the Munro "Top" of Stuc a' Choire Dhuibh Bhig 915&nbsp;m (3,001 ft) in the foreground and the two Munro summits in the background.]]
[[File:Main ridge of the cuillin in skye arp.jpg|thumb|The main ridge of the [[Cuillin]]]]
[[File:Scotland (Location) Named (HR).png|thumb|The main geographical divisions of Scotland]]
The Highlands lie to the north and west of the [[Highland Boundary Fault]], which runs from [[Isle of Arran|Arran]] to [[Stonehaven]]. This part of Scotland is largely composed of ancient rocks from the [[Cambrian]] and [[Precambrian]] periods which were [[Tectonic uplift|uplifted]] during the later [[Caledonian Orogeny]]. Smaller formations of [[Lewisian complex|Lewisian gneiss]] in the northwest are up to 3&nbsp;billion years old. The overlying rocks of the [[Torridonian|Torridon Sandstone]] form mountains in the [[Torridon Hills]] such as [[Liathach]] and [[Beinn Eighe]] in [[Wester Ross]].

These foundations are interspersed with many [[igneous]] intrusions of a more recent age, the remnants of which have formed mountain [[massif]]s such as the [[Cairngorms]] and the [[Cuillin]] of [[Skye]]. A significant exception to the above are the fossil-bearing beds of [[Old Red Sandstone]] found principally along the [[Moray Firth]] coast and partially down the Highland Boundary Fault. The [[Jurassic]] beds found in isolated locations on [[Skye]] and [[Applecross]] reflect the complex underlying geology. They are the original source of much [[North Sea oil]]. The [[Great Glen]] is formed along a [[transform fault]] which divides the [[Grampian Mountains]] to the southeast from the [[Northwest Highlands]].<ref name="Keay">{{Cite book |last=John Keay, Julia Keay |url=https://archive.org/details/collinsencyclopa00john |title=Collins Encyclopaedia of Scotland |publisher=HarperCollins |year=1994 |isbn=978-0-00-710353-9 |url-access=registration}}</ref><ref>{{Cite book |last=William Hutchison Murray |title=The islands of Western Scotland: the Inner and Outer Hebrides |publisher=Eyre Methuen |year=1973}}</ref>

The entire region was covered by ice sheets during the [[Pleistocene]] ice ages, save perhaps for a few [[nunatak]]s. The complex [[geomorphology]] includes incised valleys and [[loch]]s carved by the action of mountain streams and ice, and a [[topography]] of irregularly distributed mountains whose summits have similar heights above sea-level, but whose bases depend upon the amount of [[denudation]] to which the plateau has been subjected in various places.<ref name="EB1911">{{EB1911|inline=y|wstitle=Highlands, The|volume=13|pages=455–456}}</ref>