Quaternary
2.4 Ma to present day (Arran at present day latitudes)
The creation of the present landscape on Arran is a story shaped and scoured
by ice. The growth and retreat of glaciers, caused by climate change during
the Quaternary, has left us with a spectacular landscape of corries, arretes,
and u-shaped valleys. Glen Rosa is a fine example of a glaciated alpine
valley. Glacial drift, till, and erratics, left by the retreat of the last
glaciers, cover much of the low ground in the south and the west of Arran
as unconsolidated deposits. Glacial outwash sand is quarried in Glen Rosa
and used for water purification processes.
Accessory to the glaciated landscape, Arran has spectacular raised beaches
and cliff lines. The weight of glaciers caused the crust to subside, and
upon the retreat of the ice the rebound has been slow. This slow isostatic
recovery coupled with sea level change has allowed for the beaches, sea
stacks, cliffs and terraces to form. Over time, as the land rebounds, these
features are raised out of the sea. The coastlines at Catacol and Drumadoon
and Dougarie have excellent examples of such scenery. The King’s Cave
is a fine example of caves in the cliff of a raised beach.
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