The Outer Hebrides
The Outer Hebrides (Western Isles) include the linked islands of Lewis and Harris, North Uist, Benbecula and South Uist, Eriksay, Barra and smaller islands south to Berneray (Angus 1997). The islands are dominated by Pre-Cambrian rocks, (Lewisian gneiss), which is often irregularly layered. There are associated granites in the hilly uplands of western Lewis and Harris, some schist and limestone in southern Harris and a low-lying area of red-brown Permo-Triassic sandstones and conglomerates.
The islands were strongly glaciated in Pleistocene times, and glacial drift blankets much of the northwest of Lewis, linking some former islands. Bold cliffs occur locally on exposed N and NW coasts, dissected along joint and fault planes, down which there have been local landslides, but undercutting and the retreat of headlands has been very slow on these hard rock formations, and even on the exposed north coast there are many vegetated slopes.
The west coasts of the islands are exposed to...
KeywordsSalt Marsh Sandy Beach Rocky Shore Coastal Slope Calcareous Sand
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