The Shiants, or at least most of them, are about fifty eight and a half million years old. They were formed from a series of hot, intrusive magmas, giant plugs of molten rock rising from deep within the earth's mantle, which squeezed between much older fossil-bearing rocks above them. Although Frederick Walker's paper is now out of date (he has no understanding of the multiple intrusions which later geologists discovered) it is a fascinating description of the whole cooling mechanism. The SNH Geological Conservation Review presents the modern view in relatively non-technical language, and contains some excellent photographs of the islands and their rocks.
Shiant Isles SSSI - Geological Conservation
by Kathryn Goodenough
Scottish Natural Heritage - September 1999
Reproduced by permission of Scottish National Heritage (3.23 Mb PDF file)
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