Islay Geology

Islay has had an extremely varied geological history reflecting the wide range of climates and environments that the Island has been subjected to over many millions of years. Whatever your experience or knowledge of geology there is plenty to see on Islay.

The Islay Nature Centre is a great place to learn about the geology of the Island. As well as a display, there are hands on activities (suitable for adults and children) and a library containing publications on, and associated with, Islay's geology.

geology walk Copyright: David WebsterRegular guided geological walks take place each month through the summer. See Walk Programme for details

NEW: Tour of Snowball Earth - 21/22 October - click for more details For more background see Snowball Earth on Islay

So if you are a beginner who is keen to learn more or an expert who wants to check out the latest research on the Islay's rocks then visit the Field Centre at Port Charlotte.

GEOLOGICAL GUIDE BOOK In 2015 a new geological guide to Islay was published. Written by David Webster, Alasdair Skelton and Roger Anderton it describes 12 Excursions which explain the geology both for beginners and for those with some knowledge. Proceeds go to the Islay Natural History Trust

It can be purchased at the Centre, at the Celtic Shop Bowmore, on the Ferry or at the Mini-Market in Bruichladdich. Alternatively buy it online direct from the publishers website Guide to the Geology of Islay link or from Amazon

Some extra supporting information can be found on the companion pages Companion Site for Guide to the Geology of Islay Book

cover Copyright: David Webster

Why is the Geology of Islay so interesting?
Islay has a wonderful variety of accessible geology; virtually all aspects of the science can be demonstrated. Amongst the highlights are:

  • The Islay area is the best place in the British Isles to see the 1,800 million-year old metamorphic rocks (the Rhinns Complex) which underlie much of central Scotland.
  • Relatively undeformed sedimentary sequences (the Dalradian) deposited from 750-600 million years ago on the margins of the ancient Iapetus Ocean.
  • The best evidence in the British Isles of Precambrian life in the form of fossil microbial colonies (stromatolites).
  • A world-famous Precambrian glacial deposit (the Port Askaig Tillite) that tells of a time of severe, perhaps global glaciation.
  • Relatively low-grade metamorphism resulting in the excellent preservation of the original depositional features of the sedimentary sequences.
  • Good examples of the re-activation and reversal of extensional faults.
  • A good place to study mineralisation and investigate fluid-flow in the Earth’s crust; at least three distinct episodes can be observed.
  • A variety of igneous intrusions related to the opening of the North Atlantic Ocean about 60 million years ago.
  • A wide variety of Ice Age erosional and depositional features

Geological map Copyright: David Webster