Anglesey's coastal geology
Porth Saint, Rhoscolyn
Anglesey boasts a wealth of geological diversity and nowhere is this more clearly visible than around the island’s 125 mile coastline.
The island possesses the oldest tracts of rocks in the British Isles south of the Scottish Highlands. From the eastern limestone belt, through the windblown sands and pillow lavas of Llanddwyn to the spectacularly rugged coastline of Rhoscolyn and South Stack, the coastline of Anglesey has much to offer all with an interest in matters geological or those who are simply looking for spectacular scenery.
Economically the mineral wealth of the island has been exploited and the evidence is clearly visible in the form of quarries, several of which dot the coastline. Of particular value were the limestone deposits which provided building stone for the construction of noteworthy buildings such as Birmingham Town Hall, and the reconstruction of cities such as Liverpool and Manchester following the last World War. Such quarries can be found at Llanddona, Penmon, Moelfre and Holyhead.
Top ten geology locations
- South of Bwa Du and Gwyn, Rhoscolyn - Examples of thrusting, folding and arches
- South Stack - Cliffs, thrusts and folds
- Holyhead Mountain - Exposed quartzites, former working quarries
- Carmel Head - Thrusted and folded pre-Cambrian and Ordovician rocks
- Llanbadrig to Porthwen - The Gwna ‘melange’ – a fascinating mixture of rocks
- Lligwy, Moelfre and Benllech - Sandstone/limestone outcrops
- Llanddona/Penmon - Limestone pavement
- Shoreline, south of Beaumaris - Fine examples of dolerite dykes (volcanic extrusions)
- Menai Strait - (Opposite Caernarfon Castle) red measures/sandstones visible
- Llanddwyn - Windblown sand and pillow lavas