Geology - Rhoscolyn Anticline


Anglesey is an important study area for some of the most ancient rocks on our planet and Rhoscolyn is one of the island’s finest geological locations. It offers a spectacular display of complex, folded rocks which were old long before the mountains of Snowdonia even existed. Anglesey has long been, and continues to be, the focus of much interest, world-wide, by research scientists and students alike. From this outstanding geo-heritage, the island derives its local and regional distinctiveness and character. As a result in April 2009 Anglesey was designated as a ‘European Geopark’ giving international recognition for its importance as a geological site. Geomon are coordinating the activity of the Geopark and there is a great deal of additional information on their web site: Several University Geology Departments are regular customers at Outdoor Alternative including Southampton University, Leicester University and Brighton University. Enjoying the unique advantage of our position within walking distance of their outdoor classroom.

The Geologists view …

“The rocks around Rhoscolyn, designated a Site of Special Scientific Interest, provide one of the most visited geological localities in Great Britain. From the Field Centre one can walk directly on to easily accessible coastal exposures of deformed sedimentary rocks that show spectacular cascades of folds and associated cleavages. The sediments have been folded several times, so that one may study the effects of one fold being superimposed on another. The most famous exposures lie in the core of the Rhoscolyn Anticline, a huge, arch-shaped fold exposed in the cliffs just 15 minutes walk along the coast from Outdoor Alternative. The nearest rocks in the UK that come even close to matching such splendid exposures are those in the highlands of Scotland, so it is unsurprising that the area is so popular with universities and schools from all over England and Wales.

The ground is perfect for detailed mapping exercises and teaching students how to measure folds in the field. For the geological specialist, within a kilometer of the field centre one can visit polydeformed metapsammites, metapelites, quartzites, serpentinite, metagabbro and metabasalt, as well as fine examples of late basic dykes that cut through the metamorphic complex. Within an easy drive of Holy Island, the famous ‘Monian’ rocks of Anglesey preserve high grade sillimanitic metapelites and amphibolites, calc-alkaline granitoid rocks, the internationally known Gwna Melange (the first melange ever described), and some of the oldest blueschists on Earth. In addition there are well exposed Ordovician, Silurian, Devonian and Carboniferous sediments, some of which are richly fossiliferous, not to mention Parys Mountain, once the largest copper mine in Europe. Even for those not especially involved in geology, the huge variety of different rocks on Anglesey makes for varied and beautiful scenery, especially great for coastal walking and wildlife spotting.”

Wes Gibbons, School of Earth Sciences, University of Wales, Cardiff.