North Wales

Abstract

The geology of North Wales spans a broad time period from late Precambrian rocks on the island of Anglesey more than 500 million years of age, to much younger traces of Carboniferous sediments less than 300 million years of age found in the north east. There are traces of volcanic rock to be found in the north west and igneous seams on Anglesey and parts of the north western peninsula, indicating an interesting history. Furthermore, parts of the landscape are shaped by more recent activity during the last ice age when glaciers scoured out the valleys around Llanberis, Nant Gwynant, Tal-y-Lyn and elsewhere. In addition to Cambrian rocks of between 495 and 545 million years of age found in the north west, there are swathes of Ordovician origin, with rocks of between 443 and 495 million years of age, reaching down from Anglesey in a south east direction, with earlier Silurian rocks, around 417–443 million years of age, completing much of the picture. Later Devonian rocks of between 354 and 417 million years of age, while occurring mostly in South Wales, are occasionally to be found in the south eastern extremities of North Wales. Overall, it is an area rich in geological variety and with an interesting history which, in certain areas, is unequivocally bound to the underlying rock. It also provides some of the most beautiful landscapes to be found in Britain, with a variety of small mountains, lakes, rolling hills and valleys.