Snowdon (, ) is the highest mountain in Wales, at an altitude of above sea level, and the highest point in the British Isles outside Scotland [REF].
The rocks that form Snowdon were produced by volcanoes in the Ordovician period, and the massif has been extensively sculpted by glaciation, forming the pyramidal peak of Snowdon and the arêtes of Crib Goch and Y Lliwedd [REF].