“ SNOWDON (Wyddfa, view-place, Eryri, eagle-place) , the highest elevation in N. Wales. It is formed chiefly of slates, grits and porphyries of the Cambrian and Silurian systems. It consists of five “ribs” converging at the summit, 3560 ft. above sea-level. Between these lie such depressions as Cwm Glas (blue or green vale) to the N., and Cwm y llan (clearing, town or church vale) to the S. Snowdon is demarcated from the surrounding hills by passes famous for their scenery, such as that of Llanberis (q.v.) ”