the highest mountain in England and Wales, rises near the centre of the chain extending across the county of Carnarvon, from S.W. to N.E., from the coast near Nevin to Penmen-mawr, near Conway. The length of the chain is about 35 miles, and its average breadth 6 miles. The highest point, which is distinguished by the name of y-Wyddfa, is 3571 feet above the sea; the second, called Carnedd Llewelyn, 3460. The nucleus of the ridge consists of primitive rocks, which are flanked by strata of slate and limestone. In several places copper is found. The western side of Snowdon is more steep than the eastern, and is partially formed of basalt.