Carnarvonshire or Caernarvonshire, a maritime county of North Wales, bounded on the north by Beaumaris Bay and the Irish Sea, on the north-east by Denbighshire, on the south-east and the south by Merionethshire and by Cardigan Bay, on the south-west by Carnarvon Bay, and on the northwest by the Menai Strait, dividing it from Anglesey. Its length south-westward is 55 miles, its greatest breadth 23 miles, its circuit about 150 miles, its area 361,097 acres. The part between Cardigan Bay and Carnarvon Bay, 28 miles long, and diminishing in breadth from 13 miles to a point, is the peninsula of Lleyn, and the other parts are mainly filled with the vales and mountains of Snowdonia. Much of the Lleyn peninsula is low country, parts of the other seaboards also are low, yet these tracts abound in bold picturesque diversities, while the mountains of Snowdonia, regarded either in the group or in detail, are the richest for grandeur, force, and beauty in the British Isles. The Conway river goes along the north-eastern boundary to the sea; the Machno, the Lledr, and the Llugwy fall into the Conway; the Glas-Llyn, a romantic stream, goes to Cardigan Bay; and the Seiont and the Gwrfai descend from Snowdon to the Menai Strait. Numerous lakes lie among the mountains, and innumerable rivulets run around their bases. Cambrian and Silurian rocks, with vast and manifold protrusions of erupted rocks, fill nearly all the area. The Cambrian form considerable belts in the north-west and the south-west; the lower Silurian spread from the middle west, through all the centre, to the south and the east; and the upper Silurian form a small tract in the north-east. The erupted rocks range from granite through all the traps to the simply volcanic, and include great uplifted masses of clay-slate and other schists. Old red sandstone appears on the coast from Conway to Bangor, also in Braich-y-PwIl, and carboniferous limestone appears in Orme's Head and in a strip along part of the Menai Strait. Copper, lead, and zinc are worked, roofing slates in vast quantities are quarried, and millstone and ochre are found.