CARNARVONSHIRE, a county of North Wales (Welsh Caer'narfon, for Caer yn Arf on) , bounded north by the Irish Sea, east by Denbigh, south-east by Merioneth, south by Cardigan Bay, south-west by Carnarvon Bay and west by the Menai Straits. Area, 565 square miles. A small detached portion of the county on the north coast of Denbighshire stretches inland some 21 m. between Old Colwyn and Llanddulas. The south-west of the county, called Lleyn, projects as a peninsula separating Carnarvon and Cardigan Bays.
The denuded Archaean lowland of Anglesey preserves rocks of Devonian and Carboniferous age along a low line that crosses it from north-east to south-west and along parts of the Menai Straits; Carboniferous rocks are also preserved at the north-east corner of Anglesey and along the north coast east of the Conway, with the Great Orme's Head as an outstanding feature. Archaean rocks also form the west side of the south part of Lleyn from near Nevin to the point of Braich-y-Pwll, as well as the island of Bardsey beyond. The area immediately south-west of the Menai Straits shows a zone of Cambrian rocks between Bangor and Bethesda on the north and stretching from Aber, near Bangor, south-westward to Clynnog; it includes a belt of Ordovician rocks and two zones of igneous rocks, all elongated in the north-east south-west direction. The next zone is the highly characteristic mountain range which is the main feature of the county's geography and is almost unique in showing many features that elsewhere are met with only at twice the height or more. In it Ordovician grits and shales, interbedded with, and to a larger extent overlaid by, lavas, and also penetrated by intrusive rocks, occur in folds, the summit of Snowdon being structurally a syn cline in the upper Ordovician volcanic rocks which dominate the lower grits and shales in the great rock-wall standing above Llyn ddu Arddu. Mynydd Mawr, west of Snowdon, represents the neck of a volcano.
The north-eastern end of the main range rises from Conway Mountain (8o8 ft.) and Penmaenmawr (1,550 ft.), near the north coast, south-westward to Carnedd Llewelyn (3,484 ft.) and Carnedd Dafydd (3,426 ft.), and this section of the range is divided by the deep Ogwen Pass (1,00o ft.) from the next in which are Y Glyder Fawr (3,279 ft.) and Y Glyder Fach (3,262 ft.). Elidyr Fawr (3,029 ft.) is a western outpost in this section which is bounded on the south-west by another deep zone of faults forming the pass of Llanberis (1,169 ft.). South-west of this is Snowdon (Eryri or Yr Wyddfa, 3,56o ft.). The Snowdon mass again is separated by the pass (65i ft.) above Rhyd ddu pass from three somewhat radially arranged masses which are also separated from one another by deep lines. The most northern of these three masses is dominated by Mynydd Mawr (2,290 ft.), the median one by Garnedd Goch (2,301 ft.) and the southerly one by Moel Hebog (2,566 ft.). The median one, itself mainly of intrusive igneous rock, may be said to be followed by a series of heights, Gyrn ddu (1,712 ft.), Yr Eifl (1,849 ft.) and Garn Bodfean (918 ft.) stretching down the Lleyn peninsula.
The south-east flank of the main range is marked by another deep line, more gentle however than those cross ones which have just been named. This drains eastward to the Conway by the Gwrhyd and Llugwy, on which latter occur the Swallow Falls, and south-westward by the Glaslyn which occupies Nant Gwynant and drains its two lakes, Llyn Gwynant and Llyn Dinas. After receiving a contributor (the Colwyn) from the Rhyd ddu pass on the west of Snowdon, the Glaslyn leaves the mountains by the wild gorge of Aberglaslyn emerging on to the lowland of Traeth Mawr, partly reclaimed from the sea in recent times. South and south-east of the Llugwy, Gwrhyd and Glaslyn valleys is a subordinate range, the directive lines of which are parallel to those of the valleys and are largely determined by zones of basalt, dolerite and diabase. Here are Moel Siabod (2,86o ft.) and Cynicht (2,265 ft.), the latter a very sharp peak.
The deep-cut divisions of the range are one of its most marked features and along these lines there occur numerous elongated lakes typically with a morainic dam at the lower end. Contrasting with these lakes are others higher up the mountain sides occupying deep corries or cwms, that is, glacial cirques. Cwm Glas with its little lake on the east of Snowdon summit, and Llyn Idwal on the north side of Y Glyder Fawr are among the finest of these cirques with great precipices more than half surrounding the lakes. The rivers of the range are mostly swift, draining to the Irish Sea and the Menai Straits for the most part, with the exception of the Glaslyn already mentioned. The Ogwen, Seint (commonly Seiont), and Gwyrfai drain down the passes north-westwards to the Menai Straits. The Conway, with its feeders Machno, Lledr and Llugwy (which receives the Gwrhyd), is the chief stream and runs in a remarkably straight valley from Bettws y Coed to the sea ; it is navigable for about 12 m. from the sea. This valley separates the Snowdon range with its igneous rocks from the Denbighshire plateau of Silurian rocks without igneous intrusions which, like the Welsh highland plateau generally, remains below the 2,000 foot level.
The contrast between the Welsh Highland Plateau, with its rounded hilltops, the remains of a peneplain, and the mountain range above the 2,000 foot contour, with its sharp cirques almost against the very heart of the mountains, is a marked feature of Wales repeated in the Cader Idris range and noticeable elsewhere in greater or less degree in West Wales where the land rises above the 2,000 foot level. On the north-west and south-east flanks of the Carnarvonshire range Cambrian rocks outcrop. Their distri bution north-west of the range has been mentioned above; on the south-east of the range they occur from Blaenau Ffestiniog nearly to Criccieth and another outcrop forms the Trwyn Cilan promon tory between St. Tudwals Roads and Porth Neigwl. This last is doubtless a continuation of the outcrop farther east, the inter vening mass having sunk under Cardigan Bay, the coastline of which, low in places, has Ordovician strata with a number of igneous masses. The argillaceous Cambrian rocks were obviously subjected to intense pressure during the uprise of the folds of the mountain range and, especially towards the junctions of Cambrian and Ordovician, finely cleaved slates of economic importance are found, the chief centres being Bethesda, Llanberis and Penygroes on the north-west and Blaenau Ffestiniog on the south-east. It is usually claimed that the last important movement of land has been a downward one of post-Pleistocene date and that this has not only created the waterway of the Menai Straits but has also given the Lavan and Carnarvon sands, large areas of lost land.
The prehistoric relations of Carnarvonshire suggest that the county was of some importance in megalithic times, especially perhaps the zone between Criccieth and Carnarvon. The south eastern coastal region has yielded considerable bronze finds and the native hill-top fortresses of Penmaenmawr, Tre'r Ceiri, Dinas Emrys (near Beddgelert) etc., apparently dating from Roman times at least in their present forms, as well as the Roman posts at Segontium (Carnarvon, q.v.) and Caerhun (Conway, q.v.), show the importance of the region in Roman times. As traditional ways to Ireland lay through the county and Anglesey it may be that the early importance of Carnarvonshire was partly con nected with this fact. Deganwy on the fertile clay soil of the lower Conway seems to have been of importance in post-Roman times. During the early Middle Ages, Carnarvonshire was divided into four cantrevs, Arfon, the country from the Menai Straits to the heart of the mountains, and the centre of Welsh folk-lore, Arllechwedd from the Ogwen river in the west to Dolgarrog on the lower Conway in the east, a coastal plain with mountains behind, but also including Nant Conway, Lleyn, the south-western peninsula, marked with old roads and hospices for pilgrims to Bardsey, and Eifionydd in the south of the county at the base of the Lleyn peninsula.
After the military conquest by Edward I. (1282), the Statute of Rhuddlan converted North Wales, save the lordship of Den bigh, into shire-ground and the king had castles built at several places and notably around the mountain fastnesses at Carnarvon, Conway, Criccieth and Harlech. The 14th century witnessed many disturbances culminating early in the 15th century in the great effort of Owain Glyndwr who made himself master of Wales and tried to develop a policy of an autonomous church and two uni versities, a policy which failed through military defeat. English influences spread from the castle towns as well as from the enfranchised manors of Nevin and Pwllheli, and Anglesey became strategically important in connection with Ireland, with the result that English attention was focussed on Carnarvon, and Lleyn lost its Irish links, becoming a region of survival of Welsh speech and old customs. Arf on later became to a large extent Anglican in religion while nonconformity grew strong in Eifionydd and Lleyn.
Industries.—Agriculture, especially sheep farming, is the most important occupation. The Snowdon area is the great sheep farm ing area, while Eifionydd is noted for its mixed farming with its market focus at Criccieth. Lleyn centres on Pwllheli and has large farms growing a little wheat and a great deal of barley. Its cattle are specially good and are exported to other areas in Wales as well as to the English Midlands.
North Carnarvonshire is a region of slate and granite quarrying. The chief quarries are at Bethesda, Llanberis and Nantlle, which send their export of roofing slate and slate blocks to Penrhyn, Port Dinorwic and Carnarvon respectively. Many of the quarry men are small farmers as well. There is also a great deal of road stone quarrying, Pwllheli being an important centre. There are electrical power works at Dolgarrog and Cwm Dyli, with alumin ium works at the former place. Catering for summer visitors is also a feature of the county both in the coast resorts and inland.
Communications.—The G.W.R. runs along the Cardigan Bay coast and terminates at Pwllheli. The Welsh Highland Railway (narrow gauge) runs from Dinas, south of Carnarvon, to Port madoc, Blaenau Ffestiniog and Duffws. The L.M.S.R. main line runs along the northern coast, with branches from Llandudno junction to Blaenau Ffestiniog, along the Denbighshire side of the Conway; from Menai Bridge to Carnarvon (thence continuing to Llanberis, or, by another line, to Afon Wen, 4 m. from Pwllheli). Since 192o road transport has become very important, especially in Lleyn and the west of the county, where poor railway facilities have been supplemented by a good motor-bus service.
Administration.—The area of the administrative county is 364,108 acres. Pop. (1921) 128,183, (1931) 120,81o. The county as a whole returns two members to Parliament, one for the county and the other for the Carnarvon Boroughs, which include the municipal boroughs of Bangor, Carnarvon, Conway and Pwll heli, the urban districts of Criccieth, Llandudno, Llanfairfechan, Penmaenmawr and the civil parish of Nevin. The assizes are held at Carnarvon and are part of the North Wales circuit. Ex cept a few parishes (in and near Llandudno) in St. Asaph dio cese, Carnarvonshire is in the diocese of Bangor and contains sixty-one ecclesiastical parishes or districts, with parts of four others.