CARMARTHENSHIRE, South Wales county, is bounded north by Cardigan, east by Brecon and Glamorgan, west by Pem broke, south by Carmarthen Bay and the Bristol Channel (area 918 square m. ; the largest Welsh county) . It consists essentially of the plain of the Towy, with its continuation into the Taf Valley. This line of lowland curving from a south-west to a west direction is a worn anticline mainly floored by black shales of Tremadoc (Cambrian Age) covered at the sides by conglomerates, sandstones and shales, with beds of volcanic ash and lava of Are nig (Ordovician Age). Above these are shales, flags and lime stones named from Llandilo where they are remarkably developed. North of the Towy lowland the hills are formed of Ordovician and Silurian shales and mudstones, deeply dissected and divided into two zones, one south of Brechfa with a maximum height of goo ft., and one north of Brechfa and the Cothi reaching above 1,300 ft. South and southeast of the Towy the Silurian sandstones and mudstones form the first hills; behind and above them comes Old Red Sandstone followed by Carboniferous Limestone and Coal Measures. The Old Red Sandstone gives to the south-east the Black Mountains of Carmarthenshire rising to 2,026 ft., while south of this the scarps and moorlands of the Carboniferous Lime stone and "Farewell rock" (Millstone Grit) form the north-west rim of the South Wales coalfield, the rich coal measures of the Gwendraeth Valley and Llanelly district being within the county. The Old Red Sandstone rocks on the south side of the main Towy lowland form only very subordinate hill lines westward from the Black Mountains and the Towy makes its way through the Old Red Sandstone zone to an estuary formed by coastal sinking.
The main drainage follows the line of the denuded anticline occupied by the Towy which is fed by streams dissecting especially the northern uplands; these include the Sawdde, Cothi and Gwili. The Gwendraeth Fach and Gwendraeth Fawr and the Loughor follow north-east to south-west lines which are characteristic of the region and the Loughor divides the county from Glamorgan shire on the east. The line of the middle Towy is continued by the Taf on the west boundary of the county and after passing Whitland it turns south-east to the sea near Laugharne. Most of the hills have been rounded by ice action and deposits of boulder clay are frequent on the lower valley sides, especially west of Car marthen Town on the lowland area which shows evidences of having been a lake probably in late-glacial times. With the excep tion of Llyn y fan in the Black Mountains the lakes of the county are inconsiderable in size, the Bishop's Pond, two miles East of Carmarthen is a good example of an ox-bow lake.
The region above the 60o f t. contour is dotted with tumuli and cairns and, especially in the north-west section, with menhirs and other great stone monuments. The distribution of Bronze Age finds seems to indicate the use of the coast and rivers or valley ways at the time. Bronze objects are found especially along the South Coast, and at Conwil in the Gwili Valley. The hill top camps of Romano-British age cap spurs of the high ground and seem to be situated at defensible points that guard ways up from the sea and communications along the valleys. Garn Goch (5 in.
north-east of Llandilo) covers some 15 acres and is enclosed by a stone rampart. The Roman focus of ways across the country lay at Maridunum, later Carmarthen, the present capital of the county. The post Roman centuries saw the civilizing and Chris tianizing influence of the Celtic Saints on the one hand, leaving its mark to this day in dedications of rural churches, and on the other the numerous raids from the sea and by land of Irish and Scandinavians. The strong reign of Rhodri Mawr (c. 87o) is said to have brought a measure of peace and his grandson Howell the Good (Hywel Dda) was the first to codify the ancient laws of Wales at his palace of Ty Gwyn Ar Daf near modern Whitland. The period subsequent to 1080 saw the beginnings of the Norman intrusion. The Normans first built castles along the coast at Kid welly, Llanstephan, Laugharne, etc., and then penetrated up the valley ways to Carmarthen, Llandilo, etc. It is interesting to find that many of these castles occupy sites previously chosen for de fence by earlier rulers of the country, e.g., the castle at Dinefawr. This had been the seat of the princes of South Wales, the central point of Ystrad Tywi the nucleus of the future county. The cam paigns of Edward I. gave the Normans a more unified control of the principality and by the Statutes of Rhuddlan (1284) the counties of Cardigan and Carmarthen were formed out of the districts of Ceredigion and Ystrad Tywi. Nearly a third of the present county, however, still remained under the jurisdiction of the Lords Marchers and it was not until the Act of 27 Henry VIII. that these districts, including the commots of Kidwelly, Iscennen and Carnwillion were added to Edward I.'s original shire. The surrounding hill county made Carmarthenshire famous for its wool in the later Middle Ages. Edward III. by the statute staple of declared Carmarthen town the sole staple for Wales, order ing every bale of wool to be sealed here before it left the Princi pality. There are few remains of the mediaeval monastic houses: Talley Abbey (north of Llandilo), founded by Rhys ap Griffith prince of South Wales (late 12th century), for Benedictine monks; Whitland, or Albalanda, also a Benedictine house, probably founded by Bishop Bernard of St. David's (early 12th century), on a site long associated with Welsh monastic life and the cele brated Augustinian Priory of St. John at Carmarthen (12th cen tury). Connections with the house of Tudor through Sir Rhys ap Thomas were important in the 16th century. At Abergwili the then new palace of the Bishops of St. David's Bishop Richard Davies (1505-1581) and William Salesbury of Llanrwst trans lated the New Testament and the Prayer Book into Welsh and in the early part of the 17th century Rhys Prichard (d. 1644), the Puritan Vicar of Llandovery published his famous "Canwyll y Cymry" (the Welshman's Candle). The castles of Carmarthen shire, especially the southern ones, made a very half hearted re sistance to the parliamentarian forces. Griffith Jones (1684 1761), vicar of Llanddowror founded Welsh circulating schools, the effective beginning of the modern educational movement in Wales. William Williams of Pantycelyn 0716-90 was the chief hymnologist of the Welsh Methodist revival. Dr. Richard Price, the friend of Priestley, also belonged to the shire. Carmarthen was deeply implicated in the Rebecca riots (1842-43). The mar kets of Carmarthen, Llandilo and Llandovery received cattle driven on foot in pre-railway days, and Llandovery seems to have been an important focus for cattle being driven to the English Midlands.
Old lead mines at Llangunnor (2 m. S.E. of Carmarthen) and Rhandirmwyn (8 m. N. of Llandilo) are derelict. Stock-marts using the railway still continue. The anthracite coalfield in Car marthenshire led to growth of Ammanford, Llanelly, Pontardulais, etc., and it has tended to develop industries such as tin-plate and copper smelting. The increasing modern demand for anthracite favours the county and the collieries are now nearly all in a large combine with interests in outside fields as well. Some migration from the Glamorganshire coalfield is taking place. The G.W.R. runs from Loughor, in the south-east, along the coast to the Towy estuary which it follows up to Carmarthen and then leaves, going west via Whitland. Branches go from Llanelly to Amman ford and Llandilo, from Pembrey to the Gwendraeth valley, from Carmarthen to Pencader and Newcastle Emlyn, and from Whit land to Cardigan. The L.M.S.R. running from Shrewsbury via Craven Arms enters the north-east of the county and runs to Llandovery and Llandilo, with branches thence to Swansea and to Carmarthen, partly conjoint with the G.W.R. Carmarthen has recently become a considerable centre for road-motors.
The area of the county is 587,816 acres and the population in 1931 was 179,063. The municipal boroughs are Carmarthen (styled County Borough) (pop. 10,310), Kidwelly (pop. 3,161), Llandovery (1,980) and Llanelly (pop. 38,398). Urban districts are Ammanford (7,160), Llandilo (1,886), Burry Port Newcastle Emlyn (762). The county is in the South Wales cir cuit, and assizes are held at Carmarthen. The borough of Car marthen has a commission of the peace and separate quarter ses sions. The county is divided into two parliamentary divisions, the eastern (industrial) and the western (rural) each returning one member to parliament. The ancient county contains 75 parishes and a part of another and is wholly in the diocese of St. David's.