A mountain tract of the county 15 miles from north to south by 10 from east to west, stretching from the coast inland, is of the Cambrian age, composed of grits, quartzose, and slates, and comprising the Merionethshire anticlinal. This tract is enclosed on the north, east, and south by the Menevian, Lingula, Tremadoc, and Arenig beds, which are pierced by numerous dykes and intrusive masses, mostly greenstone. Rhobell-fawr is one of the greatest igneous masses in the whole area of the Lingula beds. The Arenig beds are interstratified with and overlaid by accumulations of volcanic ashes, felspathic traps, or lava flows, which form the rugged heights of Cader Idris, the Arans, the Arenigs, Manod, and Moel-wyn; and these are in turn overlaid by the Llandeilo and Bala beds, the latter including the Bala limestone. Extensive slate quarries are worked near Festiniog, mostly underground, in strata of the Llandeilo age, giving employment to about 4000 men. Gold, lead, copper, and manganese have been obtained in various places.

Climate and Agriculture.— The climate varies much with the elevation, in some places being bleak and cold, and in others remarkably equable and genial. At Aberdovey it is proverbially mild, and the myrtle grows in the open air. All attempts to introduce fruits have proved abortive in most parts of the county. The soil is generally thin and poor, with fertile tracts in the valleys. A great portion of the moss has been reclaimed within late years.

According to the agricultural returns for 1882, there were 154,406 acres, or considerably less than half the total area, under cultivation. Of this as much as 119,133 acres were permanent pasture, and 13,755 under rotation grasses. Of the 17,312 acres under corn crops, 11,232 were under oats and 4807 under barley. Potatoes occupied 2392 acres, and turnips only 1496 acres. The area under woods extended to 15,049 acres.

The total number of horses in 1882 was 6088. A breed of ponies is peculiar to this county and Montgomeryshire. The rearing of horned cattle and dairy-farming are largely carried on, but the number of cattle (37,643) is considerably under the average of Wales generally. On the other hand the number of sheep in 1882 was 400,553, a larger number than in any other county of Wales, and much beyond the general average in the principality. They are a small hardy breed, which grow heavy fleeces. Goats frequent the loftier crags.

According to the latest return the number of proprietors was 1695, possessing 303,374 acres, with a gross annual value of £183,253. Of the owners 1044, or 62 percent., possessed less than 1 acre, the average extent of the properties being 189 acres, and the average value per acre a little over 12s. There were ten proprietors who possessed over 5000 acres, viz., Sir w. W. Wynn, 20,295; R. J. I.. Price, 17,718; T. P. Lloyd, 16,975; Mrs Kirkby, 13,410; Hon. C. H. Wynn, 10,504; A. J. G. Corbet, 9347; Sir E. Buckley, 8738; W. E. Oakeley, 6018; W. O. Gore, 5497; and R. Μ. Rickards, 5701.

Manufactures.— Woollen goods are manufactured in various places, especially at Dolgelly. They are principally coarse druggets, Kerseymeres, and flannels. The knitting of stockings was a great industry at the close of last century, the value of the sales at Bala being estimated at from £17,000 to £19,000 annually.

Railways.— The Cambrian Railway skirts the coast from Portmadoc to Aberdovey. At Barmouth Junction a branch of the same crosses to Dolgelly, where it is joined by a branch of the Great Western Railway. Another branch of the Great Western unites Bala and Festiniog, and the latter place has railway connexion both with Llandudno Junction and with Portmadoc.

Administration and Population.— Merionethshire comprises five hundreds and thirty-three civil parishes. It has one court of quarter sessions, and the number of petty sessional divisions is six. Ecclesiastically it is partly in the diocese of Bangor, partly in that of St Asaph. The county returns one member to parliament. There is no municipal or parliamentary borough. The towns returned in 1881 as urban sanitary districts are Bala (1653), Barmouth (1512), Dolgelly (2457), Festiniog (11,272), and Towyn (3363). Since 1801 the population has nearly doubled. From 29,506 in that year it had increased in 1851 to 38,963, in 1871 to 46,598, and in 1881 to 54,793, of whom 27,576 were males, and 27,217 females.

History and Antiquities.— Originally Merioneth belonged to the territory of the Ordovices, and under the Romans it was included in Britannia Secunda. There are many Celtic, Roman, and mediaeval remains. Caer Drewyn on the Dee, near Corwen, was a British camp. There are numerous cromlechs in various parts of the county, especially near the sea-coast. The Via Occidentalis of the Romans passed through Merioneth from south to north, and at Tomen-y-Mur was joined by a branch of the South Watling Street, the Castell Tomen-y-Mur being supposed to be identical with the Roman station of Heriri Mons. The immense ruin of Castel-y-Bere was originally one of the largest castles in Wales, but has not been occupied since the time of Edward I. During the Wars of the Roses the castle of Harlech, still a fine ruin, was held by the Lancastrians, and was the last in Wales to surrender. Of ecclesiastical remains the most important is Cymmer Abbey, founded by the Cistercians in 1198, a very fine ruin containing architecture of various periods from Norman to Perpendicular. There are numerous interesting old churches.