Somersetshire, an important maritime county in the south-west of England, is bounded on the N. and W. by the Bristol Channel (the ancient 'Severn Sea'); by Gloucestershire, Wiltshire, and Dorsetshire on the NE. and E.; and by Devonshire on the S. and SW. In form oblong, with a length of some 80 miles and a breadth of 36, it has an area of 1640 sq. m. Pop. (1801) 273,577; (1841) 435,599; (1881) 469,109; (1891) 484,336. The surface is exceedingly diversified, with every variation from lofty hills and barren moors to rich vales and wide marshy levels, whence the sea is banked out by an elaborate system of dykes and sluices. The frontier between Somerset and the adjacent counties consists for the most part of a broken and picturesque hilly district. Sundry ranges of hills, running east and west, give to the county its leading physical characters. Chief of these is the Mendips (q.v.), which stretch from near the city of Wells to the coast at Brean Down, with a seaward continuation in the islets of the Steep and Flat Holms. South of the Mendips lies the great alluvial plain of central Somerset, broken by the line of the Polden Hills, which rise from the marshy levels like a long low island some 300 feet. Still farther south, beyond Taunton, are the Blackdown Hills, about twice this elevation, and continuing eastward into the broken upland which once formed part of the ancient forest of Selwood, where Somerset, Wilts, and Dorset meet. To the north-west of Taunton, bordering Bridgwater Bay, are the Quantock Hills, rising at Will's Neck to 1262 feet; and west, again, is the wild district of Exmoor Forest (q.v.), partly in Devon, but mainly in Somerset. At several points on the inland borders heights of between 800 and 1000 feet are attained. The only two rivers of commercial importance in Somerset originate elsewhere. The Bristol Avon, which forms the boundary of the county for many miles, rises near Badminton in Wilts, and enters Somerset near Bath. The Parret rises near Sonth Perrot in Dorset, and drains the middle of the county: it is tidal to beyond Bridgwater, and is one of the streams possessing a tidal 'bore.' These two rivers with their feeders dis- charge the bulk of the waters of the county. Between them the chief independent streams are the Axe and the Brne, south of the Mendips, and the Yeo, north. The Exmoor district is drained by the Exe, which falls into the sea at Exmouth, and by the Devonshire Axe, which rises, however, in Dorset.
The geological features of the county are singularly varied, ranging from Devonian upwards. Carboniferous strata occupy a wide area in the north, east, and centre, and are worked for coal in the Radstock and Nailsea basins of the Bristol coal-field; while the mountain-limestone is largely developed in the Mendips and near Bristol, where it is traversed by the magnificent gorge of the Avon. Oolitic rocks stretch along the east of the county from Yeovil to Bath, and in the neighbourhood of the latter city are extensively worked for the production of the well-known Bath building-stone; while other beds are wrought at Doultng and Ham Hill. Liassic rocks are well developed, chiefly in the central region, though in somewhat scattered fashion. Triassic rocks occupy a very wide area in the west of the county, ranging with breaks from Wellington to Bristol; and there is Greensand on the extreme south-west. Extensive caverns in the limestone of the Mendips have yielded abundant remains of prehistoric mammalia, with relics of their human contemporaries. The Mendip mining area is one of the oldest in the kingdom, for lead was raised there before the advent of the Romans, and the iron ores of the Brendon Hills, on the eastern flank of Exmoor, were also worked at a very early date.
The agriculture is mainly pastoral, the proportion of tillage to grazing and dairy-farming being small, though the low lands generally are exceedingly fertile—the fertility of the valley of the Tone, near Taunton, having passed into a proverb. Even this is exceeded by the luxuriance of the marshy meadows of the Bridgwater Level, which are, however, liable to be flooded, and are maintained against the sea at considerable expense. The orchards of Somerset are second only to those of Devon in area and importance, and cider is largely made; while Cheddar cheese has a national reputation. Manufactures maintain considerable importance, particularly in textiles (chiefly woollens), potteries, paper-making, and gloving; and though the city lies mainly on the Gloucestershire side of the Avon, and is a county to itself, Somerset may fairly claim a share also in the commercial importance of Bristol (q.v.).
The bone-caves of the Mendips have supplied evidence of the presence in Somerset of neolithic if not of palæolithic man; and there is abundant evidence of the occupation by strong and comparatively civilised tribes prior to the Roman invasion in the remains of important hill fortresses (Hamdon, Castle Neroche, Dolbury, Maesbury, Worlebury, Cadbury), while the megalithic circles and other remains at Stanton Drew are among the most interesting in the kingdom. Immediately prior to the Roman invasion under Claudius the north of the county was inhabited by the Belgæ, while the territory of the Dumnonii seems to have extended over the Devon border to the marshy and central district, which probably formed a strong natural frontier, though there is evidence that part of this area had been embanked against the sea in pre-Roman times. The Mendips must, however, have formed part of the earliest Roman conquest, as pigs of lead have been found there bearing the names of Claudius, Britannicus, and Vespasian. Somerset became one of the chief seats of Roman civilisation in Britain. Bath (q.v.), as the city of Aquæ Solis, was a centre of refinement and luxury. The remains of the baths built by the Romans for the reception of the famous mineral waters are among the most important relics of the Roman period in England. But the impress of the Roman has been left in nearly every part of the county—in villas, roads, pottery kilns, interments, and coins; while Ilchester, like Bath, was a Roman city. Tradition claims for Glastonbury (q.v.) the honour of being the first seat of Christianity in Britain. Under the Saxons the district became known as the home of the Sumersætan, and took its present name, the origin of which is disputed. Part first came under Saxon sway in 658, but its inclusion in Wessex was not complete until 710, when Gerente was defeated by Ine, who made Taunton (q.v.) his chief fortress, and founded the cathedral of Wells (q.v.), which became the seat of the bishopric of the Somersætas (since Bath and Wells) in 909. Somerset was the last home of Saxon freedom when Alfred took refuge at Athelney, defended by trackless marshes. It was at Wedmore that Alfred made his treaty with Guthrum, though the claims of Edington to be the Æthandune where he won his most memorable victory are doubtful. In the wars of the Roses Somerset was in the main Lancastrian; in the wars of the Commonwealth it was chiefly parliamentarian, and the stout defence of Taunton first made famous the name of Admiral Blake. The county was also the centre of Monmouth's operations; and it was chiefly Somersetshire men who fell at Sedgemoor (1685). The county has two cities—Bath and Taunton; an important manufacturing port in Bridgwater; one of the finest watering-places on the western coast in Weston-super-Mare; manufacturing towns in Frome, Yeovil, Shepton Mallet, and Wellington; and seven county parliamentary divisions.
See Collinson, Somerset; Phelp, Somerset; Rutter, Delineation of the N.W. Division of Somerset; Proceedings of Somersetshire Archaeological and Natural History Society; Jeboult, W. Somerset; Pulman, Book of the Axe; Eyton, Somerset Domesday; Hugo, Medieval Nunneries of Somerset; W. A. J. Archbold, The Somerset Religious Houses (Camb. 1892); Martin, Somerset; and numerous histories cited at Bristol, Bath, Taunton, Wells, Glastonbury, and other towns.