Northumberland, the most northern county of England, separated from the Lowlands of Scotland by the Tweed, and from the county of Durham by the Tyne and Derwent. The German Ocean bounds it on the E., and the county of Cumberland, with a part of Roxburghshire, on the W. Among the English counties it ranks fifth in regard to size, having an area of 1,290,312 acres. Its greatest length is 70 miles and its greatest breadth 47 miles. The surface of the county, except near the coast, is picturesque broken into rounded and conical-shaped hills and high moorland ridges. The main valleys are fertile and well wooded. The principal heights belong to the Cheviot Hills (q.v.), and are seated in the north-west part of the county. These are Cheviot (2676 feet), Hedgehope (2348 feet), Cuschat Law (2020 feet), Bloody Bush Edge (2001 feet), and Windy Gyle (1963 feet). The Simonside Hills near Rothbury attain a height of 1447 feet. The chief rivers are the Tyne (formed by the confluence of two streams, the North and South Tyne, a little above Hexham), the Wansbeck, the Coquet, the Aln, the Breamish, the Till, and the Tweed. In the south-west of the county are some small sheets of water called the Northumbrian Lakes, the largest of which is Greenley Lough. Off the coast lie a few islands—Lindisfarne or Holy Island, the Farne Islands, and Coquet Isle. The geology of the county is simple in its broad features. The beds as a whole slope to the sea, the direction of the general dip lying between south-east and east; hence the oldest rocks—the Silurian—appear in the north-west, near the head of the Rede and Coquet, and the later formations—the Triassic and Permian beds and the coal-measures—near the coast. The strata have been dislocated and broken by volcanic disturbances, during which were intruded the igneous rocks. The Cheviots, which cover an area of 200 sq. m., owe their origin to the earlier of these upheavals. They consist chiefly of andesites and porphyrites. The Whin Sill, a great sheet of basalt stretching across the county from Kyloe near Berwick to Greenhead in Cumberland in a series of columnar crags, was injected among the sedimentary rocks during the later eruptions which took place, it is supposed, at the close of the Carboniferous period. A number of basaltic dykes also cross the county. The coal-measures occupy the south-east part of the county, and the lead-measures (belonging to the Upper Limestone series or Yoredale rocks) the south-west.
The climate is cold, especially from March to the middle of June, when the prevailing winds are from the east and north-east. The winters, however, are often much milder than they are in the south. The average rainfall, too, except in the Cheviot district, is considerably less than in the counties of Devon, Dorset, Hampshire, and Sussex. Northumberland contains 541 civil parishes, and, ecclesiastically, is in the province of York. For the purposes of civil government the county is divided into nine wards (answering to hundreds or wapen-takes), three of which formed part of Durham till 1844. It comprises four parliamentary divisions—the Tyneside, Wansbeck, Hexham, and Berwick-upon-Tweed, returning four members. The principal towns are Ainwick, Morpeth, Hexham, and North Shields. Newcastle-upon-Tyne (q.v.) is a city and county of itself. A large portion of the county is agricultural, especially the fertile tracts along the principal valleys and near the coast. The usual rotation of crops is oats, turnips, and a small quantity of potatoes, spring wheat and barley, clover and other grasses, and then pasture. Turnips grow well, the cultivation of them on raised ridges being peculiar to the county, and known as the Northumbrian system. The western portion of the county is pastoral, the slopes of the Cheviots affording sustenance to large flocks of hardy sheep. In Chillingham Park there is preserved a herd of wild cattle said to be of the original British stock. The staple trade of the county is in coal, and the chief manufactures are connected with its mining and transit. The number of collieries working in the county is about 114. The salmon-fisheries of the Tyne and Tweed have long been famous. The county is traversed by the North-Eastern and North British railways. Pop. (1801) 168,078; (1841) 266,020; (1881) 434,086; (1891) 506,030.
Northumberland in the time of the Romans was inhabited by a branch of the Celtic people, the tribe of the Ottadeni. In the 6th century it was conquered and colonised by the Angles. It then formed part of the kingdom of Bernicia. Being a border county, it suffered much during the Scottish wars, and from the 11th to the 17th century was frequently the scene of much bloodshed. The battles of Otterburn, Homildon Hill, and Flodden were fought on its soil. Northumberland is very rich in memorials of the past. No county, indeed, has a more interesting collection of military antiquities, from the rude circular camps and entrenchments of the old inhabitants to the great castles and peel-towers of mediæval times. The Romans have left a mighty monument of their power in the great barrier erected across the southern portion of the county, and in the stations and roads connected with it. Other antiquities, also noticed separately, are at Bamburgh, Dunstanburgh, Hexham, Alnwick, Holy Island, Norham, &c. Northumberland is the birthplace of Bishop Ridley, Thomas Bewick, Akenside, Lord Eldon, George and Robert Stephenson, Grace Darling, the second Earl Grey, Birket Foster, and Lord Armstrong.
Works treating on the history, antiquities, geology, &c. of the county are: the Histories of Wallis (1769), Hutchinson (1778), Mackenzie (1825), and Hodgson (1820-40); Hodgson Hinde's General History of Northumberland, an addition to Hodgson's great work (1858); Hartshorne's Feudal and Military Antiquities of Northumberland (1858); Gibson's Northumbrian Castles, Churches, and Antiquities (1848-54); Bruce's Roman Wall (1874); Lebour's Geology of Northumberland and Durham (1886); Tomlinson's Comprehensive Guide to Northumberland (1888); the Proceedings of the Newcastle Antiquaries, and the Surtees Soc.; Bateon's History of Northumberland (12 vols. 1893 et seq.).