Great Britain.

Great Britain. Under this head are noticed (1) the island of Great Britain—its geology and geography; and (2) the United Kingdom of Great Britain and Ireland—its general statistics, &c.

Great Britain was so called to distinguish it from Britannia Minor, or Brittany, in France (see BRITANNIA). The name was a poetical or rhetorical expression till in 1604 James I. styled himself king of Great Britain, although the term was proposed in 1559 by the Scottish Lords of the Congregation. Lying between 49° 57' 30" and 58° 40' 24" N. lat., and between 1° 46' E. and 6° 13' W. long., Great Britain is the largest island of Europe. It is bounded on the N. by the Atlantic, on the E. by the North Sea, on the S. by the English Channel, and on the W. by the Atlantic, the Irish Sea, and St George's Channel. The most northerly point is Dunnet Head, in Caithness; the most southerly, Lizard Point, in Cornwall; the most easterly, Lowestoft Ness, in Suffolk; and the most westerly, Ardnamurchan Point, in Argyllshire. Its greatest length is about 608 miles, and its greatest breadth (from Land's End to the east coast of Kent) about 325 miles; while its surface contains 88,226 sq. m.

Geology.—The geology of Great Britain is of peculiar importance. The fossiliferous strata having been first systematically studied and expounded here, British geologists have given to the world the names whereby most of the larger divisions and subdivisions of these strata are known. Nearly all the recognised 'systems' occur in Britain, although some of these are more fully represented elsewhere. Indeed, the only system not found in Britain is the Miocene—the beds formerly classed as of this age being now included in the Oligocene. British geology is no less important from the influence it has had in the development of the country. The mineral wealth, especially the coal and the iron, are the real sinews and muscles of Britain's mighty power. No other country has similar advantages in such an area. (See also the article on the geology of EUROPE.)

We shall, in this sketch of the distribution of the British rocks, follow the order of the strata, beginning with the lowest and oldest. It may be said that, in general, the mountainous regions of the north and west are formed of the oldest rocks, and that, as we move south-eastwards, we gradually pass over newer strata, until, in the east of England, we come to the uppermost divisions of the Tertiary.

The base rocks of the whole series occur in the Outer Hebrides, in Rona, Tiree, and Coll, and along the western shores of Sutherland and Ross. They are assigned to the Archæan System (q.v.), and consist chiefly of coarse gneiss, usually hornblendic, and various schists, with occasional crystalline limestones—the whole series being veined more or less abundantly with pegmatite. Small isolated areas of Archæan occur also in England (Charnwood Forest, the Wrekin, the Malverns). No fossils are met with in any of the Archæan rocks.

The oldest fossiliferous strata in Britain belong to the Cambrian System (q.v.), and are well developed in Wales and Shropshire, attaining a thickness of more than 30,000 feet. They consist chiefly of dark-red and purple sandstones, grits, and conglomerates, with green slates and slaty shales. The fossils are not abundant, but show a remarkable variety of forms. In Scotland the Cambrian appears to be represented by the red grits, conglomerates, and sandstones which rest directly on the Archæan rocks of the outer Hebrides and the north-west Highlands.

The Silurian System (q.v.) occupies a large portion of the surface of the country. The typical rocks occur in Wales, extending over the western portion of the principality from Pembroke to Denbigh, and including the northern portions of Pembroke, Carmarthen, and Brecknock, the whole of Radnor and Montgomery, the south-west of Denbigh, and the whole of the counties to the west. The oldest or Lower Silurian beds are next the coast. The series consists of an immense thickness of shales, slates, grits, and greywackes, with intercalated limestones more or less pure. Immense tracts have hitherto proved devoid of fossils; in other districts the calcareous rocks are almost entirely composed of the remains of marine invertebrate animals, while the shales abound in zoophytes and crustacea. The high lands in the north of Lancashire and south of Westmorland are Silurian; but it is in Scotland that these strata are most extensively developed. A line drawn from Dunbar to Girvan forms the northern limit of these beds in the south of Scotland. Except the lower half of the valley of the Tweed, the whole region from this line to near the base of the Cheviots is Silurian. The rocks are chiefly greywacke, with scattered beds of impure limestone. The chief fossils are graptolites, crustacea, brachiopoda, and mollusca. The lead-mines of Wanlockhead and Leadhills are in this district. East and south-east of the Archæan and Cambrian rocks of the north-west Highlands come Silurian rocks which are more or less metamorphosed. Up to recent years geologists believed with Sir R. I. Murchison that all the schists, &c., lying to the east of the Cambrian and Archæan areas, and extending down to the borders of the lowlands in Strathmore, &c., were altered Silurian strata. Probably this is the fact, but the work of the Geological Survey in the north-west Highlands has suggested some doubts. A line drawn from Stonehaven to Helensburgh marks the southward range of those schists and slates, &c.

The Old Red Sandstone System (q.v.), consisting of conglomerates, coarse and fine grained sandstones, and dark-coloured flagstones and shales, with characteristic fossils of ganoid and placoid fish, overlies the Silurian in several districts in Scotland. Nearly all Caithness and the seaward portions of Sutherland, Ross, Cromarty, Inverness, Nairn, and Elgin, belong to these strata. A broad band, extending on the east coast between Stonehaven and St Andrews, stretches across the country to Helensburgh and Dumbarton on the west. The same strata appear again in Haddington, Berwick, and Roxburgh, in Lanark, and in Ayrshire. Old Red Sandstone likewise occurs in South Wales and the neighbouring English counties, extending from the Silurian district to the Severn and the Bristol Channel, and containing in a large basin the South Wales coalfield. The highly fossiliferous strata of north Devon, and of south Devon and Cornwall (Devonian system) are believed to be on the same geological horizon as the Old Red Sandstone. They consist of slates, sandstones, and limestones, and contain numerous corals and shell-fish.

The Carboniferous System (q.v.) may be said to occupy a broad tract extending from the Bristol Channel to the base of the Cheviots. The strata are not continuous between these limits, but are broken up in some places by the appearance on the surface of older strata, while in others they are covered by newer deposits. The various detached coalfields are (1) the South Wales, in Glamorgan and Pembroke; (2) the Bristol, and (3) the Forest of Dean, in Gloucester; (4) the Forest of Wyre, in Worcester; (5) Shrewsbury, and (6) Coalbrookdale, in Shropshire; (7) north and (8) south Staffordshire; (9) Warwickshire; (10) Leicestershire; (11) Flint and Denbigh; (12) Lancashire; (13) York and Derby; (14) Cumberland; and (15) Northumberland and Durham. In the northern portion of this great tract of carboniferous strata, where the millstone grit and carboniferous limestone are largely developed, few seams of coal of any value are contained. The limestone in Derby is rich in metallic ores. The carboniferous strata of the north of England extend beyond the Cheviots into Scotland, forming a narrow band from the Solway to the North Sea, in the counties of Dumfries, Roxburgh, and Berwick. The only coalfield in this district is one of small extent at Canonbie, in Dumfriesshire. The carboniferous strata in Scotland, with the exception just stated, are confined to the immense trough between the Silurian and Old Red Sandstone systems on the south and the Old Red Sandstone on the north, which is completely occupied by them, except where underlying older strata rise to the surface. Considerable tracts of sandstone and limestone without coal break up the coal-bearing beds into the following coalfields: the Midlothian, the Fife, the Lanark and Stirling, the Ayrshire, the Sanquhar in Dumfriesshire. Beside coal, the whole of the carboniferous series contains immense stores of argillaceous carbonate of iron, from the ore of which is produced the great bulk of the iron used in the country. The sandstones of this period form beautiful and durable building-stones, the limestones are of great commercial value, and many of the less indurated shales are good fireclays.

The Permian System (q.v.), consisting of magnesian limestone and sandstone coloured with oxide of iron, occupies a considerable area in Durham, and borders the carboniferous rocks in Dumfries, Cumberland, Westmorland, Lancashire, Cheshire, Shropshire, Stafford, Worcester, Warwick, Nottingham, and York, and in Glamorgan. The sandstone is quarried for building.

The typical triple series of the Triassic System (q.v.) occurs in Germany; the British representatives consist of variously-coloured sandstones and marls. They occupy a considerable surface in Lancashire, Cheshire, Shropshire, and Stafford, and extend as a ribbon of varying breadth, from the mouth of the Exe, through Devon, Somerset, Gloucester, Worcester, Warwick, Leicester, Nottingham, York, and Durham, to the coast at Hartlepool. The only deposits of rock-salt in Britain occur in the Triassic rocks of Cheshire and Worcestershire.

The Jurassic System (q.v.) is composed of an extensive series of limestones, marls, sandstones, and shales, which stretch in a broad belt from Yorkshire to Dorsetshire, passing through Lincoln, Worcester, Warwick, Northampton, Huntingdon, Bedford, Buckingham, Oxford, Gloucester, and Wilts. The best building materials in England are obtained from these strata. Jurassic strata occur in Scotland at Brora (Sutherland), in Skye, &c. In the Brora Oolite a seam of coal $3\backslash frac\{1\}\{2\}$ feet in thickness has been worked off and on since 1820. It is the thickest bed of pure vegetable matter detected in any Mesozoic formation in Britain.

The Cretaceous System (q.v.), consisting chiefly of chalk with underlying sands and clays, all very rich in fossil remains, occupies a broad tract to the east of the Jurassic strata, and parallel to them. Beginning a little north of Flanborough Head, the cretaceous strata may be traced through York and Lincoln, then across the Wash into Norfolk, Suffolk, Hertford, Buckingham, Oxford, Berks, to Hampshire, where they separate into three arms, the one extending south-westward through Wilts and Dorset to the south coast; another taking a south-east direction to Beachy Head; while the third stretches as a narrow band in an easterly direction through Surrey and North Kent, widening out as it nears the coast, where it occupies the district between Ramsgate and Folkstone. The fresh-water Wealden series, with its abundant remains of reptiles, fishes, shells, and insects, is developed chiefly over the tract that lies between the North and South Downs.

The Eocene System (q.v.), consisting of clays, sands, and marls, abounding in fossils which apparently indicate a subtropical climate, occupies the valley of the Thames, from Hangerford to the sea, and from Canterbury to Saxmundham, as well as a large district in Dorset, Hants, and Sussex, from Salisbury west to Dorchester, and east almost to Hastings.

The Oligocene System (q.v.) is very sparingly developed in Britain—the only deposits of note occurring in Hampshire and the Isle of Wight.

The Pliocene System (q.v.), consisting of ferruginous shelly sand and marl known as crag, occurs chiefly in Suffolk and Norfolk. The still more recent Pleistocene System (q.v.) is represented by superficial accumulations of alluvium, gravels, boulder-clay or till, bedded clays, &c., which are scattered over wide areas. To the same system belong the cave-deposits with relics and remains of primeval man.

Minerals.—In some respects the most important of British minerals is coal. The greatly-increasing consumption of coal has originated fears as to the possibility of the exhaustion of our mineral fuel (see COAL).—Formerly, the only iron produced in the country was obtained from the greensand of the south-east of England, and from the brown hematite of the Dean Forest. The ore was smelted with charcoal. But the introduction of coke and coal for smelting, and the discovery of numerous additional and unthought-of deposits, especially in connection with coal-bearing strata, immensely increased the production of iron, and met the greatly-increased demands for this important metal. In 1760, when charcoal alone was used for smelting, not more than 25,000 tons of iron were produced; now an average of 4,000,000 or 5,000,000 tons are obtained from some 12,000,000 or 13,000,000 of ore. The most important ore is the ferruginous shale, or impure argillaceous carbonate of iron, found in every British coalfield. The brown and red hematites, associated with the oldest Palæozoic rocks, yield much metallic iron.—Tin is obtained from two counties—Cornwall and Devon.—Copper is obtained from the same two counties, but the quantity obtained in Britain has greatly declined since 1860, and is trifling compared with what is smelted from imported ores. Other copper mines are or were in Lancashire, Carmarthen, and Anglesey (see COPPER).—Lead and Silver are obtained from the same ore from numerous mines in Palæozoic districts. The most productive English mines are in Northumber- land, Durham, Cumberland, Shropshire, Yorkshire, Derbyshire, Cardiganshire, Glamorganshire, and the Isle of Man. Small quantities are obtained in Somerset, Westmorland, Stafford, and Chester. All the Silurian counties of Wales contain mines. The Isle of Man yields much ore. In Scotland the most productive mines are at Wanlockhead and Leadhills.—Zinc is obtained chiefly from Cardigan, Denbighshire, Carnarvon, Flint, Cumberland, and the Isle of Man.—Sulphur Ores (iron pyrites) are raised in different parts of Great Britain.—The following minerals are also raised—viz. arsenic, manganese, gold, nickel, silver-copper, fluor-spar, and wolfram.—Salt occurs chiefly in Cheshire and Ulster.

The following table shows the minerals raised in the United Kingdom in 1888, with their value at the mines:

The total value of the coal and other minerals raised in the United Kingdom was £40,345,945 in 1866, £74,094,638 in 1880, and £69,129,664 in 1895. The total value of the metals obtainable by smelting from ores produced in the United Kingdom (aluminium, antimony, copper, gold, iron, lead, magnesium, silver, sodium, tin, zinc) in 1887 was £12,795,993; in 1898, £13,717,512.

Physical Geography.—The physical features of a country are intimately connected with its geological structure. Thus the Highlands and Southern Uplands of Scotland are built up chiefly of crystalline schists and the older Palæozoic strata, while the intervening lowlands of the so-called Central Plain are composed mainly of the younger Palæozoic rocks and overlying accumulations of superficial deposits. The mountainous tracts of Scotland consist therefore of more enduring or less readily eroded materials than the lowlands. Any wide tract of the Highlands (built up largely of crystalline schists and granitic rocks), when viewed from a commanding position, looks like a tumbled ocean in which the waves appear to be moving in all directions. The mountains are massive, generally round-shouldered and often even flat-topped, while there is no great disparity of height among the dominant points of any individual group. This is the result of denudation, guided and controlled by the petrological character and geological structure of the rocks. The mountains are monuments of erosion; they are the wreck of an old tableland, the upper