Of the three chief valleys in the central Lowlands, two, those of the Tay and the Forth, descend from the Highlands, and one, that of the Clyde, from the southern Uplands. Though on the whole transverse, these depressions furnish another notable ex ample of that independence of geological structure already re ferred to. The gorge in which the famous Falls of Clyde are situated is the best example of a river-gorge in the Lowlands. Lochs are not many. Occasional rock-tarns are found in the hills. The larger lochs of the Lowlands lie in hollows of the glacial detritus, which is strewn thickly over the lower grounds. As these hollows were caused by original irregular deposition rather than by erosion, they have no intimate relation to the present drainage lines. The lakes vary in size from pools to sheets of water several square miles in area. As a rule they are shallow in proportion to their extent and surface. They were once more numerous than they are now, for some have disappeared through natural causes and others have been drained. The largest sheets of fresh water in the Lowlands are lakes of the plains, as Loch Leven and the Lake of Menteith.
The fact that two-thirds of the population of Scotland live in the central Lowlands on one-tenth of the total area of the country, is evidence of the pre-eminent industrial position of this region. Among the geographical reasons for that pre-eminence we find, first, ease of communication, both internal and external. The Firth of Clyde on the west, the Firths of Forth and Tay on the east, deeply indent the coasts and offer access for shipping di rectly or very near to the chief industrial centres. Secondly, the Carboniferous rocks of the Lowlands carry important coal-fields, the richest that of Lanarkshire, others in Ayrshire, about the head of the Firth of Forth, in the Lothians and in Fife. Iron is allied with coal, notably in the Ayrshire and Lanarkshire fields. Oil shale is worked in Midlothian and Linlithgowshire, but its im portance has declined; lead is worked in Lanarkshire. Upon the Lanarkshire coal-field, the city of Glasgow, and its neighbouring industrial towns, there centre a variety of great manufacturing industries—shipbuilding and engineering, cotton, woollen and linen manufactures, brewing and distilling, chemical, pottery and glass manufactures, and many others. Elsewhere certain great industries are definitely localized, such as the jute manufacture and jam and marmalade making at Dundee; the woollen industry in Stirlingshire and Clackmannanshire, linen manufacture at and about Dunfermline, Arbroath and Montrose, that of linoleum and oilcloth at Kirkcaldy, that of paper in places neighbouring to Edinburgh, and the dyeing industry at Perth. All depend now upon the coal supplies ; the woollen manufactures were based originally upon the neighbourhood of wide hill-pastures for sheep, the jam-making of Dundee upon the fertile fruit-lands in the adjacent Carse of Gowrie and Strathmore; and all the textile industries, the paper mills, and the distilleries owe their establish ment in part to ample supplies of pure water. Rich agricultural lands, albeit restricted in area, lie close to the manufacturing districts, especially in the east, in Perthshire, Forfarshire, Fife and the Lothians; barley, a high yield of wheat on a small acreage, and potatoes are crops especially noted.
and form a well-defined belt of hilly ground, and though much less elevated (their highest point is 2,7641 t. above the sea) than the Highlands, rise with scarcely less abruptness above the lower tracts that bound them. Their north-western margin for the most part springs boldly above the fields and moorlands of the central plain, and its boundary for long distances continues remarkably straight. On the south and south-east their limits in general are less prominently defined but are better seen west and south-west of the Nith, from which they extend to the sea and Loch Ryan, terminating in the extreme south-west in a plateau of which the loftiest point is little over i,000ft. above the sea. The Cheviots do not properly belong to the Uplands, from which they are separated by Liddesdale and other hollows, and on which they abut abruptly. But though geologically the one set of mountains must be separated from the other, geographically it is convenient to include within the southern Uplands the whole area between the central plain and the Border. A survey of the Uplands, there fore, presents in succession from south-west to north-east the Kirkcudbrightshire and Ayrshire mountain moors, the Lowthers, the Moffat hills, the Moorfoots and the Lammermuirs. Distin guished by the smoothness of their surface, they may be regarded as a rolling moorland, traversed by many valleys conducting the drainage to the sea. This character is well observed from the heights of Tweedsmuir. Wide, mossy moors, 2,000ft. or more above the sea, and sometimes level as a racecourse, spread out on all sides. Their continuity, however, is interrupted by numer ous valleys separating them into detached flat-topped hills, seldom marked by precipices of naked rock. Where the rock projects it more usually appears in low crags and knolls, from which long trails of grey or purple debris descend till they are lost among the grass. These smooth green hills form excellent pasture-land, while the alluvial flats in the valleys, and even some of the lower slopes, are fitted for grain and green crops. Only in the higher tracts are there rugged features recalling the character of High land scenery. In the heights of Hartfell (2,651ft.) and White coomb (2,695 ft.), whence the Clyde, Tweed, Annan and Moffat Water descend, the high moorlands have been scarped into gloomy corries, with crags and talus-slopes, which form a series of landscapes all the more striking from the contrast with everything around them. In Galloway, also, the highest portions of the Uplands have acquired a ruggedness and wildness more like those of the Highlands than any other district in the south of Scotland. In that region the Silurian rocks have been invaded by large bosses of granite, and have undergone a variable amount of metamorphism which has, in some places, altered them into hard crystalline schists. These various rocky masses have yielded unequally to disintegration; the harder portions project in rocky knolls, crags and cliffs, while the softer parts have been worn down into more flowing outlines. The highest summit in the south of Scotland—Merrick (2,764ft.)—consists of Silurian strata much altered by proximity to the granite, while the rest of the more prominent heights (all in Kirkcudbrightshire)—Rinns of Kells (2,668ft.), Cairnsmuir of Carsphairn (2,612ft.), and Cairns more of Fleet (2,33i ft.)—are formed of granite.