NATURAL REGIONS.—Geological structure, land form, and climatic conditions all serve to mark off fairly well the major natural regions of the British Isles. The areas of ancient rocks are generally uplands, and being uplands have a higher rainfall and a lower temperature than the neighbouring lowlands, with the result that their vegetation and, to a certain extent, their economic development, are different. But each upland region may be considered separately, as no two of them are exactly alike. The Northern Highlands are of older rock than the Southern Uplands, their elevation is greater, and their climate more inclement. The Central Lowlands may be dis tinguished from both, not only by their physical character and climatic conditions, but by their mineral wealth and economic potentialities. The Pennine Chain differs entirely in structure from the other Palaeozoic areas of Great Britain, while each of the great coalfields, which lie upon its flanks, has, as a result of differ ences in geological environment, climate, or place relations, a well marked individuality of its own. The Lake District, the Welsh Upland, and the peninsula of Devon and Cornwall present contrasts to one another in respect to structure, mineral wealth, and climate. The Central Plain, which unites these upland regions, is itself a lowland which must be subdivided in order that due attention may be given to the Carboniferous districts within it. The south and
east of England, though generally lowland, do not form one natural region. The soils of the Jurassic area differ from those of the Cretaceous area, and the economic development of the two regions differs likewise. In the Cretaceous area, moreover, the agricultural conditions of different districts are profoundly modified by the distribution of the glacial drift. Lastly, the Tertiary basins of London and Hampshire, and the lands adjoining the estuary of the Severn, have had their past history and present conditions so profoundly modified by their position and place relations that each must be considered apart from the others. In Ireland, the Central Plain and each of the mountain masses by which it is surrounded may be considered as separate natural regions, but it is perhaps better to recognise three belts, a northern upland, a central lowland, and a southern upland ; and to subdivide each of these into two parts, an eastern and a western, the division being based partly upon physical structure and partly upon climatic conditions.