STANFORD LIBRAN CHAPTER VI PHYSICAL FEATURES AND GEOLOGICAL STRUCTURE PHYSICAL FEATURES THE Highlands, for convenience of description, are here regarded as embracing all that part of the country which lies west and north of a line drawn along the Firth of Clyde, and thence diagonally in a north-easterly direction from the mouth of the river Clyde to the east coast at Stonehaven. Nearly the whole of this region is high ground, deeply trenched with valleys and penetrated by long arms of the sea. The only considerable area of lowland lies in the north-eastern counties, embracing the eastern part of Aberdeenshire and the northern parts of Banff, Elgin, and Nairn. Along both sides of the Moray Firth a strip of lower land intervenes between the foot of the hills and the sea, while farther north the county of Caithness is one wide plain, which is prolonged into the Orkney Islands. These low grounds neither geologically nor historically form part of the Highlands; but they may for our present purpose be included therewith. Seen from the south, the front or edge of the Highlands presents a well-defined chain of hills, which rise abruptly from the plains of the Lowlands. This is best observed in Strathmore, but it is also conspicuous in the estuary of Clyde, where the low hills of Renfrewshire and Ayrshire contrast well with the broken line of rugged mountains to the north (Fig. 19). From any of the islands of the chain of the Inner Hebrides, the Highlands along their western sea-front stretch as a vast rampart, indented by many winding sealochs, and rising up to a singularly uniform general level, which sinks here and there, and allows glimpses to be had of still higher summits in the interior. The northern margin is hardly less striking when looked at from the Moray Firth, or from the plains of Caithness or Orkney. From a commanding summit in their interior, the Highlands are seen to differ from any mountain-chain such as the Alps, not merely in their inferior elevation, but essentially in their configuration and structure. They are made up of a succession of more or less nearly parallel confluent ridges, which have, on the whole, a trend from north-east to south-west. These ridges, separated by longitudinal valleys, are furrowed by transverse valleys, and the portions thus isolated rise into what are termed mountains. But all these loftier eminences are only higher parts of ridges along which their geological structure is prolonged. It is singular to observe how the general average of level of the summits of the ridges is maintained. From some points of view a mountain may appear to tower above all the surrounding country; but if it is looked at from a sufficient distance to take in its environment, it is found not to rise much above the general uniformity of elevation. This subject will be more fully treated in Chapter VII. Throughout the Highlands there are no gigantic dominant masses, no central chain of heights like a range of Alps, that must obviously be due to some special terrestrial disturbance. |