system of subterranean disturbance is seen, not only in the general parallelism of the great synclinal and anticlinal folds and the faults of the strata in Scotland, and the consequent position and features of her mountain-ranges, valleys, rivers, and lochs, together with the outlines of her coasts and islands, but equally in the direction of the strike of the outcrops of the long series of successive geological formations in England. The facts of the existence and long continuance of this great system of disturbance, and the important results produced by it, are now admitted by all geologists, whether they regard such subterranean forces, with the late Sir Roderick Murchison and the Duke of Argyll, as the immediate cause of the physical features of the country, or, with Professors Ramsay and Geikie[1], as only directing and modifying the really efficient and direct cause of those phenomena — namely denudation.
A review of the general position and relations of the strata of the north-east of Scotland appears to indicate that, over the tract now occupied by the Moray Firth, the Secondary strata were let down among the Palaeozoic rocks by a series of parallel faults ranging N.E. and S.W., and that, by the slow action of denuding forces, the great mass of these strata has been removed, a few minute patches alone escaping. The general form of this vast inlet and the position of the peninsulas which project into it have been determined by these great faults ; and it is probable that extensive deposits of Secondary age still exist beneath its comparatively shallow waters.
To some the hypothesis contained in the foregoing pages may, at first sight, appear startling — namely that, over large areas of the Highlands, Secondary strata to the thickness of from 2000 to 3000 feet (not to notice the Cretaceous and Triassic rocks) once existed, and that all of these, with the exception of a few minute fragments, have been removed by denudation. But those who have seen how many thousands of feet of apparently almost imperishable rocks, like the Laurentian gneiss, the Lower Silurian quartzites, and the Old Red conglomerates, have evidently been removed over vast areas in the Highlands, as indicated by the truncation of curved strata and the position of outlying patches, will readily admit the facility with which the same causes, under equally favourable conditions, would have swept away the comparatively soft masses composing the strata of the Secondary series.
III. Description of the Series of Secondary Formations in the North-east of Scotland.
An admirable topographical description of the areas occupied by me that a portion of a Coccosteus, a characteristic fish of the Middle Old Red, has recently been obtained from this isolated patch in Sutherland.
- ↑ Professor Geikie considers that the fault which has thrown down the patches of Oolite on the Ross-shire coast may be only a continuation of that great dislocation which certainly traverses the line of the Caledonian Canal ('Scenery of Scotland,' p. 177); if not continuous with, it is certainly parallel to, that great fault.
