Now, in a geological point of view, this angle may be regarded as a vast pyramid, rising perpendicularly from the basis furnished by the primary rocks of the latter county, and presenting newer beds and strata as we ascend, until we reach the apex. The line from south to north in the angle--from Morvheim to Dunnet-head--corresponds to the line of ascent from the top to the bottom of the pyramid. The first bed, reckoning from the base upwards,--the ground tier of the masonry, if I may so speak,--is the great conglomerate. It runs along the line of boundary from sea to sea,--from the Ord of Caithness on the east, to Portskerry on the north; and rises, as it approaches the primary hills of Sutherland, into a lofty mountain chain of bold and serrated outline, which attains its greatest elevation in the hill of Morvheim. This great conglomerate bed, the base of the system, is represented in the Cromarty section, under the Northern Sutor, by a bed two hundred and fifteen feet in thickness. The second tier of masonry in the pyramid, and which also runs in a nearly parallel line from sea to sea, is composed mostly of a coarse red and yellowish sandstone, with here and there beds of pebbles enclosed, and here and there deposits of green earth and red marl. It has its representative in the Cromarty section, in a bed of red and yellow arenaceous stone, one hundred and fourteen feet six inches in thickness. These two inferior beds possess but one character,--they are composed of the same materials, with merely this difference, that the rocks which have been broken into pebbles for the construction of the one, have been ground into sand for the composition of the other. Directly over them, the middle portion of the pyramid is occupied by an enormous deposit of dark-colored bituminous schist, slightly micaceous, calcareous, or semi-calcareous,--here and there interlaced with veins of carbonate of lime,--here and there compact and highly siliceous,--and bearing in many places a mineralogical character difficult to be distinguished from that at one time deemed peculiar to the harder grauwacke schists. The Caithness flagstones, so extensively employed in paving the footways of our larger towns, are furnished by this immense middle tier or belt, and represent its general appearance. From its lowest to its highest beds it is charged with fossil fish and obscure vegetable impressions; and we find it represented in the Cromarty section by alternating bands of sandstones, stratified clays, and bituminous and nodular limestones, which form altogether a bed three hundred and fifty-five feet in thickness; nor does this bed lack its organisms, animal and vegetable, generically identical with those of Caithness. The apex of the pyramid is formed of red mouldering sandstones and mottled marls, which exhibit their uppermost strata high over the eddies of the Pentland Frith, in the huge precipices of Dunnet-head, and which are