CHAPTER VIII.

Geology of Rum-Its curious Character illustrated-Rum famous for Bloodstones-Red Sandstones 66 Scratchings" in the Rocks - A Geological Inscription without a Key - The Lizard - Vitality broken into twoIllustrations Speculation -Scuir More - - Ascent of the Scuir - The Bloodstones -An Illustrative Set of the Gem-M'Culloch's Pebble-A Chemical Problem-The solitary Shepherd's House-Sheep versus Men-The Depopulation of Rum-A Haul of Trout-Rum Mode of catching Trout - At Anchor in the Bay of Glenelg.

THE geology of the island of Rum is simple, but curious. Let the reader take, if he can, from twelve to fifteen traphills, varying from one thousand to two thousand three hundred feet in height; let him pack them closely and squarely together, like rum-bottles in a case-basket; let him surround them with a frame of Old Red Sandstone, measuring rather more than seven miles on the side, in the way the basket surrounds the bottles; then let him set them down in the sea a dozen miles off the land, and he shall have produced a second island of Rum, similar in structure to the existing one. In the actual island, however, there is a defect in the inclosing basket of sandstone: the basket, complete on three of its sides, wants the fourth: and the side opposite to the gap which the fourth should have occupied is thicker than the two other sides put together. Where I now write there is an old dark-colored picture on the wall before me. I take off one of the four bars of which the frame is composed, the end-bar, and stick it on to the end-bar opposite, and then the picture is fully framed on two of its sides, and doubly framed on a third, but the fourth side lacks framing altogether. And such is

the geology of the island of Rum. We find the one loch of the island, that in which the Betsey lies at anchor, — and the long withdrawing valley, of which the loch is merely a prolongation, occurring in the double sandstone bar: it seems to mark-to return to my illustration—the line in which the superadded piece of frame has been stuck on to the frame proper. The origin of the island is illustrated by its structure: it has left its story legibly written, and we have but to run our eye over the characters and read. An extended sea-bottom, composed of Old Red Sandstone, already tilted up by previous convulsions, so that the strata presented their edges, tier beyond tier, like roofing slate laid aslant on a floor, became a centre of Plutonic activity. The molten trap broke through at various times, and presenting various appearances, but in nearly the same centre ; here existing as an augitic rock, there as a syenite, yonder as a basalt or amygdaloid. At one place it uptilted the sandstone; at another it overflowed it; the dark central masses raised their heads above the surface, higher and higher with every earthquake throe from beneath; till at length the gigantic Ben More attained to its present altitude of two thousand three hundred feet over the sea-level, and the sandstone, borne up from beneath like floating sea-wrack on the back of a porpoise, reached in long outside bands its elevation of from six to eight hundred. And such is the piece of history, composed in silent but expressive language, and inscribed in the old geological character, on the rocks of Rum.

The wind lowered and the rain ceased during the night, and the morning of Monday was clear, bracing, and breezy. The island of Rum is chiefly famous among mineralogists for its heliotropes or bloodstones; and we proposed devoting the greater part of the day to an examination of the hill of Scuir More, in which they occur, and

which lies on the opposite side of the island, about eight miles from the mooring ground of the Betsey. Ere setting out, however, I found time enough, by rising some two or three hours before breakfast, to explore the Red Sandstones on the southern side of the loch. They lie in this bar of the frame, to return once more to my old illustration,- as if it had been cut out of a piece of crossgrained deal, in which the annular bands, instead of ranging lengthwise, ran diagonally from side to side; stratum leans over stratum, dipping towards the west at an angle of about thirty degrees; and as in a continuous line of more than seven miles there seem no breaks or repetitions in the strata, the thickness of the deposit must be enormous, — not less, I should suppose, than from six to eight thousand feet. Like the Lower Old Red Sandstones of Cromarty and Moray, the red arenaceous strata occur in thick beds, separated from each other by bands of a grayish-colored stratified clay, on the planes of which I could trace with great distinctness ripple markings; but in vain did I explore their numerous folds for the plates, scales, and fucoid impressions which abound in the gray argillaceous beds of the shores of the Moray and Cromarty Friths. It would, however, be rash to pronounce them non-fossiliferous, after the hasty search of a single morning, — unpardonably so in one who had spent very many mornings in putting to the question the gray stratified beds of Ross and Cromarty, ere he succeeded in extorting from them the secret of their organic riches

We set out about half-past ten for Scuir More, through the Red Sandstone valley in which Loch Scresort terminates, with one of Mr. Swanson's people, a young active lad of twenty, for our guide. In passing upwards for nearly a mile along the stream that falls into the upper part of the loch, and lays bare the strata, we saw no

change in the character of the sandstone. Red arenaceous beds of great thickness alternate with grayish-colored bands, composed of a ripple-marked micaceous slate and a stratified clay. For a depth of full three thousand feet, and I know not how much more, for I lacked time to trace it further, the deposit presents no other variety: the thick red bed of at least a hundred yards succeeds the thin gray band of from three to six feet, and is succeeded by a similar gray band in turn. The ripple-marks I found as sharply relieved in some of the folds as if the wavy undulations to which they owed their origin had passed over them within the hour. The comparatively small size of their alternating ridges and furrows give evidence that the waters beneath which they had formed had been of no very profound depth. In the upper part of the valley, which is bare, trackless, and solitary, with a high monotonous sandstone ridge bounding it on the one side, and a line of gloomy trap-hills rising over it on the other, the edges of the strata, where they protrude through the mingled heath and moss, exhibit the mysterious scratchings and polishings now so generally connected with the glacial theory of Agassiz. The scratchings run in nearly the line of the valley, which exhibits no trace of moraines; and they seem to have been produced rather by the operation of those extensively developed causes, whatever their nature, that have at once left their mark on the sides and summits of some of our highest hills, and the rocks and boulders of some of our most extended plains, than by the agency of forces limited to the locality. They testify, Agassiz would perhaps say, not regarding the existence of some local glacier that descended from the higher grounds into the valley, but respecting the existence of the great polar glacier. I felt, however, in this bleak and solitary hollow, with the grooved and polished platforms at my

feet, stretching away amid the heath, like flat tombstones in a graveyard, that I had arrived at one geologic inscription to which I still wanted the key. The vesicular structure of the traps on the one hand, identical with that of so many of our modern lavas, -the ripple-markings of the arenaceous beds on the other, indistinguishable from those of the sea-banks on our coasts, the upturned strata and the overlying trap,- told all their several stories of fire, or wave, or terrible convulsion, and told them simply and clearly; but here was a story not clearly told. It summoned up doubtful, ever-shifting visions,-now of a vast ice continent, abutting on this far isle of the Hebrides. from the Pole, and trampling heavily over it, — now of the wild rush of a turbid, mountain-high flood breaking in from the west, and hurling athwart the torn surface, rocks, and stones, and clay,-now of a dreary ocean rising high along the hills, and bearing onward with its winds and currents, huge icebergs, that now brushed the mountainsides, and now grated along the bottom of the submerged valleys. The inscription on the polished surfaces, with its careless mixture of groove and scratch, is an inscription of very various readings.

We passed along a transverse hollow, and then began to ascend a hill-side, from the ridge of which the water sheds to the opposite shore of the island, and on which we catch our first glimpse of Scuir More, standing up over the sea, like a pyramid shorn of its top. A brown lizard, nearly five inches in length, startled by our approach, ran hurriedly across the path; and our guide, possessed by the general Highland belief that the creature is poisonous, and injures cattle, struck at it with a switch, and cut it in two immediately behind the hinder legs. The upper half, containing all that anatomists regard as the vitals, heart, brain, and viscera, all the main nerves, and all the larger