a vast collection of columnar basalt in the county of Antrim, on the northern coast of Ireland. It is divided into the Little, the Middle, and the Large or Grand Causeways, divided from each other by whirl-dykes, composed of amorphous basalt. The Grand Causeway consists of a most regular arrangement of innumerable polygonal columns of basalt, almost all of a hexagonal figure; one, however, has been found with only three sides, and several with nine. Though the polygons are somewhat irregular, the faces of the adjacent pillars are equal, and fit so compactly, that although perfectly distinct from top to bottom, no space is unoccupied, and water will lodge in the cavities until it evaporates, without any portion sinking between the columns. Each pillar is perfect in itself, consisting of articulations, the internodes of which vary from a few inches to some feet; sometimes the convexity, sometimes the concavity is uppermost, in some instances both ends are concave, in others both convex, but the joints of the separate portions of the columns are always accurately adjusted to each other. The diameter of the pillars is as various as their length and figure, but the general measurement is from 15 to 20 inches. The columns are of an unequal height and breadth; some of the highest, visible above the surface of the strand, and at the foot of the impending angular precipice, are about 20 feet. How deep they are fixed in the strand has not been discovered. This grand arrangement extends nearly 200 yards, visible at low water, but how far beyond is uncertain. The breadth of the principal causeway, which runs out in one continued range of columns, is in general from 20 to 30 feet; at one or two places it may for a few yards be nearly 40. In this account are not included the broken and scattered pieces of the same kind of construction which are detached from the sides of the Grand Causeway, as they do not appear to have ever been contiguous to the principal arrangement, though they have frequently been taken into account when estimating the width. The highest part of the causeway is the narrowest. The columns of this narrow part incline from the perpendicular a little to the westward, and form a slope on their tops, by which an ascent is made at the foot of the cliff, from the head of one column to the next above, gradation, to the top of the great causeway, which, at the distance of half a dozen yards from the cliff, obtains a perpendicular position, and, lowering in its general height, widens to between 20 and 30 feet, and for nearly 100 yards is always above water. The tops of the columns for this length being nearly of an equal height, they form a grand and singular parade, rather inclining to the water's edge, but easily walked on. Below high-water mark the platform lowers considerably, and becomes more uneven, so that a firm footing can only be maintained with difficulty. At the distance of about 150 yards from the cliff it turns a little to the eastward for 20 or 30 yards, and then sinks into the sea. The Little Causeway is first approached from the sea, next comes the Middle Causeway, which is commonly called the Honeycomb by the local guides; but the chief object of attraction is the Grand Causeway, which is formed of the upper surface of the first or lowest range of columnar basalt laid bare. The ends of the pillars may be distinctly traced both on the east and west sides of the causeway resting on the ochre bed, upon a concave depression of which the whole causeway probably stands, so that in the centre only are the columns perpendicular to the horizon, those at the extremities leaning over towards the middle. The causeway, properly so called, consists of three piers or moles jutting out into the sea, the greater being visible to the extent of 300 yards at low water, the other two not more than half that distance.

The cliffs connected with the causeway, especially in the bay to the eastward, exhibit in many places the same kind of columns, shaped and jointed in all respects like those of the Grand Causeway. Some of them are seen near the top of the cliffs, which in general, in those bays to the east and west of the causeway, range from 140 to 390 feet in height; others again are observed about midway, and at different elevations from the strand. A very considerable exposure of them is seen in the very bottom of the bay to the eastward, about 100 rods from the causeway, where the earth has evidently fallen away from them upon the strand, and exhibits a most curious arrangement of many of these polygonal columns in a perpendicular position, supporting in appearance a cliff of different strata of earth, clay, rock, &c., to the height of about 130 feet or more above. Some of these columns are between 30 and 40 feet high, from the top to the sloping bank below them; and, being longest in the middle of the arrangement, and shortening on either hand, they have obtained the appellation of organs, from a rude likeness in this particular to the exterior or frontal tubes of that instrument. The most remarkable of these cliffs is the Pleaskin, the summit of which is covered with a thin grassy sod, under which lies the natural basaltic rock, having generally a hard surface, somewhat cracked and shivered. At the depth of 10 or 12 feet from the summit this rock begins to assume a columnar shape, and forms a range of massy pillars of basalt, which stand perpendicular to the horizon, presenting in the sharp face of the promontory the appearance of a magnificent gallery or colonnade, upwards of 60 feet in height. This colonnade is supported on a solid base of coarse black amygdaloid, nearly 60 feet thick, with many of the cavities empty; but though comparatively irregular, it may be plainly observed to affect a peculiar figure, tending in many places to run into regular forms, resembling the shooting of salts and many other substances during a hasty crystallization. Under this great bed of stone stands a second range of pillars between 40 and 50 feet in height, less gross and more sharply defined than those of the upper story; many of them, on a close view, emulating even the neatness of the columns in the Giant's Causeway. This lower range is borne on a layer of red ochre, which serves as a relief to show it to great advantage. These two admirable natural galleries, together with the adjacent mass of irregular rock, form a perpendicular height of 170 feet; from the base of which the promontory, covered over with rock and grass, slopes down to the sea for the space of 200 feet more, making in all a mass of nearly 400 feet in height, which, in beauty and variety of colouring, in elegance and novelty of arrangement, and in the extraordinary magnitude of its objects, cannot readily be rivalled by anything of the kind at present known.

In association with the scenery and natural curiosities of the Giant's Causeway, are the ruins of the castles of Dunseverick and Dunluce, situated high above the sea on insulated crags; the swinging bridge of Carrick-a-Rede, over a chasm of 80 feet deep, and connecting a rock, which is used as a salmon-fishing station, with the mainland. Fairhead, about 550 feet in height, is the highest promontory on this coast; it is composed of columnar greenstone, and some of the pillars exceed 200 feet in height, forming the finest object on the whole line of coast.

To the geologist, the mineralogist, or the observer of nature in her more singular and fantastic moods, the Giant's Causeway and its neighbourhood is of surpassing interest; but as remarked by Inglis, "The traveller who visits the Giant's Causeway, expecting to find nature in her most majestic form, and associating, as I did, with the name, something very sublime, will certainly be disappointed; but if he goes to see something very curious—something calculated to excite wonder and admiration, he will undoubtedly leave the Causeway fully satisfied."—Hamilton's Letters from the Coast of Antrim; Dubourdieu's Statistical Survey of Antrim; Dr Richardson's Letter in the Transactions of the Royal Irish Academy, &c. &c.