THE ENGLISH REVIEW, For MARCH, 1786. ART. I. Letters concerning the Northern Coaft of the County of Antrim, containing a Natural History of its Bafaltes, by the Rev. Mr. Hamilton. 8vo. 4s. Robinsons, London, THE HE natural. curiofities in the northern coaft of Antrim, and in particular the fingular combination of basaltic pillars, commonly called the Giant's Causeway, have long attracted the attention of travellers, and been the fubject of research, and investigation to philofophers. The native inhabitants of the coaft, who were the firft obfervers of this phenomenon, accounted for its production, by a theory rude and fimple, and to men ignorant of natural hiftory not very abfurd. They obferved, that the causeway was a regular mole, projecting into the fea; they difcovered, on clofer inspection, that it was built with an appearance of art and regularity, re fembling the works of men, though on a larger scale than had ever been seen; and they concluded, that human ingenuity and perfeverance, if fupported by fufficient power, were abun dantly adequate to its production. Their own traditions, fimilar to thofe of other nations, concerning the extraordinary ftature and ftrength of their ancestors, fuggefted the caufe of this prodigy of art; and the celebrated Fingal, the hero of ancient Ireland, as well as of Scotland, became the giant under whofe forming-hand this curious ftructure was erected. It was afterwards difcovered, that a pile of fimilar pillars was placed fomewhere on the oppofite coaft of Scotland'; and as the business of latitudes and longitudes was not at that time ENG. REV. Vol, VI. March 1786. L accu accurately ascertained, a general confufed notion prevailed that this mole was once continued across the sea, and connected the Irish and Scottish coafts. Towards the clofe of the laft century, the Royal Society of London began to inquire and to fpeculate concerning this fingular phenomenon. But, as the information which they received was imperfect, the conclufions which they drew were erroneous. Dr. Molleneux took confiderable pains to illuftrate the fubject, but the neceffary attendance of his profeffion prevented him from making his obfervations in person, for which he feems to have been well qualified. By his influence, the Dublin Society employed a painter, of fome eminence, to make a general sketch of the coaft, near the causeway; but he, indulging his imagination, drew a picturefque view of the fcene, rather than a philofophical landscape. From that period, this curious work of nature passed almost unnoticed for half a century; and men of fcience turned their eyes from an object, which had hitherto baffled the attempts of every theorift. In the year 1740, Mrs. Sufanna Drury made two very beautiful and correct paintings of the Giant's Causeway, which having obtained the premium appointed for the encouragement of arts in Ireland, and being engraved by an eminent artist, directed the attention of the world again to this celebrated subject. Soon after, Dr. Pocock made a tour through the county of Antrim, and took a general view of the coaft. But, as generally happens in the infancy of fcience, he was more zealous to affign causes, than to investigate facts; and started a new but crude theory, imputing the regular figures of the bafaltic columns to accidental fits of precipitation, in a watery medium; which is not only hypothetical, but inadequate to the production of the effects. It is to be obferved, that the fpecies of ftone of which the caufeway is formed, is to be found throughout the whole extent of the contiguous country: And, within these few years, it has been discovered, that the bafaltes is a very common foffil, through every part of the world. Hence, the obfervations of men of science, in diftant places, have been united on this fubject; different theories have been compared together, and more general analogies fuggefted on which to build fome rational conjectures concerning the caufe which produced thefe wonderful columns. The ingenious author of these letters gives us the natural hiftory of thefe columnar bafaltes, previous to the investigation of the cause to which they owe their origin. The caufeway itfelf is generally described as a mole or quay, projećting from the bafe of a fleep promontory, fome hundred feet, into the the fea, and is formed of perpendicular pillars of bafaltes, which stand in contact with each other, exhibiting an appearance not much unlike a folid honeycomb. The pillars are irregular prifms, of various denominations, from four to eight fides; but the hexagonal columns are as numerous as all the others together. On a minute inspection, each pillar is found to be feparable into feveral joints, whofe articulation is neat and compact beyond expreffion; the convex termination of one joint always meeting a concave focket in the next; befides which, the angles of one frequently fhoot over those of the other, fo that they are completely locked together, and can rarely be feparated without a fracture of fome of their parts. The fides of each column are unequal among themselves, but the contiguous fides of adjoining columns are always of equal dimenfions, fo as to touch in all their parts. Though the angles be of various magnitudes, yet the fum of the contiguous angles of adjoining pillars always makes up four right ones. -Hence there are no void spaces among the basaltes, the fu face of the causeway exhibiting to view a regular and compact pavement of polygon ftones. The outfide covering is foft and of a brown colour, being the earthy parts of the ftone nearly deprived of its metallic principle by the action of the air, and of the marime acid which it receives from the feat. These are the obvious external characters of this extraordinary pile of bafaltes, observed and described with wonder by every one who has seen it. But it is not here that our admiration should cease ; whatever the procefs was, by which nature produced that beautiful and curious arrangement of pillars to confpicuous about the Giant's Causeway; the cause, far from being limited to that spot alone, appears to have extended through a large tract of country, in every direction, infomuch that many of the common quarries, for feveral miles around, seem to be only abortive attempts towards the production of a Giant's Causeway. 'From want of attention to this circumftance, a vaft deal of time and labour has been idly spent in minute examinations of the causeway itfelf-in tracing its courfe under the ocean-purfuing its columns into the ground-determining its length and breadth, and the numbers of its pillars with numerous wild conjectures concerning its original; all of which cease to `be of any importance, when this fpot is confi *Monfieur Faujas de St. Fond took much pains to search for pillars of nine fides among the bafaltes of Viverais, in confequence of the account which Mr. Molleneux and Monfieur de Lifle gave that such were to be found; but there is little doubt that both thofe gentlemen were mistaken, as none of that denomination are to be discovered at the Giant's Caufeway, or its neighbourhood. Indeed ottagonal pillars are very rarely to be met with. This coating contains iron which has loft its phlogiston, and is nearly reduced to a state of calx; for with a very moderate heat it becomes of a bright red ochre colour, the attendant of an iron earth. dered only as a small corner of an immenfe bafalt quarry, extending widely over all the neighbouring land. The leading features of this, whole coaft are the two great promon. tories of Bengore and Fairhead, which stand at the diftance of eight miles from each other: Both formed on a great and extensive scale, both abrupt towards the fea, and abundantly expofed to obfervation, and each in its kind exhibiting noble arrangements of the different fpecies of columnar bafaltes. The former of these lies about seven miles weft of Ballycaftle, and is generally described by feamen, who fee it at a distance and in profile, as an extenfive headland, running out from the coaft a confiderable length into the fea; but, ftrictly speaking, it is made up of a number of leffer capes and bays, each with its own proper name, the tout enfemble of which forms what the feamen denominate the headland of Bengore. • These capes are compofed of variety of different ranges of pillars, and a great number of fiata; which, from the abruptness of the coast, are extremely confpicuous, and form an unrivalled pile of natural architecture, in which all the neat regularity and elegance of art is united to the wild magnificence of nature. The most perfect of these capes is called Pleafkin, of which I fhall attempt a description, and along with it hope to fend a drawing which my draftsman has taken from the beach below, at the rifque of his neck; for the approach from these promontories down to the fea is frightful beyond defcription, and requires not only a strong head, but very confiderable bodily activity, to accomplish it. The fummit of Pleafkin is covered with a thin graffy fod, under which lies the natural rock, having generally an uniform hard furface, fomewhat cracked and shivered. At the depth of ten or twelve feet from the fummit, this rock begins to affume a columnar tendency, and forms a range of mafly pillars of bafaltes, which itand perpendicular to the horizon, prefenting, in the fharp face of the promontory, the appearance of a magnificent gallery or colonade, upwards of fixty feet in height. This colonade is fupported on a folid bafe of coarse, black, irregular rock, near fixty feet thick, abounding in blebs and air-holes-but, though comparatively irregular, it may be evidently observed to affect a peculiar figure, tending in many places to run into regular forms; refembling the shooting of falts and many other fubitances during a hafty crystallization. Under this great bed of stone stands a fecond range of pillars, between forty and fifty feet in height, lefs grois, and more sharply defined than thofe of the upper ftory; many of them, on a clofe view, emulating even the neatnefs of the columns in the Giant's Causeway. This lower range is borne on a layer of red ochre ftone, which ferves as a relief to fhew it to great advantage*. The only inftances of different ranges of bafaltes, that have hitherto been difcovered, occur in the valuable work of Monf. Faujas de St. Fond on the volcanoes of Viverais, &c. but the arrangement which appears there, even with the neatnefs that always attends an engraving, isy inferior to that of Pleakin. Thefe These two admirable natural galleries, together with the interjacent mafs of irregular rock, form a perpendicular height of one hundred and feventy feet; from the bafe of which, the promontory, covered over with rock and grafs, flopes down to the fea for the space of two hundred feet more, making in all a mafs of near four hundred feet in height, which in beauty and variety of its colouring, in elegance and novelty of arrangement, and in the extraordinary magnitude of its objects, cannot readily be rivalled by any thing of the kind at present known *. Befides the bafalt pillars of these two magnificent promontories, there are many other fimilar arrangements through the country. In the mountain of Dunmull, two different ranges of columns may be difcovered. They are found alfo at Dunluce-hill; in the bed of the river bufh; on the fummit of the mountain of Croaghmore; in the highland over Ballintoy; in the island of Rhagery; and various other places, through an extent of coaft, about fifteen miles in length and two in breadth. Beyond this tract, which abounds in perfect pillars, an attentive observer will trace the fame fpecies of foffils in very diftant parts of the country, fo far as the northern shore of Loughneagh, and the mountains of Derry; in many places of which imperfect columnar forms may be obferved: So that the great cause which generated this fpecies of ftone has been exerted through a space of more than forty miles in length, and twenty in breadth; that is, through above eight hundred fquare miles. In the 9th letter Mr. Hamilton gives an analysis of the bafaltes, and an explanation of its moft remarkable properties, from the known elements of which it is compofed. Its principal component parts are iron in a metallic ftate, combined chiefly with filicious and argillaceous earths. From a knowledge of these elementary parts of the bafaltes, we are furnished with an analogy tending to throw light on the regula rity of its form. Silicious earth, which is one of its component parts, frequently affects a regular figure. Thus rock chrystal, which is a pure flinty earth, is commonly difpofed in the form of hexagonal prifms, the denomination of fides which chiefly prevails among the bafaltic pillars.-Thus various crystallizations are found to take place in the metal of * Mr. Pennant is much mistaken in his opinion that the little island of Staffa, whofe greatest height is but one hundred and twenty-eight feet, contains any object equal to the bold promontories of Bengore. -Neither are the beft fpecimens of pillars at Staffa at all comparable to those of the Giant's Causeway in neatness of form, or fingularity of articulation.' |