¹Thackeray, William M. The Irish Sketchbook of 1842 and Character Sketches. Boston: Houghton, Mifflin and Co., 1889. 325.
The unabridged quote: "It looks like the beginning of the world, somehow: the sea looks older than in other places, the hills and rocks strange, and formed differently from other rocks and hills—as those vast dubious monsters were formed who possessed the earth before man. The hill-tops are shattered into a thousand cragged fantastical shapes; the water comes swelling into scores of little strange creeks, or goes off with a leap, roaring into those mysterious caves yonder, which penetrate who knows how far into our common world. The savage rock-sides are painted of a hundred colours. Does the sun ever shine here? When the world was moulded and fashioned out of formless chaos, this must have been the bit over—a remnant of chaos!"
The book may be read in its entirety here.

²"Giant's Causeway." Wikipedia, the Free Encyclopedia. Web. 10 June 2011. <http://en.wikipedia.org/wiki/Giant's_Causeway>.

³Wilson, William. The Post Chaise Companion, Or, Traveller's Directory through Ireland. Dublin, 1813. 42.

⁴"The Giant's Causeway." The Dublin Penny Journal 1.5 (1832): 33.

⁵"Giant's Causeway." Wikipedia, the Free Encyclopedia. Web. 10 June 2011. <http://en.wikipedia.org/wiki/Giant's_Causeway>.

⁶Just as with the Giant's Causeway in Ireland, some authors insisted that Fingal's Cave in Scotland was a manufactured, rather than a natural phenomenon. This excerpt is from a popular science magazine of 1882: "Until it is shown that a thousand yards of landlocked, iron-bound coast can be cut and tunneled in utter disregard of every known law of mechanical action, the caves in Staffa, on the west coast of Scotland, driven into igneous rock, not modified by local conditions, or in the weak places 'of an exposed cliff,' can not be classified as merely remarkable instances of caves worn by the sea." Whitehouse, F.C. "Is Fingal's Cave Artificial." Popular Science Monthly 22.12 (1882): 240. The article may be read in its entirely here. More information here.
The sound of the water rushing in and out of Fingal's Cave apparently inspired Felix Mendelssohn to compose his Hebrides overture. It was, and is, considered good fortune for a visitor to enter the cave by small boat and touch the back wall. Such luminaries as Johnson and Boswell, Queen Victoria and Prince Albert, Sir Walter Scott, John Keats, and Robert Lewis Stevenson all made the effort. (Smith, Terence. "Where They Drink Whiskey in the Morning." The Atlantic December (2013): 49. Web. <http://www.theatlantic.com/magazine/archive/2013/12/in-the-wake-of-dr-johnson/354666/>.)

⁷"Finn MacCool" Causeway Coastal Route. Web. 10 June 2011. <http://www.causewaycoastalroute.com/index.php?option=com_content&view=article&id=76&Itemid=61>.

⁸Kennedy, Alasdair. "In Search of the 'True Prospect': Making and Knowing the Giant's Causeway as a Field Site in the Seventeenth Century." British Society for the History of Science 10.10 (2007): 21-22.
An earlier article with the same subject was published in 1896: "No mention is made of this marvellous work of Nature in the Four Masters, the Chironicon Scotorum, or the Annals of Ulster, nor does any medieval author apparently allude to it, although other objects of curiosity in Ulster are described...The learned antiquaries of a later date—Camden, Boate, and Ware—alike seemed ignorant of its existence. Equally do the geographical map makers—Mercator (1594), Speed (1610), and others, down to the I8th century—omit it in their various publications…So late as 1727, when Les Délices la Grande Bretagne et de l’Irlande was published in 8 vols. at Leydern, no mention occurs of its existence. A more remarkable circumstance, however, is its omission by Richard Dobbs in his description of the natural features of the County Antrim, which he wrote for Pitt's Atlas in I683. This was printed for the first time in extenso in the Rev. George Hill's Macdonnells of Antrim. Dobbs mentions Dunluce, Bushmills, and Ballycastle, and was particularly fond of natural history and mineralogy. It may be possible that he had intended to add an account of the Giant's Causeway to his other notices of County Antrim, but certainly he has not done so. This strange omission of any mention of such a remarkable natural phenomenon is the more curious, when we consider how very fond our ancestors were of tabulating natural wonders, and how many pages in old books are filled with descriptions of trivial objects of interest." "Early Notices and Engraved Views of the Giant's Causeway." Ulster Journal of Archaeology Second 3.1 (1896): 41-42.

⁹Kennedy.

¹⁰"Early Notices and Engraved Views of the Giant's Causeway." Ulster Journal of Archaeology Second 3.1 (1896): 43.

¹¹Pococke, Richard. "An Account of the Giants Causeway in Ireland, in a Letter to the President from the Rev. Richard Pococke." Philosophical Transactions 45 (1748): 124-27.

Lord, Richard. "An Account of a Production of Nature at Dunbar in Scotland, Like That of the Giants- Causeway in Ireland;." Philosophical Transactions 52 (1761): 98-99.

Strange, John. "An Account of a Curious Giant's Causeway, or Group of Angular Columns, Newly Discovered in the Euganean Hills, Near Padua, in Italy." Philosophical Transactions 65 (1775): 418-23.

As a refutation to all suggestions that the Causeway was not a work of nature, the author of Hibernia Curiosa in 1764 wrote: "The romantic supposition of its having been a causeway from Ireland to Scotland is ridiculous and absurd at first view. The nearest coast of Scotland to this place is at least 30 miles; if any use or design of this kind can be imagined ever to have taken place, it must to have been to some island not far from the shore, which the sea has swallowed up. But the general form and construction of the several parts is at the utmost distance from favoring such a supposition. Nor is the ridiculous opinion that is met with in some of the old natural histories of this kingdom less absurd, on a comparison that is made of this to Stonehenge on Salisbury-plain, that this, as well as that, may have been originally a monumental pile, or some ancient place of worship, for there is no more likeness in the comparison than would be found between two of the most dissimilar productions of art, or nature. Into such ridiculous fancies will men suffer themselves to be led, who have never seen the originals, of which they pretend to give a description; but implicitly write from the authority of others, equally with themselves, unacquainted with them." Bush, John. Hibernia Curiosa: A Letter from a Gentleman in Dublin, to His Friend at Dover ... :. London, 1764. 59-60.

¹²"A Guide to the Giants' Causeway." The Dublin Penny Journal Supplement 2 (1834): xiv-xv.

¹³"The Causeway Court Case" Causeway Coastal Route. Web. 10 June 2011. <http://www.causewaycoastalroute.com/index.php?option=com_content&view=article&id=77&Itemid=61>.

¹⁴Thackeray 326.