*32 On Bafalt es. 



is compofed, difplaying a variety of the bafalt, of different 

 forms and of a different principle of conftru£tion, internal' 

 and external ; fuch as is not met with or not noticed in any 

 other part of the world. 



As we row along the bafe of thefe ftupendous/^tfJ«, we 

 enjoy a fcenery magnificent beyond defcription,. and difcover 

 many curious circumftances which have hitherto efcaped the 

 notice of naturalifts : I will mention one. 



The Giants' Caufeway, compared by Dr. Hamilton to a 

 mole or quay, and fuppofed by Meffrs. Defmareft and Rafpe 

 to be a jet or current of lava running into the fea from the 

 bafe of a volcanic hill, now appears to be a part of one of 

 the original ftrata of our globe, placed at its interferon with 

 the plane of the fea. This ftratum is forty-four feet thick, 

 and entirely compofed of bafalt pillars of that length : it is 

 inclined to the horizon in a fmall angle, and, when traced 

 from the caufeway eaftward, afcends obliquely along the face 

 of the precipice. It culminates at the diftance of about a 

 mile from the caufeway : its upper furface is now elevated 

 near 250 feet above the furface of the fea : proceeding eaft- 

 ward, it dips and finally emerges at Portmoon, two miles eaft 

 from the caufeway, forming at its immerlion the vafes of two 

 beautiful conical iflands. 



Magnificent as the colonades may be fuppofed, which this 

 ftratum difplays in fo ex ten five a eourfe acrofs the face of 

 thefe mighty precipices, they are by no means our fineft; 

 the ftratum next but one above (his is eleven feet thicker, 

 and of eourfe the pillars, of which it alfa is entirely com- 

 pofed, are fifty-five feet each, and its extent is fomewhat 

 greater than the former. The intermediate ftratum is com- 

 pofed of another variety of bafalt, prifmatic, but not co- 

 lumnar : this is fifty-four feet thick. 



The Giants' Caufeway ftratum, where it attains its greateft 

 height, is the eighth, counting from the fea ; all the lower 

 ones emerge in fucceflfian as we approach Portmoon ; and, 

 where this ftratum finally emerges, it has eight over it, four 

 of them columnar, the pillars being of very different lengths, 

 determined by the thicknefs of the ftratum. But in each 

 feparate ftratum the diameters of the pillars, and the perfec- 

 tion or imperfection of their confi ruction, appear pretty much 

 the fame, while the whole mafs of the ftrata are fteadily pa- 

 rallel to each other. 



When I laft fummer found at the Giants' Caufeway an 

 ingenious and riling artift, Mr, Robinfon, whom I knew to 

 be highly favoured by my friend the biftiop of Dromore, 

 employed to make a drawing of it^ I at flrft thought I would 



kave 



