On Bafalfes. 1 35 



All lavas are accompanied by fcoria, not a particle of 

 which is to be found at the Giants' Caufeway, or any where 

 on our coaft *. 



Currents of lava are dated by Sir William Hamilton, 

 Ferber, and Spalanzani, always to vary in their denfity, 

 their materials being generally arranged according to their 

 fpecific gravities : thus, at the bottom compact lava, then 

 cellular lava, then fcoria, laitly cinders and volcanic afhes. 

 Now, if bafalt be of volcanic origin, our ftrata muft be cur- 

 rents of lava, of courfe mould be governed by the fame rule ; 

 inftead of which, every bafalt ftratum here is of uniform den- 

 fity and uniform material from top to bottom. 



Marine (hells and their impreffions have lately been difco- 

 vered in fome of our bafaltsf: this proves they never were in 

 fufion, as fuch fubftances calcine and turn into lime with a 

 very moderate heat. 



Bafalt pillars have alfo been lately found with cavities filled 

 with frefh water; a facl: incompatible with igneous fufion %. 



Mr. Kirwan derives every thing from aqueous folution; 

 and fays, that the material of which our caufeway is formed 

 was fplit into columns by deficcation. 



Eminent as this great man undoubtedly is in the chemical 

 and mineralogical branches of natural hiftory, yet on this 

 fubject his theory feems to be as infufficient as thofe of any 

 of his predeceflbrs; for his fyftem does not account for the 

 delicate articulations of our pillars, by far the moft curious 

 circumftance attending them, and moft happily exhibited in 

 different points of view in the prefent picture. 



This theory, too, is incompatible with the different ranges 

 or ftrata of pillars placed on one another with folid rock be- 

 tween them. 



But, above all, it is contradicted by facl:, our pillars being 



" r Some travellers have thought they obferved veftiges of fire and fcoria 

 of iron ; but, if they had broke the {tones, they would have found they 

 had been deceived by the exterior appearance, and that the internal ftruc- 

 ture was incompatible with any fuch principle. Some (tones which have 

 been picked up on our coaft have been produced as exhibiting real marks 

 of lire ; but then; had been ufed in forming hearths for the burning of kelp. 



t Thefe had not been dilcovered when Dr. Hamilton's book was pub- 

 lished. 



t That fuch water could not poffibly have got through any chinks or 

 clefts between the bafalt columns will be mown below; for nothing can 

 be more compact and clofely joined, fo as not to admit the minuteft in- 

 terval. Indeed, this water is always found as a kind of nucleus, within' 

 the moft compact part of the ftone, and inclofed in a glazed covercle or 

 glorify fhell, which feems to have Formed its nidus from the firft formation 

 of its {tony bed. 



K 3 in 



