[Footnote 122: Account of Two Giants' Causeways in the Venetian State, &c. by John Strange, Esq. Phil. Trans. vol. lxv. (1775,) p. 5, &c.] 239. Several other hints contained in this paper are highly deserving of notice; for we not only find in it the notion of a formation of basaltic rocks, igneous though not volcanic, but also that of their simultaneous crystallization,[123] together with the suggestion, that granite and basalt are of the same origin,[124] These opinions had not, I believe, occurred at that time to any mineralogist except Dr Hutton, nor had they been communicated by him to any but a few of his most intimate friends; so that Mr Strange has without doubt all the merit of a first discoverer. Indeed, without the knowledge of the principle of compression, such as it is laid down by Dr Hutton, it was hardly possible for him to proceed further than he has done. He remarked the unburnt limestone that lies on the tops of some of the Euganean basaltes, and seems to have been aware of the great difficulty, which it was reserved for the Huttonian Theory to overcome. His letter contains also some excellent general remarks on the rocks of the Vivarais and Velay, which he had visited, before FAUJAS DE ST FOND had published his curious and elaborate description of these countries. [Footnote 123: Phil. Trans, _ubi supra_, p. 17.] [Footnote 124: _Ibid._ p. 36 and 37.] 240. The cause of the peculiar structure which has just been observed to distinguish whinstone from volcanic countries, is easily assigned in the Huttonian Theory. According to that theory, the whinstone rocks were formed, in the bowels of the earth, of melted matter poured into the rents and openings of the strata. They were cast, therefore, in those openings, as in a mould; and received the impression and character of the rocks by which they were surrounded. Hence the tabular masses of whinstone, which when soft have been interposed between strata, and compressed by their weight, so as almost to have themselves acquired the appearance of stratification. Hence the perpendicular faces of the same rocks, produced by their being abutted when yet soft, against the abrupt sides of the strata. The rocks which formed those moulds have, in many cases, entirely disappeared; in others, a part still remains, surrounding, or even covering, the basaltes, as in the Euganean Hills, in those of the Val di Noto in Sicily, the rocks near Lisbon,[125] and in different parts of Great Britain. [Footnote 125: Recherches sur les Volcans Eteints du Vivarais; Lettre du Dolomieu, p. 443.] Above all, the veins of whinstone which intersect the strata, are the completest proofs of the theory here given of these rocks, and the most inconsistent, in all respects, with the hypothesis of their volcanic origin.