237. But, besides the evidence deduced from calcareous spar and zeolite, against the rocks containing them being real lava, there are other marks, even less equivocal perhaps, that distinguish the lavas which we suppose to have flowed in the mineral regions, from those which have actually flowed on the surface. These are what we collect from the disposition, the organization, or, as we may say, the physical geography of whinstone countries, unlike, in so many respects, to that of volcanic countries. The shape of whinstone hills; their large flat terraces, rising one above another; their perpendicular faces, and the correspondence of their heights even at considerable distances; have nothing similar to them in the irregular torrents of volcanic lavas. The phenomena of the former are also on a scale of magnitude very far exceeding the latter, and clearly indicate, that though both have been produced by fire, it has been by fire in very different circumstances, and regulated by very different laws. The structure of the two kinds of rock agrees, in many respects, and so does their chemical analysis; but their disposition and arrangement are so dissimilar, that they cannot be supposed to be of the same formation. 238. This argument, I believe, was first stated by Mr Strange, in a letter to Sir JOHN PRINGLE, published in the 65th volume of the _Philosophical Transactions_.[122] That intelligent observer, after visiting the countries in Europe most remarkable either for burning, or for what are accounted, extinguished volcanoes, and examining them with a very discriminating eye, remained convinced, that there are two distinct species of rock, which both owe their origin to fire; but to fire acting in circumstances and situations extremely different. The first is the common volcanic lava; the other, to which he gives the name of a basaltine rock, comprehends such rocks as the Giant's Causeway, the basaltes of the Vivarais, of the Euganean Hills, &c. and differs in nothing from that which is called here by the name of whinstone. Mr Strange conceived, that the one of these kinds of stone could, no more than the other, be accounted the work of aqueous deposition, but was led to the distinction just mentioned, by observing the organization and arrangement in the rocks of the latter kind, and comparing them with the disorder and ruin that every where mark the footsteps of volcanic fire He does not pretend to determine the nature of the fire to which the basaltine rocks owe their formation, nor the circumstances in which it has acted: he is satisfied with the negative conclusion, that it is not volcanic; and his paper affords a specimen of what is perhaps rare in any of the sciences, and certainly most rare of all in geology, viz. a philosophic induction carried just as far as the facts will bear it out, and not a single step beyond that point.