That the account now given of their origin is well founded, may be proved by unquestionable facts. For, first, though, agreeably to the observation just made, the ancient strata do but rarely contain any remains of organized bodies, they are not entirely destitute of them. Different places in this island have been pointed out by Dr Hutton, where marine objects have been discovered in primary limestone, either by himself or others, and it would not be difficult to add more instances of the same kind.[5] In Dauphine, coal, which is certainly a derivative substance, has been found among mountains which have a title to the character of primitive, such as no one will dispute. These facts put the composition of such rocks from loose materials, beyond all doubt, and also prove their formation to be posterior to the existence of an animal and vegetable system. They do indeed prove this in the strictest sense, only of the particular beds in which they are found; but as these beds are in all other respects as much to be accounted primary as any part of the mineral kingdom, it is evident that the negative instances are here of no force, and that nothing can be gained to the adversaries of this opinion by denying it in general, if they are obliged to admit it in a single case. [Footnote 5: NOTE IV.] 9. Again, it is certain, as Dr Hutton remarks, that there are few considerable bodies of schistus, even the most decidedly primitive, where sand and gravel may not in some parts be observed. Indeed, it is not only true that they are to be found in some parts of them; but, in fact, among many of the primitive mountains, we find large tracts, composed entirely of a schistose and much indurated sandstone, in beds highly inclined, sometimes alone, sometimes alternated with other schisti. In many of them, the sand of which they consist appears to be entirely of granite, from the detritus of which rock it should seem that they were chiefly formed. 10. Thus we conclude, that the strata both primary and secondary, both those of ancient and those of more recent origin, have had their materials furnished from the ruins of former continents, from the dissolution of rocks, or the destruction of animal or vegetable bodies, similar, at least in some respects, to those that now occupy the surface of the earth. This conclusion is not indeed proved of every individual portion of rock, but it is demonstrated of many and large parts, and those scattered indifferently through all the varieties of the strata; and therefore, from the rules of the strictest reasoning, we must infer, that the whole is derived from the same origin.[6] [Footnote 6: NOTE V.] Thus far concerning the materials of the strata; and, as these were originally loose and unconnected, we must next consider by what means they were consolidated into stone. 2. _Consolidation of the Strata_.