Whether we examine the Alps in the Old World, or the Andes in the New, we always find the evidence of this proposition, That the exposed parts of the solid earth are decaying and degraded; that these materials are hauled from the heights to be travelled by the waters over the surface of the earth; and that the surface of the earth is perpetually changing, in having materials moved from one place and deposited in another. But these changes follow rules, which we may investigate; and, by reasoning according to those rules or general laws, upon the present state of things, we may see the operation of those active principles or physical causes in very remote periods of this mundane system, and foresee future changes in the endless progress of time, by which there is, for every particular part, a succession of decay and renovation. CHAP. XIII. _The same Subject continued._ The Chevalier de Dolomieu, in his most indefatigable search after natural history and volcanic productions, has given us the description of some observations which are much calculated to put this subject in a conspicuous point of view. I give them here as examples of the operation of water wasting the land and forming valleys in a system where every thing is tending to the wisest end or purpose; but they are no less interesting as proper to give us a view of the mineral operations of the globe. That therefore which, according to the order of the subject, ought to be cited in another part of this work, is here necessarily mixed in the narrative of this natural historian. There is, upon this occasion, such a connection of the facts by which the mineral operations of the earth, either consolidating the materials deposited at the bottom of the sea, or elevating land by the power of subterraneous heat, are to be understood, and of those by which the operations of the surface are to be explained, that while they cannot be separated in this narration, they throw mutual light upon each other. It is in his Mémoire sur les Volcans éteints du Val di Noto en Sicile. Journal de Physique, Septembre 1784. «Je trouvai les premiers indices de ces volcans, en allant de Syracuse à Sortino, à une lieue de cette ville, au fond du profond vallon qui y conduit. Quelques morceaux de laves entraînés et arrondis par les eaux m'annoncèrent d'avance que j'allois entrer dans un pay volcanique. Mon attention se fixa bientôt après sur un courant de laves que je vis sortir d'une montagne calcaire qui étoit sur ma droite, il étois coupé par une vallon dont les eaux couloient sur un sol calcaire, et alloit se perdre dans le massif également calcaire qui étoit sur ma gauche. Je passai en suite alternativement sur des matières calcaires et volcaniques, pour arriver à Sortino, ville baronale bâtie sur une montagne calcaire qui domine la vallon, et qui lui presente des escarpemens de plus de 200 toises d'élévation, dans lesquels les banc de pierres dure sont horizontaux, et exactement parallèles.»