There are but two ways in which those appearances may be explained; one of these is that which M. Bouguer has adopted; the other, again, belongs to the present Theory, which represents the action of running water upon the surface of the earth as instrumental in producing its particular forms, and thus forming many natural appearances upon the surface of the earth. The first of these, viz. that a mass of solid land, in such a shape as that here described, should remain while all around it sinks, is an opinion which, however possible it may be, is not supported, I believe, by any example in nature; the last again, viz. that the parts around those insulated masses, and those that had intervened between the corresponding mountains, have been carried away by the natural operation of the rivers, is not only the most easy to conceive, but is also, so far as those operations are concerned, conform to every appearance upon the surface of the globe. It is not necessary to go to South America, and the rivers of the Cordeliers, for examples to illustrate that which every one may see performed almost at his own door; but it is there that an example has occurred, which, though it has imposed upon an eminent philosopher, cannot properly be employed in support of any other theory but the present. Our author proceeds: «Je ne connois les environs de l'Orénoque que par relation, mais je sçais qu'en plusieurs endroits les montagnes y sont également formées de couches horizontales, et qu'elles ont souvent en haut des plateformes qui sont exactement de niveau. On ne trouve à ce que je crois rien de semblable au Pérou malgré la variété presque infinie qui y est répandue. Toutes les couches y vont en s'inclinant autour de chaque sommet, en se conformant à la pente des collines.» It would appear that it is a rare thing to find a great extent of indurated strata in a horizontal position. Now, this circumstance is necessary in affording the appearances here considered; those particular appearances, therefore, are only to be found more partially in other places, where the strata are inclined. If here, therefore, where the strata are horizontal, and where the spaces between the summits of those mountains had evidently been as solid as the masses which remain, we find mountains formed by the waste of land, and a system of rivers forming valleys amidst these mountains, Have we not reason to conclude, that in other mountainous regions, where the regular position of the strata has been broken and confounded, and where the same system of river and valley universally is found, the form of the surface has been produced upon no other principle than that of the natural waste of the solid mass, and the washing down of the heights for the formation of the fertile plains?