180. The last of the facts just mentioned is curiously commented on by Mr Kirwan. As he has proved, he says, that the mountains higher than 8500 feet were all formed before the creation of fish, it follows, that the shells found at Guanca-Velica, must have been carried there by the deluge.[89] Now, without objecting to the proof here referred to, (though it seems very open to objection,) it is sufficient to remark, that, if the shells at Guanca-Velica were carried there by the deluge, or any other cause that operated after the formation of the rock of which the mountain consists, they can make no part of that rock, but must lie, like other adventitious fossils, loose and detached on the surface, or at most externally agglutinated to the stone. This, however, is certainly not the fact; for, in the account just quoted, we read, that Don Ulloa told M. le Gentil, "qu'il avoit détaché ces coquilles d'un banc fort épais." This seems plainly to indicate, that the shells were included in a bed of rock; But, granting that the expression is a little ambiguous, on turning to the _Mémoires Philosophiques_ of the same author, the difficulty is completely removed, and it is made evident, that these shells are in fact integrant parts of the rock. "On voit dans ces montagnes-là, (about Guanca-Velica, and particularly at that in which is the quicksilver mine,) des coquilles entières, petrifiées et enfermées au milieu de la roche, que les eaux de pluie mettent à decouvert. Ces coquilles font corps avec la pierre; mais malgré cela, on remarque que la partie qui fut coquille, se distingue par la couleur, la structure, la qualité de la matière de tout autre corps pierreux qui l'enferme, et du massif qui s'est fixé entre les deux ecailles,"[90] &c. He goes on to say, that one can distinguish marks of these shells having been worn, before they were included in the stone. [Footnote 89: Geol. Essays, p. 54.] [Footnote 90: Mém. Philosophiques de Don Ulloa, Discours xvi. vol. i. p. 364.] 181. Thus it appears, that whatever proof any fossil shell affords, that the rock in which it is found was formed under the sea, the same is afforded by the fossil shells of Guanca-Velica; and we are, therefore, perfectly entitled to conclude, that the relative level of the sea and land has changed, since the formation of the latter, by more than 14000 feet. The height assumed in § 37 is therefore much under the truth; and the water, for which the Neptunists must provide room in subterraneous caverns, might very well have been stated at more than a five-hundredth part of the whole mass of the earth.