We find the marks of marine animals in the most solid parts of the earth; consequently, those solid parts have been formed after the ocean was inhabited by those animals which are proper to that fluid medium.  If, therefore, we knew the natural history of those solid parts, and could trace the operations of the globe, by which they had been formed, we would have some means for computing the time through which those species of animals have continued to live.  But how shall we describe a process which nobody has seen performed, and of which no written history gives any account?  This is only to be investigated, first, in examining the nature of those solid bodies, the history of which we want to know; and, 2_dly_, In examining the natural operations of the globe, in order to see if there now actually exist such operations, as, from the nature of the solid bodies, appear to have been necessary to their formation.

But, before entering more particularly into those points of discussion, by which the question is to be resolved, let us take a general view of the subject, in order to see what it is which science and observation must decide.

In all the regions of the globe, immense masses are found, which, though at present in the most solid state, appear to have been formed by the collection of the calcareous exuviae of marine animals.  The question at present is not, in what manner those collections of calcareous relics have become a perfect solid body, and have been changed from an animal to a mineral substance; for this is a subject that will be afterwards considered; we are now only inquiring, if such is truly the origin of those mineral masses.

That all the masses of marble or limestone are composed of the calcareous matter of marine bodies, may be concluded from the following facts: 

1_st_, There are few beds of marble or limestone, in which may not be found some of those objects which indicate the marine origin of the mass.  If, for example, in a mass of marble, taken from a quarry upon the top of the Alps or Andes[2], there shall be found one cockle-shell, or piece of coral, it must be concluded, that this bed of stone had been originally formed at the bottom of the sea, as much as another bed which is evidently composed almost altogether of cockle-shells and coral.  If one bed of limestone is thus found to have been of a marine origin, every concomitant bed of the same kind must be also concluded to have been formed in the same Manner.

[Note 2:  “Cette sommite elevee de 984 toises au dessus de notre lac, et par consequent de 1172 au dessus de la mer, est remarquable en ce que l’on y voit des fragmens d’huitres petrifies.—­Cette montagne est dominee par un rocher escarpe, qui s’il n’est pas inaccessible, est du moins d’un bien difficile acces; il paroit presqu’entierement compose de coquillages petrifies, renfermes dans un roc calcaire, ou marbre grossier noiratre.  Les fragmens qui s’en detachent, et que l’on rencontre en montant a la Croix de fer, sont remplis de turbinites de differentes especes.”  M. DE SAUSSURE, Voyage dans les Alpes, p. 394.]