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 sommité élevée de 984 toises au dessus de notre lac, et par conséquent de 1172 au dessus de la mer, est remarquable en ce que l'on y voit des fragmens d'huîtres pétrifiés.--Cette montagne est dominée par un rocher escarpé, qui s'il n'est pas inaccessible, est du moins d'un bien difficile accès; il paroît presqu'entièrement composé de coquillages pétrifiés, renfermés dans un roc calcaire, ou marbre grossier noirâtre. Les fragmens qui s'en détachent, et que l'on rencontre en montant à la Croix de fer, sont remplis de _turbinites_ de différentes espèces." M. DE SAUSSURE, _Voyage dans les Alpes_, p. 394.] We thus shall find the greatest part of the calcareous masses upon this globe to have originated from marine calcareous bodies; for whether we examine marbles, limestones, or such solid masses as are perfectly changed from the state of earth, and are become compact and hard, or whether we examine the soft, earthy, chalky or marly strata, of which so much of this earth is composed, we still find evident proofs, that those beds had their origin from materials deposited at the bottom of the sea; and that they have the calcareous substance which they contain, from the same source as the marbles or the limestones. 2_dly_, In those calcareous strata, which are evidently of marine origin, there are many parts that are of a sparry structure, that is to say, the original texture of those beds, in such places, has been dissolved, and a new structure has been assumed, which is peculiar to a certain state of the calcareous earth. This change is produced by crystallisation, in consequence of a previous state of fluidity, which has so disposed the concreting parts, as to allow them to assume a regular shape and structure proper to that substance. A body, whose external form has been modified by this process, is called a _crystal_; one whose internal arrangement of parts is determined by it, is said to be of a _sparry structure_; and this is known from its fracture.