with calcareous matter, others with siliceous, and others with iron or copper pyrites.
But these facts, however important and interesting, cannot, when considered by themselves, add much to our knowledge respecting the formation and structure of the earth. To derive any information consequence from them, on these subjects, it is necessary that their examination should be connected with that of the several strata, in which they are found.[1]
Already have these examinations, thus carried on, taught us the following highly instructive facts. That exactly similar fossils are found in distant parts of the same stratum, not only where it traverses this island, but where it appears again on the opposite coast: that, in strata of considerable comparative depth, fossils are found, which are not discovered in any of the superincumbent beds: that some fossils, which abound in the lower are found in diminishing numbers through several of the superincumbent, and are entirely wanting in
- ↑ This mode of conducting our inquiries was long since recommended by Mr. W. Smith, who first noticed that certain fossils are peculiar to, and are only found lodged in, particular strata; and who first ascertained the constancy in the order of superposition, and the continuity of the strata of this island. It will appear from the following quotation, that these observations have lately also occurred to Messrs. Cuvier and Brongniart whilst examining into the nature of tho strata of the neighbourhood of
Paris. “ Cette constance dans l'ordre de superposition des couches les plus minces, et sur une étendue de 12 myriamètres au moins, est, selon nous, un des faits les plus remarquables que nous ayons constatés dans la suite de nos recherches. Il doit en résulter pour les arts et pour la géologie dos consequences d'autant plus intéressantes, qu'elles sont plus sures.”
“ Le moyen que nous avons employé pour reconnoitre au milieu d'un si grand nombre de lits calcaires, un lit déjà observé dans un canton très-éloigné, est pris de la nature des fossiles renfermés dans chaque couche, ces fossiles sont toujours généralement les mêmes dans les couches correspondantes, et présentent des differences d'espéces assez notables d'un systéme des couches à un autre système. C'est un signe do reconnoissance qui jusqu'à présent ne nous a pas trompés.” Annales du Museum d'histoire naturelle, tome XI. p. 307.
