Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/337

 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.

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