Mr. Parkinson on the Strata^ ^c, 325 



nated 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 of 

 consequence from them, on these subjects, it is necessaiy 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 



* This mode of conducting our inquiries was long since recommended by Mr. W. 

 Smith, who first noticed that cer/ am fossils are peculiar to, and are oiiljj found lodged 

 in, particular strata ; and wlio first ascertained the constancy in the order of super- 

 position, and the contimdtij of the strata of this island. It will appear from the following 

 quotation, that these observations hare lately also occurred to Messrs. Cuvier and 

 Brongniart whilst examining into the nature of the strata of the neighbourhood of 

 Paris. " Cctte Constance dans I'ordrc do superposition des couches les plus minces, ct 

 *' sur une etendue de 12 myriametres au moins, est, selon nous, un des faits les plus 

 " remarquables que nous ayons conctates dans la suite de nos recherches. II doit en 

 " resulter pour les arts et pour la geologic des consequences d'autant plus intercs- 

 •' santes, qu'elles sont plus fures. 



" Le moyen que nous avons employe pour reconnoitre au milieu d'un si grand nombre 

 " de lits calcaires, un lit deja observe dans un canton tres-eloign , est jiris do la nature 

 " des fossiles renfermes dans chaquc couchc, ccs fossilcs sont toujours generalement 

 *' les niemcs dans les couches correspondantcs, et presentcnt des cliflcrencos d'especcs 

 " assez notables d'un sysfeme des couches a un autre systemc. C'est un signe dc recon- 

 " noissancc qui jusqn'a present nc nous a pas trompes." Aanales du Museum d'his- 

 toirc naturcllc. (omc XI. p. 307. 



