330 Horner's Geological Address. 



Ammonites in a prolongation of the same bed ; and in reply to 

 M. Agassiz, also present, affirmed, that he had found this bed 

 containing belemnites and coal plants over an extent of from 

 25 to SO leagues. We have thus the same species of plants 

 continuing to exist throughout the whole Carboniferous, Per- 

 mian, and Triassic periods, and into that of the lower portion 

 of the oolite age. I need not say how important a bearing 

 this remarkable fact has on the theories of climate, and of the 

 prevalence of an atmosphere loaded with carbonic acid gas 

 during the Carboniferous period. 



M. Adolphe Brongniart, in his memoir above cited, thus 

 accounts for the anomalous position of these coal plants : — 

 A I'epoque o^ la formation du lias se deposait en Europe, notre 

 globe presentait tres-probablement deux regions tres-diverses 

 par leur climat et par les vegetaux qui y croissaient. L'une 

 comprenait TEurope et peutetre toute la zone temperee, et 

 6tait habitee par des vegetaux fort differens de ceux qui y crois- 

 saient a une epoque plus reculee, et qui avaint donne naissance 

 aux couches de houille ; I'autre s'etendant sans doute sur les 

 parties plus chaudes du globe, etait encore couverte des memes 

 vegetaux qui, dans des temps plus anciens, avaient habite la 

 region europeene, et forme les depots houillers. Les vegetaux 

 de cette partie du globe pouvant dans certaines circonstances, 

 ^tre transportes dans les regions plus temperees, auraient don- 

 ne lieu a ces anomalies apparentes que presentent les terrains 

 d'anthracite des Alpes qui, d'apres les observations geologiques 

 et zoologiques, appartiennent ^ Tepoque de formation du lias, 

 et dont les vegetaux sent cependant les memes que ceux du 

 terrain houiller.'' This theory therefore admits that the same 

 species of plants existed through the whole series of ages that 

 passed from the time of the deposition of the carboniferous 

 series to that of the lias ; that they and belemnites were co- 

 existing, but in different regions. It is not very easy to con- 

 ceive how such delicate vegetable bodies should be drifted the 

 vast distance between a tropical and temperate zone, to form 

 parts of thin continuous strata thousands of square miles in ex- 

 tent, in successive layers of great thickness on the same spot, 

 in the depths of the sea. 



It is extremely improbable that this case in the Tarentaise 



