222 Successive Geological Development. 



equivalents of the lias, but also as corresponding in age to 

 the Oxford clay or middle oolite, as, for example, at Cbardon- 

 net near Brian^on, to which Mr Bunbury has alluded in his 

 paper.* Hence we should be called upon to believe that cer- 

 tain species of Sigillaria and Stigmaria, of Asterophyllite, 

 Lepidodendron, and Calamite, together with a multitude of 

 Ferns, had lived on through the Carboniferous and Permian 

 periods, through the lower and upper Triassic, and still sur- 

 vived in the eras of the lias, inferior oolite, and Oxford clay, 

 without permitting any of the characteristic species of these 

 several epochs to intrude themselves into their company. 



The late celebrated palaeontologist, M. Voltz, when he 

 conversed with me on this subject in 1833 at Strasburg, had 

 satisfied himself that certain islands in the tropics quite iso- 

 lated from other lands, had continued to grow the plants in 

 question throughout the vast interval of time which separated 

 the coal from the lias, and that fragments of their stems and 

 leaves were drifted by a marine current over the ocean and 

 buried with belemnites and marine shells in muddy liassic 

 sediment thrown down in the latitude of the Alps. However 

 violent such an hypothesis may appear, no other has since 

 been invented of a more plausible kind, unless w^e escape 

 from the difficulty by explaining away what is called " physical 

 evidence" or the " order and position of the beds." It is 

 conceded on all hands that in no region of the globe, hitherto 

 studied by geologists, has the original arrangement of strata 

 been subsequently so much altered by complicated foldings 

 and dislocations, and by metamorphic action, which last has 

 sometimes superinduced a crystalline structure on older for- 

 mations, while those of newer date retain their ordinary 

 mineral condition. 



In a district of such chaotic confusion, we may well despair 

 of being able to trace out the true chronological sequence of 

 fossil iferous groups, and we therefore hail with pleasure the 

 discovery of an undisturbed region not very remote, where 

 strata wearing the same mineral and palaeontological aspect 

 occur. It appears that recently, in 1850, the two Italian 



* Quart. Journ. Geol. Soc, vol. v., pp. 133, 136. 



