22 NEWEST TERTIARY STRATA. [Ch. II. 



remains which characterize each of the three successive 

 periods above alluded to, approximate more nearly to the 

 assemblage of species now existing, in proportion as their 

 origin is less remote from our own era, or, in other words, the 

 recent species are always more numerous, and the extinct more 

 rare, in proportion to the low antiquity of the formation. But 

 the discordance between the state of the organic world indi- 

 cated by the fossils of the Subapennine beds and the actual 

 state of things is still considerable, and we naturally ask, are 

 there no monuments of an intervening period ? no evidences of 

 a gradual passage from one condition of the animate creation 

 to that which now prevails, and which differs so widely ? 



It will appear in the sequel, that such monuments are not 

 wanting, and that there are marine strata entering into the 

 composition of extensive districts, and of hills of no trifling 

 height, which contain the exuviae of testacea and zoophytes, 

 hardly distinguishable, as a group, from those now peopling 

 the neighbouring seas. Thus the line of demarcation between 

 the actual period and that immediately antecedent, is quite 

 evanescent, and the newest members of the tertiary series will 

 be often found to blend with the formations of the historical 

 era. 



In Europe, these modern strata have been found in the dis- 

 trict around Naples, in the territory of Otranto and Calabria, 

 and more particularly in the island of Sicily ; and the bare 

 enumeration of these localities cannot fail to remind the reader, 

 that they belong to regions where the volcano and the earth- 

 quake are now active, and where we might have anticipated 

 the discovery of emphatic proofs, that the conversion of sea 

 into land had been of frequent occurrence at very modern 

 periods. 



