• 



T 









Ch. XIV.] 



IN THE ANIMATE WORLD. 



313 



world having been effected < without the intervention of any 

 convulsion or abrupt changes, certain species having from 

 time to time died out, and others having been introduced, 

 until at length the existing fauna was elaborated.' 



In no part of Europe is the absence of all signs of man 

 or his works, in strata of comparatively modern date, ^ more 

 striking than in Sicily. In the central parts of that island 

 we observe a lofty table-land and hills, sometimes rising to 

 the height of 3,000 feet, capped with a limestone, in which 

 from 70 to 85 per cent, of the fossil testacea are specifically 

 identical with those now inhabiting the Mediterranean. 

 These calcareous and other argillaceous strata of the same 

 age are intersected by deep valleys which have been gradu- 

 ally formed by denudation, but have not varied materially in 

 width or depth since Sicily was first colonised by the Greeks. 

 The limestone, moreover, which is of so late a date in geo- 

 logical chronology, was quarried for building those ancient 

 temples of Girgenti and Syracuse, of which the ruins carry 



emote 



If we are lost 



in conjectures when speculating on the ages required to 

 lift up these formations to the height of several thousand 



much 



when the same 

 waters ! 



formed 



The intense cold of the Glacial period was spoken of in 

 the tenth chapter. Although we have not yet succeeded in 

 detecting proofs of the origin of man antecedently to that 

 epoch, we have yet found evidence that most of the testacea, 

 and not a few of the quadrupeds, which preceded, were of the 

 same species as those which followed the extreme cold.^ m - 



To 



may 



the distribution of species, it seems to have done little in 

 effecting their annihilation. We may conclude therefore 

 from a survey of the tertiary and modern strata, which con- 



stitute a more com 



and unbroken series than rocks 

 of older date, that the extinction and creation of species 

 has been, and is, the result of a slow and gradual change m 



the organic world. 



JJnifi 



f 



considered, thirdly, in reft 



to 



