6 



ETNA. 



[Ch. XXVI. 



extinct and the rest now common in 



Mediterra 



of 



Phillippi obtained from the same district 76 species 

 which onlj 3 were extinct, while a larger number (109) 

 from Cefali in the suburbs of Catania yielded a proportion 

 of about 6 per cent, of extinct as compared to living species 

 A still larger collection of 142 species of shells which Dr 

 Aradas kindly lent to me in 1858 yielded 8 per cent, of 

 extinct species.* But these results are not so inconsistent 

 as they at first appear, because all the abundant species 

 (except Buccinum semistriatum, already mentioned as the only 

 extinct shell out of 100 found in the ancient tuflfe of Somma) 

 are now living in the neighbouring sea, whereas nearly all 

 the lost species are so exceedingly rare that sometimes sir 

 individuals of them have alone been found. Nevertheless I 

 regard the most ancient part of Etna as somewhat older than 

 the foundations of Vesuvius, and if I were asked what relation 

 the tertiary strata near Catania bear in point of age to our 

 British formations, I should answer that they are abont 

 the age of the Norwich crag. In reference therefore to the 

 Glacial Period T consider the oldest eruptions of Etna as of 

 older date than the era of greatest cold in central and 

 northern Europe. 



The reader must not suppose that the marine strata with 

 the associated basaltic rocks were first formed and then 

 raised to their present height above the level of the sea, and 

 that the great subaerial cone of Etna was a superstructure of 

 later date ; for there is reason to believe that a general and 

 gradual upheaval of the foundations of Etna, together with 

 the neighbouring country, was ahvays going on during the 



ne eruptions. And this slow upward 

 movement is probably still continuing, since raised beaches 

 or sands with littoral shells of living species often retaining 

 their colour are observed at the eastern base of Etna skirting 

 the shore, and there are also lines of inland cliff cut in the 

 tertiary strata and in the volcanic tuffs bearing witness to 

 successive alterations in the relative level of sea and land. 



. Fossil plants of living sjoecies in ancient tuffs of Etna.— We 



J See 'Mode of Origin of Mount Etna,' by tlio Author, riiil. Trans. Part II. for 



looo, p. 7 iO. 



mar 





