METAMORPHIC ROCKS. 251 



Let me here make a special mention of the Parian 

 and Carrara marbles, to which the noblest works of 

 sculpture have given such celebrity, and which were so long 

 regarded in our geological collections as the types of primi- 

 tive limestone. The action of granite has been exerted 

 sometimes by immediate contact, as in the Pyrenees ; ( 277 ) 

 sometimes through intermediate beds of gneiss or of mica 

 slate, as in Greece, and the islands of the ^Egean 

 Sea. In both cases the transformation of the calcareous 

 rock has been cotemporaneous with the granite, but the 

 process has been different. It has been remarked that in 

 Attica, in the island of Euboea, and in the Peloponnesus, 

 " the limestone superposed on mica slate is more beautiful and 

 more crystalline, as the mica slate is most pure, or least argil- 

 laceous," and it is known that mica slate and becta of gneiss 

 shew themselves at many pcSts beneath the surface m Paros 

 and Antiparos.( 278 ) Xenophanes of Colophon (who supposed 

 the whole surface of the earth to have been originally covered 

 by the sea), remarked, in a notice preserved by Origen, ( 279 ) 

 that marine fossils had been found in the quarries of Syra- 

 cuse, and the impression of a small fish (a sardine) at the 

 bottom of that of Paros : supposing the latter statement to 

 have been correct, we might infer the presence of a fossiliferous 

 bed but partially metamorphosed. The Carrara (Luna) marble, 

 which, from the Augustan era, and even from an earlier period, 

 has afforded the principal supply of statuary marble, and will 

 probably continue to do so unless the quarries of Paros are 

 reopened, is a bed, altered by plutonic action^ of the same 

 calcareous sandstone (macigno), which in the insulated Alp 

 of Apuana, shews itself between micaceous and talcose 

 schists. ( 28 ) A very different origin has, indeed, been 

 assigned for marble in some other localities; and whether in 



