Professor Hoffmann 07i the Geology ofMassa Carrara, 126 



those altered rocks have been exposed, was accompanied by the 

 uprising of a granitic mass, which in this district did not remain 

 far under the bottom of the deeply-seated valleys. The whole 

 process, according to the facts deduced directly from observation, 

 took place very probably in the oldest period of the formation of 

 the chalk, for even the oldest strata of the Macigno, those re- 

 posing directly on the Jura limestone, are distinctly altered and 

 converted into Galestro. In the newer strata, we find not un- 

 frequently enclosed fragments of shining mica and clay slates, 

 which have been produced by the processes described. Mica 

 and talc slates and the marble altered from limestone, appear to 

 the south in the far projecting Promontorio Arge7UarOy in the 

 mountain group of Campiglia, and in the island like separated 

 Monte Pisani ; and to the north of the Apuanian Alp, there is 

 that mountain chain which surrounds the Gulf of Spezzia which 

 presents a very perfect representation on a small scale of the 

 phenomena we have described. Of the granite whose eruption at 

 this last period of its formation probably produced all these ap- 

 pearances, we know almost nothing in this part of the mainland 

 of Italy ; it is said to occur at Campiglia, and there only. What 

 is here concealed under the surface, is displayed rising above 

 the sea in an immense mass in Elba ; and a recent examination of 

 that island made by the author proves that there the granite 

 which forms mountains more than 3000 feet high, is intermixed 

 with the older limestone of the Apennines (under the Macigno), 

 and converts it by direct contact into marble. It is highly pro- 

 bable, that phenomena analogous to those ascribed to the action 

 of the granite in the district described, have in the Apennines 

 been produced by the out-break of the Galestro, whose appear- 

 ance must have followed immediately the completion of the 

 great Macigno formation. 



