ITALY. LETTER XXIII. 30! 



LETTER XXIIL 



I 



Turin, June 36.^! 



TH E trafl of land between Genoa and this 

 place confifts of the following varieties of 

 mountains and hills. 



1. Behind Genoa, grey and blackim limeftone. 



2. The hills of the Bochetta confift of black 

 undulated flate, green Gabbro or Serpentine-ftone, 

 polzevera or gabbro with calcareous veins, argil- 

 laceous (late, glimmery and fplendentas fifh-fcales; 

 .and finally, of grey limeftone. Thefe ftones alter- 

 nated without any fenfible order in the fituation ; 

 and it feemed as if, in the fame hill, one part 

 confided of flate, another of Gabbro, and another 

 of limeftone. This feems to confirm that clay is 

 a condiment part of Serpentine or Gabbro, which 

 differs from the flate and its clay but by a mixture 

 of feveral other particles. The calcareous veins 

 in the Gabbro produced the polzevera near the 

 adjaceut limeftone. Some parts of the green Gab- 

 bro 



