of Serpenlmr,S(c. in the Apennines. 183 



Alpine limestone, and probably more recent than the tran- 

 sition rocks mentioned at the commencement of this memoir. 



The hills of Castellamonte and Baldissero, at the foot of 

 the eastern side of the Alps, eight leagues to the N.W. of 

 Turin, present the serpentine formation in a state of alter- 

 ation that seems to remove it entirely from the rocks I have 

 just described or mentioned. 



But when Ave do not attach ourselves too much to mine- 

 ralogical details ; when we place ourselves as it were at a 

 distance, so as to cause these details to disappear, and to 

 see the whole together, the serpentine formation is recog- 

 nised in these hills with all its essential circumstances. 

 Diallage serpentine occurs as the predominant rock, especi- 

 ally at Baldissero, but is rarely solid ; it is even extremely 

 altered, traversed by a multitude of veins of magnesite (B). 

 The diallage rock, instead of being a bed in the midst of, 

 or beneath the rock, appears to be disseminated in nodules, 

 (rf) pure at their centres, but more and more altered from 

 the centre to the surface. 



The jasper is still found, but it passes into hornstone ; ft 

 is yellowish or greenish, and instead of occurring in beds 

 extended beneath the diallage rock, it forms nodular veins 

 (c), that are irregularly ramified in the midst of the magne- 

 sian serpentine. It is not abundant, at least in the places 

 I have visited ; but it appears to have been replaced by 

 every variety of opal, which is disposed in small irregular 

 plates (fl), mammilated on the surface, in the midst of 

 magnesite veins. Such are the characteristic features of 

 these mountains which I have no intention of describing ;' 

 for, to make them known, more time must be devoted to it 

 than I have given, and details must be entered into that 

 would too much augment the extent of this memoir. 



This formation is only covered by one of rolled rocks (A), 

 to which I shall elsewhere return : this is an interesting 

 point to remark, because it presents the commencement of 

 the tertiary rocks (sediment superieur), that cover so large a 

 portion of Italy from Turin to the extremity of Calabria. 



