200 M. Brokgniaut on the position 



not quote him solely for the purpose of compliment, but as 

 an authority on which I depend, to give more force to the 

 general conclusions I draw from my observations. 



M. Brocchi * in the first place establishes, that the rocks 

 which I have described under the names of schistose mica- 

 ceous sandstone, and spangled argillaceous slate (phyllade 

 paillette), and v.'hich he names macigiio, are not argillaceous 

 schists ; he refers them to greywacke, and he admits vege- 

 table remains in it, at many points, as at Fiesole, Sestola, &c. 

 but never marine shells, at least in that of Tuscany. 



He refers this rock, the smoke grey compact limestone 

 with a scaly fracture, &c. and the calcareous sandstone of 

 the environs of Florence, named pietra-forte, to the transi- 

 tion class, yet notices an ammonite in it. He does not give 

 these limestones the name of Apennine limestone ; but he 

 applies this name to a homogenous white limestone, con- 

 taining chert (des silex), often blending its characters with 

 the Jura limestone, but which differs from it by the fineness 

 of its grain, &c. 



He considers the serpentine as the primitive rock most 

 generally spread over the Apennines of Eastern Liguria, 

 "where, he says, it is covered by transition limestone, argil- 

 laceous schist, greywacke, &c. and he cites Spezia, Monte- 

 Cerboli,+ and even the black transition limestone at Pian- 

 del-Monte. It is accompanied by jasper at Fiegline near 

 Prato (it is that of Monte Ferrato described above) ; he 

 conjectures that the jasper forms part of the general ground, 

 posterior to the serpentine, and even formed long after it.J 

 He states the opinion of M, Bardi on the position of the 

 jasper beneath the serpentine of Monte-Ferrato ; but se- 

 duced by the generally received idea, that the serpentine is 

 of primitive formation, he desires him to assure himself of 



• Conchiologia fossile subapennina con osservazioni geologiche sugli 

 Apennini e sul suolo adjacente. Milano, 1814. 

 f Tome 1. p. 36. 

 J Ibid. p. 49. 



