1 



388 M. Brongniart on the position 



part of the mountain exposed to the S.W. shews the naked 

 rock in many places. Oblique beds are there obserred, 



1st. Of a fine compact limestone, of a pale ash grey 

 colour, of a conchoidal fracture, traversed by numerous 

 calcareous spathose veins, and completely resembling that 

 of Rochetta and Pietramala. 



2ndly. Of a hard and micaceous calcareous sandstone 

 traversed by spathose veins, and entirely resembling that of 

 Pietramala, Barigazzo, &c. 



Sdly. Of a dull marly argillaceous slate. 



These three rocks alternate together, I do not say with- 

 out real order, but without any order as yet understood • 

 there is not as far as this any difTerence between this for- 

 mation and that which is beneath the serpentines at Rochetta 

 and Pietramala. The limestone is a rock common to the 

 three points ; the calcareous sandstone, common to Pietra- 

 mala, and Doccia, establishes the resemblance of tliis latter 

 place to Rochetta, where I have not seen the sandstone, and 

 to Barigazzo, where I have not seen the limestone. 



But there is here a peculiarity in this limestone that I 

 have not observed in the other places, it is the presence of 

 hornstone in numerous nodules, placed in the same line. 

 This peculiarity seems greatly to remove this limestone from 

 that which is commonly considered as belonging to the tran- 

 sition rocks. 



The high hill of Fiesole, on the N.E. of Florence, form- 

 ing, like that of Doccia, part of the first line of the Apen- 

 nines on this side, is celebrated for the numerous quarries 

 there worked, and which furnish the stones employed in all 

 the works at Florence. It shews, from about a third of its 

 height to the summit, a very solid micaceous and calcareous 

 sandstone, of a greyish, blueish, and yellowish colour, in 

 beds sometimes horizontal, sometimes highly inclined in dif- 

 ferent directions, but more particularly towards the north. 

 This sandstone, completely resembling that of Doccia, Pie- 

 tramala, Barigazzo, &c. alternates with beds, more or less 

 thick, of yellowish micaceous argillaceous slate, and exposes 

 fragments of brownish schistose sandstone, which have been 



