Dr. Holland on the manufacture , &c. 295 
miles distant. The ascent towards the mountain from Sestri, 
the nearest point on the coast, is uniform, though rugged; 
following the .©curse of the rapid torrent, called the Panigaro. 
The ravine of this torrent is interesting, inasmuch as it forms 
the division between a high ridge of serpentine, which occurs 
on its eastern side; and an insulated formation of magnesian 
limestone, which composes the hill of Monte del Gazzo, to 
the north of Sestri, and other adjacent heights on the western 
side of the stream. This magnesian limestone, which in 
Monte del Gazzo reaches a height of more than 1200 feet, 
forms in various places naked cliffs, distinctly showing the 
stratification of the rock : which stratification, as well as the 
colour of the limestone, is very remarkably contrasted with 
the character of the serpentine rocks, on the opposite side of 
the ravine. 
The latter, together with some argillaceous and chlorite 
slate of the same formation, compose for several miles, the 
ridge of hills between the torrent of Panigaro, and the broader 
valley of the Polcevera to the east ; stretching upwards in a 
direct line from the sea towards the summit of Monte della 
Guardia. The primitive schistus is doubtless the base of this 
formation ; the serpentine reposes upon it in vast unconform- 
able masses ; exhibiting a surface of great ruggedness, and 
almost entirely bare of vegetation ; with the dark green colour , 
and usual resinous lustre of this mineral. 1 observed much stea- 
tite, talc, and asbestus in it ; also many small veins of pyrites. 
The asbestus of this place affords numerous fine specimens to 
the cabinets of Genoa. 
Monte della Guardia may be considered the summit of this 
ridge. It exposes to the south a somewhat concave outline ; 
