440 ON THE GEOLOGY OF THE 
In leaving the village of Tende, to ascend the tremendous 
pass of the Col di Cornio, by far the worst of any by which 
Italy is entered, the long desired change of rocks presented it- 
self, with the limestone of Tende resting in unconformable po- 
sition, and so distinct, that there was little possibility of de- 
ception. I traced this limestone to the summit of the mountain, 
where it rested directly on rocks which appeared to me to be- 
long to the transition series ;—from which, if my conjecture be 
correct, it is fair to infer, that the first limestone of Nice, is of the 
kind I was originally induced to suspect it belonged. It is very 
femarkable, however, that in England there is no similar lime- 
_ stone that I am aware of; nor do I know any in Scotland or 
Ireland which can be classed with it, notwithstanding the great 
extent which it occupies in this quarter of the globe. 
These few substances comprehend the whole of the rocks, so 
far as I had an opportunity of observing, that are to be found 
in the vicinity of Nice; but before quitting them, I must again re- 
vert to the First Limestone, in order to deseribe the fissures fill- 
ed with marine shells, which -prevailed not only in the rock of 
Nice Castle, but in the adjacent promontory of Mount Boron. I 
name these localities, as it was there only I had an opportuni- 
ty of examining them, though I have no doubt phenomena of 
the same kind abound throughout the neighbourhood. The 
fissures I now talk of, seem to have been formed after the con- 
solidation of the brescia, already described, and are literally 
filled, in some places, with sea shells, of species all now alive in 
the Mediterranean,—a circumstance which suggested to M. 
Risso the appropriate name of Marbre Mediterranéene. Many 
of these shells retain their pearly lustre and colour; and although 
combined in masses, perfectly solid, they preserve their con- 
tour and aspect almost as fresh as the day they were deposited. 
The fissures which contain these organic remains, are sometimes 
partly filled up with solid limestone, without any appearance of 
petrifactions, 
