M. Beudant m the Pitchstme qf Saxmy, 
ed them in 1817. There they assuredly form a part of a sand- 
stone deposit which fills the small valley in which Grantola is 
situated, and which lies to the west upon transition limestones 
and rocks of mica-slate, stretching toward the east over a consi- 
derable extent. These sandstones have all the characters of the 
red sandstone, and it is remarkable that they present indications 
of coal, which would seem to give additional strength to this 
opinion. The following are the varieties which I found at 
Grantola, in the deposit alluded to 
1. Quartzose arenaceous deposits, including rolled pebbles of 
mica-slate and quartz, and abundance of scales of mica. They 
rest immediately upon the gneiss. 
% Above these sandstone deposits, there occur fine sands 
more or less argillaceous, in the midst of which there exist ah 
ternating beds of more or less compact red matters, which have 
all the characters of claystone, and which pass insensibly into 
the sandstones, which have all the characters of varieties of red 
sandstone. These last sandstones appear to form considerable 
masses ; they occur on both sides of the valley. On the right, 
above Grantola, they occur associated with conglomerates, 
having very numerous and very large pebbles, which are yet 
perfectly similar to those of the red sandstone formation. 
3. The species of claystone which I have just mentioned, 
terminate by forming of themselves hills of considerable size, 
where they assume still more distinctly the characters of those 
which we have mentioned at Freyberg. They present in some 
points a porphyritic structure ; in others, they exhibit white 
spots, which are formed of a very soft substance, like lithomarge. 
This substance becomes more or less abundant ; but it happens 
that it is destroyed at the surface, being washed away by the 
waters, and leaving irregular cavities, which give a scoriaceous 
aspect to the rock ; and, in fact, it appears that these varieties 
have occasionally been considered as true scoriae? 
4. Through successive passages, we come from the porphy?? 
ritic claystone to a true porphyry of a brown colour, which has 
the greatest analogy with those which occur in the similar beds 
of Chemnitz in Saxony. The basis of these porphyries becomes 
gradually more compact, its fracture more conchoidal, and its 
lustre resinous. We come then, by degrees, to the vitreous rock^ 
