regarding the Rocks of the Red Sandstone Formation. 77 
evidently that they are igneous formations, which cannot in the 
least be explained as having been produced by the aqueous 
mode. 
That the amygdaloids being intimately connected with 
the porphyries and basalts, the}? are also evidently of igneous 
origin. 
In short, it is infinitely probable that all the preceding rocks 
are of igneous origin, and there is not a single probability that 
they are of aqueous origin, — a proposition which will ultimately 
be victoriously proved, malgre le deli de M, Beudant,^^ (p. 
203), by the best argument, the argumentum ad hominem, viz. 
the geognostical position f these masses. 
It is acknowledged that the pitchstones are every where asso- 
ciated with deposits of red sandstone, and that they form amongst 
these rocks, contrary, I am sorry to say, to M. Beudant’s asser- 
tion, veins *, imbedded masses., and even short heds^ (if this con- 
cession can alford any pleasure). The pitchstones in old red 
sandstone, which have hitherto been detected in Europe, are, 
those in the Isle of Arran, and some other parts of Scotland, at 
Mohorn, in the Valley of Trebitschthal, at Planitz, and at 
Grantola. Some lithoid varieties have also been observed around 
Ereyberg, in the Thuringerwald, and a similar variety, passing 
into the feldspathic basalt, is found in the Palatinate. These are 
the pnly known localities of this rock. All these I have visited, 
excepting the problematically situated mass of Grantola ; and in 
all these places I can confidently assert that their geognostical 
position is such as I have represented it above. In Arran, the 
pitchstones form veins ; and it is most singular to see M. Beu- 
dant holding out that pitchstones are never found in such a po- 
sition, when, besides myself,- Professor Jameson asserts and mi- 
nutely describes the fact. Let me be allowed to ask from whence 
can arise this disbelief of the truth .? Perhaps we may not alto- 
gether be wrong, if we imagine that we perceive here the predi- 
lection for a favourite idea, which has escaped against the 
author’s will. Nevertheless, it is clear, from his work, that he 
looks upon the basaltic veins as igneous products elevated in the 
• See M. Beudant’s Travels, p. 203, where he says that pitchstones are neves: 
in veins. 
