South-west and North of France, and South of Germany. 131 
there running parallel to the plane of stratification of the slates. 
This statement, contrary to the opinion of the most learned geo- 
logists, is supported by the limited space of these masses , by the 
existence of innumerable true granite veins , by the phenomena 
exhibited by an infinite number of small granitoid veins , which 
are associated with the last, by the fragments of slate im- 
bedded in the granite , and the particular appearances observable 
in the roclcs near the junction fthe granite. 
On these different points I may only here observe, that the 
distinction of two granites in the Pyrenees forms no objection to 
my ideas ; and farther, that the fragments of slate in granite are 
seen in the Pyrenees not merely in small pieces, but sometimes 
in immense wedge-shaped masses, or even hillocks, supported 
by granite. No country exemplifies this more clearly ; and the 
fact explains the imbedded masses of slate in the porphyry 
of Schemnitz mentioned by Beudant in his Travels in Hun- 
gary. The alterations in the condition of the slates near the 
granite, similar to those near the prophyry of Vendee and 
the Erzgebirge, are to be seen in the Pyrenees on a great 
scale. Whoever has seen the beautiful series of granitic 
veins which cut and sometimes support the granite of Louerup, 
Cierp and Massat, will no longer doubt the igneous origin of 
granite posterior to the slate formation. If the rock named Blaue 
Kuppe be a clear proof of the truth of the igneous theory respect- 
ing basalt, these places shew that the true origin of granite had 
also been discovered by Plutton; and our respect for the views of 
this original thinker is increased by observing, that the masses of 
granular limestone seem to be in close dependence upon the masses 
of granite. Where these appear, the compact limestone is more 
or less changed, and in it minerals have been produced, for 
which we search in vain in the other parts of the slate formation. 
But Plutton furnished no explanation of the most difficult 
point, I mean the origin of gneiss, of crystalline slate, connected 
with transition slate. The Pyrenees seem also to afford a hint 
of this particular process of nature. Gneiss is not, like granite, 
an igneous product ; many objections oppose themselves to such 
an opinion, and the shelly granular limestone imbedded in the 
gneiss of the Pyrenees, and its passage into transition slate, seem 
to render it very improbable. Viewing the crystalline slates 
i 2 
