It has evidently been formed of
such argillaceous and siliceous materials, not only indurated, so as to
lose its character, as an argillaceous stone, but to have been brought
into that degree of fusion which produces perfect solidity. Of the same
kind are those hornstein rocks of the nature of flint, sometimes tending
to the nature of a fine sandstone. Here is the same induration of
sandstone by means of fusion, that in the argillaceous strata has
produced jasper. But oblique veins of jasper are represented as
traversing these last strata; now this is a fact which is not
conceivable in any other way, than by the injection or transfusion of
the fluid jasper among those masses of indurated strata.
All this belongs to the east side of the mountains. On the west, again,
we find the same species of strata; only these are not changed to such a
degree as to lose their original character or construction, and thus to
be termed differently in mineralogy.
Our author then proceeds. (p. 53.)
"Nous pourrons parler plus decisivement sur les _montagnes secondaires
et tertiaires_ de l'Empire, et c'est de celles-la, de la nature, de
l'arrangement et du contenu de leurs couches, des grandes inegalites et
de la forme du continent d'Europe et d'Asie, que l'on peut tirer avec
plus de confiance quelques lumieres sur les changemens arrives aux
terres habitables.
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