ks
of its original or marine composition extremely obliterated, and many
subsequent veins of melted mineral matter interjected; we should then
reason to suppose that here were masses of matter which, though not
different in their origin from those that are gradually deposited at the
bottom of the ocean, have been more acted upon by subterranean heat and
the expanding power, that is to say, have been changed in a greater
degree by the operations of the mineral region. If this conclusion shall
be thought reasonable, then here is an explanation of all the peculiar
appearances of the alpine schistus masses of our land, those parts which
have been erroneously considered as primitive in the constitution of the
earth.

We are thus led to suppose, that some parts of our earth may have
undergone the vicissitudes of sea and land more than once, having been
changed from the summit of a continent to the bottom of the sea, and
again erected, with the rest of that bottom, into the place of land. In
that case, appearances might be found to induce natural philosophers to
conclude that there were in our land primary parts, which had not the
marine origin which is generally to be acknowledged in the structure
of this earth; and, by finding other masses, of marine origin,
superincumbent upon those primary mountains, they might make strange
suppositions in order to explain those natural appearances.

Let us now see what has been advanced by those philosophers who, though
they term these parts of the earth _primordial_, and not _primitive_, at
the same time appear to deny to those parts an origin analogous to that
of their secondary mountains, or strata that are aquiform in their
construction.

M. de Luc, after having long believed that the strata of the Alps had
been formed like those of the low countries, at the bottom of the sea,
gives an account of the occasion by which he was first confirmed in the
opposite opinion.[26] Like a true philosopher, he gives us the reason of
this change.

[Note 26: Lettres Physique et Morales sur l'Histoire de la Terre, tom.
2. pag. 206.]

"Ce fut une espece de _montagne_ tres commune, et que j'avois souvent
examinee qui dessilla mes yeux. La pierre qui la compose est de
la classe appellee _schiste_; son caractere generique est d'etre
_feuilletee_; elle renferme _l'ardoise_ dont on couvre les toits. Ces
_feuillets_ minces, qu'on peut prendre pour des _couches_, et qui le
font en effet dans quelques p