are indurated or consolidated and extremely elevated, without the least
appearance of subterraneous fire or volcanic productions, it will now be
proper to compare with this another tract of country, where the strata,
though not erected to that extreme degree, have nevertheless been
evidently elevated, and, which is principally to the present purpose,
are superincumbent upon immense beds of basaltes or subterranean lava.
This mineral view is now to be taken from M. de Luc, Lettres _Phisiques_
et Morales, Tom. 4.

This naturalist had discovered along the side of the Rhine many ancient
volcanos which have been long extinct; but that is no part of the
subject which we now inquire after; we want to see the operations of
subterraneous lava which this author has actually exposed to our view
without having seen it in that light himself. He would persuade us, as
he has done himself, that there had been in the ancient sea volcanic
eruptions under water which formed basaltic rocks; and that those
eruptions had been afterwards covered with strata formed by the deposits
made in that sea; which strata are now found in the natural position in
which they had been formed, the sea having retreated into the bowels of
the earth, and left those calcareous and arenaceous strata, with
the volcanic productions upon which they had been deposited, in the
atmosphere.

It would be out of place here to examine the explanation which this
author has given with regard to the consolidation of those deposited
strata which is by means of the filtration of water, but as in this
place there occurs some unusual or curious examples of a particular
consolidation of limestone or calcareous deposits, as well as similar
consolidations of the siliceous sort, it may be worth while to mention
them in their place that so we may see the connection of those things,