belonging to the Arvc and the Rhone were the channels through wliich the sea made,
in process of time, its way from the high Alps, during one of its retreats. The boideverseme
«s, or irregular appearances, which now exist in the interior of those valleys,
seem strongly to corroborate this supposition, as well as the abrupt state of the strata of
the lateral mountains, their wide fissures, and the immense pieces of rock that now lie
at their basis; in short, the heterogeneity in their structure in general—all seem to
demonstrate that they really owe their origin to the causes suggested in tlie tenth and
subsequent articles.
The sea having then, in consequence of its gradual retreat, left uncovered that
largo or extensive tract of country situate behind the Jura, and between the Jorat
and the Rhine, with a few lakes dispersed in the hollows, of which some still exist,
as the Joux, the Morat, that of Neufchatel, Bienne, &;c. it may be naturally supposed
that it remained for a length of time in the extensive basin which then formed
the lake {which was even so large as to extend from the Salêve to the Jura, and from
Mont Sion to Mont Jorat, 8ic.), and, likewise, that it remained to a considerable height,
considering the extreme elevation of those mountains. Nevertheless, it appears, that
by some internal commotion, operating in that part of the Alps, the Jura suddenly
severed from top to bottom, and formed the defile of Cluse ; that, in consequence
thereof, the waters of the lake threw themselves into it with extreme violence, furrowing
to a great depth, in process of time, not only the sides of that mountain, but those
of the Vouaches, leaving them in the state we now see them,—carrying likewise away,
by their weight and velocity, the large and immense pieces of rock which had dctached
themselves from those mountains at the time of their separation. Thus was prepared
the Perle, or Loss, of the Rhône, which is visibly formed by those same fragments, and
thin calcareous strata (produced by the sediments of the sea at the time of its accidental
retreat), which bodies have since been, in great part, covered by a quantity of fragments,
successively brought down from the primitive mountains by the waters, and
now absolutely form the hills at the basis of the Credo, in the vicinity of the Perte:
for these waters, at first so long restrained, as already observed, finding at once an
aperture, flowed with such impetuosity, that, deeply furrowing the bottom of the bed of
the lake, which was, as 1 have before said, as high as are at present the hills of Cologny,
Labatie, and St. J e an, traced a number of valleys, which afterwards gave birth to
those beautiful hills now nearly contiguous to the lake, which time, and the culture of
the first or original inhabitants of the country, have since brought to their present state
of perfection.
Thus have I concisely stated my ideas concerning the original formation of the
Lake of Geneva, including the valleys which terminate in its vicinity,—ideas which I
really consider, in a great measure, to be equally applicable to the formation of all other
similar extensive basins, and in general to most of the valleys in the Alps or primitive
chain. Many other interestmg facts, or data, might also have been added to the above
remarks, had I not been fearful of becoming tedious, by dwelling too long on a subject
which can be interesting only to naturalists and philosophers. I shall however venture
to annex some few observations relative to the principal mountains that screen the lake,
beginning with the Saleve.
This mountain, which is situated south of Geneva, in a direction tending nearly
from north-north-east to south-south-west, is one of the most curious of those which
now shelter the lake, and is well worth the investigation of the naturalist, both on
account of its abrupt state, and the naked strata, which at once show their difference
of structure and direction, and on account of a deep, and wide hollow, which forms
on its summit the delightful Vale of Monetier, which divides the mountain into the
great and little Saleve.
The strata of the great Saleve are nearly parallel to the horizon, and those of the
little Saleve so extremely inclined, that they appear to lose themselves in the earth,
and seem exactly as though the mountain had been broken where the valley now is,
by the sudden sinking of the vaulted roof, or by the operation of some subterraneous
explosion, and subsequent falling in of some subterraneous cavern, into which sunk the
extremity of the little Saleve,—a circumstance which may probably have given the
strata that inclined direction, so conspicuous on that side of the mountain, and likewise
formed the valley itself. For a further explanation of this subject, see the Author's
Maritime Alps, page 53, fig. L and IL where the causes which may have produced the
various directions exhibited by most of the beds or strata of the secondary and tertiary
mountains are fully detailed.
But what, in this instance, appears forcibly to prove that the great and little Saleve
originally made one and the same mountain, is the great analogy of strata, similaritv of
structure, and relative thicknesses which exist between them, containing also the same
species of fossils, &C.