es et des poudingues. On fait que ce dernier genre est
ordinairement classe parmi les montagnes tertiaires, ou de la formation
la plus recente. Mais ces poudingues-ci, qui ne contiennent aucun
fragment de pierre calcaire, qui ne sont meme point unis par un gluten
calcaire, ne sont vraisemblablement pas posterieures a la formation des
montagnes calcaires, ou du moins ils ne doivent point etre confondus
avec ces gres et ces poudingues de formation nouvelle, qui entrent dans
la composition des montagnes du troisieme ordre.

"Quant aux ardoises que se trouvent interposees au milieu de ces gres
et de ces poudingues, Sec. 1054, elles sont de nature argilleuse, et dans
l'ordre des pierres que l'on nomme secondaires.

"Ces ardoises, de meme que toutes les pierres de ces montagnes, ont
leurs couches dans une situation verticale: mais nous avons vu qu'il y a
lieu de croire qu'elles ont ete anciennement horizontales."

It is singularly fortunate that such remarkable appearances, as are
found in the rocks of this place, had called the attention of M. de
Saussure to investigate a subject so interesting to the present theory;
and it is upon this, as well as on many other occasions, that the value
of those observations of natural history will appear. They are made by a
person eminent for knowledge; and they are recorded with an accuracy and
precision which leaves nothing more to be desired.

From _Martigny_ to _St. Maurice_, about three leagues, there is a most
interesting valley of the Rhone, through which this river makes its way
from the _Vallais_, or great valley above, among those mountains which
seem to have shut up the _Vallais_, and through which the river must
pass in running to the lake. M. de Saussure found some singular masses,
which attracted his attention, in examining the structure of the rocks
on the left side of this little valley. Like a true philosopher, and
accurate naturalist, he desired to compare what was to be observed
in the other side of this valley of the Rhone, which he had found so
singular and so interesting on that which he had examined. Accordingly,
in Spring 1785, he made a journey for that purpose. In this survey he
found the most perfect correspondence between the two sides of this
valley, so far as rocks of the same individual species, and precisely in
the same order, are found upon the one side and upon the other.

This author, after describing those particular appearances, sums up
the evidence