"
M. Schreiber continues his reasoning upon those mineral appearances, in
adducing another argument, which I do not think equally conclusive. He
says, "Le filon de la Gardette devoit pareillement exister avant la
montagne calcaire, car s'il s'etoit forme apres, je ne voit pas la
raison pour laquelle il s'y seroit arrete court, et pourquoi il ne se
seroit pas prolonge dans cette espece de rocher." It is not necessary,
in the formation of a vein, that it should proceed in traversing all the
strata which then are superincumbent; it is reasonable to suppose, and
consistent with observation to find them stop short in proceeding from
one stratum to another. Had M. Schreiber found any pieces of the vein
contained in the calcareous rock, he would have had good reason for
that assertion; but, to conclude that fact from grounds which do not
necessarily imply it, is not to be permitted in sound reasoning, if
certainty is the object, and not mere probability.
SECT. II.--The Theory confirmed from Observations made on purpose to
elucidate the subject.
Having got a distinct view of the primary and secondary mineral bodies
or strata of the globe, and having thus acquired a particular object to
inquire after, with a view to investigate or illustrate this piece of
natural history, I was considering where we might most probably succeed
in finding the junction of the low country strata and alpine schistus.
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