he gypseous red marl of Aix, in Provence, formerly
supposed to be a marine secondary group, is now acknowledged to be a
tertiary freshwater formation. In Nova Scotia one great deposit of red
marl, sandstone, and gypsum, precisely resembling in mineral character
the "New Red" of England, occurs as a member of the Carboniferous group,
and in the United States near the Falls of Niagara, a similar formation
constitutes a subdivision of the Silurian series.[238]

Nor was the nomenclature commonly adopted in geology without its
influence in perpetuating the erroneous doctrine of universal
formations. Such names, for example, as Chalk, Green Sand, Oolite, Red
Marl, Coal, and others, were given to some of the principal
fossiliferous groups in consequence of mineral peculiarities which
happened to characterize them in the countries where they were first
studied. When geologists had at length shown, by means of fossils and
the order of superposition, that other strata, entirely dissimilar in
color, texture, and composition, were of contemporaneous date, it was
thought convenient still to retain the old names. That these were often
inappropriate was admitted; but the student was taught to understand
them in no other than a chronological sense; so that the Chalk might not
be a white cretaceous rock, but a hard dolomitic limestone, as in the
Alps, or a brown sandstone or green marl, as in New Jersey, U. S. In
like manner, the Green Sand, it was said, might in some places be
represented by red sandstone, red marl, salt, and gypsum, as in the
north of Spain. So the oolitic texture was declared to be rather an
exception than otherwise to the general rule in rocks of the Oolitic
period; and it often became necessary to affirm that no particle of
carbonaceous matter could be detected in districts where the true Coal
series abounded. In spite of every precaution the habitual use of this
language could scarcely fail to instil into the mind of the pupil an
idea that chalk, coal, salt, red marl, or the Oolitic structure were far
more widely characteristic of the rocks of a given age than was really
the case.

There is still another cause of deception, disposing us to ascribe a
more limited range to the newer sedimentary formations as compared to
the older, namely, the very general concealment of the newer strata
beneath the waters of lakes and seas, and the wide exposure above waters
of the more ancient. The Chalk, for example, now seen str