e of Perm in Russia, where rocks of this age are
extensively developed. Formerly these rocks were grouped with
the succeeding formation of the Trias under the common name of
"New Red Sandstone." This name was given them because they contain
a good deal of red sandstone, and because they are superior to the
Carboniferous rocks, while the Old Red Sandstone is inferior.
Nowadays, however, the term "New Red Sandstone" is rarely employed,
unless it be for red sandstones and associated rocks, which are
seen to overlie the Coal-measures, but which contain no fossils by
which their exact age may be made out. Under these circumstances,
it is sometimes convenient to employ the term "New Red Sandstone."
The New Red, however, of the older geologists, is now broken up
into the two formations of the Permian and Triassic rocks--the
former being usually considered as the top of the Palaeozoic series,
and the latter constituting the base of the Mesozoic.

In many instances, the Permian rocks are seen to repose unconformably
upon the underlying Carboniferous, from which they can in addition
be readily separated by their lithological characters. In other
instances, however, the Coal-measures terminate upwards in red
rocks, not distinguishable by their mineral characters from the
Permian; and in other cases no physical discordance between the
Carboniferous and Permian strata can be detected. As a general
rule, also, the Permian rocks appear to pass upwards conformably
into the Trias. The division, therefore, between the Permian
and Triassic rocks, and consequently between the Palaeozoic and
Mesozoic series, is not founded upon any conspicuous or universal
physical break, but upon the difference in life which is observed
in comparing the marine animals of the Carboniferous and Permian
with those of the Trias. It is to be observed, however, that
this difference can be solely due to the fact that the Magnesian
Limestone of the Permian series presents us with only a small,
and not a typical, portion of the marine deposits which must have
been accumulated in some area at present unknown to us during the
period which elapsed between the formation of the great marine
limestones of the Lower Carboniferous and the open-sea and likewise
calcareous sediments of the Middle Trias.

The Permian rocks exhibit their most typical features in Russia
and Germany, though they are very well developed in parts of
Britain, and they occur in North America. Whe