n well developed,
they exhibit three main divisions: a lower set of sandstones,
a middle group, generally calcareous, and an upper series of
sandstones, constituting respectively the Lower, Middle, and Upper
Permians.

In Russia, Germany, and Britain, the Permian rocks consist of
the following members:--

1. The _Lower Permians_, consisting mainly of a great series
of sandstones, of different colours, but usually red. The base
of this series is often constituted by massive breccias with
included fragments of the older rocks, upon which they may happen
to repose; and similar breccias sometimes occur in the upper
portion of the series as well. The thickness of this group varies
a good deal, but may amount to 3000 or 4000 feet.

2. The _Middle Permians_, consisting, in their typical development,
of laminated marls, or "marl-slate," surmounted by beds of magnesian
limestone (the "Zechstein" of the German geologists). Sometimes
the limestones are degenerate or wholly deficient, and the series
may consist of sandy shales and gypsiferous clays. The magnesian
limestone, however, of the Middle Permians is, as a rule, so well
marked a feature that it was long spoken of as _the_ Magnesian
Limestone.

3. The _Upper Permians_, consisting of a series of sandstones
and shales, or of red or mottled marls, often gypsiferous, and
sometimes including beds of limestone.

In North America, the Permian rocks appear to be confined to the
region west of the Mississippi, being especially well developed
in Kansas. Their exact limits have not as yet been made out,
and their total thickness is not more than a few hundred feet.
They consist of sandstones, conglomerates, limestones, marls,
and beds of gypsum.

The following diagrammatic section shows the general sequence of
the Permian deposits in the north of England, where the series
is extensively developed (fig. 133):--

[Illustration: Fig. 133. GENERALISED SECTION OF THE PERMIAN ROCKS
IN THE NORTH OF ENGLAND.]

The record of the _life_ of the Permian period is but a scanty
one, owing doubtless to the special peculiarities of such of the
deposits of this age with which we are as yet acquainted. Red rocks
are, as a general rule, more or less completely unfossiliferous, and
sediments of this nature are highly characteristic of the Permian.
Similarly, magnesian limestones are rarely as highly charged with
organic remains as is the case with normal calcareous deposits,
especially when