This view,
at any rate, would explain some of the more puzzling physical
characters of the formation, and would not be definitely negatived
by any of its fossils.
A large portion of the Permian series, as already remarked, consists
of sandstones and marls, deeply reddened by peroxide of iron, and
often accompanied by beds of gypsum or deposits of salt. In strata
of this nature few or no fossils are found; but their shallow-water
origin is sufficiently proved by the presence of the footprints
of terrestrial animals, accompanied in some cases by well-defined
"ripple-marks." Along with these are occasionally found massive
breccias, holding larger or smaller blocks derived from the older
formations; and these have been supposed to represent an old
"boulder-clay," and thus to indicate the prevalence of an arctic
climate. Beds of this nature must also have been deposited in
shallow water. In all regions, however, where the Permian formation
is well developed, one of its most characteristic members is a
Magnesian limestone, often highly and fantastically concretionary,
but containing numerous remains of genuine marine animals, and
clearly indicating that it was deposited beneath a moderate depth
of salt water.
It is not necessary to consider here whether this formation can
be retained as a distinct division of the geological series.
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