Upon this set of
deposits comes a new bed of coal with the remains of a new forest, and.
above this again a layer of materials left by a second freshet, and so
on through a number of alternate strata. It is evident from these facts
that there have been a succession of forests, one above another, but
that in the intervals of their growth great floods have poured over the
marshes, bringing with them all kinds of loose materials, such as sand,
pebbles, clay, mud, lime, etc., which, as the freshets subsided, settled
down over the coal, filling not only the spaces between such trees as
remained standing, but even the hollow trunks of the trees themselves.
Let us give a glance now at the animals which inhabited the waters of
this period. In the Radiates we shall not find great changes; the three
classes are continued, though with new representatives, and the Polyp
Corals are increasing, while the Acalephian Corals, the Kugosa and
Tabulata, are diminishing. The Crinoids were still the most prominent
representatives of the class of Echinoderms, though some resembling the
Ophiurans and Echinoids (Sea-Urchins) began to make their appearance.
The adjoining wood-cut represents a characteristic Crinoid of the
Carboniferous age.
[Illustration]
Among the Mollusks, Brachiopods are still prominent, one new genus among
them, the Productus, being very remarkable on account of the manner in
which one valve rises above the other.
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