water, and laid down in a mud paste, afterwards hardened. Volcanic
disturbances break up the rocks; the pieces are worn in seas; and a
deposit of conglomerate is the consequence. Of porphyry, there are
some such pieces in the conglomerate of Devonshire, three or four
tons in weight. It is to be admitted for strict truth that, in some
parts of Europe, the carboniferous formation is followed by superior
deposits, without the appearance of such disturbances between their
respective periods; but apparently this case belongs to the class of
exceptions already noticed. {93} That disturbance was general, is
supported by the further and important fact of the destruction of
many forms of organic being previously flourishing, particularly of
the vegetable kingdom.



ERA OF THE NEW RED SANDSTONE. TERRESTRIAL ZOOLOGY COMMENCES WITH
REPTILES. FIRST TRACES OF BIRDS.



The next volume of the rock series refers to an era distinguished by
an event of no less importance than the commencement of land animals.
The New Red Sandstone System is subdivided into groups, some of which
are wanting in some places; they are pretty fully developed in the
north of England, in the following ascending order:- 1. Lower red
sandstone; 2. Magnesian limestone; 3. Red and white sandstones and
conglomerate; 4. Variegated marls. Between the third and fourth
there is, in Germany, another group, called the Muschelkalk, a word
expressing a limestone full of shells.