strict of
Hungary was suspected of containing the seeds of subterranean fire, and
the suspicion has been confirmed by an actual eruption. Germany and
Bohemia contain a great number of extinct volcanoes, as does the south
of France, and particularly Auvergne. In Spain, too, the proofs of a
volcanic agency are clear and decisive.

Greenland and Iceland present a third group of volcanoes; in the latter
island, a single volcano was in a state of continuous eruption for five
or six years. The Azores, the Canaries and Madeiras, also contain
numerous volcanoes, both active and extinct, as do the Caribbean
islands.

In comparing together volcanoes that are in present activity, and others
in which the crater and the streams of emitted lava are too distinct to
permit a doubt of their having arisen from the same cause, differences
are observed that only have arisen from great differences in the
circumstances under which the eruption has taken place. In many of the
ancient volcanoes, we find the emitted streams are arranged in prismatic
forms, constituting basalt, and frequently passing into what under other
circumstances would be styled _trap_ by the Wernerians. Now, we know
that when streams of lava enter the sea, they spontaneously assume the
prismatic structure. Hence we may infer, that these ancient volcanoes
originally gave vent to their craters beneath the level of the sea, at a
time when the rocks through which they penetrated, and over which their
streams have passed, were beds of the primitive ocean. The trap rocks
themselves may have been formed in a similar manner, by upward pressure
of the igneous fluid beneath, through the veins and fissures formed on
the breaking of the solid crust. Trap traverses, in dykes of unknown
depth, many formations, and is occasionally seen forming beds between
successive strata. It frequently occurs in faults, and sometimes in
extensive overlying masses. Close observation, and a just course of
analogy, lead to the irresistible conclusion, that all the trap rocks,
however situated or arranged, grow out of the same great cause, the
rising of the liquid interior of the earth to its surface. An action
sometimes taking place through veins and fissures in the solid crust,
and sometimes by the eruption of volcanoes, both occurring during the
pressure of water upon the surface. One of the most extensive groups of
trap-rocks is to be seen in the north-eastern part of the state of
New-Jersey. The H