wever, we fail to observe any decided instances of breached
craters, with lava-streams, such as those I have described.[13] In
nearly all cases the ramparts appear to extend continuously round the
enclosed depression, solid and unbroken; or at least with no large gap
occupying a very considerable section of the circumference. (See Fig.
38.) Hence we are led to suspect that there is some essential
distinction between the craters on the surface of the moon and the
greater number of those on the surface of our earth.

It is scarcely necessary to add that the volcanic mountains of the moon
offer no resemblance whatever to the dome-shaped volcanic mountains of
our globe. If it were otherwise, the lunar mountains would appear as
simple luminous points rising from a dark floor, over which they would
cast a conical shadow. But the form of the lunar volcanic mountains is
essentially different; as already observed, they consist in general of a
circular rampart enclosing a depressed floor, sometimes terraced as in
the case of Copernicus, from which rise one or more conical mountains,
which are in effect the later vents of eruption.

In our search, therefore, for analogous forms on our own earth, we must
leave out the craters and domes of the type furnished by the European
volcanoes and their representatives abroad, and have recourse to others
of a different type. Is there then, we may ask, any type of volcanic
mountain on our globe comparable with those on the moon? In all
probability there is.

If the reader will turn to the description of the volcanoes of the
Hawaiian group in the Pacific, especially that of Mauna Loa, as given by
Professor Dana and others, and compare it with that of Copernicus, he
will find that in both cases we have a circular rampart of solid lava
enclosing a vast plain of the same material from which rise one or more
lava-cones. The interiors in both cases are terraced. So that, allowing
for differences in magnitude, it would seem that there is no essential
distinction between lunar craters and terrestrial craters of the type of
Mauna Loa. Dana calls these Hawaiian volcanoes "basaltic," basalt being
the prevalent material of which they are formed. Those of the moon may
be composed of similar material, or otherwise; but in either case we may
suppose they are built up of lava, erupted from vents connected with the
molten reservoirs of the interior. Thus we conclude that they belong to
an entirely different