, since the Gulf of
Mexico has been constantly growing smaller, and the Mediterranean is
being invaded by the land, I reason that similar causes will produce
like effects here, and give to each continent an area far greater than
our entire globe. The stormy ocean we behold in the west, which
corresponds to our Atlantic, though it is far more of a mare clausum in
the geographical sense, is also destined to become a calm and placid
inland sea. There are, of course, modifications of and checks to the
laws tending to increase the land area. England was formerly joined to
the continent, the land connecting the two having been rather washed
away by the waves and great tides than by any sinking of the English
Channel's bottom, the whole of which is comparatively shallow. Another
case of this kind is seen in Cape Cod and the islands of Martha's
Vineyard and Nantucket, all of which are washing away so rapidly that
they would probably disappear before the next Glacial period, were we
not engaged in preventing its recurrence. These detached islands and
sand-bars once formed one large island, which at a still earlier time
undoubtedly was joined to the mainland. The sands forming the detached
masses are in a great processional march towards the equator, but it is
the result simply of winds and waves, there being no indication of
subsidence. Along the coast of New Jersey we see denudation and
sinking going on together, the well-known SUNKEN FOREST being an
instance of the latter. The border of the continent proper also
extends many miles under the ocean before reaching the edge of the
Atlantic basin. Volcanic eruptions sometimes demolish parts of
headlands and islands, though these recompense us in the amount of
material brought to the surface, and in the increased distance they
enable water to penetrate by relieving the interior of part of its
heat, for any land they may destroy."

CHAPTER XI.

A JOVIAN NIAGARA.

Four days later, after crossing a ridge of mountains that the pressure
on the aneroid barometer showed to be about thirty-two thousand feet
high, and a stretch of flat country a few miles in width, they came to
a great arm of the sea. It was about thirty miles wide at its mouth,
which was narrowed like the neck of a bottle, and farther inland was
over one hundred miles across, and though their glasses, the clear air,
and the planet's size enabled them to se