e the movement of the waves.

If the waters of the ocean and seas were drained away so that we could
inspect the portion of the earth's surface which they cover as readily
as we do the dry lands, the most conspicuous feature would be the
innumerable volcanic eminences which lie hidden in these watery
realms. Wherever the observer passed from the centres of the present
lands he would note within the limits of those fields only mountains,
much modified by river action; hills which the rivers had left in
scarfing away the strata; and dales which had been carved out by the
flowing waters. Near the shore lines of the vanished seas he would
begin to find mountains, hills, and vales occasionally commingled with
volcanic peaks, those structures built from the materials ejected from
the vents. Passing the coast line to the seaward, the hills and dales
would quickly disappear, and before long the mountains would vanish
from his way, and he would gradually enter on a region of vast rolling
plains beset by volcanic peaks, generally accumulated in long ranges,
somewhat after the manner of mountains, but differing from those
elevations not only in origin but in aspect, the volcanic set of peaks
being altogether made up of conical, cup-topped elevations.

A little consideration will show us that the fact of volcanoes being
in the limit to the sea floors and to a narrow fringe of shore next
certain ocean borders is reconcilable with the view as to their
formation which we have adopted. We have already noted the fact that
the continents are old, which implies that the parts of the earth
which they occupy have long been the seats of tolerably continuous
erosion. Now and then they have swung down partly beneath the sea, and
during their submersion they received a share of sediments. But, on
the whole, all parts of the lands except strips next the coast may be
reckoned as having been subjected to an excess of wearing action far
exceeding the depositional work. Therefore, as we readily see,
underneath such land areas there has been no blanketing process going
on which has served to increase the heat in the deep underlying rocks.
On the contrary, it would be easy to show, and the reader may see it
himself, that the progressive cooling of the earth has probably
brought about a lowering of the temperature in all the section from
the surface to very great depths, so that not only is the rock water
unaffected by increase of heat, but may be act