y agrees both
in size and shape, though its enormous volcanic mountains rise to nearly
14,000 feet high. {311} Three of the smaller islands are each about the
size of Hertfordshire or Bedfordshire, and the whole group stretches from
north-west to south-east for a distance of about 350 miles. Though so
extensive, the entire archipelago is volcanic, and the largest island is
rendered sterile and comparatively uninhabitable by its three active
volcanoes and their widespread deposits of lava.

[Illustration: MAP OF THE SANDWICH ISLANDS.]

The light tint shows where the sea is less than 1,000 fathoms deep.
The figures show the depth in fathoms.

The ocean depths by which these islands are separated from the nearest
continents are enormous. North, east, and south, soundings have been
obtained a little over or under three thousand fathoms, and these profound
deeps extend over a large part of the North Pacific. We may {312} be quite
sure, therefore, that the Sandwich Islands have, during their whole
existence, been as completely severed from the great continents as they are
now; but on the west and south there is a possibility of more extensive
islands having existed, serving as stepping-stones to the island groups of
the Mid-Pacific. This is indicated by a few widely-scattered coral islets,
around which extend {313} considerable areas of less depth, varying from
two hundred to a thousand fathoms, and which _may_ therefore indicate the
sites of submerged islands of considerable extent. When we consider that
east of New Zealand and New Caledonia, all the larger and loftier islands
are of volcanic origin, with no trace of any ancient stratified rocks
(except, perhaps, in the Marquesas, where, according to Jules Marcou,
granite and gneiss are said to occur) it seems probable that the
innumerable coral-reefs and atolls, which occur in groups on deeply
submerged banks, mark the sites of bygone volcanic islands, similar to
those which now exist, but which, after becoming extinct, have been lowered
or destroyed by denudation, and finally have altogether disappeared except
where their sites are indicated by the upward-growing coral-reefs. If this
view is correct we should give up all idea of there ever having been a
Pacific continent, but should look upon that vast ocean as having from the
remotest geological epochs been the seat of volcanic forces, which from its
profound depths have gradually built up the islands which now dot i