he old, was
offered to the view. There appeared wheat-sheaves, mushrooms, stags'
horns, cabbage-leaves, and a variety of other forms, glowing under
water with brilliant tints, of every shade betwixt green, purple, brown,
and white; equalling in beauty and surpassing in grandeur the most
favourite flower-bed of the curious florist. These appearances were, in
fact, different sorts of _coral_, and fungus, growing, as it were, out
of the solid rock, and each had its own peculiar form and shade of
colouring, but yet the spectators, who knew their ship to be hemmed in
by rocks of this material, while considering the richness of the scene,
could not long forget with what power of destruction it was gifted.

The cause of these coral rocks and islands, which are slowly, but
certainly, increasing, is a very small marine insect, by which the
substance called coral is formed. These work under water, generation
after generation contributing its share in the construction of what, in
the course of ages, becomes a solid rock, exalting its head above the
face of the surrounding waters, and rising sometimes from the depth of
200 fathoms, and perhaps even more. To be constantly covered with water
seems necessary to these minute animals, for they do not work, except
in holes upon the reef, beyond low-water-mark; but the coral and other
broken remains thrown up by the sea lodge upon the rock and form a solid
mass with it, as high as the common tides reach. The new bank is not
long left unvisited by sea-birds; salt-plants take root upon it, and a
kind of soil begins to be formed; a cocoa-nut,[13] or the seed of some
other tree, is thrown on shore; land-birds visit it, and deposit the
seeds of fresh shrubs or trees; every high tide, and still more every
gale, adds something to the bank; the form of an island is by degrees
assumed; and, last of all, comes man to take possession.

[13] "A cluster of these trees would be an excellent beacon to warn
mariners of their danger when near a coral reef, and at all events
their fruit would afford some wholesome nourishment to the ship-wrecked
seamen. The navigator who should distribute 10,000 cocoa-nuts amongst
the numerous sand banks of the great ocean and Indian Sea, would be
entitled to the gratitude of all maritime nations, and of every friend
of humanity."--FLINDERS' _Voyage to Terra Australis_, vol. ii. p. 332.

[Illustration: EXPLORERS FINDING THE BED OF A DRIED UP RIVER.]