ards from the shore, which were headlands of points
running out into the sea within the remembrance of the inhabitants. The
tops continue covered with trees or shrubs; but the sides are bare,
abrupt, and perpendicular. The progress of insulation here is obvious and
incontrovertible, and why may not larger islands, at a greater distance,
have been formed in the revolution of ages by the same accidents? The
probability is heightened by the direction of the islands Nias, Batu,
Mantawei, Pagi, Mego, etc., the similarity of the rock, soil, and
productions, and the regularity of soundings between them and the main,
whilst without them the depth is unfathomable.

CORAL ROCKS.

Where the shore is flat or shelving the coast of Sumatra, as of all other
tropical islands, is defended from the attacks of the sea by a reef or
ledge of coral rock on which the surfs exert their violence without
further effect than that of keeping its surface even, and reducing to
powder those beautiful excrescences and ramifications which have been so
much the object of the naturalist's curiosity, and which some ingenious
men who have analysed them contend to be the work of insects. The coral
powder is in particular places accumulated on the shore in great
quantities, and appears, when not closely inspected, like a fine white
sand.

SURF.

The surf (a word not to be found, I believe, in our dictionaries) is used
in India, and by navigators in general, to express a peculiar swell and
breaking of the sea upon the shore; the phenomena of which not having
been hitherto much adverted to by writers I shall be the more
circumstantial in my description of them.

The surf forms sometimes but a single range along the shore. At other
times there is a succession of two, three, four, or more, behind each
other, extending perhaps half a mile out to sea. The number of ranges is
generally in proportion to the height and violence of the surf.

The surf begins to assume its form at some distance from the place where
it breaks, gradually accumulating as it moves forward till it gains a
height, in common, of fifteen to twenty feet,* when it overhangs at top
and falls like a cascade, nearly perpendicular, involving itself as it
descends. The noise made by the fall is prodigious, and during the
stillness of the night may be heard many miles up the country.

(*Footnote. It may be presumed that in this estimation of its height I
was considerably deceived.)

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