The Malay Archipelago, vol 1 | Page 9

Indo-Malayan and the Austro-Malayan divisions of the Archipelago.
On referring to pages 12, 13, and 36 of Mr. Earl's pamphlet, it will be
seen that he maintains the former connection of Asia and Australia as
an important part of his view; whereas, I dwell mainly on their long
continued separation. Notwithstanding this and other important
differences between us, to him undoubtedly belongs the merit of first
indicating the division of the Archipelago into an Australian and an

Asiatic region, which it has been my good fortune to establish by more
detailed observations.
Contrasts in Natural Productions.--To understand the importance of this
class of facts, and its bearing upon the former distribution of land and
sea, it is necessary to consider the results arrived at by geologists and
naturalists in other parts of the world.
It is now generally admitted that the present distribution of living
things on the surface of the earth is mainly the result of the last series
of changes that it has undergone. Geology teaches us that the surface of
the land, and the distribution of land and water, is everywhere slowly
changing. It further teaches us that the forms of life which inhabit that
surface have, during every period of which we possess any record, been
also slowly changing.
It is not now necessary to say anything about how either of those
changes took place; as to that, opinions may differ; but as to the fact
that the changes themselves have occurred, from the earliest geological
ages down to the present day, and are still going on, there is no
difference of opinion. Every successive stratum of sedimentary rock,
sand, or gravel, is a proof that changes of level have taken place; and
the different species of animals and plants, whose remains are found in
these deposits, prove that corresponding changes did occur in the
organic world.
Taking, therefore, these two series of changes for granted, most of the
present peculiarities and anomalies in the distribution of species may be
directly traced to them. In our own islands, with a very few trifling
exceptions, every quadruped, bird, reptile, insect, and plant, is found
also on the adjacent continent. In the small islands of Sardinia and
Corsica, there are some quadrupeds and insects, and many plants, quite
peculiar. In Ceylon, more closely connected to India than Britain is to
Europe, many animals and plants are different from those found in
India, and peculiar to the island. In the Galapagos Islands, almost every
indigenous living thing is peculiar to them, though closely resembling
other kinds found in the nearest parts of the American continent.

Most naturalists now admit that these facts can only be explained by
the greater or less lapse of time since the islands were upraised from
beneath the ocean, or were separated from the nearest land; and this
will be generally (though not always) indicated by the depth of the
intervening sea. The enormous thickness of many marine deposits
through wide areas shows that subsidence has often continued (with
intermitting periods of repose) during epochs of immense duration. The
depth of sea produced by such subsidence will therefore generally be a
measure of time; and in like manner, the change which organic forms
have undergone is a measure of time. When we make proper allowance
for the continued introduction of new animals and plants from
surrounding countries by those natural means of dispersal which have
been so well explained by Sir Charles Lyell and Mr. Darwin, it is
remarkable how closely these two measures correspond. Britain is
separated from the continent by a very shallow sea, and only in a very
few cases have our animals or plants begun to show a difference from
the corresponding continental species. Corsica and Sardinia, divided
from Italy by a much deeper sea, present a much greater difference in
their organic forms. Cuba, separated from Yucatan by a wider and
deeper strait, differs more markedly, so that most of its productions are
of distinct and peculiar species; while Madagascar, divided from Africa
by a deep channel three hundred miles wide, possesses so many
peculiar features as to indicate separation at a very remote antiquity, or
even to render it doubtful whether the two countries have ever been
absolutely united.
Returning now to the Malay Archipelago, we find that all the wide
expanse of sea which divides Java, Sumatra, and Borneo from each
other, and from Malacca and Siam, is so shallow that ships can anchor
in any part of it, since it rarely exceeds forty fathoms in depth; and if
we go as far as the line of a hundred fathoms, we shall include the
Philippine Islands and Bali, east of Java. If, therefore, these islands
have been separated from each other and the continent by subsidence of
the intervening tracts