Travel Reference
In-Depth Information
generally be a measure of time; and in like manner the change which organic forms have un-
dergone is a measure of time. When we make proper allowance for the continued introduc-
tion of new animals and plants from surrounding countries, by those natural means of dis-
persal which have been so well explained by Sir Charles Lyell
*
and Mr. Darwin, it is re-
markable how closely these two measures correspond. Britain is separated from the contin-
ent 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 shal-
low 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 of land, we should conclude that the separ-
ation has been comparatively recent, since the depth to which the land has subsided is so
small. It is also to be remarked, that the great chain of active volcanoes in Sumatra and Java
furnishes us with a sufficient cause for such subsidence, since the enormous masses of mat-
ter they have thrown out would take away the foundations of the surrounding district; and
this may be the true explanation of the often-noticed fact, that volcanoes and volcanic chains
are always near the sea. The subsidence they produce around them will, in time, make a sea,
if one does not already exist.
But it is when we examine the zoology of these countries that we find what we most re-
quire—evidence of a very striking character that these great islands must have once formed
a part of the continent, and could only have been separated at a very recent geological
epoch. The elephant and tapir of Sumatra and Borneo, the rhinoceros of Sumatra and the al-
lied species of Java, the wild cattle of Borneo and the kind long supposed to be peculiar to
Java, are now all known to inhabit some part or other of Southern Asia. None of these large
animals could possibly have passed over the arms of the sea which now separate these coun-
tries, and their presence plainly indicates that a land communication must have existed since
the origin of the species. Among the smaller mammals a considerable portion are common
