Contributions to the theory of natural selection. A series of essays ... By Alfred Russel Wallace ...

10 ON THE LAW WHICH HAS REGULATED
pagos Islands, which contain little groups of plants
and animals peculiar to themselves, but most nearly
allied to those of South America, have not hitherto received any, even a conjectural explanation.
The Galapagos are a volcanic group of high antiquity, and have probably never been more closely
connected with the continent than they are at
present. They must have been first peopled, like
other newly-formed islands, by the action of winds
and currents, and at a period sufficiently remote
to have had the original species die out, and the
modified prototypes only remain. In the same way
we can account for the separate islands having each
their peculiar species, either on the supposition that
the same original emigration peopled the whole of
the islands with the same species from which differently modified prototypes were created, or that the
islands were successively peopled from each other,
but that new species have been created in each on
the plan of the pre-existing ones. St. Helena is a
similar case of a very ancient island having obtained
an entirely peculiar, though limited, flora. On the
other hand, no example is known of an island which
can be proved geologically to be of very recent
origin (late in the Tertiary, for instance), and yet
possesses generic or family groups, or even many
species peculiar to itself.
When a range of mountains has attained a great
elevation, and has so remained during a long geological period, the species of the two sides at and