CHAP. XV.] 
OCEANIC ISLANDS. 
311 
fact, taken in connection with the volcanic or coralline origin of 
all of them, powerfully enforces the conclusion at which we have 
arrived in the earlier portion of this volume, that during the 
whole period of geologic time as indicated by the fossiliferous 
rocks, our continents and oceans have, speaking broadly, been 
permanent features of our earth’s surface. For had it been 
otherwise — had sea and land changed place repeatedly as was 
once supposed — had our deepest oceans been the seat of great 
continents while the site of our present continents was occupied 
by an oceanic abyss — is it possible to imagine that no fragments 
of such continents would remain in the present oceans, bringing 
down to us some of their ancient forms of life preserved with 
but little change ? The correlative facts, that the islands of our 
great oceans are all volcanic (or coralline built probably upon 
degraded and submerged volcanic islands), and that their pro- 
ductions are all more or less clearly related to the existing in- 
habitants of the nearest continents, are hardly consistent with 
any other theory than the permanence of our oceanic and 
continental areas. 
We may here refer to the one apparent exception, which, 
however, lends additional force to the argument. New Zealand 
is sometimes classed as an oceanic island, but it is not so really ; 
and we shall discuss its peculiarities and probable origin 
further on. 
