If, Instead Of An Island, We Had Taken The Shore Of A Continent
Fringed With Reefs, And Had Imagined It To Have Subsided,
A Great Straight Barrier, Like That Of Australia Or New
Caledonia, Separated From The Land By A Wide And Deep Channel,
Would Evidently Have Been The Result.
Let us take our new encircling barrier-reef, of which the
section is now represented by unbroken lines, and which, as
I have said, is a real section through Bolabola, and let it go
on subsiding.
As the barrier-reef slowly sinks down, the
corals will go on vigorously growing upwards; but as the
island sinks, the water will gain inch by inch on the shore -
the separate mountains first forming separate islands within
[picture]
one great reef - and finally, the last and highest pinnacle
disappearing. The instant this takes place, a perfect atoll
is formed: I have said, remove the high land from within an
encircling barrier-reef, and an atoll is left, and the land has
been removed. We can now perceive how it comes that
atolls, having sprung from encircling barrier-reefs, resemble
them in general size, form, in the manner in which they are
grouped together, and in their arrangement in single or
double lines; for they may be called rude outline charts of
the sunken islands over which they stand. We can further
see how it arises that the atolls in the Pacific and Indian
Oceans extend in lines parallel to the generally prevailing
strike of the high islands and great coast-lines of those
oceans.
Enter page number
PreviousNext
Page 727 of 776
Words from 194856 to 195116
of 208183