572
‘
THE SEAS
of which frequently descend to depths of hundreds and
thousands of fathoms respectively.
It is the mystery
surrounding their mode of formation which has 'attracted the
attention of zoologists and geologists since reefs were rst
'
accurately described, and has led to the development of a
number of theories which attempt to explain the mystery.
The most important of these are discussed below and,
though no one of these has met with universal”acceptance,
yet all may contain elements of truth or apply to the forma‘
tion of reefs in particular areas.
THEORIES OF REEF FORMATION
'
The rst, and most famous, theory concerning the origin
of barrier reefs and atolls was put forward by the great
Charles Darwin in 1842;
He had observed, during his
'
voyage round the world in H.M.‘S. Beagle, that reef—building
can
only exist in shallow water while, as a distin—
'
guished geologist, he also knew that the level of the earth
may vary from time to
By putting these two facts
together he was able to elaborate
Which, in its
simplicity, bears the star'np of genius.
He imagined '
a
fringing reefdeveloping, in the mannershownab‘0ve, off
land which was slowly. sinking as . a result of a general
subsidence of the earth in that reg-bn; Asthe land -sank,'
the corals' would grow upwardsä.nd keep pace, more or
,
less, —with it, so that the outward edge of the reef about the
boulder zone would maintain its position near or above
the surface, but the shallow Channel between it and the
land would»become deeper and deeper as the land sank and
-
also broader as, bit
bit, the land was Overrun by the sea.
a typical barrier reef would'beformed, often
_
miles from the new coastline, and with
up to
fathoms in depth-.
Herethematter would rest-should some
‘
of the land remain above water—as in the” case of Great
‘
THE SEAS
of which frequently descend to depths of hundreds and
thousands of fathoms respectively.
It is the mystery
surrounding their mode of formation which has 'attracted the
attention of zoologists and geologists since reefs were rst
'
accurately described, and has led to the development of a
number of theories which attempt to explain the mystery.
The most important of these are discussed below and,
though no one of these has met with universal”acceptance,
yet all may contain elements of truth or apply to the forma‘
tion of reefs in particular areas.
THEORIES OF REEF FORMATION
'
The rst, and most famous, theory concerning the origin
of barrier reefs and atolls was put forward by the great
Charles Darwin in 1842;
He had observed, during his
'
voyage round the world in H.M.‘S. Beagle, that reef—building
can
only exist in shallow water while, as a distin—
'
guished geologist, he also knew that the level of the earth
may vary from time to
By putting these two facts
together he was able to elaborate
Which, in its
simplicity, bears the star'np of genius.
He imagined '
a
fringing reefdeveloping, in the mannershownab‘0ve, off
land which was slowly. sinking as . a result of a general
subsidence of the earth in that reg-bn; Asthe land -sank,'
the corals' would grow upwardsä.nd keep pace, more or
,
less, —with it, so that the outward edge of the reef about the
boulder zone would maintain its position near or above
the surface, but the shallow Channel between it and the
land would»become deeper and deeper as the land sank and
-
also broader as, bit
bit, the land was Overrun by the sea.
a typical barrier reef would'beformed, often
_
miles from the new coastline, and with
up to
fathoms in depth-.
Herethematter would rest-should some
‘
of the land remain above water—as in the” case of Great