DETAILED TABLE OF CONTENTS
DETAILED TABLE OF CONTENTS
DESCRIPTION OF THE PLATES
INTRODUCTION
CHAPTER I.—ATOLLS OR LAGOON-ISLANDS
SECTION I.—DESCRIPTION OF KEELING ATOLL. Corals on the outer margin.—Zone of Nulliporæ.—Exterior reef.—Islets.—Coral-conglomerate.—Lagoon.—Calcareous sediment.—Scari and Holuthuriæ subsisting on corals.—Changes in the condition of the reefs and islets.—Probable subsidence of the atoll.—Future state of the lagoon.
SECTION II.—GENERAL DESCRIPTION OF ATOLLS. General form and size of atolls, their reefs and islets.—External slope.— Zone of Nulliporæ.—Conglomerate.—Depth of lagoons.—Sediment.—Reefs submerged wholly or in part.—Breaches in the reef.—Ledge-formed shores round certain lagoons.—Conversion of lagoons into land.
SECTION III.—ATOLLS OF THE MALDIVA ARCHIPELAGO—GREAT CHAGOS BANK.
Maldiva Archipelago.—Ring-formed reefs, marginal and central.—Great
depths in the lagoons of the southern atolls.—Reefs in the lagoons all
rising to the surface.—Position of islets and breaches in the reefs, with
respect to the prevalent winds and action of the waves.—Destruction of
islets.—Connection in the position and submarine foundation of distinct
atolls.—The apparent disseverment of large atolls.—The Great Chagos
Bank.—Its submerged condition and extraordinary structure.
CHAPTER II.—BARRIER REEFS
Closely resemble in general form and structure atoll-reefs.—Width and
depth of the lagoon-channels.—Breaches through the reef in front of
valleys, and generally on the leeward side.—Checks to the filling up of
the lagoon-channels.—Size and constitution of the encircled
islands.— Number of islands within the same reef.—Barrier-reefs of
New Caledonia and Australia.—Position of the reef relative to the slope
of the adjoining land.—Probable great thickness of
barrier-reefs.
CHAPTER III.—FRINGING OR SHORE-REEFS
Reefs of Mauritius.—Shallow channel within the reef.—Its slow
filling up.—Currents of water formed within it.—Upraised
reefs.—Narrow fringing-reefs in deep seas.—Reefs on the coast of E.
Africa and of Brazil.—Fringing-reefs in very shallow seas, round banks of
sediment and on worn-down islands.—Fringing-reefs affected by currents of
the sea. —Coral coating the bottom of the sea, but not forming
reefs.
CHAPTER IV.—ON THE DISTRIBUTION AND GROWTH OF CORAL-REEFS
SECTION I.—ON THE DISTRIBUTION OF CORAL-REEFS, AND ON THE CONDITIONS FAVOURABLE TO THEIR INCREASE.
SECTION II.—ON THE RATE OF GROWTH OF CORAL-REEFS.
SECTION III.—ON THE DEPTHS AT WHICH REEF-BUILDING POLYPIFERS CAN LIVE.
CHAPTER V.—THEORY OF THE FORMATION OF THE DIFFERENT
CLASSES OF CORAL-REEFS
The atolls of the larger archipelagoes are not formed on submerged craters, or
on banks of sediment.—Immense areas interspersed with
atolls.—Recent changes in their state.—The origin of barrier-reefs
and of atolls.—Their relative forms.—The step-formed ledges and
walls round the shores of some lagoons.—The ring-formed reefs of the
Maldiva atolls.—The submerged condition of parts or of the whole of some
annular reefs.—The disseverment of large atolls.—The union of
atolls by linear reefs.—The Great Chagos Bank.—Objections, from the
area and amount of subsidence required by the theory, considered.—The
probable composition of the lower parts of atolls.
CHAPTER VI.—ON THE DISTRIBUTION OF CORAL-REEFS WITH
REFERENCE TO THE THEORY OF THEIR FORMATION
Description of the coloured map.—Proximity of atolls and
barrier-reefs.— Relation in form and position of atolls with ordinary
islands.—Direct evidence of subsidence difficult to be
detected.—Proofs of recent elevation where fringing-reefs
occur.—Oscillations of level.—Absence of active volcanoes in the
areas of subsidence.—Immensity of the areas which have been elevated and
have subsided.—Their relation to the present distribution of the
land.—Areas of subsidence elongated, their intersection and alternation
with those of elevation.—Amount and slow rate of the
subsidence.—Recapitulation.
APPENDIX
INDEX