XIV CONTENTS. 



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 page 56 to 68 



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 sedi- 

 ment and on worn-down islands — Fringing-reefs affected by 

 currents of the sea — Coral coating the bottom of the sea, but not 

 forming reefs 69 to 79 



CHAPTER IV. 



ON THE GROWTH OF CORAL-REEFS. 



Section I. — On the distribution of coral-reefs, and on the 



CONDITIONS FAVOURABLE TO THEIR INCREASE . . 80 to 95 



Section II. — On the rate of growth of coral-reefs 95 to 107 



Section III. — On the depths at which reef-building corals 

 live . . 107 to 116 



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 — Their subsidence — The effects of storms and earthquakes on 

 atolls — Recent changes in their state — The origin of barrier-reefs 

 and of atolls — Their relative forms — The step-formed ledges and 



