io CONTENTS. 



PAGE 



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 extra- 

 ordinary structure . . . 50 to 60 



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 . 61 to 72 



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 . . . 73 to 82 



