IV CONTENTS. 



CHAPTER III. 



FORMATION OF REEFS AND CAUSES OF THEIR FEATURES AND GEO- 

 GRAPHICAL DISTRIBUTION. 



Page. 

 Formation of Reefs, 69 



Causes Modifying the Forms and Growth of Reefs, 79 



Rate of Growth of Reefs, 85 



i Origin of the Channels within Barriers and of the Atoll Form of Coral Islands, 87 



Geographical Distribution of Coral Reefs and Islands, 97 



CHAPTER IV. 



Geological Conclusions from the Structure and Composition of Coral Reefs 



and Islands, 110 



[ 



CHAPTER V. 



ON CHANGES OF LEVEL IN THE PACIFIC OCEAN. 



Evidences of Change of Level, 118 



Subsidence indicated by Atolls and Barrier Reefs, 120 



Extent and Effect of the Subsidence, 124 



Period of the Subsidence, 125 



Elevation of Modern Eras in the Pacific, , 126 



Changes of Level in the Pacific preceding the Coral Reefs, 136 



Note. — By a recent letter from Rev. C. F. Winslow, we are informed that he has 

 examined with acids the supposed coral material on Maui, referred to on p. 132, 

 and found that it does not effervesce and is not calcareous. It is therefore no evi- 

 dence of an elevation of the island. 



