CHAPTER VII. 
PACIFIC OCEAN. 
In the succeeding pages on the Pacific Ocean, we take up in order 
the following subjects. 
I. General Review of Volcanic Action in the Pacific. 
II. Mineral Constitution of the Pacific Basaltic Islands. 
ILI. Origin of the Valleys of the Pacific Islands. 
IV. Changes of Level in the Pacific. 
V. General Arrangement of Land in the Pacific. 
VI. Origin of the General Features of the Pacific, with the bear- 
ing of the facts upon the cause of the physiognomic peculiarities of 
the globe. 
I GENERAL REVIEW OF VOLCANIC ACTION IN THE PACIFIC, 
1. VOLCANIC CONES. 
The Hawaiian and other Pacific islands have afforded examples of 
the different kinds of cones which occur in volcanic regions. They 
may be referred to the three following divisions, though not always 
wholly distinct :— 
1. Cinder cones; consisting of loose grains or scoria, fine and 
coarse, and usually presenting some traces of stratification. 
2. Tufa cones; consisting of fine volcanic material, earthy in ap- 
pearance, and distinctly laminated. 
3. Lava cones; consisting of cooled streams of lava or molten rock. 
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