828 DYNAMICAL GEOLOGY. 



great approximately-elliptical area. Recent deep-sea soundings con- 

 firm the conclusion, drawn by the author from the sizes of the atolls 

 over the Pacific, that the axial area north of the equator, where no 

 islands occur, is the region of greatest depth. 



The double or triple system of curves around Australia, from New 

 Hebrides, or perhaps northern New Zealand, to New Guinea and 

 Timor, are such as might arise from pressure acting against that stable 

 continental area of Australia, for they are concentric with it; and 

 the branch of the central Pacific chain, leading off westward through 

 the Carolines, has been shown, on page 34, to conform to this Aus- 

 tralian system. The rising curve from Java, through Sumatra, sug- 

 gests that here pressure acted from the direction of the Indian Ocean 

 as well as the Pacific ; and this is further confirmed by the fact that 

 the deep-water channel, separating the Australian seas from the 

 Asiatic, passes just north of New Guinea and Celebes, and south of 

 Java. 



The East Indian Archipelago lies between the North Pacific and 

 the Indian Ocean ; and the two, along with the reacting stable conti- 

 nental areas, have together modeled out the group. The West Indian 

 Archipelago has a similar position between the North Atlantic and 

 the South Pacific, and hence the resemblances to the East Indian, 

 pointed out on pages 35, 36. 



The curves along eastern Asia, in the islands and continental moun- 

 tain-ranges (page 35), seem to show that the pressure from the direc- 

 tion of the Pacific, which produced the curves, was unequal along 

 different parallel lines. The courses and positions of the groups of 

 Pacific islands prove that the bottom has its ranges of southeast and 

 northwest elevations and depressions, crossing the ocean ; and this 

 would occasion the unequal action required. 



5. America simple in Evolution, because of its situation between the 

 Great Oceans. — From the above, we perceive why it is that North 

 America should illustrate most simply and perfectly the laws of the 

 earth's genesis. Unlike the other continents, it is bounded on all sides 

 by oceanic basins ; on one side, the North Atlantic with a northeast 

 trend ; on the other, the greater Pacific with a northwest trend. The 

 conditions under which the lateral pressure acted were, therefore, the 

 simplest possible ; and the evolution was, consequently, regular as well 

 as systematic. Europe has Africa on the south, and Asia on the east, 

 and hence the complexity in its feature lines ; yet, even amid that 

 complexity, results according with the general principles here ex- 

 plained may be made out. 



5. Arrangement of the Continents and Oceans. — Why the conti- 

 nents are gathered about the North Pole, and the waters about the 



