and Diastrophism in Oceanica. 105 



northwest and southeast, nearly all of which went down more 

 and more beneath the level of the sea to a maximum depth 

 of about four miles and an average depth of between one and 

 two and a half miles. Small parts of the ridges still protrude 

 above the ocean (at least New Caledonia), but most of what 

 we see are the volcanoes that have built themselves up above the 

 folded rocks to the level of the sea. Further, the entire oceanic 

 area of the Oceanides also subsided during the Mesozoic and 

 Cenozoic, and possibly as much as 7,000 feet; while this was 

 taking place the bottom was apparently folded and built up by 

 volcanic material into many more or less parallel ridges, the 

 Oceanides, a series of arcs extending over an area of about 

 3,500 miles east and west and the same distance north and 

 south. Finally, we may add that the entire western half of the 

 Pacific bottom, and especially the Australasian region, appears 

 to be as mobile as any of the continents of the northern hemi- 

 sphere, with the difference that the sum of the continental 

 movements is upward, while that of the ocean bottoms is 

 downward. 



