SUBSIDENCE IN PACIFIC CORAL REGIONS. 359 
subsidence continues its progress, or when it is too rapid for 
the growing reef, it finally smks the coral island, which, 
therefore, disappears from the ocean. Now, it is a remarkable 
fact that while the islands about the equator above alluded 
to indicate greater subsidence than those farther south, there 
is over a region north of these islands, — that is, between 
them and the Hawaiian Group, —a wide blank of ocean 
without an island, which is nearly twenty degrees in breadth. 
This area lies between the Hawaiian, the Fanning and the 
Marshall Islands, and stretches off, between the first and last 
of these groups, far to the northwest. YT me, 
Is it not, then, a legitimate conclusion that the subsidence,” 
which was least to the south beyond the boundary line and 
increased northward, was still greater or more rapid over this 
open area ; that the subsidence which reduced the size of the 
islands about the equator to mere patches of reef, was further we 
continued, and caused the total disappearance of islands that 
once existed over this part of the ocean ? en 
_ d. That the subsidence gradually diminished southwest- 
wardly from some point of greatest depression situated to the 
northward and eastward, is apparent from the Feejee Group 
alone. Its northeast portion (see chart) consists of immense 
barriers, with only a few points of rock remaining of the 
submerged land; while in the west and southwest there 
are mountain islands of great magnitude. Again, along the 
north side of the Vanikoro Group, Solomon Islands, and 
New Ireland, there are coral atolls, but scarcely one to the 
south. 
In view of this combination of evidence, we are led to 
believe that the subsidence increased from the south to the 
northward or northeastward, and was greatest between the 
Navigator and Hawaiian Islands, near the centre of the area 
