TOPOGRAPHICAL FEATURES. 433 
Fanning’s Group, which lie nearly in a straight line. On the same 
chart, the green line (A B), from north of Pitcairn’s towards northern 
Niphon, is that which I had before arrived at for the coral island sub- 
sidence. The close approximation of the two is a point of high 
interest. It strongly confirms the position that the subsidence in 
progress during the coral epoch was the conclusion of a long period 
of progressive subsidence. We have shown, moreover, that subsi- 
dence is probably still in progress at the northern Carolines, the 
islands which he nearest this axis. 
The curving direction of ranges is another result of the grand cause 
to which we have appealed. ‘The curve in the central Pacific chain 
has already been alluded to. Its probable connexion with a vast 
elliptical area of subsidence is too obvious to require farther remark. 
Large areas of non-contraction should occasion a similar result. 
The subsiding Pacific area, has to the southwest the semi-continent 
New Holland, where contraction was in much slower progress. The 
lateral tension would naturally produce fractures around this area; 
and in conformity, we observe the curving ranges which bend around 
its north and east coasts. ‘The same ranges again bend north, as if 
modified in direction by the large island of Borneo, and the position 
of the Indian Ocean to the south and west. 
The fact of unequal subsidence in different parts of the Pacific will 
be gathered from what has been stated on the preceding pages. 
Indeed, perfect equality is seen at once to be altogether impossible. 
In the coral epoch, as shown on page 399, the area of subsidence had 
an irregular southern border. This inequality is a necessary source of 
curves in the lines of fractures. ‘The tension, exerted in parallel lines 
across an area, will usually have its line of maximum intensity, from 
which line it will diminish laterally. It could not, therefore, in this 
case produce a straight series of fractures; for as the fractures depend 
on the force, they will differ in position according to the amount of it, 
and any regular variation of the force not in simple arithmetical ratio, 
should produce a series of fractures having a curved form. ‘There 
should, therefore, be long ranges of curves from the action across wide 
areas, and also subordinate curved lines from an inequality of tension 
in certain parts of these wide areas. Thus it is that the Pacific 
might be bordered with a series of grand curves, as from the Aleutian 
Archipelago to Borneo, having the relation to one another and close 
connexion which has been pointed out; and also other smaller curves 
might exist like that of New Ireland; that by the Sooloo Islands, and 
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