420 PACIFIC OCEAN. 
with a course nearly north and south, and gradually bends towards 
east and west. 
In the great central chain of the Pacific, the islands of a group 
seldom make a direct straight line, but show a tendency to bend a 
little northward, in the northwestern portion of each. ‘Thus the 
general course of the Radack Group is northwest in its lower half, and 
much more northerly in its northern portion. The same is true of the 
Kingsmills. Consequently a line representing the general course of 
these groups must be somewhat curved; and like the main range the 
curve for each is convex westward. 
The prevalence of curves throughout the island ranges of the 
Pacific Ocean and East Indies is so obvious, that we cannot fail to 
consider it a fact of general importance, bearing upon any theory that 
explains the physiognomy of the earth. It is interesting to observe 
them in Eastern Asia: the courses of the mountain chains, as well as 
coast lines, curve like the chains of islands off the coast. The Sta- 
novoi and the Khingan Mountains form three great curves, convex 
towards the Pacific or to the southeast. The Altai have a parallel 
course. ‘The mountains of the globe will probably be found to illus- 
trate fully the principles we are endeavouring to present, when their 
courses are ascertained and laid down on charts with accuracy. 
We have remarked that islands are but the culminant peaks of moun- 
tains, and consequently whatever has been ascertained with regard to 
the chains of islands, is so much with reference to mountain chains. 
The mountains of Australia are shown by Strzelecki to consist of a 
series of curves, convex eastward; and the same, as stated by Prof. 
Rogers, is the character of the Appalachians in America.* 
4. Mode of Curvatures.—In our remarks on fissures, we observed 
that the fissures were frequently in advancing or receding series. This 
fact alone is the occasion of curves, as in 
_ the annexed cut. This, as we have shown, 
= is the arrangement of the islands in the 
- Kingsmills, by which the curved form of 
this linear group is produced. The same 
principle is seen to some extent in the great chains of the ocean. In 
the central or Samoan chain, the Rarotonga, Aitutaki and Society 
lines form the southeastern extremity, and the Rarotonga line is 
the most external of the whole range. Going westward from this 
group, the lines are successively in advance of one another, and it is 
* Trans. Assoc. Amer. Geologists, 1840-1842, p. 540. 
