132 
THEORY OF THE FORMATION 
Ch. V. 
quakes are felt in the Marshall atolls, which are far 
from any high land, and likewise in the islands of 
the Caroline Archipelago. On Oulleay atoll, one of 
the latter, Admiral Lutke informs me that he ob- 
served several straight fissures about a foot in width, 
running for some hundred yards obliquely across the 
whole width of the reef. Fissures indicate a stretching 
of the earth’s crust, and, therefore, probably changes 
in its level ; but these coral-islands, which have been 
shaken and fissured, certainly have not been elevated, 
and, therefore, probably have subsided . 1 We shall 
hereafter see that the position of certain ancient build- 
ings in the Caroline Archipelago clearly indicates recent 
subsidence. In the chapter on Keeling atoll. I have 
also attempted to show, by direct evidence, that the 
island subsided during the earthquakes lately felt there. 
The facts then stand as follows : — there are many 
large spaces of ocean, without any high land, inter- 
spersed with reefs and islets formed by the growth 
of those kinds of coral which cannot live at great 
depths ; and the existence of these reefs and low 
islets in such numbers and at such distant points, 
is inexplicable, excepting on the theory that their 
rocky bases slowly and successively sank beneath the 
level of the sea, whilst the corals continued to grow 
upwards. No positive facts are opposed to this view, 
and some direct evidence, as well as general considera- 
tions, render it probable. There is also evidence of 
1 [It seems to me doubtful whether the argument from the ex- 
istence of fissures can be pressed. — T. G. B.] 
