1 
DISTlll 13 U TJ ON OF CUKAL-UEJils. 
OH. \ 1. 
subsided, at least to any considerable amount, for the 
effects of subsidence on a small scale would hardly be 
distinguishable. Such shores must either have remained 
stationary since the period when they were first fringed ; 
or they may have been repeatedly upraised, with new 
lines of reefs successively formed round them. If, how- 
ever, coral-reefs became attached for the first time to a 
shore which was subsiding, or if a barrier-reef was de- 
stroyed and submerged with a new reef re-attached 
to the shore, this would necessarily belong at first 
to the fringing class, and would be coloured red, 
although the land w 7 as sinking. So it would be with 
a subsiding shore, if it plunged at a very high angle 
beneath the sea, for in this case the reef would remain 
closely attached to the land as it grew upwards, and 
would resemble in all respects a fringing-reef. This 
source of doubt applies especially to atolls which 
have been upraised (such as Metia and Elizabeth 
Islands), for from the steepness of their sub-marine 
flanks, a reef growing up during a subsequent 
period of subsidence round them, would still continue 
closely to skirt the land, and would therefore be 
coloured red. Well-characterised atolls or encircling 
reefs, where several occur together in a group, or a 
single barrier-reef if of large dimensions, clearly indicate 
a movement of subsidence. The evidence from a single 
atoll, or from a single encircling-reef, must be received 
with caution, for the former may be based upon a sub- 
merged crater or bank, and the latter on a submerged 
margin of sediment or of worn-down rock. 
