ORIGIN OF BARRIER REEFS AND ATOLLS. 267 
reefs, no longer increasing in height, would go on to widen, 
and the accumulations produced by the sea would commence 
the formation of dry land, as exhibited in figure 2. Verdure 
may soon after appear, and the coral island will finally be 
completed. 
All the features of atolls harmonize completely with this 
view of their origin. In form they are as various and irreg- 
ular as the outlines of barrier reefs. Compare Angau of the 
Feejees, with Tari-tari of the Gilbert Group (p. 165); Nairai 
or Moala with Tarawa; Nanuku with Maiana or Apamama. 

SECTION ILLUSTRATING THE ORIGIN OF ATOLLS. 
The resemblance is close. In the same manner we find the 
many forms of lagoon reefs represented among barrier reefs. 
We observe, also, that the configurations are such as would 
be derived from land of various shapes of outline, whether a 
narrow mountain ridge (as in Taputeuea, one of the Gilbert 
Islands), or wide areas of irregular slopes and mountain 
ranges. Among the groups of high islands, we observe that 
abrupt shores may occasion the absence of a reef on one side, 
as on Moala; and a like interruption is found among coral 
islands. Many of the passages through the reefs may be thus 
accounted for. 
