Ch. VI, DISTRIBUTION OF COKAL-KEEFS. 163 



will now consider bow far the distribution of tbe dif- 

 ferent kinds of coral-islands and reefs corroborates our 

 theory. A glance at the map shows that the reefs 

 which are coloured blue and red, and which are believed 

 to owe their origin either to widely different move- 

 ments, or in the case of the red to a stationary condition, 

 are not indiscriminately mingled together. Atolls and 

 barrier-reefs, as may be seen by the two blue tints, 

 generally lie near each other ; and this would be the 

 natural result of both having been produced by the same 

 movement of subsidence. Thus all the Society Islands 

 are encircled by barrier-reefs, and to the N.W. and 

 S.E. there are several scattered atolls. To the eastward 

 lies the great Paumotu or Low Archipelago consisting 

 entirely of atolls ; and still further to the N.E., we meet 

 with the Mendana or Marquesas Islands, which, from 

 their abrupt and deeply indented shores, Dana 1 be- 

 lieves have probably subsided ; though hardly any coral- 

 reefs exist there, which might have afforded additional 

 evidence of subsidence. In the midst of the Caroline 

 atolls, there are three fine encircled islands. The 

 northern point of the barrier-reef of New Caledonia 

 apparently forms, as before remarked, a great atoll. 

 The Australian barrier is described as including both 

 atolls and small encircled islands. Captain King 2 men- 

 tions many atoll-formed and encircling coral-reefs, 

 some of which lie within the barrier, and others may be 



1 Corals and Coral Islands, 1872, p. 325. 



2 Sailing Directions, appended to vol. ii. of his Surveying Voyage to 

 Australia. 



m 2 



