lf>8 DISTRIBUTION OF CORAL-REEFS. Cn. VI. 
themselves are generally elongated in the same direc- 
tion with the group. The Chagos group is less elon- 
gated than is usual, and the individual atolls in it are 
likewise but little elongated ; this is strikingly seen by 
comparing them with the neighbouring Maldiva atolls. 
In the Marshall and Maldiva archipelagoes, the atolls 
are ranged in two parallel lines, like a great double 
mountain-chain. Some of the atolls in the larger archi- 
pelagoes stand so near to each other, and have such 
an evident relationship, that they compose little sub- 
groups ; in the Caroline Archipelago, one such sub-group 
consists of Pouynipete, a lofty island encircled by a 
barrier-reef, and separated by a channel only four miles 
and a half in width from Andeema atoll, with a second 
atoll a little further removed. 
On the direct evidence of the blue spaces in the map 
having subsided during the upward growth of the reefs 
thus coloured, and of the red spaces having remained 
stationary, or having been upraised. — With respect to 
subsidence, we cannot expect to obtain in semi-civil- 
ised countries proofs of a movement which tends to 
conceal its own evidence. But on coral-islands we see 
plain signs of a round of decay and renovation — on 
some, the last vestiges of land— -its first commence- 
ment on others : we hear of storms washing away and 
desolating the islets to an extent which astonished the 
inhabitants ; we know by the great fissures with which 
some of these islands are traversed, and by the earth- 
quakes felt under others, that subterranean disturbances 
are in progress. All these appearances accord well with 
