CORAL REEFS AND SUBMARINE BANKS 203 
pauses in the phrase, “‘the lagoon channel will be deeper or shal- 
lower, in proportionto .. . . theaccumulationofsediment ... . 
also, to the rate of subsidence and the length of the intervening 
stationary periods.” He later distinguished the consequences 
of recent and of ancient subsidences, and thus recognized that 
they need not be everywhere contemporaneous, illustrating the 
first case by the island of Vanikoro, in the Santa Cruz group of 
the Western Pacific, where ‘“‘the unusual depth of the channel 
[lagoon] between the shore and the [barrier] reef, the almost entire 
absence of islands on the reef, its wall-like structure on the inner 
side, and the small quantity of low alluvial land at the foot of the 
mountains [in the encircled island], all seem to show that this 
island has not remained long at its present level, with the lagoon 
channel subjected to the accumulation of sediments, and the reef to 
the wear and tear of the breakers’; and: then illustrating the. 
second case by certain members of the Society group, ‘“‘where .. . . 
the shoalness of the lagoon channels round some of the islands, 
the number of islets formed on the reefs of others, and the broad 
belt of low land at the foot of the mountains indicate that, although 
there must have been great subsidence to have produced the 
barrier reefs, there has since elapsed a long stationary period” 
(128). Outgrowth during a supposed stationary period was called 
upon to explain the broad reefs of Christmas atoll, in the Central 
Pacific (74), and of Diego Garcia, in the Indian Ocean (70); and 
the widened phase of reef development resulting from the trans- 
formation of a narrow young reef into a mature reef plain during 
a time of no sinking was clearly foreshadowed in the statement 
that ‘‘an old fringing reef, which had extended itself a little on 
a basis of its own formation, would hardly be distinguished from 
a barrier reef, produced by a small amount of subsidence, and 
with its lagoon channel nearly filled up with sediment during a long 
stationary period” (102). 
To these well-considered statements another was soon added, 
for the conclusion to which Darwin was finally led was that “the 
islands in the Low Archipelago [Paumotus! have, like the Society 
Islands, remained at a stationary level for a long period; and this 
is probably the ordinary course of events, subsidence supervening 
