516 Proceedings of the Boyal Society 
Throughout the volcanic islands of the great ocean basins the 
evidence of recent elevations are everywhere conspicuous. Jukes 
has given most excellent reasons for believing that the coast of 
Australia fronted by the barrier reef, and even the barrier reef 
itself, have recently been elevated.* Dana and Couthouy have given 
a list of islands in almost every barrier reef and atoll region which 
have recently been elevated. f 
This is what we should expect. Generally speaking, all the 
volcanic regions which we know have in the main been areas of 
elevation, and we would expect the same to hold good in those vast 
and permanent hollows of the earth which are occupied by the waters 
of the ocean. It must be remembered that, probably, all atolls were 
seated on submarine volcanoes. Areas of local depression are to 
be looked for in the ocean basins on either side of and between 
groups of volcaiiic islands and atolls, and not on the very site of 
these islands. This is what the deep-sea soundings show if 
they show any depression at all. Subsidence has been called in 
in order to account for the existence of lagoons and lagoon channels, 
and the narrow bands of reef which enclose these ; but it has 
been shown that these were produced by quite other causes, — by the 
vigorous growth of the corals where most nourishment was to be 
had, and their death solution and disintegration by the action of 
sea- water and currents J at those parts which cannot be, on account 
of their situation, sufficiently supplied with food. 
All the chief and characteristic features of barrier reefs and atolls 
may, indeed, exist with slow elevation, for the removal of lime from 
the lagoons and the dead upper surface of the reefs by currents, 
and in solution by rain and sea-water might keep pace with the 
upward movement. 
The most recent charts of all coral reef regions have been exa- 
mined, and it is found possible to explain all the phenomena by the 
principles here advanced; while on the subsidence theory, it is 
most difficult to explain the appearances and structures met with in 
* Voyage of the Fly, vol. i. p. 335. 
t Dana’s Corals and Coral Islands, p. 345. Couthouy’s ‘ ‘ Remarks on Coral For- 
mations,” Bost. Jour. Nat. Hist. See also Stutchbury, West of England Journal. 
t Very strong currents run out of the entrances into lagoons and lagoon 
channels, and when the tow-net was used in these entrances it showed that a 
large quantity of coral detritus was being carried seawards. 
