PREFACE TO THE SECOND EDITION. 
Vll 
can affect the whole circumference of a large island 
is not clear. Nor does this fact, if fully established, 
falsify my generalisation that volcanos in a state of 
action are not found within the areas of subsidence, 
whilst they are often present within those of elevation ; 
for I have not been influenced in my judgment by the 
absence or presence of coral-reefs round active volcanos ; 
I have judged only by finding upraised marine remains 
within the areas of elevation, and by the vicinity of 
atolls and barrier-reefs with reference to the areas 
of subsidence. Professor Dana apparently supposes 
(p. 320) that I look at fringing-reefs as a proof of 
the recent elevation of the land ; hut I have ex- 
pressly stated that such reefs, as a general rule, 
indicate that the land has either long remained at the 
same level or has been recently elevated. Neverthe- 
less, from upraised recent remains having been found 
in a large number of cases on coasts which are fringed 
by coral-reefs, it appears that of these two alternatives 
recent elevation has been much more frequent than a 
stationary condition. Professor Dana further believes 
that many of the lagoon-islands in the Paumotu 
or Low Archipelago and elsewhere have recently 
been elevated to a height of a few feet, although 
originally formed during a period of subsidence ; but I 
shall endeavour to show in the sixth chapter of the 
present edition that lagoon-islands which have long 
