Actions of Volcanoes. 281 
- The general importance of this remark must be very apparent. 
It is quite possible that this may have been the true source of 
many of the appearances connected with alluvia and with fossil 
remains of different origins, that have been the causes of so 
‘much trouble to observers. It must be remembered, that 
although all the land be supposed to have been elevated from 
the sea, it by no means follows, that this was a single event. It 
is much more probable that it was successive, and that the 
causes operated through a long series of ages. Hence there 
‘may be a chain of intervals in time, connecting the most remote 
catastrophes of this nature with that of Italy, and uniting even 
‘this one with the latest formations of volcanic islands. Among 
some of these, at least, we might expect to find analogous ap- 
pearances to those which have here been discussed ; as it is im- 
possible to conceive an elevation of rocks which was not accom- 
panied by that also of the unconsolidated submarine materials 
that chanced to be present. I will not, however, dwell on this 
‘suggestion ; as I know not of any positive observations at this 
moment that could be brought to bear on it. Yet geologists 
must see that they have been somewhat hasty in limiting the 
causes of alluvia to diluvian operations, or to those more tedious 
actions which form so conspicuous a part of one of the most 
noted theories of the earth. 
I must now proceed to consider the case of the coral islands, 
as offering the same proofs of the elevation of submarine strata 
by the action of volcanic force. These also, which appear to be 
of dates considerably distant, serve to connect the catastrophe 
which generated Italy as it now is, with those which, in Pliny’s 
time, formed the Greek volcanic islands, and with the more 
recent ones, which in our own have produced the new islands of 
Iceland and the Azores. 
The production of the coral islands which are scattered over 
the great Pacific ocean, which endanger the navigation of the 
Indian Archipelago, and which, by their daily increase, are ruin- 
ing that of the Red Sea, is a phenomenon completely distin- 
guished from all the others which are objects of geological: in- 
vestigation. By-the siJent and almost unnoticed operations of 
