PRESIDENTS ADDRESS. ~ 469 
though it is also probable that some of them have been 
formed during periods of slow subsidence. Many years ago 
I wrote in my diary of certain islands in the New Britain 
group—that it was impossible to account for their present 
condition by the subsidence theory alone. On several 
islands I noticed distinct terraces, far above the present 
sea-level, which still showed deep indentations which had 
evidently been hollowed by the action of the surf. I 
noticed also steep points of land, notably one near Point 
Hunter, which had once evidently been separate islands, but 
are now united by low lands, and it was not at all difficult 
to see that this low land had formerly been a channel 
between the two, and owed its formation in the first 
instance to tidal waves, or to the backing-up of the tides 
during the N.W. monsoon; and this was confirmed by 
native tradition. In Blanche Bay, also, as I have already 
related, I was myself the spectator of the formation of an 
island. In New Guinea, also, I have seen islands com- 
posed of true coralline limestone, the cliffs of which rise 
so perpendicularly from the blue ocean that the natives 
have to ascend and descend by ladders in going from the 
ocean to the top, or vice versd. A large steamer can go 
so close to these cliffs that she could be moored alongside 
of them in calm weather. It is not at all improbable, I 
think, that in these islands we have the two factors in the 
formation of islands, viz., subsidence, during which these 
“immense cliffs were formed, and subsequent upheaval. 
This is the only way, I think, in which we can account for 
these perpendicular cliffs in the midst of deep blue ocean. 
The only alternative theory is the highly improbable one 
that the present sea-level is several hundred feet lower now 
than it was in former years. The formation of the new 
island in Tonga is well known as having taken place in 
recent years, and have grown in size very considerably 
since they were first discovered, whilst the dyke of basalt 
underlying the coralline formation in Eua is also another 
proof of upheaval. Professor Darwin’s statement that 
volcanoes are often present in the areas which have lately 
risen, or are still rising, is clearly proved by the present 
condition of the groups under consideration. I think it 
very probable, however, that many of the atolls have been 
formed by subsidence, and the steady growth of coral on 
the shore or fringing reefs round the now submerged 
land; but, as far as my experience goes, I am inclined to 
believe in the old theory that by far the largest proportion 
of the islands in the Pacific are either the tops of moun- 
tain ranges, or have been uplifted by volcanic agency. 
