sinking of the other. Taking into consideration the proofs of recent
elevation both on the fringed coasts and on some others (for instance,
in South America) where there are no reefs, we are led to conclude that
the great continents are for the most part rising areas: and from the
nature of the coral-reefs, that the central parts of the great oceans
are sinking areas. The East Indian archipelago, the most broken land
in the world, is in most parts an area of elevation, but surrounded and
penetrated, probably in more lines than one, by narrow areas of
subsidence.
I have marked with vermilion spots all the many known active volcanos
within the limits of this same map. Their entire absence from every
one of the great subsiding areas, coloured either pale or dark blue, is
most striking and not less so is the coincidence of the chief volcanic
chains with the parts coloured red, which we are led to conclude have
either long remained stationary, or more generally have been recently
upraised. Although a few of the vermilion spots occur within no great
distance of single circles tinted blue, yet not one single active
volcano is situated within several hundred miles of an archipelago, or
even small group of atolls. It is, therefore, a striking fact that in
the Friendly archipelago, which consists of a group of atolls upheaved
and since partially worn down, two volcanos, and perhaps more, are
historically known to have been in action. On the other hand, although
most of the islands in the Pacific which are encircled by
barrier-reefs, are of volcanic origin, often with the remnants of
craters still distinguishable, not one of them is known to have ever
been in eruption. Hence in these cases it would appear, that volcanos
burst forth into action and become extinguished on the same spots,
accordingly as elevatory or subsiding movements prevail there.
Numberless facts could be adduced to prove that upraised organic
remains are common wherever there are active volcanos; but until it
could be shown that in areas of subsidence, volcanos were either absent
or inactive, the inference, however probable in itself, that their
distribution depended on the rising or falling of the earth's surface,
would have been hazardous. But now, I think, we may freely admit this
important deduction.
Taking a final view of the map, and bearing in mind the statements made
with respect to the upraised organic remains, we must feel astonished
at the vastness of the areas, which have suffered changes in level
450