The larger areas,
coloured red and blue, are all elongated; and between the two
colours there is a degree of rude alternation, as if the rising of
one had balanced the 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.
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