280 CORALS AND CORAL ISLANDS. 
If they are only fringing reefs marking different stages in 
the elevation, they are like elevated sea-beaches, and if each 
is no thicker than the depth of growing corals, they have no 
bearing on any theory of coral islands. But the descriptions 
say that only coral rock exists on the island. 
b. The fact that elevated reefs and other evidences of 
elevation occur at the Pelews, a region of wide barrier reefs 
and atolls, has been presented by Prof. Karl Semper,’ after a 
study of those islands, as bearing in the same direction; that 
is, against the theory of subsidence, for by the subsidence 
theory we have in such facts (in the words of another), “a 
cumbrous and entirely hypothetical series of upward and 
downward movements.” Professor Semper reports the exist- 
ence of reefs raised 200 to 250 feet above the sea-level in the 
southern third of the larger of the islands, while the other 
two thirds exhibit evidence of but little, 1f any, elevation. 
The facts are like those of other elevated reefs and atolls 
discussed on former pages. The Pelew region is one of 
comparatively modern volcanic rocks and this renders local 
displacements a probability. The elevations are proof of 
local change of level; and likewise of a recent change in each 
case; for the top layer of the elevated reef-rock and all below 
it through the coral-made structure were completed previous 
to the uplift. They prove nothing as to the changes that 
were in progress when all this coral-rock was in process of 
formation. 
c. The occurrence of great numbers of large and small 
masses of coral rock, in some places crowded together, upon 
the western or leeward reef of the several Pelew islands, and 
1 First in 1868, Zeitschr. Wissensch. Zool. xiii. 558; additions in Die Philippi- 
nen und ihre Bewohner, Wiirzburg, 1869, and still later in his “ Animal Life ” pub- 
lished in Appleton’s International Scientific Series in 1881. 

