366 CORALS AND CORAL ISLANDS. 
Il. EFFECT OF THE SUBSIDENCE. 
The facts surveyed give us a long insight into the past, 
and exhibit to us the Pacific once scattered over with lofty 
lands, where now there are only humble monumental atolls. 
Had there been no growing coral, the whole would have 
passed without a record. These permanent registers, exhibit 
in enduring characters some of the oscillations which the 
“stable” earth has since undergone. 
From the actual size of the coral reefs and islands, we 
know that the whole amount of high land lost to the Pacific 
by the subsidence was at the very least fifty thousand square — 
miles. But since atolls are necessarily smaller than the land — 
they cover, and the more so, the further subsidence has pro- 
ceeded ;—since many lands, owing to their abrupt shores, 
or to volcanic agency, must have had no reefs about them, 
and have disappeared without a mark; and since others may 
have subsided too rapidly for the corals to retain themselves 
at the surface; it is obvious that this estimate is far below 
the truth. It is apparent that in many cases, islands now 
disjoined have been once connected, and thus several atolls 
may have been made about the heights of a single subsiding 
land of large size. Such facts show additional error in the 
above estimate, evincing that the scattered atolls and reefs tell 
but a small part of the story. Why is it, also, that the Pa- 
cific islands are confined to the tropics, if not that beyond 
thirty degrees the zodphyte could not plant its growing reeg- 
isters ? 
The island of Ponape, in the Caroline Archipelago, affords 
evidence of a subsidence in progress, as Mr. Horatio Hale, the 
Philologist of the Wilkes Expedition, gathered from a for- 
eizner who had been for a while a resident on this island. 
a 
