marine flats formed by the erosion of pre-existing land surfaces.

In face of this accumulated evidence, it must be admitted that the
subsidence theory of Darwin is inapplicable to a large number of coral
reefs and islands, but it is hardly possible to assert, as Murray does,
that no atolls or barrier reefs have ever been developed after the
manner indicated by Darwin. The most recent research on the structure of
coral reefs has also been the most thorough and most convincing. It is
obvious that, if Murray's theory were correct, a bore hole sunk deep
into an atoll would pass through some 100 ft. of coral rock, then
through a greater or less thickness of argillaceous rock, and finally
would penetrate the volcanic rock on which the other materials were
deposited. If Darwin's theory is correct, the boring would pass through
a great thickness of coral rock, and finally, if it went deep enough,
would pass into the original rock which subsided below the waters. An
expedition sent out by the Royal Society of London started in 1896 for
the island of Funafuti, a typical atoll of the Ellice group in the
Pacific Ocean, with the purpose of making a deep boring to test this
question. The first attempt was not successful, for at a depth of 105
ft. the refractory nature of the rock stopped further progress. But a
second attempt, under the management of Professor Edgeworth David of
Sydney, proved a complete success. With improved apparatus, the boring
was carried down to a depth of 697 ft. (116 fathoms), and a third
attempt carried it down to 1114 ft. (185 fathoms). The boring proves the
existence of a mass of pure limestone of organic origin to the depth of
1114 ft., and there is no trace of any other rock. The organic remains
found in the core brought up by the drill consist of corals,
foraminifera, calcareous algae and other organisms. A boring was also
made from the deck of a ship into the floor of the lagoon, which shows
that under 100 ft. of water there exists at the bottom of the lagoon a
deposit more than 100 ft. thick, consisting of the remains of a
calcareous alga, _Halimeda opuntia_, mixed with abundant foraminifera.
At greater depths, down to 245 ft., the same materials, mixed with the
remains of branching madrepores, were met with, and further progress was
stopped by the existence of solid masses of coral, fragments of porites,
madrepora and heliopora having been brought up in the core. These are
shallow-water corals, and t