y true of the province of Oriente,
where Eocene fossils have been collected. During, and possibly previous
to that period, volcanic agencies were active in Oriente, since volcanic
rocks are found interbedded with sediments of the Eocene age. The same
forces were probably active in other sections of the island, and the
intrusion of Diorite porphyries in Santa Clara and other provinces
probably took place during that period.

A portion of the island, at least in the vicinity of Baracoa, was deeply
submerged during the lower Oligocene times, as is proved by the
occurrence of radiolarian earth beneath the upper oligocene limestones
near the above town. Radiolarian oozes are at present being formed on
the sea bottom at depths of between 2,000 and 4,000 fathoms. This, of
course, does not prove that the deposits of Baracoa were laid down at so
great a depth as present day dredging would indicate, but we can at
least feel confident that they were formed in very deep water. This does
not imply however that the whole island was sunken to the abysmal
depths.

During the upper Oligocene time very nearly the whole island was
undoubtedly submerged. Previous to this volcanic agencies had been very
active throughout the larger portion of the island. Mountain building in
Oriente had begun before the deposition of upper Oligocene strata, and
the Sierra Maestra had already been elevated to a considerable height
above the sea. It is probable that the sea at this time covered the
whole of the island, with the exception of portions of Oriente province
along its north and south coast, and occasional high peaks along the
axis of the provinces further west.

The Miocene period was one of general uplift. The whole of the island as
we at present know it, was above the level of the ocean's waters. There
were foldings and uplifts during this period, and volcanic elevation
along the axial line being greater than at the sides. It is probable
that the folding of the Oligocene strata noted in the vicinity of Havana
and Matanzas took place during this time. It may be inferred that the
central portion of the province of Oriente was more highly elevated than
the coastal portions, since upper Oligocene limestones occur in this
section at considerably higher elevations than along either the north or
south coast.

It is furthermore very probable that the terracing of the Oligocene
coral reefs, such as may be seen in the vicinity of the city of
Santiago,