ng the geologic period at which the pre-cretaceous erosion
began, but the region has doubtless been standing above the waters of
the ocean for a very long interval, since the amount of rock carried
away has been manifestly great.

The surface upon which the cretaceous sediments were deposited, appears
to have been reduced by erosion to a very low relief, so that the land
was a featureless plain when the cretaceous subsidence began. The time
interval required for the accomplishment of this erosion must have been
very long, since when it began the region was undoubtedly mountainous.

The complex character and disturbed altitude of the pre-cretaceous
rocks, the granites, diorites and other granular rocks which appear on
the surface because of this erosion, were originally formed deep within
the crust of the earth, and therefore furnish a reason for believing
that this period of erosion was exceedingly long.

It has been suggested that during the Jurassic times, the southeastern
coast of the United States was connected by a long isthmus, following
the line of the Antilles, to the northeastern coast of South America.
The data presented would seem to indicate that at least the eastern half
of Cuba stood high above the level during this period of the earth's
history, and although data concerning the western half are less
definite, it too was probably composed of high land masses.

The elevation, and long period of erosion just described, were followed
by subsidence, and on the surface of these old rocks the cretaceous
formations were deposited. The lowest cretaceous rocks yet found are
composed of an arkose, derived in large part from the original igneous
mass. The main body of the strata is composed of limestones, and such
fossils as they contain belong to the genera similar to those of the
cretaceous rocks of Jamaica--Radiolites, Barrettra, Requienia, etc.

During this time the whole of the Island of Cuba was probably submerged
below the level of the sea. The cretaceous rocks in Santa Clara province
occur in the bottoms of synclines, and the projected dips appear
sufficiently to carry the beds over the tops of the dividing anti-clinal
axis. It is believed, however, that the depth of the cretaceous sea over
the island was probably never very great.

Owing to a lack of paleontological data, the history of the island
during the Eocene time is vague, but it is probable that a large part of
it was submerged. This is certainl