ge, occupy considerable areas in British
Honduras, Honduras and northern Nicaragua, and occur also in Costa
Rica and perhaps in Panama; and wherever the strike has been observed,
it is approximately from west to east. The presence of Palaeozoic
rocks has been proved in Guatemala and the adjacent state of Chiapas,
where limestones have been found containing many unmistakable
Carboniferous fossils, and below these is a considerable thickness of
beds supposed to be Silurian. Nowhere else in the Central American
region is there any palaeontological evidence of Palaeozoic rocks.

The Mesozoic series begins with sands and red or yellow clays
containing plant remains and possibly of Triassic age; but the
occurrence of these deposits is limited to a few small isolated
outcrops. Jurassic beds have been found in Mexico but not in Central
America. The Cretaceous system, consisting of a lower series of clays,
sandstones and conglomerates, followed conformably by an upper series
of limestones, covers a considerable area in Chiapas, Guatemala and
Honduras, and is found also in Costa Rica. The upper series contains
hippurites. The greater part of the eastern half of the Mexican
plateau is also formed of Cretaceous beds.

The Tertiary system may be conveniently divided into two divisions.
The lower, of Eocene and Oligocene age, consists generally of sand and
clays which were evidently laid down near a shore line. The upper
division also, including the Pliocene and Pleistocene (which have not
yet been clearly distinguished from each other), is usually of shallow
water origin; but in the northern part of Yucatan it includes beds of
chalky limestone, like those of the Antilles, which may have been
deposited in a deeper sea.

It is probable that folding took place at more than one geological
epoch, and the whole series of beds up to the Oligocene is involved in
the folds. The Pliocene, on the other hand, is usually undisturbed,
and the final effort must, therefore, have occurred during the Miocene
period, which appears to have been a period of great earth movement
throughout the Caribbean region. From the southern extremity of the
Mexican plateau to the Colombian border, the strike of the folds--of
the Mesozoic and early Tertiary deposits, as well as of the older
rocks--is in general from east to west; but there is one considerable
exception. On both sides of the dee