levated mountains of Cagayan disappeared,
and on the island of Mindanao, in 1675, a passage was opened to the
sea and a vast plain emerged. The more recent of the convulsions
occurred in 1863 and in 1880. The destruction of property was great,
especially in Manila.

The general belief is that the Philippines once formed a part of an
enormous continent from which it was separated by some cataclysm. This
continent probably extended from Celebes to the farthest Polinesian
islands on the east, to New Zealand on the south, and the Mariana
and Sandwich islands on the north.

These islands, according to Ramon Jordana, are divided into two
volcanic regions, the eastern and the western. The principal point is
the volcano Taal, located in the northeastern portion of the province
of Batangas. It is situated on a small island in the center of the
Bombon laguna, and has an altitude of 550 feet above sea level. Its
form is conical, and the rock is composed of basalt feldspar with
a small quantity of augite. The crater is supposed to be 232 feet
deep. Its sides are almost vertical, and there are two steaming
lagunas at its bottom.

In the regions embracing the provinces of Manila, Bulacan, Pampanga,
Tarlac, and Pangasinan the soil is mostly composed of clay containing
remnants of sea shells, a circumstance which gives rise to the belief
that the coast of Manila has risen from the sea in not so remote
an epoch. Smooth, dark gray tophus predominates; it forms the bed
of the Rio Pasig, and rising forms hillocks in the vicinity of the
city of Binangonan. Farther on, trachyte and banks of conchiferous
sand predominate.

The vast plain of Panpanga extends to the north of Manila Bay, to
the south of which is situated Mount Arayat, of doleritic nature.

The disposition of the mountain ranges in parallel chains affords space
for the development of streams both in Luzon and Mindanao. The larger
islands contain inland seas, into which pour countless small streams
from the inland hills. Many of them open out into broad estuaries,
and in numerous instances coasting vessels of light draft can sail to
the very foot of the mountains. Rivers and inland lakes swarm with
varieties of fish and shellfish. By reason of Spanish restrictions,
but little can be said as to the character of the stream banks
and beds. Four of the rivers are navigable, and, by the statements
of those who have spent some little time on the islands, most are
fordable. Drinki