e channel becomes so much obstructed that
the efflux is less than the evaporation, the water ceases to flow
over the edge, and the mineral dross, during the continual cooling
of the water, is then deposited, with the greatest uniformity, over
the inner area of the basin. When, however, the surface of the water
sinks, this formation ceases at the upper portion of the basin; the
interior wall thickens; and, if the channel be completely stopped up
and all the water evaporated, there remains a bell-shaped basin as
even as if excavated by the hand of man. The water now seeks a fresh
outlet, and bursts forth where it meets with the least obstruction,
without destroying the beautiful cone it has already erected. Many such
examples exist. In the largest cones, however, the vapors generated
acquire such power that, when the outlet is completely stopped up,
they break up the overlying crust in concentrically radiating flakes;
and the water, issuing anew copiously from the center, deposits a fresh
crust, which again, by the process we have just described is broken
up into a superimposed layer of flakes. In this manner are formed
annular layers, which in turn are gradually covered by fresh deposits
from the overflowing water. After the pyramid of layers is complete
and the outlet stopped up, the water sometimes breaks forth on the
slope of the same cone; a second cone is then formed near the first,
on the same base. In the vicinity of the silicious springs are seen
deposits of white, yellow, red, and bluish-grey clays, overlaying
one another in narrow strata-like variegated marl, manifestly the
disintegrated produce of volcanic rocks transported hither by rain
and stained with oxide of iron. These clays perhaps come from the
same rocks from the disintegration of which the silicious earth has
been formed. Similar examples occur in Iceland and in New Zealand;
but the products of the springs of Tibi are more varied, finer,
and more beautiful than those of the Iceland Geysers.

[A world wonder.] The wonderful conformations of the red cone are
indeed astonishing, and hardly to be paralleled in any other quarter
of the world. [106]

CHAPTER XIV

[Quinali river.] On my second journey in Camarines, which I undertook
in February, I went by water from Polangui, past Batu, as far as
Naga. The Quinali, which runs into the south-eastern corner of the
lake of Batu, runs out again on the north side as the Bicol River,
and flows in a north