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-westerly direction as far as the Bay of San Miguel.  It forms the medium of a not inconsiderable trade between Albay and Camarines, particularly in rice; of which the supply grown in the former province does not suffice for the population, who consume the superfluity of Camarines.  The rice is conveyed in large boats up the river as far as Quinali, and thence transported further on in carabao carts; and the boats return empty.  During the dry season of the year, the breadth of the very tortuous Bicol, at its mouth, is a little over sixty feet, and increases but very gradually.  There is considerable variety of vegetation upon its banks, and in animal