542 PHILIPPINES. 
same material. Ascending the river, four or five miles towards the 
Laguna de Bay, the banks, which below are but five or six feet high, 
rise to forty and fifty feet, and in some places to sixty feet, and they 
expose a vertical front of tufa. It is a soft rock easily worked, and 
constitutes the common building material in the city. It consists of 
fine volcanic earth or cinders, with fragments of scoria, pitchstone or 
pumice, which occasionally are of considerable size. Impressions of 
leaves and silicified wood are of common occurrence, and some of the 
wood is beautifully opalized, though the greater part has the pitchy 
lustre of resenite. Many fine specimens of these vegetable remains 
were received by the Expedition from Don Inigo Azaola. They are 
mostly palms, and appear to be recent species. 
A similar tufa occurs also around the Laguna de Bay, and constitutes 
the plain on the south side. Sections may be seen near Bafios, and 
between Bay and Bajios along the bed of a smal] stream. The layers 
in view were generally several feet thick, in some places fifteen feet. 
There are several volcanic summits about the Lagunade Bay, vary- 
ing in altitude from fifteen hundred to six thousand or seven thousand 
feet. The highest is called Mathathai.* Near Bay and Calawan are 
other summits of undoubted volcanic origin, though now much broken 
in outline, and densely enveloped in forests. Near San Pablo, there 
are said to be nine craters, which are now occupied by small lakes. 
Towards Calamba, to the northeast of Los Bajos, there are three small 
volcanic hills, one of which contains a pool of water that nearly com- 
municates with the lake. 
Near Bafios, about a mile back from the lake, commence the decli- 
vities of Mount Magueling, the only one of these ancient cones which 
I had an opportunity to ascend, and that to a height of only two 
thousand feet. Its height by estimate is three thousand or three thou- 
sand two hundred feet. ‘The rocks were seldom in sight on the 
ascent, on account of the deep soil and abundant growth of vegeta- 
tion: where visible they were either trachyte or tufa. The tufa of 
the gently sloping plains around the base of this mountain had _ pro- 
bably here originated ; yet the summit was so broken, and the declivi- 
ties were so much worn that no distinct crater was seen. There are 
several small subordinate cones on these plains, one of which was ob- 
served at the foot of the mountain, about two miles back of Los Bafios, 
and another on a jutting point along the lake, between Los Bajios and 
Bay. The latter was about one hundred and fifty feet high, and as 
* Pronounced Myhyhy. 
