226 ^^6 Philippine Journal of Science i9i6 



of the lake occupied a position which is now submerged, indi- 

 cating subsidence in that region ; likewise the lake is believed to 

 be encroaching at the present time upon the land near Calamba 

 on its southwest shore. To the north and northeast, on the 

 other hand, there are considerable areas of low, flat country 

 which were probably at one time a part cf the lake floor, but have 

 emerged through slow elevation. 



Laguna de Bay is important as a waterway, and steamers ply 

 constantly between Manila and the towns about its perimeter. 

 It supports an extensive fishing industry, and there are rich 

 agricultural communities on the low lands near its shores. 



LAKE BOMBON OR TAAL 



Taal Lake is situated in southwestern Luzon to the south of 

 Laguna de Bay. It is roughly oval in outline, and the active 

 volcano Taal forms an island some 25 square kilometers in area 

 near its center; several smaller islands lie to the east of the 

 volcano. Taal Lake has an area of 267.5 square kilometers and is 

 comparatively deep ; in its southeastern portion maximum sound- 

 ings of 177 meters are recorded by the Coast and Geodetic Survey. 

 In 1909 the surface of the lake was 2.13 meters above sea level ; 

 it varies only slightly from this mean altitude. Only small 

 streams enter the lake, but the outlet, Pancipit River, which 

 empties into the sea at Lemery about 8 kilometers southwest of 

 the southern shore of the lake, has a flow of considerable volume. 

 The land surrounding Taal Lake on the north and west slopes 

 generally away from the lake as a center and is made up of nearly 

 horizontal beds of water-laid volcanic tuff; walls of this ma- 

 terial rise to an elevation of several hundred meters and closely 

 encircle that part of the lake. On the southeast where the lake 

 is deepest it washes the foot of Mount Macolod, an andesite 

 peak which is 958 meters high. Elsewhere about the lake the 

 shores rise more gradually. 



Several early investigators acquiesced in the idea that Taal 

 Lake resulted from the collapse of a volcanic cone. Becker ^ 

 discusses this theory, but inclines to the belief that the lake was 

 formed through an explosive eruption of a former great volcano, 

 a gigantic predecessor of the modern Taal, rather than through 

 collapse, the occurrence of which he considers improbable. The 

 former existence of a volcano of great size on the site of Taal 

 is argued by Becker and others from the presence of the abrupt 

 walls surrounding the lake and the relatively high areas of tuff 



' Op. cit., 53. 



