248 The Philippine Journal of Science 1917 



A peculiar feature of Taal Volcano is the fact .that the main 

 floor of the crater before the eruption was very nearly at sea 

 level and that, owing to the ejection of much material during 

 the eruption, the crater floor is now much lower. The volcano 

 was little altered in outward appearance in the eruption of 1911, 

 but the crater proper was greatly changed. According to the 

 description by Pratt (7) — 



The absence of vegetation and the smooth drifted surface of the ash 

 covering which is almost white in the sunlight, give the island an appear- 

 ance of a vast snow heap. The crater rim is unbroken and save for minor 

 fissures and cracks is intact. * * * 



The interior of the crater has been transformed. * * * The well- 

 known Green Lake and Yellow Lake, which were small bodies of water, 

 one of which (Yellow Lake) was quite shallow, referred to in descriptions 

 of Taal since earliest historic times, are gone. In the position of the 

 former Green Lake there is a new one, the water of which appears milky- 

 white, due to suspended solid matter. The level of this lake was on 

 February 17 approximately 70 meters below that of the sea. Green Lake 

 had stood 5 meters above sea level. Two streams of hot water, the 

 combined flow of which was estimated at 100 to 150 cubic meters per 

 minute, were pouring into the lake. These streams came out of the crater 

 walls about 50 meters above the lake level, seeping from just over a layer 

 of fine-grained, impervious, bedded tuff. On the west shore of the lake 

 a conical rock 50 to 70 meters in diameter rose to a height of 115 meters 

 above the lake level. The upper 50 meters of this natural obelisk appeared 

 to be bedded tuff, but the lower portion is massive basalt. A week later, 

 the streams pouring into the crater lake had increased both in volume 

 and in number, and the lake itself had risen apparently about 5 meters. 

 * * * 



Although hot and heavily mineralized, the water which is flowing into 

 the new crater probably is seepage from Lake Bombon through the crater 

 walls. Since Lake Bombon stands a few meters above sea level, the new 

 crater lake will probably rise in time to about sea level. 



A comparison of the old and new craters is shown in fig. 1. 



As predicted, the water entering the crater formed a single 

 new lake, leaving no trace of the small lakes previously present 

 (Plate I, fig. 2). This new lake, which is over a kilometer in 

 width and at least 70 meters deep, has no visible inlet nor outlet. 

 The following description was written by Gates, (6) in 1914: 



It [the crater] is about 2.3 kilometers long and 1.7 kilometers wide at the 

 top. More than half of the bottom is occupied by a lake, whose elevation 

 is about 2.5 meters above sea level, the same as that of the surrounding 

 Lake Bombon. The water of the crater lake is clear, although dark colored, 

 and salty. Its temperature decreased from about 37° C. in October, 1913, 

 to about 32° in April, 1914. Swimming in it, although much like salt 

 water bathing, was of course more exciting. Very little steam, if any, 

 arose from the lake in either October or December, 1913, but in April, 

 1914, some steam was noticed arising from a few places along the shore 

 of the lake, as well as from small vents in the north crater wall, both 



