LAKES 531 



up this river report that there is a bewildering network of channels con- 

 necting these lakes, and that the whole area resembles a vast swamp in 

 which the water has risen far up on the trunks of the trees growing in it. 

 Laguna de Bombon. — This lake, which may be likened to Crater Lake 

 in Oregon, United States of America, has been studied by several geol- 

 ogists, but particularly by Gr. I. Adams, formerly on the staff of the Divi- 

 sion of Mines of the Bureau of Science, Philippine Islands. As his views 

 appear to the writer to be as satisfactory as any yet expressed, and as he 

 incorporates in his discussion the important statements contributed by 

 previous writers, the following quotation is made from his paper: 



"Taal Lake is evidently a caldera formed by peripheral and radial faulting 

 and the subsidence and collapse of the many cones which have been formed 

 within its area during prehistoric eruptions. The pi'ocess of formation has 

 been continued to a small degree during historic time. 



"The fact that the caldera is occupied by a lake prevents in a large measure 

 the study of its origin. However, in the brief notes concerning the two erup- 

 tions of Taal, it is recorded that within Taal Lake a new cone arose as an 

 island and subsided, leaving as its remnants two small islands which lie to the 

 east of Taal Volcano. In another eruption a portion of the shore of Taal Lak'. 

 near the former site of the settlement of Taal subsided below the water. Many 

 who see the sheer face on the west side of Mount Macalod form the opinion 

 that a large mass of the mountain has subsided into Taal Lake, and as sub- 

 stantiating this idea it is pointed out that the deepest part of the lake is found 

 near this mountain. While studying the shores of the lake it was observed 

 that in certain parts they are precipitous, while in others they are eroded into 

 gentle slopes. It may be that some of the precipitous shorelines are due to 

 recent faulting and displacement, but it will require a detailed study to prove 

 this." ... 



The evidence for Adams' conclusion can not all be given here, but the 

 two most important points are the existence of faulting in the region 

 surrounding the lake and the shape of the proiile of the country along a 

 line drawn through the center of the lake. The consensus of opinion 

 among geologists who have studied the lake (the writer is of this num- 

 ber) is that a combination of circumstances — explosions, subsidences, 

 etcetera — caused the present condition of things — that is to say, that this 

 lake and Crater Lake in Oregon might not improbably have had very 

 similar histories. 



Taal differs from Crater Lake particularly in the matter of elevation. 

 The former is only 2 or 3 feet above sealevel, while the latter is nearly 

 8,000 feet above. Taal Lake has an active volcano in its center, while 

 the Oregon lake has not. The coloring of Crater Lake is much finer 

 than that of the Philippine lake. 



There are many smaller calderas occupied by water in the region where 



XL — Bull. Geol. See. Am., Vol. 28, 1916 



