GEOLOGIC RECONNAISSANCE OP SOUTHWESTERN LUZON. 65 



the streets of the town. Some of the lakes are probably very deep, 

 while others are shallow and show evidence of filling up, and in one 

 case a part of the bed is cultivated. The walls are usually steep and 

 the level of some of the lakes is as much 30 or 40 meters below the rim. 

 Outside this preeminently crater-lake country there is a well-known 

 crater lake on a peninsula just to the west of Los Bahos. A small one 

 to the southwest of Nasugbu, probably lies in the remnants of a once 

 well-defined crater. 



A few cinder cones are shown on the geologic map. There is one to 

 the northeast of Batangas, another is situated just north of New Rosario, 

 and a third lies to the south of Lipa. These small hills have a conical 

 appearance when seen from a distance, but upon close examination are 

 found to have a crescentic plan, or a central depression indicating the 

 position of the crater. Tuluc Hill, between Santo Tomas and Calamba 

 near Bigaa and to the west of the road, is probably a cinder cone, but 

 shows no crater. La Mesa Hill, south of Calamba, is a cinder cone with 

 a slight depression indicating a crater. Around it there is a crescentic 

 outer crater. Similarly, Pansol Hill and Mayzondon Hill, near Los 

 Banos, are probably remnants of cinder cones. A careful survey will 

 probably disclose others. 



The stream valleys in the area of the tuff plains are consequent and 

 nearly all flow in deep, narrow, gorge-like valleys for the greater part 

 of their courses, so that the best routes of travel lie between the streams. 

 To the north of Mount Banahao the country adjacent to the eastern 

 cordiller'a is an upland. Nearly all the streams which flow from this 

 area have picturesque falls or gorges. Pagsanjan Gorge and the falls 

 near Pagsanjan, as well as Botocan Falls between Majayjay and Luisiana, 

 are noted for their scenic beauty and are visited by many tourists. In- 

 deed, Taal Volcano and Lake, the hot springs at Los Banos, the crater- 

 lake country and the falls and gorges just mentioned, combined with 

 the imposing views of volcanic mountains, make this region one of the 

 most inviting to tourists in the Philippines. The extension of the Ba- 

 tangas railway lines and the constructing of more good roads will 

 certainly make it one of the most interesting scenic districts of the Is- 

 lands. 



GEOLOGY. 

 WESTERN CORDILLERA. 



Geologic mapping. — The only geologic mapping within the region of 

 the western or Zambales cordillera which has previously been published 

 is by Von Drasche, Plate I. He quotes Eoth's statements in regard 

 to the rocks of the Natib, Mariveles and Pico de Loro Mountain masses 

 and says that, accepting this, he colored the corresponding part of his 

 map as dolerite. He did not visit the area. Further north, and just 



