﻿BAGUIO MINERAL DISTRICT. 217 



North of the Baguio district, at Tublay, hot springs also exist of the 

 same general character, but slightly lower in temperature (70° C.) and 

 containing a smaller amount of salts in solution. Iron springs, now 

 apparently quiet, have left large deposits in the vicinity of Bua, and in 

 various other localities hot-spring action is plainly indicated. 



The northern part of Benguet Province is particularly richly endowed 

 with mineral springs, hot and cold, and the geology of this and adjacent 

 regions clearly indicates, geologically speaking, the evidence of only 

 recent vulcanism, or more strictly, its final and dying phenomena. 



PHYSIOGRAPHY AND TOPOGRAPHY. 



The Baguio district — that is, the region covered by the topographic 

 map accompanying this paper — is a small portion of a part of northern 

 Luzon, with which it is very closely connected and of which it is rep- 

 resentative; it so happens that this small region is immediately on one 

 of the main tectonic axes of the Philippine Islands, and hence of the 

 Malayan Archipelago. The Cordillera del Norte situated a few miles 

 to the east of Baguio is the main axis, at least of the western half of 

 northern Luzon. The mountain system of Benguet, on the southern end 

 of which the Baguio district is located, is only one of the many rami- 

 fications of this master axis, which has its origin on the east side of 

 southern Luzon and which may safely be continued to east Mindanao. 

 This major axis is probably one of the original tectonic axes of the Asiatic 

 Continent, formed by the wrinkling of the more plastic crust of the 

 earth as the globe has contracted. In it the oldest of the Philippine 

 rocks are found and on it all of the agencies of construction and destruc- 

 tion have been at work since the Philippine Islands, as such, originated. 



Throughout the Province of Benguet there runs a subsidiary chain, 

 the two ends of which are established by Mount Data on the north and 

 by Mount Santo Tomas on the south; this range, or more strictly 

 speaking, this ridge, describes a curve, concave to the east. 



The Agno River, cutting its valley, which originally was a purely 

 tectonic depression, between the Benguet Bidge and its main trunk, the 

 Cordillera, has incised its main valley so deeply and has, by erosion of 

 its tributaries over its catch basin, removed such an amount of material 

 to the plains lying toward the south, that the Benguet Ridge stands out 

 as a mountain range, small but fully developed, between the coastal 

 plain along the China Sea and the Cordillera Central, del Norte, the 

 backbone of Luzon, with a large valley, that of the Agno River, separ- 

 ating them. The mountain region of Benguet then, of which the 

 Bagnio district is representative, is of this simple type. It represents 

 no diastrophic change of the earth's crust, as the "block" type of 

 mountains in which huge blocks of strata have been uplifted along a 

 fault plane and tilted into prominence, as is the case in the southern 



