﻿BAGUIO MINERAL DISTRICT. 221 



THE INCISED VALLEY SYSTEM. 



As has been stated before, the Bued Valley is noteworthy for its 

 beauty and grandeur. Its side slopes will average much over 30° and 

 in that portion of it covered by the map, it gains an elevation of from 

 2,000 to 5,000 feet. In the transverse section there is evidence of several 

 stages of deepening and at Kias there is pronounced evidence of recent 

 uplift, tilting from the south ; nowhere is the V-shaped gorge sufficiently 

 wide at is bottom, nor sufficiently gentle of slope to support more than 

 an Igorot hut or two, and it is only since the construction of the Ben- 

 guet road along the valley that it has been the scene of human activity. 

 Hanging valleys are common along its course and the entire evidence 

 of topographic forms tends to the conclusion that the drainage has 

 been of more recent origin than that of the Baguio Plateau. It is 

 especially evident that this is the case where lateral gorges enter the 

 main valley, and at the southern end of the valley the present stream 

 is cutting at a rapid rate vertically into its V-shaped canon. 



GEOLOGY. 



Although the Baguio district is but small in area, there are involved 

 in it geological problems almost too broad and complex to be Avithin the 

 scope of this reconnaissance. Such data as have been gathered, and 

 which will have to serve until a study may be made of a more extended 

 field, will be subject to greater or less modifications in the light of 

 future work. Beginning with the oldest rocks, we have a basal mass 

 composed of dioritic rocks which can be correlated with, and evidently 

 is, an integral part of the dioritic base exposed in Lepanto and in other 

 northern provinces of Luzon. Excepting certain local variations of 

 composition and texture, these two rocks are petrographically identical, 

 and the stratigraphic evidence is all on the side of the hypothesis of 

 a dioritic igneous core, of at least this one (Luzon) of the Philippine 

 Islands. It has been taken for granted by a number of the few who 

 have heretofore written on Philippine geology on such evidence as was 

 available, that the hidden core of the 'Philippine group would eventually 

 be found to consist of crystalline schists upon which post-Tertiary sedi- 

 mentaries have been laid down and to which mass the neo-volcanics 

 have been added, but so far, at least in northern Luzon, the areas seen 

 have uniformly exhibited a massive dioritic base. Becker x has care- 

 fully summarized all the occurrences of schists and older rocks of the 



1 Report on the geology of the Philippine Islands, U. 8. G. 8. 21st. Ann. Rep. 

 (1899-1900). 



