304 Th e Philippine Journal of Science wis 



quently leaves the observer inefficient through exhaustion before 

 his day's work is fairly begun. 



If the petroleum resources are developed, it is anticipated that 

 the additional and more accurate data which will become avail- 

 able as the jungle is cleared away and deep wells are drilled will 

 modify, or perhaps reverse, some of the conclusions of this pre- 

 liminary report. However, the present work should serve as a 

 basis for future investigation. 



METHODS OF FIELD WORK 



Field work on Bondoc Peninsula requires complete camp equip- 

 ment and the importation of all supplies from Manila. Moving 

 camp — a frequent task because of the limited area to which oper- 

 ations from each center are necessarily confined — involves pack- 

 ing everything on the backs of carriers, except along the coast 

 where small boats can be employed. The carabao, which is 

 used to a small extent as a pack animal by the native, is not 

 efficient in the interior, because water in quantity for its require- 

 ments is not usually available. 



The geologic and topographic mapping, which is embodied in 

 the map accompanying this report, was executed in large part 

 with improved compasses, known as pocket transits, during the 

 main period of field work. The coast line and the elevations of 

 the principal points, the altitudes of which could be determined 

 by triangulation from the sea, are taken from a coast survey by 

 the Bureau of Coast and Geodetic Survey. Upon this base is 

 plotted a triangulation survey which established the relative 

 locations of a number of points between Mount Maglihi and 

 Mount Cambagaco, made by Mr. Dalburg, using a standard 

 surveying transit. A stadia traverse by Mr. W. D. Buxton, of 

 the Bureau of Lands, from the town of Bondoc, via Bacau, to the 

 mouth of Bahay River and the small number of public land sur- 

 veys in the region are likewise included. For the rest, compass 

 surveys along the principal trails and stream lines — the distances 

 being paced — with vertical angle calculations and aneroid barom- 

 eter readings for elevations were made to serve. 



The measurements and observations involved in defining the 

 stratigraphy and the geologic structure were made a part of the 

 compass traverses, data of this sort being most readily obtained 

 along water courses. It is recognized that the reliability of 

 stratigraphic and structural determinations made from measure- 

 ments along streams has been questioned by eminent geologists, 

 and the objection may be admitted, but the fact remains that 

 usually in the tropics the only clue to the nature of the rocks 

 beneath the surface debris is to be obtained in the streams. 



