284 The Philippine Journal of Science 1015 



wells in apparent conformity with the lower strata. It is a 

 fine-grained, spongy, white rock, which breaks with a conchoidal 

 or porcelanic fracture and is composed largely of minute frag- 

 ments of volcanic glass. In its extension to the southwest the 

 lower beds of the tuff grade into an increasingly coarse-grained 

 volcanic agglomerate or breccia. A prominent hill, about 1.5 

 kilometers west-southwest of the oil wells and stratigraphically 

 above (?) the beds which the wells pierce, consists of this 

 agglomerate, the fragments in which are porphyritic andesite. 



Overlying the tuff is the coralline limestone which fringes the 

 entire Island of Cebu. In this locality it is 100 meters or more 

 thick, consists principally of unconsolidated, imperfectly bedded 

 coralline material, and dips about 35" northwest. Abella con- 

 sidered this limestone to be of Post-Pliocene age. 



Below the horizon at which the wells are located the strata 



Fig. 1. Geologic section across strike of beds at Toledo, Cebu ; partly diagrammatic, 

 a, coralline limestone ; 6, tuff and agglomerate ; c, Miocene shales, sandstones, conglomerates, 

 and limestones ; d, basal igneous complex. 



include coarse sandstones, sandy shales, elastics, and limestone, 

 in the order named from the position of the wells to the igneous 

 basement. These beds have the same strikes but dip somewhat 

 more steeply than those at the well site. The whole thickness 

 of sedimentary strata on this flank of the cordillera appears 

 to be at least 2,000 meters, the oil wells occupying a position 

 near the middle of the series. There are no beds in this series 

 which are conspicuously petroliferous, but some of the sand- 

 stones near the oil wells emit an odor of petroleum. 



The oil wells must have pierced the petroliferous sandstones 

 close to their outcrop. A well drilled to the northwest of the 

 old site would encounter these sandstones under cover and should 

 prove whether or not petroleum can be obtained from them in 

 large quantities. It would be expected that any but a viscous 

 oil would be dissipated from the open edges of the strata in a 

 monocline dipping as steeply as do the beds at this point. All 

 the rocks in the vicinity of Toledo which appear to offer any 



