VIII, A, 5 



Pratt and Smith: Petroleum Resources 



317 



On Dumalog Creek (Table XIII) north of the line of the 

 section in Table IV, sandstone and conglomeratic sandstone occur 

 above the Bacau stage of the Vigo shale apparently bedded in 

 conformity with the shale below them, and a small outcrop of 

 volcanic agglomerate is found at an apparently lower horizon 

 in the Vigo shale than that of the agglomerate on Tangob Creek. 



The Vigo shale appears to undergo a change in character from 

 east to west in that the upper beds become more sandy. This 

 lateral transition from shale to sandstone is revealed by com- 

 paring Table V, which is a section of the western limb of the 

 Central anticline, exposed in Matataha River, with Table IV. 

 The Canguinsa sandstone is not well exposed along the western 

 coast, and cannot be separated sharply from the Vigo, shale. The 

 evidence of unconformity at the base of the Canguinsa sandstone 

 which was noted in Table IV does not appear in the Matataha 

 River section. 



Table V. — Geologic section along Matataha River from the western coast 

 to the axis of the Central anticline. 



Formation. 



Description. 



Approx- 

 imate 

 thickness. 







Meters. 



Malumbang series 



Lower limestone, yellow to white coralline lime- 



30 





stone overlying sandy, bedded limestone; dip 35° 







southwest. 





Canguinsa sandstone 



Concealed interval 



50 



Canguinsa sandstone, Vigo 





shale 



Interbedded sandstone, sandy shale, and shale with 



260 





occasional conglomeratic sandstone beds with 







small pebbles of diorite, andesite, etc.; gray to 







brown or yellow; almost horizontal in Mount 







Cancalao. 







Blue to black shale (Bacau stage?); traces of in- 



20 





flammable gas; base of Mount Cancalao. 







Sandstone and shale interbedded, dip southwest. 



800 



Vigo shale 



increasing toward the east up to 25°. 

 Thin-bedded shale, sandy shale, and sandstone, 



500 







general color brown or yellow; dip west-south- 







west increasing toward the east from 25° to 70°; 







strata vertical in axis of anticline. 





The upper formations are exposed in section along the crest of 

 the Central anticline in the valley of upper Canguinsa River 

 while the Vigo shale is uncovered in scattered outcrops only. 

 The section in Table VI was obtained in Balinsog Hill and the 

 eastern wall of the valley of Canguinsa River. Table VII shows 



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