VIII, A, 5 



Pratt and Smith: Petroleum Resources 



319 



Table VIII. — Geologic section in the eastern wall of Canguinsa Valley at 

 Bacau; from the rim of the valley to the bed of the river. 



Formation. 



Description. 



Approx- 

 imate 

 thickness. 





Upper limestone; yellow* to white coralline and 

 sandy limestone, imperfectly bedded; dip 15° to 

 25° northeast. 



Cudiapi sandstone; calcareous, medium-grained 

 sandstone; alternate beds of different thick- 

 nesses; dip 15° to 45° northeast. 



Lower limestone; coralline; poor exposures, not 

 certainly in place. 



Gray sandstone, jointed and clayey ; exposures poor . 



Meters. 

 30 



80 



20 

 100 





Unconformity; abrupt change in 

 angle of dip. 



Vigo shale 



Bacau stage; blue to black petroliferous shale, 

 petroleum seep; bedding is indistinct and appear- 

 ance massive; fine-grained clay shale with 

 irregular, subordinate sandy zones; dip 55° east- 

 northeast. 



Thin-bedded blue to black shale; occasional layers 

 of sandstone; dip 60° east-northeast; outcrops in 

 stream floor. 



30 







Above the Vigo shale in the western wall of Canguinsa Valley 

 at Bacau there are about 100 meters of clayey gray sandstone. 

 About 1 kilometer farther to the northwest the Lower limestone 

 occurs above this sandstone. 



The section in Table IX represents the eastern face of South 

 Cudiapi Mountain down to Cauayan Creek. The rocks here dip 

 eastward at low angles, lying in the western limb of the Ayoni 

 anticline. 



Table IX. — Geologic section down the western slope of South Cudiapi 

 Mountain to Cauayan Creek. 



Formation. 



Description. 



Approx- 

 imate 

 thickness. 



Malumbang series 



Upper limestone; not present; removed by erosion?. 



Cudiapi sandstone; yellow to brown calcareous 

 sandstone; bedded, medium-grain size; summit of 

 South Cudiapi Mountain. 



Lower limestone; yellow to white coralline lime- 

 stone. 



Gray clayey sandstone; bedded and calcareous in 

 upper portion; massive, sandy fossiliferous clay 

 at base. 



Meters. 



80 



20 

 170 



Canguinsa sandstone 







Bacau stage; blue to black thin-bedded shale, traces 

 of inflammable gas; occasional exposures only. 









