VIII. A, 6 



Pratt and Smith: Petroleum Resources 



333 



River section, the section on Malipa Creek in the southern limb 

 of the Malipa anticline shows 800 meters of Vigo shale, and the 

 section on Guinhalinan River indicates 600 meters. None of 

 these sections exposes the base of the formation. The apparent 

 thickness of the sections as measured along the outcrop may be 

 in excess of the actual thickness as a result of superficial expan- 

 sion of the beds or of the repetition of beds from faulting or close 

 folding. 



As is indicated on the geologic map, the Vigo shale is promi- 

 nent in the north-central portion of the field. A smaller area 

 is exposed along the southwestern coast. The deeper valleys 

 have uncovered Vigo shale in other parts of the peninsula. 



A small number of fossils were observed in the lower part of 

 the Vigo, and the shale in the Bacau stage and the overlying con- 

 glomeratic sandstone are fossiliferous. The specimens are frag- 

 ile and upon removal disintegrate readily, in a manner that 

 suggests the effects of calcination. Frequently they are envel- 

 oped in a film of oil or grease as are the shells in the clay beds 

 of the Canguinsa sandstone. 



At fossil locality 11 on Dumalog Creek, fossils were found in 

 bedded blue-black shale which is placed in the Bacau stage of 

 the Vigo. This locality is on the trail from San Narciso to Mu- 

 lanay on the west slope of Cambagaco Ridge at an elevation of 

 130 meters. 



The stratigraphic relations are shown in Table XIII. 



Table XIII. — Geologic section downstream on Dumalog Creek. 

 Fossil locality 11. 



Formation. 



Description. 



Thickness. 







Meters. 



Malumbang series and Can- 



In the east slope and the crest of Cambagaco 



200 



guinsa sandstone. 



Ridge, limestone and sandstones are encountered 

 in obscure relations. The general dip is east- 

 ward at an angle of about 30°. 







Gray to brown sandstone and fine conglomerate. 



10 





Strike, north 50° west; dip, northeast, 45°. 







I Black laminated clay or shale. Carbonized leaf- 



20 





impressions and lenses of lignite, 5 millimeters 







thick. 





Vigo shale 



J Gray to brown sandstones, massive, coarse grained _ 



10 





| Bacau stage; thin-bedded shale with subordinate 



50 





sandstone beds; dip 65° northeast; fossils found 







in the shale beds. 







Concealed interval 



400 



Volcanic agglomerate, a single small outcrop in 





\ thin-bedded shale and sandstone. 





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