334 The Philippine Journal of Science ma 



Among the fossils collected the following were identified. 



Fossils collected at locality 11. 



Conus loroisii Kien. + Tapes rimosa Phil. + 



Pyrula sp. Conus striatellus Jenk. 



Area sp. Conus hochstetteri K. Mart. 



Ndtica sp. indet. Fusus sp. indet. 



In a specimen of the conglomeratic sandstone which occurs 

 in the upper part of the Vigo shale in Matataha Valley one 

 species of Mitra and one of Pyrula were noted. Globigerina 

 (Plate V) was found in the Vigo shale, more abundantly in the 

 Bacau stage. 



The general aspect of the fossils in the Bacau stage of the 

 Vigo shale is very similar to that of the fossils in the base of the 

 Canguinsa sandstone (Plate IV). The age of the beds is not 

 fixed definitely, but the fresh appearance of the shells and the 

 number of species still living make it improbable that they rep- 

 resent a period earlier than the Miocene. The base of the series 

 may be as old as the Oligocene. 



The Vigo shale includes all the known petroliferous horizons 

 in this field. Seeps of petroleum and inflammable gas occur in 

 the Bacau stage, generally within a few meters below the base 

 of the Canguinsa sandstone; on Malipa Creek, however, traces 

 of oil and gas are observed with 250 meters of Vigo shale 

 exposed above them. The occurrence of petroleum is discussed 

 on page 349. 



As to the character of the rocks which occur below the Vigo 

 shale, there is little evidence. The shale may rest directly upon 

 the basal diorite which is cited by Becker 14 as probably the 

 oldest formation in the Philippine stratigraphic column, or upon 

 a sedimentary series older than the Vigo shale. Elsewhere in 

 the Philippines, Miocene shale has been found in some cases to 

 overlie Eocene shale and limestone, in others to rest immediately 

 upon a base of older igneous rocks, and rarely to be underlain 

 by older "slates" which are probably of Jurassic age. 



At Peris, about 25 kilometers northwest of San Narciso, the 

 common basal diorite occurs, overlain unconformably by the 

 Cudiapi sandstone. Toward the south, successively older forma- 

 tions, down to and including the Vigo shale, at least, undoubtedly 

 overlap the diorite base just as the Cudiapi sandstone does at 

 Peris. Possibly sedimentary rocks older than the Vigo shale 

 intervene between it and the lowest parts of the diorite floor. 



"Becker, G. F., 21st Ann. Rep. U. S. Geol. Surv., 1899-1900, pt. Ill 

 (1901), 24 of reprint. 



