RECONNAISSANCE OF SOUTHEASTERN LUZON. 475 



tioned is along the coast from Catanauan to Mulanay and the Ayoni 

 Valley and thence across to the Vigo River, following down that stream 

 and then along the coast southward to the Bahay Eiver. The usual 

 time required to go from Catanauan to the Bahay Eiver would be three 

 days, travelling with carabaos. The oil showings in the Tayabas Penin- 

 sula are fully as important as some which have led to the bringing 

 in of successful wells and the exploiting of large fields in the United 

 States. 



At the date of wTiting the present report, the Bahay Valley Oil 

 Company has a standard rig located on its property and is drilling.® 



VINAS LOWLAND. 



The geologic formations of this physiographic district are Tertiary 

 sedimentaries with some alluvial and littoral deposits. The character 

 of the Tertiary formations has already been described sufficiently in 

 discussing the Eastern Cordilleia. The alluvial deposits are found 

 along the vallej^s which drain the lowland. The rivers are tidal, but 

 are not bordered by very extensive bottom lands and in many places 

 there are low hills on the banks. The littoral deposits are narrow. 



Von Drasche mapped a belt of alluvium with raised calcareous beds 

 and marls with recent shells between the head of Ragay Gulf and 

 Calauag Bay. It was liis idea that this isthmus had been a. strait in 

 geologically young time. 



Prom the exposures seen while making the reconnaissance for this 

 report it is fairly certain that the formations on the isthmus belong 

 to the series which is classed as Tertiary. No shore lines of a former 

 strait were seen and no recent Aiarine deposits were found. The con- 

 clusion was reached that the area is now lower than formerly. It is 

 probable that with the gro'ni;h in elevation of the Eastern and South- 

 eastern Cordilleras there has been in the intermediate zone submergence 

 which has produced the tidal conditions of the rivers of the isthmus. 



GATBO UPLAND. 



This minor subdivision is formed by a remnant of the Tertiary 

 formations. There are some raised coral beaches on its seaward margins. 

 In the eastern part of the area the Tertiary beds dip slightly to the 



* More detailed examination of the Tayabas oil district, made by one of the 

 writers subsequent to the work done for this report, revealed two outcrops of 

 igneous rock near the eastern coast of the peninsula, one several kilometers below 

 the oil seep on the Vigo River, the other farther north, just west of San Narciso. 

 The rock is a typical andesitic agglomerate and apparently forms the core of the 

 high ridge which borders the eastern coast in this locality. The flanking sedi- 

 mentary strata are locally much disturbed, and dip steeply iway from the axis 

 of the ridge. The discoveiy of this igneous formation does not alter the general 

 conclusions already drawn concerning the district as a whole, but it is evidence 

 which should be considered in locating drill holes. 



