viii, a, 5 Pratt and Smith: Petroleum Resources 325 



ranges from 40 to 135 meters. The exposure on the summit of 

 South Cudiapi Mountain is about 80 meters thick. 



The Lower limestone is generally less than 20 meters thick. 

 It is harder and more compact than the Upper limestone, and 

 is more frequently bedded. In other respects, the limestones 

 of the two horizons are similar and hardly to be distinguished. 



On Mount Cambagaco, in the stratigraphic position of the 

 Lower limestone, a rock of unusual appearance is to be seen. 

 It is composed mainly of limestone concretions, 1 centimeter or 

 more in diameter, which have a concentric structure. The con- 

 cretions lie close together in a cement which is also calcareous, 

 giving the rocks a magnified oolitic texture. This particular 

 variety of the Lower limestone was not observed outside the 

 one vicinity near Mount Cambagaco. 



The Malumbang series attains its greatest development in the 

 vicinity of Malumbang Plain extending north beyond Balinsog 

 Hill, south through Mount Banaba and Mount Guinamuan, and 

 southwest to Tala and Sili with a detached area farther south on 

 top of Bondoc Head (see geologic map) . The lower two members 

 are found in the Cudiapi Range, while the ridge along the east 

 coast consists of a single limestone (Lower?) overlying the Vigo 

 shale with a concealed interval between. San Narciso Peninsula 

 is covered by the Upper limestone. 



All three horizons in the Malumbang series are fossiliferous. 

 Fossils were collected at two places on the hills at the northern 

 edge of Malumbang Plain, which are capped by the Upper lime- 

 stone. Specimens from fossil locality 61 were obtained on the 

 hills north of Mount Anuing near the eastern rim of Canguinsa 

 River valley at Bacau, and others (fossil locality 63) were found 

 on the hills immediately to the east on the northern border on 

 Malumbang Plain. The Upper limestone in this vicinity is 

 sandy, and grades imperceptibly into the Cudiapi sandstone be- 

 low it. The fossils are embedded in sandy, calcareous material 

 which might be designated either as sandstone or limestone. 



Fossils collected at locality 61. 



Pecten senatorius Gmel. + Conus indet. 



Pecten leopardus (?) Reeve. + Olivia indet. 



Cytherea indet. ■ Strombus labiosus Gray. + 



Cardium indet. Melania sp. 



Schizaster subrhomboidalis Herkl. Dosinia sp. 



Xenopkora dunkeri K. Mart. (?) Lagenum multiforme K. Mart, var. 



Turbo indet. tayabum var. nov. 



