vra.A, 5 Pratt and Smith: Petroleum Resources 329 



when freshly exposed, and becomes gray upon weathering; it is 

 fine and compact, but not bedded. Some of the rocks which have 

 been classed as marl in Java and Sumatra are probably similar 

 to the slightly calcareous clayey zone in the Canguinsa sandstone. 



The clay and sandstone banks in the base of the formation are 

 fossilif erous and sometimes contain myriads of small shells. The 

 fossils are often greasy and appear to be well preserved, but in 

 reality they are very fragile, and can be removed entire only 

 with care. 



In the section on lower Bahay River, the Canguinsa sandstone 

 includes a few meters of limestone and conglomerate. On Mount 

 Maglihi and Mount Morabi limestone which contains coarse sand 

 and small pebbles of diorite, quartz, and andesite is present in 

 the Canguinsa sandstone, but no conglomerate was observed. 

 In the lower part of the gorge on Canguinsa River, also, a sub- 

 ordinate thickness of limestone was found in the Canguinsa 

 sandstone. 



Volcanic agglomerate, with some appearance of bedding, out- 

 crops at the junction of Bagacay Creek and Vigo River in the 

 base of the Canguinsa sandstone, or possibly between it and the 

 underlying formation. The outcrop is of limited extent, and is 

 the only instance of volcanic rocks above the Vigo shale. 



The thickness of the Canguinsa sandstone varies from 50 to 

 160 meters. Although it occurs unconformably over the Vigo 

 shale, the contact between the two formations is found always 

 near the same horizon in the Vigo shale, and the base of the 

 Canguinsa sandstone serves as a datum for rough correlation. 



The Canguinsa sandstone is not encountered in large areas, 

 but occurs in steep slopes along streams where it has been pro- 

 tected from erosion by the overlying Malumbang series. It is 

 exposed at the surface or overlain by patches of the Lower lime- 

 stone, in parts of Malipa Creek valley, and is prominent among 

 the rocks of the Cambagaco-Dagmit ridge along the eastern 

 coast. On the western coast it is little in evidence, although it 

 occurs in the western slope of South Cudiapi Mountain. Calca- 

 reous sandstone and limestone, overlying Vigo shale and conse- 

 quently referred to the Canguinsa formation, cap a ridge between 

 two branches af Mulanay River in the northern part of the field. 

 Pieces of agglomerate, in which, among other constituents, peb- 

 bles of schist were noted, are found in this vicinity, and are pro- 

 bably to be referred to the volcanic agglomerate horizon. 



Two groups of fossils from the Canguinsa sandstone proper 

 (fossil localities 7 and 12) ; and fossils from the included lime- 

 stone beds on Mount Morabi (fossil locality 62) and Mount Mag- 



