342 The Philippine Journal of Science 1913 



smaller number of exposures show the usual north-northwest 

 strike with dips to the west or occasionally to the east. 



Northeast of this region, between Guinhalinan River and the 

 eastern coast, the formations are found in their usual relations — 

 striking north-northwest and dipping to the east from 35° to 

 40°. On Ajus River to the northwest, likewise, the prevailing 

 strike conforms to the established order ; but the position of the 

 beds indicates an overturned fold with the lower part of the Vigo 

 shale, which dips to the eastward at angles of from 60° to 90°, 

 recumbent upon the sandstones and conglomerates in its upper 

 portion. The overturn does not persist through the younger 

 formations apparently, since these are found in the range of hills 

 along the coast, dipping at an angle of about 45°, westward. 



Inland from Catanauan and northwest of Ajus, the lime- 

 stone in the coastal ridge dips to the southwest at an angle of 

 about 45°. In the valley east of this ridge, Vigo shale is exposed, 

 dipping 50° to the southwest. Thus, the slight overturn at 

 Ajus appears to adjust itself along the strike of the formations; 

 the strata resume a steep southwestern inclination, northwest 

 of Ajus, corresponding to the lesser dip in the same direction 

 at Matataha and Ayoni, southeast of Ajus. 



Summarizing the discussion of the structure north of the Cen- 

 tral anticline, the seaward dipping formations near each coast 

 may be interpreted as evidence of a general arch across the width 

 of the peninsula. The relations in the crest portion of the sug- 

 gested arch are complicated and obscure. It appears that fold- 

 ing at right angles to the general structural lines has occurred, 

 together with close folding and overturns along the main lines 

 of structure. 



Malipa anticline. — The strikes and dips in the Vigo shale near 

 Cabongahan indicate the presence of a subordinate anticlinal 

 undulation in the eastern limb of the Central anticline. The 

 smaller fold, known as the Malipa anticline, trends north 65° 

 to 70° west, making an angle of about 40° with the axis of the 

 Central anticline. Its crest is roughly coincident with the lower 

 course of Vigo River. The fold is well developed in the Vigo 

 shale, but is only faintly reflected in the younger formations lying 

 in the ridge near the eastern coast. In the southern limb of the 

 anticline, along Malipa Creek, a thickness of 800 meters of Vigo 

 shale is exposed, dipping to the south-southwest at an angle of 

 about 55°. Above the Vigo shale, the Canguinsa sandstone ap- 

 pears, overlain by patches of coralline limestone. 



Only a few exposures were observed which can be referred 



