RECONNAISSANCE OF SOUTHEASTERN LUZON. 471 



Coal. — The coal deposits of Batan Island are the best developed of 

 any in the Philippines. A detailed account of the outcrops may be 

 found in Smith's report. 



RAGAT COAST HILLS. 



This area is occupied by Tertiary sedimentaries with the exception 

 of a small strip of the coast north of Pasacao which contains igneous 

 rocks. Von Drasehe mapped a part of the territoiy as younger coral- 

 line limestone and near Pasacao indicated older crystallines in the 

 locality of the igneous rocks which Both had described from Jagor's 

 specimens and notes. 



The most interesting of the igneous rocks is a diorite which in 

 part is gneissic and schistose. Von Drasehe calls attention to the 

 importance of determining the relations of the sedimentary beds at this 

 point, since if they overlie the diorite, it indicates that the crystalline 

 schists form the base of all the other fonnations in southern Luzon. 

 From the field relations it is certain that this diorite is older than 

 the limestone near by, but it does not follow that the basis of all of 

 the younger rocks are crystallines containing diorite. 



At the northern end of the area there is basalt, and some associated 

 rocks, difficult to determine because decomposed, but probably basaltic 

 or andesitic. A hot spring issues at some distance from the good ex- 

 posures of basalt near the mouth of the Tinalmud Eiver. On Eefugio 

 Island, south of Pasacao, there is basalt and on the shore opposite hot 

 springs occur. These basalts may be rather recent intrusions since there 

 are hot waters near them. The field relations are not clear. 



Von Drasehe concluded that the form of Mount Bantuin as he saw 

 it from the mouth of the Ragay Eiver indicates it to be of volcanic 

 origin. When seen from other points it does not have the form of a 

 rounded cone, and close examination proves it to contain sedimentaries, 

 some of the limestone being conspicuous. 



The sedimentaries of the Eagay Coast Hills are principally limestones 

 with some sandstone and conglomerates and coal aggTegating more than 

 1,000 meters. The exposures of the limestones are the more conspicuous 

 since they form ledges and escarpments. In general, the dip of the 

 beds is toward the Eagay Coast, but there are minor folds and local 

 disturbances in many places. A noted exception is Mount Bernacci 

 or Amtig which has a monoclinal structure, the beds dipping a few 

 degrees to the northeast. 



The conglomerate beds contain boulders of andesite and basalt, and 

 rarely of diorite or other igneous rocks. They are nearly all in the basal 

 part of the series and indicate adjacent land areas. Such low-lying land 

 areas containing igneous rock, which furnished sediments, probably ex- 

 isted during the earlier stage of deposition. As deposition progressed 

 and the coralline limestones were formed, the seas must have been clearer. 



