470 ADAMS AND PRATT. 



vertical bed not of economic importance. It is situated southwest of 

 Caramuan. This is the only place at which coal was seen, although 

 the other reported occurrences were visited. 



On certain published maps the presence of copper is indicated near 

 the eastern end of the peninsula. When the reconnaissance of this 

 area was made, nothing could be learned concerning copper at the place 

 shown on the map, but it was reported that some copper occurs near 

 Sipaco, which is in the central part of the northern coast. 



BATAN ISLAND CHAIN. 



The Batan chain of islands includes San Miguel, Cacraray, Batan, 

 and Kapu-Eapu; it is so named in this paper for the reason that Batan 

 Island is the best known of the group because of its coal deposits. 

 San Miguel Island was discussed by Roth who reported that it con- 

 tained dolerite rocks, similar to those of Malinao Volcano, and also 

 tuffs. Von Drasche, on the strength of Roth's statements, mapped 

 the island as dolerite tuff. 



Batan Island has been studied by Smith® whose report is accom- 

 panied by a geologic map showing the coal outcrops. The island is 

 described as consisting principally of Tertiary sedimentaries, while an 

 area of pre-Tertiary igneous rocks forms its eastern end and also is 

 indicated on the west end of Rapu-Rapu, and the Tertiary is likewise 

 indicated on the coast of Cacraray adjacent to Batan. 



The igneous rock on the east end of Batan is described as a peri- 

 dotjte grading into a pyroxenite. In the text of the report, igneous 

 rocks are noted as occurring in small exposures near Caracaran and 

 Liguan! For a fuller discussion of the structure of the island, readers 

 are referred to the original report. For the purposes of the present 

 paper the general geologic conditions may briefly be outlined as follows: 



The Tertiary beds were laid down upon the igneous rocks. In the 

 base of the sedimentaries there is in places a conglomerate formation 

 containing quartz and pebbles and boulders of iron ore. The higher 

 beds are shales, grits, sandstones, and limestones with intercalated beds 

 of coal. There is considerable evidence of disturbance of the strata, 

 especially near the west end of the island, but the details of the folding 

 and faulting have not been worked out. 



The Batan Island chain, as indicated by the structure of the islands 

 and the thickness of the sedimentaries exposed on their coast, is 

 probably a fault block. Whether the stratified formations were once 

 continuous with some of the adjacent areas of the same age is not 

 certain, but it is probable that they were, and that the emergence of 

 this chain was concomitant with the submergence and erosion of exten- 

 sive Tertiary deposits on the eastern flank of the cordillera. 



•The Coal Deposits of Batan Island, etc. Bull. P. I. Min. Bur. (1905), No. 5. 



