472 ADAMS AND PRATT. 



It is probable that subsidence was in progress, since the mass of lime- 

 stones has a thickness far greater than the depth of water in which 

 corals live. The elevation of the series of sediments to their present 

 position was brought aboiit by the growth of tlie cordillera, on the wes- 

 tern flank of which they lie. 



Coal. — Yon Drasche cites the occurrence of unimportant indications 

 of coal in the Eagay Hills about 9 kilometers southwest of Bato Lake 

 and states that the importance of this locality, called "Mines of Batac/' 

 is overestimated. The history of the discovery of this coal can be found 

 in Burritt's compilation on the Coal Measures of the Philippines. The 

 thickness of the bed is stated to be from 2 to 8 centimeters. The dip 

 is 60° in the direction south 70° west. Float coal is reported at a num- 

 ber of places along the coast, but no prospecting has been done that has 

 discovered workable beds. 



BICOL VALLEY. 



The surface formation of the lowland along the Bicol Valley is nearly 

 everywhere alluvial. It consists of materials brought from the vol- 

 canics of the Southeastern Cordillera and the sedimentaries of the Eagay 

 Coast Hills. Jfear the head of the valley there is considerable material 

 that has been washed down from the slopes of Mayon and has aggraded 

 the surface. 



At some places where excavations have been made, beds of shells have 

 been found, and in drilling artesian wells shells have been encountered 

 at considerable depths. The character of the formations indicates that 

 brackish water conditions prevailed over the lower part of the valley. 

 South of Bato Lake no wells have been drilled and information accord- 

 ingly is not obtainable concerning the deeper lying beds. The tide 

 affects the Bicol Eiver up to Bato Lake and formerly it may have reached 

 farther. In fact, it seems probable that during a former time when 

 Mayon Volcano was still in its younger stages of growth, a strait ex- 

 tended from San Miguel Bay to Albay Gulf. 



An arm of the formation found in the Bicol Valley extends to Ragay 

 (rulf at Pasacao through a gap in the coast hills which may once have 

 been a seaway. 



EASTERN CORDILLERA. 



The portion of the Eastern Cordillera represented in Tayabas Penin- 

 sula is its southern termination and does not show the typical geologic 

 features which are found much farther north, where it contains high 

 mountains of eruptive rocks and has a rugged topography. In the part 

 shown on the accompanying geologic map the cordillera is formed of 

 folded and faralted Tertiary sedimentaries with the exception of a small 

 area of diorite near Peris. The diorite occurs in a hill and represents a 

 part of the igneous fonnation which gradually was covered by the strati- 



