﻿COMPOSTELA-DAXAO COAL FIELD. 395 



associated with the biotite. and in small specks' in the groundmass. It is 

 generally fresh, but rarely is somewhat decomposed, staining the surrounding 

 portion of the slide with iron oxide. 



The grour.dmass is for the most part a mass of cloudy decomposition products 

 and secondary calcite. Occasional remnants of feldspar microlites can be made 

 out. There are also numerous small rods and specks, visible only with the highest 

 power objective. These are colorless, brown and opaque, but not clearly resolvable. 

 Xumerous small specks of magnetite also occur. 



THE UPPER LIMESTONE. 



The upper limestone is quite hard, dazzling white on fresh exposures 

 and the boundary of the formation is readily followed even where it 

 happens to be covered with talus. This formation is found in more or 

 less detached areas, it being remnants of what was most probably a 

 continuous blanket. It rarely reveals any stratification and hence its dip 

 and strike is generally a matter of conjecture. It is my conception that 

 prior to the formation of this blanket of limestone there existed many 

 irregularities in the surface, due to previous erosion, and that the lime- 

 stone deposit first filled in these irregularities. 



This horizon of the limestone in places is quite coralline, with many of 

 the characteristic genera now growing in the surrounding reefs. These 

 corals now appear to be segregated in colonies, although there may pre- 

 viously have been a continuous reef formation of which we have merely 

 the remnants left, the other portion having been destroyed by erosion. 



The lower part of the formation is in places very fossiliferotts and the 

 mollusca now fossilized undoubtedly lived in colonies, as we know them 

 to do to-day. At an elevation of 275 meters (900 feet) and near the 

 barrio of Mabasa I found a great many fossils which had weathered out 

 of the rock. They are all casts and a number of them are in poor con- 

 dition. (Pis. Ill and IV.) Some of the genera represented are: 



Cerithium. Trochus. 



Fusii*. Bulla. 



Turbo. Pectin. 



Xafii'i. Dosinia. 



Teredina. Conus. 



It is not my intention to make this a paleontologic discussion and 

 therefore I shall leave these fossils with the statement that I have com- 

 pared them with many of Martin's illustrations in his monograph on 

 the Tertiary of Java and have found many that I believe to lie identical 

 with those from which his illustrations are taken. 



I have thought it best not to treat of the paleontology at this time, as it 

 is my purpose later to prepare a monograph on the Tertiary fossils of 

 the Philippines. 



