224 ^/ic Philippine Jonrval of Science i9i5 



Sample 2323, macroscopic. — The rock is pinkish with occa- 

 sional fine black streaks in it, rather fine-grained, and fissile, 

 so that it breaks into more or less thin slabs. 



Microscopic. — The groundmass consists of cry ptocry stall ine 

 silica, dotted with small roundish and oval areas filled with small 

 irregular grains of silica but little larger than those constituting 

 the groundmass. These roundish areas undoubtedly represent 

 tests of Radiolaria, but nothing now remains save the cast. 



In another sample tests of Radiolaria belonging to the follow- 

 ing three genera were identified : Stylosphxra, Dictyomitra, and 

 Cenosphxra. The species of the first-named could not be told, 

 but under the second, the species affinis was distinguished without 

 difficulty, and of the third genus, which is by far the commonest, 

 the species minuta and disseminata were recognized. 



We have now found this radiolarian chert in Ilocos Norte 

 and Bulacan, Luzon, in Panay Island, and in Balabac Island — 

 from the northernmost to the southernmost part of the Ar- 

 chipelago. Outside the Philippines the same rocks are known 

 to occur in the Moluccas,'' in the Federated Malay States," and in 

 California,^" and everywhere they are referred to the Jurassic. 

 We have every reason then to believe that this formation, or 

 group of strata, in the Philippines is distinctly older than the 

 Tertiary. 



Associated with these red rocks are some gre6n rocks, which 

 in a thin section are shown to be serpentine, and these, we have 

 seen, accompany the cherts of central Borneo. 



IGNEOUS ROCKS 



As Abella has devoted no little space to the igneous rocks which 

 he found in the cordillera, I shall not discuss them at length. 

 His list includes the following: 



1. Andesite. 6. Gabbro. 



2. Basalt. 7. Picrite. 



3. Diabase. 8. Serpentine. 



4. Diorite. 9. Tonalite. 



5. Diorite (quartz). 10. Trachyte. 



Of these the difi'erent varieties of andesite constitute the 

 dominant rocks of the cordillera, and similar rocks have been 

 described in Philippine literature. Of the rest we need call 

 attention only to the tonalite and the picrite. We have found 



' Martin, R., Reisen in den Molukken. Geolog. Theil. 2te Lief., 171. 

 'Scrivenor, J. B., Geol. Mag. (1912), 9, 241^8. 

 "Fairbanks, H. W., Journ. Geol. (1895), 3, 418. 



