THE PHILIPPINE 



Journal of Science 



A. Chemical and Geological Sciences 

 and the Industries 



Vol. V 



MARCH, 1910 



]S T o. 2 



GEOLOGIC RECONNAISSANCE OF SOUTHWESTERN 



LUZON. 



By George I. Adams. 

 {From the Division of Mines, Bureau of Science, Manila, P. I.) 



CONTENTS. 



Introduction. 



Physiographic regions. 

 Western cordillera. 

 Central plain. 

 Eastern cordillera. 

 Loboo Mountains. 

 Southwestern volcanic region. 

 Geology. 



Western cordillera. 



Geologic mapping. 



Older sedimentaries. 



Igneous rocks. 



Limestones. 



Marine conglomerates. 



Tufaeeous foraminiferal marls. 



Geologic history. 

 Central plain. 



Water-laid tuff. 



Alluvium. 

 Eastern cordillera. 



Schists. 



Diorites. 



Andesites. 



Basalts. 



93217 



Geology — Continued. 



Eastern cordillera — Continued. 



Tertiary limestones, sandstones 

 shales, and coal. 

 Loboo Mountains. 



Diorities. 



Ande3ites. 



Tertiary sedimentaries. 



Coralline limestones and marls. 



Geologic history. 

 Southwestern volcanic region. 



Extinct volcanoes. 



Eruptives. 

 . Cinder cones. 



Crater lakes. 



Active Volcano Taal. 



Historic eruptions of Taal. 



Agglomerates. 



Tuff formation. 



Coralline limestones and marls. 



Classes of igneous rocks. 



Structure of the region. 



Origin of Taal Lake. 



Origin of Bay Lake. 



57 



