114 B. KOTO : THE GEOLOGIC STRUCTURE OF 



west shore, passes through the ishmds of Lubang, and the 

 basaltic Calamians, and finally reaches Paragua, which seems to be 

 connected with the north end of Borneo. In Paragua, an old 

 limestone is said to occur. The Zambales-Paragua ridge curves 

 quite like the coast of Annam, just as New Caledonia and New 

 Zealand conform to the outcurve of Eastern Australasia. 



The ridge of Northern Luzon forks into two arms, viz., the 

 Cordillera del Norte and the Sierra Madrés, with the basin of 

 the Rio Grande de Cagayan between them. In the tobacco- 

 producing region, Isabella and Nueva Vizcaya, of that basin, 

 especially in the former, the earlier Miocene tuffite, and compact 

 sandstone seem to have a wide distribution, as is proved by the 

 occurrence of the typical fossils, viz., Vicarya callosa Jenk., 

 Ranella ranionoides, IMart., Rostellaria javana, Mart., just as in 

 Cebii and Java.'^^ 



Separated on the east from the Cordillera del Norte by the 

 Rio de Abra, and the Rio Agno, and on the west, from the Sierra 

 de Zambales by the Golfo de Lingayan there runs the meridional 

 Sierra Tovalina through the maritime provinces of Union, Ilocos 

 Sur, and Ilocos Norte, Chlorite-schist and sericite-schist seem 

 to form the foundation of this ridge, as can be seen in a trans- 

 verse valley near the port of Vigan. This geological island of 

 crystalline schists, which seem to have some resemblance to 

 the oldest rocks of Taiwan (Formosa), is concealed by its covering 

 of the Agno bed, a complex of sandstone, and breccia derived 

 from the detritus of diabase, gabbro and diorite, which have 

 intruded throu&h and overflowed the Archseicum. At a later 

 time, volcanic activity was renewed through eruptions of trachyte. 



73) K. Martin, Sammlungen des geolof/ischen Reichs-Museums in Leiden, Bd. Y, Heft ?>, p. 58. 



