THE GEOLOGY OF LUZON, P.1. 49 
by intermarriage with the natives, but the Chinaman as a China- 
man need not be considered further in this article. 
GEOLOGY 
GENERAL CONSIDERATIONS 
If we examine the general geological map of the Island of Luzon, 
we distinguish in the southern part, a rough lining up of formations 
into belts or long strips having a northwest-southeast trend. 
First, at the extreme southeast, there is a zone of metamorphic 
rocks beginning on the small island of Rapu-rapu and extending 
northward through Ambos Camarines in the vicinity of Mambulao. 
Their continuation will undoubtedly be picked up some day along 
the east coast of Luzon, farther north. 
Next, to the westward, is a belt of recent volcanics. In this 
belt, are the well-known cones of Bulsan, Mayon, Iriga, Isarog, and 
the pretty well worn-down stock of Bagacay. 
Third, the narrow Albay Plain. 
Fourth, a broader belt of folded sediments in the western part 
of the Sorsogan peninsula, and constituting practically the 
whole of Tayabas peninsula. This belt continues up into Central 
Luzon, where it becomes partially concealed by later volcanic flows. 
_ Fifth, another volcanic zone which takes in Taal, Talim and 
Arayat, in the eastern portion of the Central Plain. 
Sixth, the plain belt, beginning with the Cavite Plain and the 
Central Plain, extending north to Lingayan gulf. 
Seventh, the line of andesite stocks constituting. the Zambales. 
Eighth and westernmost, the very basic and dense rocks of the 
Cinco Picos range, just west of Subig Bay. This last is really 
almost insignificant in area, but very important as has already 
been mentioned. 
In the northern part, we cannot, as yet, make such clean-cut 
separations, owing largely to our ignorance. However, a rude 
parallelism of belts can be made out. 
Having considered the distribution of formations geographically, 
let us now turn to a consideration of the stratigraphic sequence; 
this is best shown by the tabular scheme in Table 1. 
The absence of older formations than the Tertiary from this 
column may be explained by one or more facts, namely: 
