270 FANNING. 
along the cordilleras and which are especially abundant at Para- 
cale, Benguet, and Bontoc and can be traced northward into 
Ilocos Norte. These veins are almost without exception con- 
fined, or genetically related, to igneous intrusives or extrusions 
of Tertiary age. The age determination is positive owing to 
the intrusion of Tertiary sedimentaries. 
The Ilocos Norte cherts are probably the work of siliceous sub- 
marine springs,” and it is to be suggested that possibly these 
belonged to the great Tertiary period of spring activity mani- 
fested throughout the Philippines. It is also to be remembered 
that the geology of Ilocos Norte is quite similar to the geology 
of northwestern Pangasinan—indeed, they are not far distant 
along the same coast of Luzon—and it seems more natural to 
compare these, rather than to.make the comparison with Cali- 
fornia. It is to be noted that the Pangasinan cherts lie at the 
base of the Miocene sedimentaries, which is in striking con- 
formity with the probable occurrence of the formation in Ilocos 
Norte. 
Conglomerates.—Conglomerates were not found in hee: area 
and it is a singular fact that they have not been found anywhere 
in the Zambales Mountains with the exception of the so-called 
“marine conglomerate” of Manila and Olongapo Bays, to which 
reference has already been made in this paper. 
Conglomerates are so characteristic of basal beds, and are 
found in such abundance along the adjacent, parallel, Kastern 
Cordillera of Luzon as to raise a question as to their real absence 
and, if such is true, the cause of this absence. 
Coral.—Uplifted Tertiary coral is found following the cones 
between the basal igneous and the sedimentaries; that is, they 
follow the old shore line. The coral does not occur as a large 
mantle covering the country, as it does in Cebu and some other 
regions, but is found as isolated cliff-bound mesas 10 to 30 meters 
high. The coral, because of its superior hardness, is resistant 
to erosion, and acts in many cases as a hard cap to the underlying 
sedimentaries. Recent coral, as noted under topography, is 
found along the present shore line, and is similar to types abun- 
dantly described by others. 
STRUCTURAL GEOLOGY. 
The area comprises the northern extremity of the Zambales 
Cordillera and marks the termination of the tectonic line ex- 
tending from Mariveles (near Manila) northward through 
** Smith, zbid., 159. 
