NORTHWESTERN PANGASINAN. 963 
found over large areas and also as dikes within the coarser- 
grained rocks. 
A specimen from the bar7io of Cabulalwan, 4 kilometers north 
of Barlo, under the microscope, showed porphyritic, dopatic 
fabric. The phenocrysts were feldspar and hypersthene lying in 
a background consisting mainly of lath-like microlites of feldspar 
with intersertal serpentine. A dike rock from Pao Bay showed 
similar structure and mineralogy, but was very much decomposed. 
Another dike from the same locality was felsitic in texture and is 
probably andesitic in nature. The abundance of gabbros in the 
district would naturally suggest the presence of augite-andesites ; 
that is, the fine-grained or porphyritic derivatives of the gabbros. 
These are known to occur abundantly in other parts of the Zam- 
bales Mountains and therefore are to be anticipated in Panga- 
sinan. 
Basalt.—A most interesting olivine basalt was found 4 kilome- 
ters north of Barlo. In hand specimen the rock is rather decom- 
posed, is dark brown in color, and shows an amygdaloidal struc- 
ture. Under the microscope the rock shows a porphyritic fabric 
with phenocrysts of pyroxene and olivine, the latter being greatly 
altered to serpentine. Amygdules, probably delessite, occur in 
large quantities filling vesicular cavities. They are generally 
spherical, but also occur in irregularly rounded and elongated 
shapes. The amygdules are made up of alternate light and 
dark shells of radial crystals with generally isotropic centers. 
In parallel light these shells show merely light and darker shades 
of yellowish brown, but under crossed-nicols they become sub- 
divided into various colored bands with numerous isotropic ones. 
In some cases six separate shells were seen. The glassy back- 
ground, adjacent to the amygdules, is frequently altered to give a 
surrounding ring of serpentine. 
This is the first reported occurrence of delessite in the Phil- 
ippines and Philippsite-bearing rocks (rare for the Philippines) 
in proximity makes the discovery all the more interesting. 
Basalt is found along the Zambales Range, and specimens from 
Mariveles have been accurately described by Iddings.® 
Tertiary sedimentaries.—Tertiary sedimentaries are found 
over the majority of the area, and extend in unbroken series 
from Barlo northward to the China Sea. The strata comprise 
' tuffaceous marls, tuffaceous limestones, and water-laid tuffs. 
The strike is generally northeast with a slight monoclinal dip to 
*Ibid., 1638. 
