are, tS ee! Te 
ea 
— 
618 
of certain prospect work carried on by some prospectors from Batangas 
on a group of twenty-one claims in the Loboo Mountains, and trips east 
and west to the coast from these workings. 
The site of these claims is indicated by crossed hammers on the general 
map (Pl. 1), which has been adapted from d’Almonte. They are 
situated on the headwaters of the Calbasahan River in the pueblo of 
San Pedro, some 40 miles more or less from Batangas, and about 6 
from San Juan de Bocboc. 
The writer wishes to acknowledge the many courtesies and valuable 
assistance rendered by Messrs. Harris, Weeden, Weber, and others of this 
camp. Particular mention is due to Mr. Weber for the fossils shown on 
Plate IV, and for several compass route surveys which may be of con- 
siderable value in the future. 
DISCUSSION. 
Physiography.—The topography of this region is typical of moun- 
tainous country in the Philippines. The Loboo Mountains rise rather 
abruptly from a plain, with the steeper and shorter slopes to the east 
and south. Save for a considerable break where the Loboo River cuts 
through to the south, they extend as a chain continuously and approxi- 
mately parallel with the coast. ‘To judge from the trend of the range 
and this break, one might infer a fault with considerable horizontal dis- 
placement. However, no further indications of the latter have been seen, 
The mountains themselves exhibit nothing which materially differs 
from the usual erosion features of mountains in general; that is to say, 
they are not of the faulted block type, Karpathian or Jura, etc., although 
they approach more nearly the last. They attained their bulk and eleva- 
tion from their particular mode of structure, which was that of a great 
anticline of stratified rocks pushed up from below, when the old, igneous 
stump slowly rose; following upon this rise there ensued the growth of 
the mountain topography by which they attained to their present accen- 
tuated relief. 
The softer sedimentaries would produce rounded forms, while the 
more resistent igneous core would form the backbone of the range and 
stand up in peaks and sharp ridges. 
Physiographically, the plain country possesses a particular interest. 
It is a plain of deposition, made up of heterogeneous materials, has a 
fairly even sky line and is being dissected by streams which run in deep 
gorges. As the writer went overland from Calamba, through Lipa to 
Batangas, he had a good opportunity to study the materials of this plain 
which on examination were seen to have been deposited in part from 
yoleanic showers and in part by streams. 
The country just east of Batangas, toward the Loboo Mountains, 1s 
an extension of the Taal tuff area. Its average elevation in the vicinity 
of the latter range is about 1,000 feet, but this increases gradually to 
