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San Juan de Bocboc; and the Calbasahan, the smallest of the four, 
heading in the vicinity of the district where the present prospecting is 
being carried on and flowing due east to the sea near Guinasepa. 
Although the actual flow of water has not been measured on the Calba- 
sahan, it seems fairly certain that at all times of the year there will be 
a sufficiency to supply all of the ordinary mining needs, should such 
arise. 
Good harbors are to be found near Batangas, in Batangas Gulf, and 
at Layan. The one at San Juan is inferior, because of its exposure in 
the time of the northeast monsoon. All this coast has been charted and 
can be more critically studied from the Coast and Geodetic chart, 
No. 4714. 
Vegetation—The Loboo Mountains are heavily clothed on both their 
east and west slopes with a forest growth, some of the trees being red and 
yellow narra (Pterocarpus), balete (Ficus), and the anahao palm (Livis- 
tona) ; these are all of goodly proportions and quite abundant, so that it 
will be easy to procure timber. 
Large areas, on which the grasses talahib (Saccharum spontaneum) 
and cogon (Imperata exaltata) run riot, are on the plains at the foot 
of the mountains; occasional sampaloe (V'amarindus) and antipolo 
(Arlocarpus) trees are also seen. 
General and local geology=—A summary of the general geology is 
as follows; it is shown in the ideal section on Plate IL: 
PROVISIONAL, TABULAR STATEMENT OF STRATIGRAPHY. 
Recent: Tuff and alluvial deposits. 
Pierstocene: Tuff deposits containing fragments of mammalian 
teeth. 
PLIOcENE: Limestone fossils with Bornean affinities. 
MrocENE: Sandstone. 
Miocene: Shaly sandstone containing Vicarya callosa. 
Unconrormity: Basal conglomerate. 
PRE-MIOCENE: (Igneous) Diorite with quartz fissure-veins, cuprif- 
erous and auriferous. 
The basement rock of the region is one to which the field name of 
diorite has been given—i. e., it has a granitic texture and contains 
plagioclase-feldspar and hornblende as primary minerals. In some 
places it was seen to verge upon a granite, in others it kept its strictly 
dioritic composition but became very decidedly gneissic. The rock as 
a whole is decidedly coarse grained. 
It is in fissure veins which cut this rock, that the minerals of economic 
interest are found. As the diorite in this region is all more or less 
altered and stained with either iron or copper oxides and carbonates, 
considerable difficulty was experienced in obtaining a good sample from 
which to make a petrographic examination. 
