The Philippine Journal oe Science, C. Botany. 
Vol. V, No. 4, September, 1910. 
THE FLORA OF MOUNT PULOG. 
By E. D. Merrill and M. L. Merritt. 
(From the Botanical Section of the Biological Laboratory, Bureau of Science, and 
from the Bureau of Forestry, Manila, P. I.) 
The entire northwestern part of Luzon, west of the Cagayan Valley, 
is high and mountainous, the region being essentially that of a cordillera 
or a series of cordilleras, in which the streams are deeply incised, haying 
sharp V-shaped valleys. The topography is generally that of youth, 
with here and there isolated table-lands, of which the Baguio plateau is 
the principal one. Above the general upland of from 1,200 to 1,600 m 
elevation a number of peaks arise, some of which attain an altitude of 
nearly ' 2,900 m. Mr. Eveland, 1 in ■ discussing the -central cordillera,' 
considers it to be the master axis of Luzon, and probably one of the 
original tectonic axes of the Asiatic continent, formed by a wrinkling 
of the more plastic crust of the earth as the globe has contracted. In 
it the oldest of the Philippine rocks' are found, and on it all the agencies 
of construction and destruction have been at work since the Philippine 
Islands, as such, originated. 
The geology of north-central Luzon is only incompletely known, but 
in general the region may be said to consist of a core of dioritic rock, 
overlying which is found a rather confused mass of eruptive rocks, in 
the main, andesites. On the flanks of this core, dipping east and west 
are Tertiary sediments, limestones, and shales, which may have once 
extended over the whole region in the form of a broad anticline. Speci- 
mens from rock outcropping on the summit of Mount Pulog proved to 
be andesite. 
Dr. Warren D. Smith, of this Bureau, thinks that probably at the end 
of the Miocene, at the time of the great earth movements which took place 
all over the world, a period of ore deposition occurred in the Philippines. 
In the area under discussion there are two principal centers of ore deposi- 
tion, the copper deposits about Mancayan, northwest of Mount Pulog, 
and the gold deposits near Baguio. The later history of this part of 
'This Journal 2 (1907) Gen. Sci. 217. 
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