28 The Philippine Journal of Science 1922 
Pikit, is both very able and willing to assist visitors to this 
region. 
Valuable notes relating to costs of transportation and sup- 
plies, furnished by Captain Gutierrez, of the Philippine Constab- 
ulary, are printed in the appendix to this article. 
Climate——Cotabato Province is in that portion of the Archi- 
pelago having no sharply defined rainy and dry seasons. Jan- 
uary and February are generally considered the best months for 
field work. This region is outside the typhoon area and, there- 
fore, is scarcely ever subject to storms. As there is no meteor- 
ological station nearer than Cotabato, near the coast, the writer 
does not know the rainfall of this interior basin. At Cotabato 
the mean annual precipitation is given by the Philippine 
Weather Bureau as 2,272 millimeters. It is probable that it is 
gomewhat below this figure in the central Cotabato Valley. 
At Cotabato the mean annual minimum temperature is 19.7° C., 
the mean annual normal is 26.6° C., and the mean annual max- 
imum is 33.8° C. The annual normal is slightly less than that of 
Manila. 
Population—The population of Cotabato Province is about 
21,000 persons, consisting largely of Moros segregated in towns 
along the Rio Grande, with some Manobos scattered through the 
hill country. In the Pidatan district the population is very 
sparse. 
The Moros are Mohammedans, while the Manobos are pagans. 
Judged by the standards prevailing in the Christian provinces, 
these people are extremely backward. They engage in very 
crude agriculture, fishing, and trading. In the Pidatan district 
the few Moros and Manobos present lead an exceedingly pre- 
carious existence and appear to be on the verge of extinction. 
GEOLOGIC 
General statement.—The geology of the region briefly stated 
is as follows: The principal formations, as indicated on an early 
map published by the division of mines of the Bureau of Science, 
consists of Tertiary sediments: limestones, sandstones, and 
shales. These are intruded on the edges of the field by igneous 
rocks, principally basalts and andesites. There is considerable 
agglomerate also in the region. Owing to these intrusions and 
also to more widespread regional earth movements, these sedi- 
ments have been folded and faulted, as in other parts of the Ar- 
chipelago; some of them, especially the lower series, including 
the Vigo shales (the petroliferous horizon of the Philippines), 
