X, A. 3 Smith: Geology of Panay 217 



wood left on her mountains, and the Philippines would soon 

 be in the same plight but for the Government's timely forest 

 conservation policy. 



GENERAL GEOLOGY 



As already pointed out by Abella, the general classes of rocks 

 found on Panay are: The recent formations of the plains; 

 the Tertiary limestone, shales, and sandstone in the foothills; 

 the core of igneous rocks in the cordillera; and some doubt- 

 ful rocks, approaching slates, which come between the igneous 

 formations and the Tertiary series. 



The best development of sedimentaries I have yet seen in the 

 Philippines exists on Panay, and the best sections for studying 

 them are perhaps to be found there. On Suague River Mr. Pratt 

 estimated that the total thickness of the Tertiary series amounts 

 to more than 9,000 meters, and if we include the older series of 

 "slaty" rocks at the headwaters of Ulion River the total will 

 be about 10,000 meters. I found very much the same series 

 on Tigum River, the two streams being roughly parallel and 

 only a few miles apart. A short distance above the barrio of 

 Tinayoc Tigum River has cut into the hillside, affording an 

 excellent section, which is typical, as follows: 



Meters. 



Thin-bedded sandy shale 15-20 



Heavy-bedded sandstone 5 



Sandstone i 



Carbonaceous shale I 



Sandstone i 



Carbonaceous shale, less than i 



Heavy-bedded sandstone 5 



Thin-bedded sandstone and shale 16 

 Heavy-bedded sandstone at base 



The dip at this point is 30° to the southeast, and the strike 

 is north 10° east. Descriptions of three different samples of 

 the sandstone follow: 



Sample 2312. — Buff to gray, very coarse, and apparently made 

 up of triturated particles from various kinds of igneous rocks 

 occurring in the cordillera. There is little quartz in the speci- 

 men, but fragments of ferromagnesian minerals predominate. 

 The buff color is largely due to fragments of olivine washed out 

 of the decomposing picrites known to occur in the cordillera. 

 This rock has a porosity of only 5.5 per cent, the voids being 

 filled largely with iron oxide and calcium carbonate as a cement- 

 ing material. 



