378 SMITH. 



Montano has left a few notes regarding the east coast of Mindanao. 

 He sa5's: 



At the center of the island between Bislig on the map shown and the Rio 

 Simulao, a tributaiy of the Agusan, I crossed the Cordillera Central at an alti- 

 tude of 130 meters by the passage of Mount Bucan, the formation of which is made 

 up of a thick bed of brown clay, but at the foot and to the west of this mountain 

 the iliaga, a tributary of the Simulao, has some cascades and rapids which 

 reveal massive Miocene andesites of great thickness. The east coast of Mindanao 

 between Bislig and Pugada Bay presents a succession of capes generally elevated 

 and rounded and formed by the projecting spurs of the Cordillera Central. Be- 

 tween Bislig and Cateel upon this coast I collected some madrepores altered at 

 the contact with serpentine. It is along this part of the coast that elevation 

 seems to be most evident. Some large banks of madrepores rest above the level 

 of the sea, occurring as large horizontal tables polished by the waves which the 

 northeast winds raise above their normal height. These banks of madrepores are 

 especially prominent between Cateel and Point Bagoso. They are without doubt 

 of the same origin as those produced by the waves between Bislig and Cateel, 

 which in bad weather are dangerous to approach. These rock breakers form a 

 cordon parallel to the bank upon which the sea dashes with fury, although a 

 relative calm exists in the zone which they protect. Particularly along this coast, 

 and even more so between Point Bagoso and Pugada Bay, the evidences of uplift 

 are manifest. One finds there all gradations between the broken madrepores 

 mixed with humus upon the summits of the capes, and those which, raised at the 

 edge of the coast, have lost their organic material only recently. Upon the same 

 coast one finds at eveiy step some conglomerates which are formed by a mixture 

 of sand and debris of gi'ound-up molluscs and madrepores. In the Gulf of Mayo, 

 near the Bay of Pugada. the cliffs of Butuan, which are quite extensive and have 

 an elevation of from 20 to 60 meters, are formed of a pudding stone in which 

 molluscs abound similar to those which live to-day in the gulf. I have collected 

 some madrepores and some gypsum mixed with pyrites of iron upon the coast 

 of the Bay of Pugada, and upon the ridge which separates it from the Gulf of 

 Davao, some breeeiated quartz. 



Economic. — Much more has been done in the way of prospecting near 

 the northern part of the district of Surigao, but we have still very meager 

 geologic details regarding the country. Goodman, formerly mining en- 

 gineer in the Bureau of Science, has ^vritten concerning the gold fields of 

 the Surigao Peninsula from the view of the engineer. This report was 

 published in 1909 in the second bulletin of the Mineral Eesources of the 

 Philippine Islands.* 



The country rock of the region is andesite intersected by a system 

 of veins running in general about north 55° east and dipping 60° to 

 70° toward the southeast. Many of these veins are mere quartz stringers 

 less than one centimeter in thickness. In general, the walls of these 

 stringers have become silieified to a greater or less extent, making the 

 limits of the mineralization very definite. Most of the prospecting work 

 has been confined to the neighborhood of Placer on the east coast. In 

 Goodman's opinion the best way to work this ground is by hydraulic 



"Min. Resources P. I. Bur. Soi., Div. Min. (1909), 40. 



