GEOLOGIC RECONNAISSANCE OF MINDANAO AND SULU. 475 



Much less has been accomplished in relation to the geology, but there is ample 

 excuse for this lack of results. To use the expression of Dr. G. F. Becker, "such 

 work in a country where the natives are not on the best of terras with you is 

 more exciting than profitable." 



Among our Spanish predecessors, Sainz de Baranda, Centeno, Montano, Espina, 

 and Abella have contributed to our knowledge of the geology of Mindanao. The 

 work of the latter was confined almost entirely to the Misamis region, but it is 

 the best of all the contributions from that part of the island. 



The following appear among other Europeans who collected in Mindanao or 

 studied its geologj': Semper, Richthofen, Minard, and Renard. K. Martin worked 

 on some fossils which came from Mindanao and Oebbeke described certain rocks 

 collected on that island. Martin and Oebbeke have never been in the region. 



Dana, Ashburner, and Nichols were Americans who visited Mindanao before 

 the American occupation and who contributed to a knowledge of its geology and 

 finally, Dr. Becker was in the Archipelago in 1898, just at the outbreak of hostili- 

 ties with the natives. 



Guillemard and Becker seem to have been the only investigators who touched 

 at any part of the Sulu group. The former barely mentions Cagayan de Sulu, 

 and the latter could only study the islands from the deck of the vessel, as the 

 natives were at that time in a very warlike humor. 



Dr. Becker ^ in his report gives a brief summary of the previous work in 

 Mindanao and the following is a quotation : 



"Concerning the great Island of Mindanao, only scattered observations are 

 available. Sainz de Baranda - noted the occurrence of serpentine on the east 

 coast of the island at Canmahat and in Misamis Province at Pigtao. Mr. Centeno 

 states that at Pigholugan, near Cagayan, in the Province of Misamis, there are 

 quartz veins in talcose schists. The auriferous districts of the Province of 

 Surigao may, he points out, be regarded as a continuation of the Misamis district. 

 The most notable deposits here are in the mountains of Canimon, Binuton, and 

 Canmahat, a day's journey southward from the tovsTi of Surigao. The terrane is 

 here composed of much altered talcose slate and serpentine.^ Mr. Semper collected 

 on the Mapnti, which is an upper tributary of the Agusan River in Surigao. 

 Here he found a uralitic gabbro and a chloritized, aphanitie, augite-plagioclase 

 rock, containing a few plagioclase phenocrysts. The specimens have been described 

 by Mr. Oebbeke.* They are probably facies of the melaphyres found by Mr. Montano. 

 Mr. Ashburner examined a slate belt in the extreme northern portion of the island, 

 about 8 miles to the southward of the town of Surigao, at the headwaters of the 

 Cansuran River. It contains auriferous quartz stringers. Mr. Montano collected 

 melaphyres at a number of points in eastern Mindanao. Such are the eastern 

 shore of the Bay of Butuan, the eastern coast of the island between Bislig and 

 Catel, and the di\'ide between the waters which flow northward into Butuan Bay 

 and those which flow southward into the 'Gulf of Davao. The river of this 

 southern drainage basin IMontano terms the Sahug. Other authorities give it 

 diiferent names. In its headwaters he found float consisting of melaphyre 



' Report on the Geology of the Philippine Islands, U. S. O. S. 21st An. Rep. 

 (1899-1900), Pt. 3, 507. 



-He also mentions crystals of rutile from an island called Bigat, which is 

 ^mkno^vn to me. Anal. d. Min., Madrid (1841), 2, 197-212. 



' Memoria geologico-minera ( 1876 ) , 49. 



'Neues Jahrb. f. Mineral., etc. (1881), Beil.-Band 1, 498. 



