RECONNAISSANCE OF MINDANAO AND SULU : IH. 383 



the marl-limestone formation, whieh I hare classified as middle Tertiaiy, and 

 these in turn upon formations still older, it results that the placers must have 

 been formed after the Mioc-ene period and before the present formation. 



I have already said that the formations which are the most extensively developed 

 in the whole district, at least provisionally, could be considered as belonging to 

 the middle Tertiary, not simply because of the doubtful determinaticMi of the 

 gQius Turbinolia. but more by reason of their petrographic characteri5ti<s and 

 their stratigraphic position. 



With regard to the slaty formation which is more or less metamorphosed, as 

 it occurs in many places, it is difficult to assign any age to it which would not 

 be more or less subject to error, because of the insufficient Utholc^c data I have 

 been able to gather. However, I can be sure that it is the oldest formation I 

 have crossed, but I can not be more exact, and I leave the question unanswered 

 until an opportunity for malring more detailed observations can be found or until I 

 shall have had greater experience in these studies. 



During the reconnaissance here mentioned and others of less importance which 

 I have had occasion to mak^ I have seen no deposits other than the auriferous 

 ones I have described in detail in the report, and I have had only reports of 

 some beds of coal which they told me had been discovered to the soutGeast of 

 Nauan, a one- or two-day trip from this town. Although I did not finally see 

 samples which they promised to show me, from the description they gave me 

 of it and the adjacent terrain, I corroborated what I had suspected, namely that 

 this coal occurs in the Miocene formation which extends as far as that locality, 

 and because of this I believe it must be a lignite and that but for this it might 

 be of great future use. 



Moreover, they have indicated to n»e in a vague sort of way that to the west 

 of nigan the existence of plumbiferous and pyritiferous minerals which, to be 

 exact, oc-cur in localities little known and which are not very safe, in the 

 dangerous vicinity of the Moros which live around Tligan. 



Some oecurrences of gold have been reported to the southeast of Xauan. 

 but they have not been investigated by Abella or any of the later engineers, 

 except 'Sis. J. Clayton Xiehols who visited this region in 1900 in a 

 private capacity. His report ^' has added very little new information 

 about the geolc^y. His conclusions regarding the po^biUties for mining 

 are of interest. He says that the Iponan Biver is an ideal stream upon 

 which to work a dredge. He also makes some observations on the climate 

 as follows: 



At no season of the year is there a scarcity of water and during a few days 

 only is the water so high as to interfere with operations. The working season 

 is from one years end to the other. Frost is unknown in Mindanao. The climate 

 is delightful and the country is healthful and fertile. Parts of it, especially the 

 lower Iponan Valley, are thickly inhabited. Native labor is plentiful at a low 

 rate of wages. Tropical fruits, com. coeonuts, rice, vegetables, and sugar are 

 pleotiful and cheap. 



The gold production of this region can only be estimated, as the natives 

 sell most of their winnings to local Chinee traders and it never passes 

 through the hands of any officials. Eight thousand pesos are said to 



''The Gold Deposits of Pigtao, etc.. Trans. Am. Inst, of Mia. Eng. (1901), 

 31, 611. 



