RECONNAISSANCE OP MINDANAO AND SULU : III. 373 



small cone of sulphur, in some cases a meter high, has formed around 

 each vent. The sulphur is quite pure and of a beautiful yellow color, 

 but I doubt if there is anj^ commercial quantity of it; however, if, 

 there should be any considerable amount of the element buried or other- 

 wise concealed by the weathered rock, in my opinion it can not be trans- 

 ported to the coast with any reasonable profit; in fact, it took our 

 party three daj's of most strenuous climbing to reach this point on the 

 mountain. A cableway might be erected, but at considerable cost. A 

 little lake which rests on a shelf, or hanging valley, lies 450 to 600 

 meters below the summit of the north side of the mountain, but this 

 probably exists only in wet weather. The top of Mount Apo is exceed- 

 ingly rugged and covered with a scattered growth of blueberry bushes 

 with very much twisted and stunted branches. This makes excellent 

 firewood. Water usually stands in the circular depression just below 

 the summit; this, although slightly salty, can be used after boiling. 



My determination of the elevation of this mountain was made by 

 hypsometer and is calculated to be 3,955.0 meters. The elevation 

 obtained by the Spanish Survey was 3,145 meters. The recent geodetic 

 work in that region carried on by the United States Coast and Geodetic 

 Survey has given the altitude at 2,912 meters which proves that the 

 hypsometer is quite accurate within 30 or 40 meters, probably much more 

 accurate than a mercurial barometer and certainly far more so than 

 an aneroid. 



The difference in the character of the material on Mounts Apo and 

 Pumantigan is well seen in the canon of the Cibulan Elver. The for- 

 mation here is a volcanic agglomerate, the rock being andesite, but in 

 irregular boulders in a volcanic matrix. In one place where we stopped, 

 the canon is about 300 meters deep. There is an andesite conglomerate 

 below which changes above into a solid flow of andesite. I suppose 

 these zones alternate many times before the top of the canon is reached. 

 It seems very evident that there have been one or more tremendous 

 explosions from the crater, of which Mounts Culelan and Pumantigan 

 are the highest points. 



I know of no economic deposits in this district, but the country is 

 practically unprospected. 



On April 28, 1911, Major E. R. Heiberg, governor of the Cotabato 

 District, and party made the ascent of Mount Matutum, the next highest 

 point in Mindanao, and which is situated between Mount Apo and 

 Sarangani Bay. He found the elevation to be 7,880 feet (2,872 meters). 

 Samples collected from a point of about 2,000 meters elevation, and 

 submitted to me, have been classified as andesite. 



Major Heiberg says in his report: 



The peak is perhaps twenty feet in diameter and (with the exception of some 

 scrub growth about six feet high) was, fortunately for us, quite bare, enabling 



