RECONNAISSANCE OF MINDANAO AND SULU : III. 371 



An oil seep is reported near Kudarangan ; however, I have not seen it. 

 It is not at all improbable that oil may occur in the sedimentaries ot 

 this valley. The conditions for artesian water are certainly favorable, 

 as the sandstone would make an excellent water bearing stratum. 



I have no information regarding economic deposits in this district. 

 Prospecting at some future date, when the country is more settled, 

 will doubtless reveal many valuable deposits of which we know nothing 

 at the present time. The limestones and clays near Cotabato may 

 possibly be utilized at some future date for making cement. The lime- 

 stone is very pure, but no analj'ses have as yet been made of the clay. 

 This is essentially an agricultural district and should develop into 

 one of the most productive parts of Mindanao. 



The limestone in Constabulary Hill is very fine, with veiy little 

 magnesia and fairly white, inclined to be slightly pinkish. It contains 

 numerous recent marine fossil shells. Among them are the following 

 genera : Pectin, Conus, Oliva, Turho, and Cypraa. 



Soil. — As most of this district is covered, with transported soil, the 

 rich alluvium of the Bio Grande, there can be no richer agricultural 

 tracts in the Island of Mindanao, and it should be capable of growing 

 almost any kind of tropical crops. 



THE TIRUBAY DISTRICT. 



Very little is known of the geology of this region, the only Govern- 

 ment officials who have crossed the country being Lieutenant Van Horn, 

 17th Infantry, and Mr. E. B. Christie, ethnologist of the Bureau of 

 Science. This was in 1902. Lieutenant A^an Horn's report shows 

 that the country is exceedingly rugged, there being possibly more than 

 one distinct mountain range between the Cotabato Eiver and tlie coast. 

 Very few people live in this region and they are of the lowest station 

 in life. Some of the peaks in the central part of the district, particu- 

 larly Mount Lubuagan, 1,220 meters, may be old volcanic cones. 



THE APO DISTRICT. 



An irregular and interrupted chain of old volcanoes is situated to 

 the east of the Cotabato district. Mount Apo, approximately in the 

 center of the region, is dominant. Mount Matutan, about eighty kilo- 

 meters to the south, and Mount Magolo between the latter and Apo, 

 are other prominent peaks. The range to the north of Mount Apo 

 is still unexplored, only one white man, to my knowledge, Mr. Jetar, 

 having ever crossed it. On our march from the junction of the Eio 

 Grande to the Kabakan Eiver south of Mount Apo and to Digos on 

 the Gulf of Davao, we were traveling continually in j.ungle where we 

 had very little opportunity for studying the formations. Occasionally, 

 we saw very small outcrops in the stream beds but no large sections 

 or extended exposures. The formation is largely sandstone, with andesite 



