GEOLOGY OF THE PHILIPPINE ISLANDS. 311 



THE INTERMEDIATE UPLANDS. 



Under this heading I shall consider all the upland territory between 

 the foothills and an elevation of 1,500 meters. This includes the rolling 

 grass-covered hills of Cebu, Masbate, etc.; the smaller forest-clad ranges 

 of Luzon, the fertile slopes of such volcanoes as Mayon, Canlaon, and 

 Apo, and such semiplateaus as Baguio in Luzon, and the Lanao district 

 in Mindanao. 



Only the most primitive people at present live in the uplands, but when 

 the mineral and forest resources of the Islands are developed it will be 

 found that this zone possibly will furnish the larger portion of the wealth 

 of the Islands. The upland zone probably includes 75 per cent of the 

 whole area of the Philippines. 



The principal rocks of the upland zone are the Tertiary sedimentaries, 

 with some recent volcanics which flank the igneous cones of the Cordil- 

 leras. They are found inclined at all angles. However, the sedimenta- 

 ries are not encountered everywhere. Some of the upland country, like 

 that for instance of a part of northern Masbate, is denuded of sediments 

 and characterized by old, worn-down volcanic stocks, while the uplands 

 of western Mindanao are covered by a sheet of basalt. All the lode 

 mining operations practically are carried on in the upland country. 



Upland limestone country is, contrary to the general opinion, not so 

 fertile as that underlain by igneous rock, because the limestone is more 

 readily soluble and the rich ingredients are rapidly leached out. Cebu 

 Island, which is largely comjiosed of limestone, has a poor soil in the 

 upland tracts, but has quite rich patches in the valley areas. On the 

 other hand, the Lanao upland has an unusually rich soil formed largely 

 from the decomposition of basalt. 



Slope also has a great deal to do with the formation of soil. I know 

 of several hill districts in the Philippines where the slopes are so steep 

 and the rainfall so excessive that soil can not accumulate. The Manca- 

 yan-Suyoc district, for instance, is for this reason a country adapted 

 neither for cattle nor for agriculture. 



THE CORDILLERAS. 



It is difficult to make a genetic distinction between the intermediate 

 uplands and the Cordilleras. It is quite clear that a true cordillera may 

 not in its highest parts reach the upper limits I have already placed for 

 the intermediate uplands. For instance, the highest point in the Island 

 of Cebu is not much over 1,000 meters above the sea, but the central 

 range in this island, which varies from 600 to 1,000 meters in altitude, is 

 as wild and uninhabitated as the central range in Luzon, which attains 

 to a height of over 2,000 meters, and, technically, it is just as much a 

 cordillera. 



