336 



SMITH. 

 Philippine soils. 



< 

 Soils. 



Origin. 



Resulting soil. 



Residual 

 Transported.- 



Basalt _ _ 



SLaterite. 



Clay with much insoluble matter, poor soil. 



Clay loam. 



Sandy loam to very poor sandy soil. 



Silt. 



Sand, gravel, etc. 



Andesite 



Limestone ._ „ 

 Shale — 



Sandstone 



(Fluvial ._ . 



ISubaerial _ _ _ _ 





As the rocks in the Philippines are largely volcanic and as the pre- 

 dominating class is andesite, or the olivine variety of it which is termed 

 basalt^ it is to be expected that a large area of the Islands would be 

 covered by a soil derived from the disintegration of these rocks, and such 

 is the case. This soil is usually heavy, red, and because of the large 

 amount of magnesia, iron, calcium, alumina, etc., which it contains, it is 

 exceedingly fertile. This ferruginous soil so much resembles some of 

 the material in India which has been called laterite that I shall so term it 

 in this discussion. However, all of the formations classed in India as 

 laterite have not originated in the manner outlined in the beginning 

 of this paragraph. 



Examples of this soil are to be found covering large tracts of Bataan 

 Province, Luzon ; much of western Mindanao and its upland, the vicinity 

 of Sarangani Bay on the same island ; ISTegros ; northern Luzon, especially 

 near Baguio ; Basilan and Albay, Luzon. This soil is much like that of 

 the Hawaiian Islands and is very well adapted to sugar growing, rubber, 

 hemp, etc. 



Limestone is the next formation which plays an important part in the 

 geology of the Islands. Vast areas are covered by this material and it is 

 found on the summits of some of the highest mountains, such as Mount 

 Data in Luzon. The formation is largely derived from triturated coral. 

 Although a limestone largely is made up of soluble matter, it almost 

 always contains some insoluble clay; the latter stays behind while the 

 soluble part is carried off by streams. Therefore, a limestone formation, 

 contrary to the usual belief, does not yield a very fertile residual soil. 

 On the other hand, the transported soil originating from limestone is 

 exceptionally fertile. As an instance, we need only point to the limestone 

 covered tracts of parts of Cebu. There the crops, chiefly corn, are very 

 poor, while in the coves some of the best agricultural land in the Islands is 

 to be found. 



The coal measures, which include sandstone shale and clays, are 

 productive of very good soils. Sandstone ordinarily is too high in urn 

 combined silica to afford plants much nourishment, but the sandstone in 



