GEOLOGY OF THE PHILIPPINE ISLANDS. 



335 



Clay. — Crude ware, pilones, cooking pots, brick and tile, all burning 

 red and unglazed, are made throughout the Islands. Some glazed ware 

 has been manufactured, using common salt glazing, but little fine faience 

 has been attempted. 



In Laguna Province some deposits of kaolin are located, but they are 

 not "extensively' worked. Orthoclase feldspar and sand suitable for glass 

 making have been found in a very few places. Good glass sand has 

 recently been discovered in Ambos Camarines. 



SOILS. 



Although the greatest application of geology is to mining, its relation 

 to agriculture is of growing importance and not always appreciated. A 

 mechanical analysis of soils is perhaps the most important for the scien- 

 tific agriculturist, but next comes that of the chemical composition, and, 

 finally, a knowledge of the geologic formation throws much light on the 

 interpretation of the results. 



Soils are classified in several ways, namely, according to size of the 

 grains, the chemical composition, origin, and lastly for what they are best 

 suited. 



The unconsolidated part of the earth's crust, of which the soil is only 

 the uppermost layer, is known as the regolith or blanket rock. According 

 to Merrill 26 the subdivision of the regolith are as follows : 



( t> .j i [Residuary gravels, sands and clays, 

 Sedimentary....] wacke, laterite, terra rossa, etc. 



|Cumulose.~. Peat, muck, and swamp soils, in part. 

 Colin "al I Talus and cliff debris, material of 

 j avalanches. 



i Modern alluvium, marsh and swamp 

 (paludal) deposits, the Champlain 

 clays, loess, and adobe, in part. 

 iEolian I Wind-blown material, sand dunes, 



adobe and loess, in part. 

 Claris 1 Morainal material, drumlins, eskars, 



j osars, etc. 



Leaving out of account the relative merits of the systems mentioned 

 on the previous page, I shall discuss the soils of the Philippines in relation 

 to their origin. This course seems best for two reasons : First, it is the 

 only one which a geologist should attempt to take, and, second, it is my 

 own belief that the only true classification is a genetic one. 



Two great subdivisions might then be made as follows : 



The regolith.. 



* Transported < 



!G A Treatise on Rocks, Rock-Weathering and Soils. New York, The Mac- 

 millan Company (1906), 228. 



