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to one-tenth of that of the subsoil, as in an old Quaternary 

 field in Kiushu. The case is quite! ' different on the continent ; 

 for instance, in an arable soil in Germany and Belgium, the 

 contents of fertilising elements are about equal both in the top- 

 and the subsoil. Also it is an established fact that the top soil 

 is : more fertile than. the subsoil. The important constituents 

 formed by the action of weathering or added ' by manuring, 

 thus tend to pass .away more quickly than on the continent. 

 Biit, on the other hand, there is an advantage derived from 

 this quick weathering, viz., that our farmers are able to restore 

 the lost fertility by 'the art of cultivation, ploughing and 

 trenching in relatively' short periods. The rocks may be 

 classified as follows :— 



1. Old Eruptive Rocks, 



"Plutonic Rocks (Granite, Quartz-porphyry, etc). 



2. Young Eruptive Rocks, , - , . 



Vbicanic Rocks (Andesite, Volcanic tuffs. Volcanic 

 ■ ashes and gravels.) 



3. Metamorphid Rocks,. 



Arclieah ' Formation (Granite- Gneiss, Crystalline 

 ""'Schist.'Chlorite Schist, etc.) 



4. Se'M'fti¥rita'ry' Rocks, 



Paleozoic Rocks (Schalstein, Quartzite, etc.) 

 Mesozoic Rocks (Trias, Jurassic, Cretaceous.) 

 .Tertiary Rocks- (Phylite} Tuffs, etc.) 

 Old Quaternary (Alternate Strata of Soil, Sand and 

 Gravel. Sometimes covered with volcanic' ashes 

 with.adrriixture of humus.) 



Young Quaternary (Consisting of rich alluvial 

 deposits near streams, rivers and seas.) 



