216 



TIw Geohxjy of til" Gold Fields of' British Guiana. 



COMPOSITIONS OF THK DIJIKD FIM': SOILS. 



The arenaceous granitic soils are dark-grey and sandy, are very 

 deficient in their retentive power for water, and whilst they might yield, 

 in favourable seasons, small ci'ops of various kinds, such as cassava, sweet 

 potato, etc., from plants which prefer arenaceous soils, during dry 

 seasons these crops would fail. Any attempt at permanent cultivation. 

 U})on the arenaceous soils must prove futile. 



The compositions of the ai'gillaceous soils are more promising than 

 are those of the arenaceous ones for permanent cultivations. Like 

 the latter, the crops on them will be liable to sutler from drought, 

 owing to their low retentive power for water. Their contents of 

 nitrctgen and potash are sufficient for many permanent products, and 

 fair crops of the usual so-called ground provisions and of upland rice 

 could be readily raised on them. Probably these soils, after a few 

 crops had been raised on them, would require the addition of calcareous 

 and of phosphatic manures to enable them to yield satisfactory 

 returns. 



The soils derived from (iuai-t/.-}iorphyrv and allied rocks are of 

 somewhat lighter texture than are the argillaceous granitic soils, and 

 on the whole, from their texture, are better suited for permanent crops. 

 They are probably well adaj^ted for the cultiA'ation of rubber-bearing 

 trees and similar products. 



