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PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 25, 



all their variety of rich colours and beautiful forms, giving a gorgeous 

 pavement to the sea, are not found until this space is passed. 



In some places solid beds of calcareous conglomerate are forming 

 on the beaches ; and ferruginous conglomerates, breccias, and sand- 

 stones are found wherever highly ferruginous rocks exist behind 

 sandy shores. 



TIL Relation of the Rocks to Animal and Vegetable 

 Life ; and their Economical Uses. 



Although the soils of the district have not the fertility of the vol- 

 canic and calcareous soils which occur in many parts of the Indian 

 Archipelago, they are covered with an indigenous vegetation of great 

 vigour and luxuriance, supporting numbers of animals of dilferent 

 species. The hills of plutonic rock support dense and continuous 

 forests, composed of more than 200 species of trees *, many of which 

 are of great size. So long as the iron is not in such excess as to 

 recompose the clay into stone, or render it hard, those soils which 

 contain most iron are the most fertile. The purely or highly fel- 

 spathic are the worst. Rut even felspathic soils, when they have a 

 sufficient proportion of quartz, are, in this climate, capable of pro- 

 ducing an abundant vegetation. 



Although it is obvious to every observer that there is no kind of 

 soil in the District for which nature has not provided plants that 

 flourish luxuriantly in it, yet it must not be hastily concluded, as 

 some have done, that this exuberant vegetation indicates a general 

 fertility in the soil. It is found, on the contrary, when the native 

 plants are destroyed, and the land employed for agriculture, that 

 there are very few soils in which cultivated plants not indigenous to 

 the region, but whose climatic range embraces it, will flourish spon- 

 taneously. While the cocoa-nut, betel-nut, sago, gomuti, and the nu- 

 merous Malayan fruits succeed well with little care, the nutmeg and 

 clove are stunted and almost unproductive, unless constantly culti- 

 vated and highly manured ; yet the climate is perfectly adapted to 

 them. Place them in the rare spots where there is naturally a fertile 

 soil, or create one artificially, and their produce is equal to that of 

 trees in the Molucca plantations. With respect to the indigenous 

 plants, gambier, pepper, and all the fruit-trees flourish on the plu- 

 tonic hills, provided they are not too deficient in iron and quartz. 

 The hills of violet- coloured shale, where they are not too sandy, are 

 equal to the best plutonic soils, — those, namely, in which there is a 

 sufficient proportion of hard granules to render them friable, and 

 sufficient iron to render them highly absorptive of water without be- 

 coming plastic. The sandstone and very arenaceous shale soils are 

 the worst. Of the alluvial soils, the sand, particularly when it con- 

 tains a mixture of vegetable matter or triturated shells, is the proper 

 soil of the cocoa-nut, and the vegetable mud is best suited to the 

 sago. When the country has been better and longer drained and cul- 

 tivated, the latter soil will become a rich mould ; at present it is every- 



* My list contains at present 217 trees, but it is not complete. 



