xiii.] FORMATION OF COAL IN BORNEO 



colour, similar to those which can be obtained artificially. By a 

 natural association of ideas this possible manner of accumulation 

 of carbonic elements suggests the hypothesis of an analogous 

 origin in the case of coal in Borneo. 



That certain deposits must be formed in the Kapuas lakes can 

 scarcely be doubted, for they are surrounded by forest, and receive 

 rivers and streams. Even admitting that the forest retains the 

 greater part of the floating timber which is swept away by the force 

 of the floods, it is certain that a large quantity of vegetable detritus — 

 besides that resulting from decomposed leaves, which does not visibly 

 alter the clearness of the water — must find its way to the lakes and 

 ultimately sink in their depths. 



Even supposing that only a millimetre of carbonic substance were 

 each year deposited, in a thousand years a layer over three feet 

 thick would be the result ; and this sufficiently demonstrates how 

 rapidly the carboniferous deposits of Borneo may have been formed, 

 if such be their origin. 



That pure coal must have been formed and consolidated in 

 basins where no earthy deposits took place cannot be questioned 

 by any one. For this reason it is evident that it had its origin in 

 forest regions where no extensive process of denudation could 

 take place. The absence of the slightest traces of lime in the coal 

 deposits of Labuan 1 proves that the area occupied by the forests 

 which gave origin to them was not formed of limestone, and leads 

 one to infer that the streams which ran through them, flowing into 

 the deposit basins, contained black water. In Borneo the coal- 

 fields are very extensive, and it is hardly probable that they were 

 all formed contemporaneously. One cannot, therefore, generalize on 

 their origin ; but the fact that no traces of marine organisms have 

 been found in Labuan coal (Teni son-Woods, loc. cit.) permits the 

 inference that some, at least, are of lacustrine origin. Admitting 

 as valid the foregoing conclusions, and bearing in mind the absence 

 of lime in the Labuan coal, we may well imagine that these coal- 

 fields were formed in black-water lakes analogous to those of the 

 Kapuas. All this is quite apart from any considerations concern- 

 ing the age of the carboniferous deposit, for I have had no oppor- 

 tunity of examining any organic remains from the Bornean coal- 

 fields. For the rest I quite concur with the conclusions arrived at 

 by Mr. Tenison- Woods in the paper quoted, the perusal of which 

 suggested the theory here expressed. 



With regard to the asserted temporary drying up of the Kapuas 

 lakes, I do not believe that Danau Lamadjan can ever become 

 perfectly dry, for I have since learnt that a Dutch steamer visits 



1 J. E. Tenison-Woods. The Borneo Coal-Fields ; in Nature, April 23, 

 1885, p. 553. 



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