246 J. B. Scrireiior — Radinhirian Rocks, East Indies. 



they do not contain any constituents indicative of a terrigenous origin, 

 and tliat the organic remains they contain all belong to Plankton 

 organisms ^vith siliceous tests, chiefly Kadiolaria. 



"In an uncemented state, in which such deposits are still con- 

 tinually laid down on the bottom of the oceans at the present day, the 

 deposits of the first type are called Kadiolarian ooze and those of the 

 second type red clay. Radiolarian ooze and red clay gradually pass 

 one into the other, and only differ in the percentage of organic remains 

 thej" contain. ^lurraj', for instance, places the limit between red clay 

 and Radiolarian ooze at a point where 20 per cent of the deposit 

 consists of tests of lladiolaria." 



In the Peninsula, on the otlier liand, but for a few occurrences near 

 Bentong (Pahang) of red and green chert, the Radiolarian rocks differ 

 markedly from the Central Borneo rocks in being dark grey or black, 

 owing to the abundance of carbon, which is sometimes so thick as to 

 render a thin section almost opacjue. The pi'escTice of this carbon and 

 the presence of carbon in the limestone referred to above also suggest 

 that whatever its source the limestone and chert have at least one 

 point in common in their mode of formation, and the abundance of 

 carbon in the cherts marks them off as something distinct from the 

 Central Borneo rocks. 



The presence of carbon in Kadiolarian chert has been noted before, 

 but I have not any recollection of remarks as to its significance. Thus 

 in 1899 Professor T. W. E. David and E. F. Pittman mentioned 

 streaks of carbon in chert found in New South Wales.^ Dr. Hinde 

 says the supposed carbonaceous matter may be partly ferruginons. 

 Again, in the cherts of the Lower Culm Measures of England, 

 Dr. Hinde and Mr. Howard Fox mention carbonaceous or ferrous 

 material as being in part the cause of fine lamination. These 

 authors also mention rhombohedral casts, found in the cherts. These 

 casts occur sometimes in the Peninsular cherts and in the Billiton 

 chert, the latter of which Dr. Hinde says contains a dust of ferrous 

 or carbonaceous origin.^ 



The origin of the carbon in the Peninsular clierts is doubtful, but 

 it is significant that in some specimens cell-structures have been found 

 believed to be the remains of algae {vide plate vii of the publication 

 on the Geology and ^Mining Industries of Ulu Pahang).* Moreover, 

 the shales associated with the Peninsular cherts cannot be regarded 

 as devoid of terrigenous matter. Like the shales with the limestone 

 they appear to consist of very fine sediment. The presence of 

 Radiolaria in them has only been proved in the case of those rich in 

 carbon. 



Anyone who reads Pi'ofessor Moleugraaf's views on the Central 

 Borneo rocks will realize that his case for their being oceanic deposits, 

 in the same sense as the deposits of Barbados are oceanic, is so strong 

 that those who would question it must examine the relations of the 



1 Q.J.G.S., vol. Iv, p. 34. - Q.J.G.S., vol. 11, pp. 629-31, 1895. 



» Op. cit., p. 223. 



'^ I am indebted to Mr. H. N. Eidley, F.R.S., for examining these specimens, 

 and to Dr. Hinde for examining cherts with Radiolaria found in Singapore, 

 but not i7i situ. 



