J. B. Scrivenor — Radiolarian Rocks, East Indies. 243 



the Central Borneo cherts and hornstones, but produces fresh 

 evidence to show that the Radiohirian rocks extend eastwards for 

 650 kilometres and cover about 40,000 square kilometres, the 

 composition of the cherts and hornstones remaining perfectly 

 constant throughout. In the map accompanying this paper the 

 Radiolarian rocks are shown striking towards the southern part of 

 Sambas, where Mr. Wing-Easton found Upper Triassic, Jurassic, and 

 Cretaceous Radiolaria-bearing rocks. One would not expect, therefore, 

 to find sucli divergent views regarding the origin of the Radiolarian 

 rocks in Central and West Borneo, but the difference of the litho- 

 logical characters of the rocks described by the two authors is so 

 evident that it is difficult to believe that the West Borneo rocks are 

 really an extension of those in Central Borneo. 



Another instance of Radiolarian chert being considered evidence of 

 deep-sea conditions is afforded by a rock found in the island of 

 Billiton and described by Dr. Hinde.^ Dr. Hinde declares for deep- 

 sea conditions on the palseontological evidence, but in the text 

 Dr. Yerbeek gives some significant information regarding this rock.^ 

 It came from the bed-rock of a certain mine, and occurred as a bed 

 about half a metre thick between sandstones and clay-slates. 



My own experience of Radiolaria-bearing rocks in the East Indies 

 has been in the Malay Peninsula and in Sarawak. 



In the Malay Peninsula thei'e is a series of rocks that I have called 

 the Chert Series, consisting of chert beds with Radiolaria, too poorly 

 preserved to be of homotaxial value, and very fine-grained shales. 

 These shales are sometimes light grey or yellow in colour, and the 

 chert is sometimes green or bright red like jasper, but a common 

 feature of both chert and shales is the abundance of carbon. In the 

 shales this is easily recognized, but in both shales and cherts it has 

 been separated from the other rock constituents and proved to be 

 carbon. In both rocks it has acted as a precipitant of metallic 

 sulphides, and I have a specimen showing beautiful little casts of 

 Radiolaria in pyrite.^ 



Another point that reqiiires more than a passing mention about the 

 Radiolarian cherts of the Peninsula is that where the best exposures 

 occur, namely in Ulu Pahang and in Kedah, they are close to large 

 outcrops of quartzite and conglomerate. They also occur, however, 

 on the Pahang River associated with lavas and ashes. 



At first sight it might be supposed that the cherts and accom- 

 panying shales are so closely connected with the arenaceous rocks, 

 which have yielded marine fossils, as to be part of one big series 

 comprising both cherts and quartzite, the one conformable to the 

 other, but although this would not be very surprising in the light of 



^ E. D. M. Verbeek, " Geologische Beschrijving van Banka en Billiton," 

 Appendix 1 by Dr. G. J. Hinde, pp. 223-7 : Jaarb. v. h. Mijnwezen in Neder. 

 Oost-Indie, Weten. Gedeelte, 1897. 



2 p. 92. 



^ These rocks and their relation to other rocks are discussed in The Geology 

 and Mining Industries of Ulu Pahang, Kuala Lumpur, 1911, ch. ix and xii, 

 pis. v-vii, xiii, obtainable at the Malay States Information Agency, 88 Cannon 

 Street, E.G. 



