450 E, S. Willboum — The Pahang Volcanic Series — 



Fossils are rarely met with, but a collection made by Mr. Scrivenor 

 from a limestone hill near Kuala Lipis indicates a Carboniferous age 

 for the Raub iSeries, and the fossiliferous Myophorian sandstone at 

 the base of the Gondwana rocks corresponds to the Rhaetic period. 

 Some fossils in shales at Lubok Sukum indicate a Permian age for 

 the beds there. Shales and sandstones, i.e. Gondwana rocks, are 

 exposed near here, but at the time the trip was made down the 

 Pahang River the fossiliferous shales were not exposed, and 

 Mr. Scrivenor, who collected the fossils, was of the opinion that they 

 occurred in Raub rocks. The field evidence of the relations of the 

 Raub shales and limestones in Pahang suggests that they constitute 

 an alternating series, aud that some Raub shales are older, whilst 

 others are younger, than the Raub limestones, but in other districts, 

 for instance in Negri Sembilan*, there is a possibility that the upper 

 part of the Raub Series consisted of calcareous shales which are now 

 (in Negri Sembilan) altered to phyllites and talc schists. 



distribution of pahang volcanic series throughout 

 the Peninsula. 



The Map (Plate XXX) indicates the known places of occurrence 

 in the area of greatest development in the Peninsula, but it must 

 be remembered that little is known of the country not actually 

 penetrated by rivers, roads, or railway. All places mentioned in the 

 text that are not marked on the Map occur outside this area. 



It is clear that volcanic activity was stronger during the Raub 

 period than during the deposition of the Gondwana rocks which 

 followed. In the south of Negri Sembilan* and north of Johore * 

 there is a considerable development of Pahang Yolcanic Series tuffs, 

 but few lavas or intrusive rocks have yet been noted there. In 

 Singapore* certain core-boulders of quartz-porphyry and dolerite 

 have been examined by Mr. Scrivenor, 1 but as the rocks do not occur 

 in situ nothing can be said about their age. Similar core-boulders 

 have been found on the Kuala Lumpur * to Bentong * road where it 

 crosses the Main Range, and their age too is rather a matter of doubt, 

 but there is little doubt as to the age of an igneous rock like a lava 

 which is found near here interstratified with chert being that of the 

 Pahang Volcanic Series. There are numerous exposures of a por- 

 phyritic rock which forms the greater part of the hill-cap, and is 

 seen in road-cuttings both on the Selangor* and Pahang side of the 

 Main Range. It contains abundant colourless rhombic and monoclinic 

 pyroxene, biotite, quartz and felspar (oligoclase and labradorite) set 

 in a fairly fine-grained mosaic of felspar (some of it labradorite) and 

 quartz. This rock, which may be tei'med granite-porphyry, and the 

 quartz-porphyry which occurs as core-boulders, are both fresh, and 

 contain no calcite or epidote, but they show signs of considerable 

 shearing. 



The quartz-porphyry is seen in situ at Jeram Gading*, a tributary 

 of the River Klang*, near its source (outside the area shown on the 

 Map), and forms a steep gorge about four miles upstream from the 

 point where the tributary flows into the main river. In this gorge 



1 Geol. Mag., Dec. V, Vol. VI, No. 535, January, 1909. 



