Federated Malay Stales. 505 



quartz grains may be shattered fragments from the volcanic neck. 

 They are probably not a sandy admixture brought down by streams, 

 for the fragmental volcanic rocks of this district are interstratified 

 with a series of shales which were at one time calcareous, and from 

 which sandy beds are typically absent. 



A volcanic breccia was found occurring as boulders at Kuala Seli* 

 in Selangor at the 13J mile from Kuala Lumpur on the road to 

 Ginting Bidei (not shown on map), and reference has already been 

 made to the rock as perhaps revealing the age of the purple quartz- 

 porphyry which is found as boulders on the Main Kange between 

 Kuala Lumpur and Bentong. 



It is green in colour and is made up of angular fragments of the 

 following rocks ; quartz-porphyry something like that occurring in 

 situ at Jeram Gading * and as boulders in this district and on Ginting 

 Sempak *, quartzite, and small rounded pieces of a homogeneous 

 fine-grained siliceous rock like those which occur in the felspathic 

 grits that are so often associated with cherts. They may be of 

 sedimentary origin or they may be devitrified lava. There are 

 pseudomorphs of epidote and an opaque dust which have a wavy 

 •outline, and in form resemble the altered biotite crystals in the 

 Ginting Sempak quartz-porphyry. In addition grains of quartz make 

 up a considerable part of the rock, some of them angular, others 

 having a rounded corroded appearance, and broken crystals of 

 orthoclase and oligoclase-andesine felspar are also common. There 

 is very little fine-grained material, but amongst it can be noticed 

 some grains of secondary epidote. 



About half a mile west of Tembelinga deposit of andesite-rhyolite- 

 breccia is exposed in the railway- cutting which is probably near 

 a volcanic neck, for it is a coarse-grained red rock, the fragments 

 being often more than an inch across, and consisting of quartzite, 

 limestone, lava (both andesite and rhyolite), and crystals of felspar, 

 quartz, and occasionally augite, the cement being quartz-aggregate, 

 calcite, and iron-ores. 



The andesite-lava fragments are well preserved, and belong to the 

 type with a ground-mass of very small microliths of felspar enclosing 

 well-shaped augites partly altered to chlorite, calcite and magnetite, 

 and biotite crystals which have been bleached and have sometimes 

 been entirely obliterated by secondary iron-ores. The rhyolite 

 fragments are much, more altered, the ground-mass now consisting 

 of a secondary aggregate of quartz in which round bodies which were 

 originally spherulites can occasionally be distinguished under crossed 

 nicols. The shape of the lava fragments is very irregular, but there 

 is no sign of a rapidly cooled margin. These lava fragments are 

 distinct in character from the deposits of boulders in tuff which will 

 be described later, the principal point of difference being that they 

 are not water- worn. 



Another slightly different type exposed in the railway-cuttings 

 near Kuala Tekal may be described as an andesite-rhyolite-tuff, and 

 in the hand-specimen it is a dark-green rock containing small black 

 lava fragments, and crystals of felspar, quartz, and biotite, varying 

 up to J cm. across. 



