﻿180 



DR. W. R. JONES ON THE SECONDARY 



[vol. lxxii, 



It seems clear, therefore, that the distribution of the eastern 

 and western ' clays and boulder-clays ' is directly related to the 

 present drainage, for Mr. Scrivenor has taken the Kinta River as 

 the dividing-line between these two clays. 



The tourmaline-corundum rocks have been found in situ at 

 Kacha, Redhills, and Batu Gajah on the west of the Kinta 

 Valley, and it is to be expected that they should be found in 

 clays which are at lower levels and on the same drainage-side of 

 the valley. 



Large blocks of pure corundum have not been, so far as is known 

 at present, discovered in situ, but small veins carrying corundum 

 are common at Tekka Ltd. Mine on the east ; also at Kramat 

 Pulai large corundum-boulders are very plentiful in recent alluvium 

 overlying the beds of lignite, and are obviously derived from the 

 schists near the granite-junction about 300 yards away. The 

 presence in these ' clays and boulder-clays ' of tourmaline-corundum 

 and pure corundum-rocks seems to offer a very definite proof that 

 they are derived from rocks metamorphosed by the intrusion of 

 the Mesozoic granite. 1 



It is clear, therefore, that the characteristic rocks present in 

 these supposed glacial ckys on the west of the Valley are known 

 to be in situ in many places in the Kinta district, and that, before 

 • being metamorphosed by the granite of the Main Range and the 

 Kledang Range, the original rocks (described by Mr. Scrivenor as 

 having been deposited ' under conditions similar to those when 

 radiolarian cherts ' were deposited elsewhere 3 ) differed very sharply 

 from the Gondwana Rocks of India, the bulk of which have 

 yielded terrestrial forms only, and even from the supposed Gond- 

 wana Rocks of Ulu Pahang (F.M.S.) : for, in the geological map 

 of this latter locality, the Radiolarian Chert Series is excluded 3 from 

 the deposits mapped as Gondwana Rocks. Indeed, it is stated 4 

 that an unconformity exists between the two. 



It is significant that no rocks or minerals not present in situ 

 in the district (unless the large corundum boulders be taken as 

 an exception) have been found in the ' clays and boulder-clays.' 

 The complete list 5 of boulders found at Gopeng and Tekka is as 

 follows : — 



Quartz, abundant ; sandstone, probably weathered quartzite ; sandy schists 

 with white mica, abundant ; phyllite, rare ; hornstone, rare ; hornblende- 

 schist, rare ; tourmaline-rock, generally blue, abundant ; quartz-muscovite 

 rock, abundant ; quartz-tourmaline-muscovite rock, abundant ; quartz-kaolin 



1 J. B. Scrivenor, ' The Tourmaline-Corundum Rocks of Kinta ' Q. J. G. S. 

 vol. lxvi (1910) p. 439 & pis. xxx-xxxi ; also Geol. Mag. dec. 6, vol. i (1914) 

 pp. 309-11. 



2 Q. J. G. S. vol. lxvi (1910) p. 439. 



3 J. B. Scrivenor, ' The Geology & Mining Industries of Ulu Pahang ' 

 Kuala Lumpur, 1911, pp. 35-37 & sketch-map. 



4 J. B. Scrivenor, Q. J. G. S. vol. lxix (1913) p. 349. 



5 J. B. Scrivenor, ' The Geology & Mining Industry of the Kinta District ' 

 1913, p. 33. 



