﻿190 



DE. W. R. JONES ON THE SECONDARY 



[vol. lxxii, 



In Ulu Pahang (Federated Malay States), where younger Gond- 

 wana rocks are presumed to occur, Mr. Scrivenor writes : 



' Apart from the Machi tin-field, all the tin-ore being won in Ulu Pahang 

 to-day is clearly derived from the granite of the Main Range.' 1 



' The Machi tin-field is remarkable in that there is no known outcrop of 

 granite in the immediate vicinity of the mines, although there is good reason 

 to believe that it exists not far from the surface. The ore worked is alluvial, 

 the j3ay-dirt being sandy with little or no impurities.' (Op. cit. p. 22.) 



Of the tin-field north-west of the Kinta district in Larut, Perak, 

 Patrick Doyle wrote 3 : — 



' All the land at the foot of these ranges is more or less stanniferous. Its 

 level is even now being altered by the alluvium brought down from the hills by 

 a rainfall which exceeds 150 inches per annum. All the ore worked up to the 

 present time has been found in the alluvium derived from the mountain- 

 ranges, i. e. in mining language, in stream- works. The ore has been traced 



up to veins in the rocks, but these have not hitherto been worked 



There can be no doubt that these beds have been formed by degradation of 

 the mountains ; these, as has been stated, consist of granitic rock, in which 

 the tin-stone associated with iron-ore occurs in veins.' 



Mr. Scrivenor describes 3 this same area as consisting of a 



' vast alluvial flat, from which has been extracted that wealth of tin-ore which 

 has made the district of Larut justly famous ' ; 



and, in discussing the origin of tin-ore at Ayer Kuning in this 

 neighbourhood, he states 4 : 



. ' Now these facts can only point to one conclusion, and that is that the 

 white overburden and the karang with the cassiterite have been derived 

 from the small changkat on which the hospital stands : and further, judging 

 from the nature of the alluvium, it may be concluded that the changkat owes 

 its existence to a hardening of the shale and sandstone series, over and above 

 whatever may have been effected in this direction by the main granite mass, 

 consequent on the intrusion of a mass of pegmatite, isolated on the surface, 

 but certainly connected in depth with the other igneous rocks of the Taiping 

 Range.' 



In Ulu Selangor, which has always contained some of the most 

 productive tin-fields of Malaya, the following paragraph from 

 my repoi't is incorporated in the Geologist's Annual Peport for 

 1913 (§ 25, p. 3) :— 



' Too much importance cannot be attached to the fact that the ore of Ulu 

 Selangor is derived from rocks now in situ in that district, and this fact 

 should guide prospecting in that part of the Peninsula. Where the valleys 

 are rich in tin-ore the hills should be very carefully prospected right up to 

 the source of the streams running into the valleys. In the case of every 

 valley in Ulu Selangor I have been able to find in this way, tin-ore in situ 

 in the granite. Local enrichments with angular ore should be very carefully 

 examined, and the bed-rock itself tested for ore by crushing and washing.' 



1 ' The Geology & Mining Industries of Ulu Pahang ' Kuala Lumpur, 1911, 

 p. 23. 



2 Q. J. G. S. vol. xxxv (1879) p. 229. 



3 ' A Preliminary Report on the Geology of the Neighbourhood of Taiping, 

 Perak' Kuala Lumpur, 1904, p. 1. 



4 Ibid. p. 7. 



