﻿174 



DE. W. R. JONES ON THE SECONDARY 



[vol. lxxii,. 



that part of Malaya which is on the same side of the Main Range 

 as the Kinta district, that the cliffs are the result of uneven denu- 

 dation, is particularly clear. 



In the Kanching Valley in Ulu Selangor, a valley which is 

 remarkably like that of Kinta in its topography and geological 

 structure and, for its size, quite as rich in tin-ore, two limestone 

 cliffs appear. Like those of Kinta they lie between two streams,, 

 and, isolated as they seem from one point of view, they are,, 

 nevertheless, part of a ridge that can be clearly seen from Ulu 

 Kanching. 



This seems the proper place, before leaving the geological history 

 of the district, to deal with Mr. Scrivenor's contention that the 

 tin-ore deposits at the foot of these cliffs could not have been, 

 deposited by the streams because, on account of the recession of 

 the sea, ' for some time back the grade of the rivers has been 

 increasing : i. e., they had farther and farther to fall from source 

 to otitlet, which again postulates erosion of the valley-floors.' 1 It 

 seems difficult to understand why a river, the course of which is- 

 stated to be lengthening, can, on that account alone, be said to be 

 increasing in erosive power, for the opposite is generally the case- 

 The courses of all the chief rivers in the Malay Peninsula 3 are 

 markedly meandering for several miles from their mouths, and it 

 is impossible to understand how such rivers could in the past have- 

 had a lower gradient than they now have. The Kinta River has 

 a fall of only 85 feet from Batu Grajah, in the centre of the Kinta 

 district, to the sea — a distance of about 20 miles. If the Kinta 

 River and its tributaries have never had ' the opportunity of de- 

 positing alluvium,' 3 it may be asked by what agency were the 

 thick beds of lignite and sand, described by Mr. Scrivenor as 

 recent alluvium and filling the big limestone-cups, carried to their 

 present position ? How also did the alluvium shown covering the 

 whole surface in the diagram on p. 49 of his Kinta Memoir 

 accumulate ? It remains to add that the Kinta River and its 

 tributaries have cut deep valleys in the Main Granite Range, and 

 in the past must have removed thousands of feet of the strata 

 which, of course, once covered the granite. With a source thus 

 obviously lowered by thousands of feet, and a bed considerably 

 raised towards its mouth, where a thickness of 150 feet of allu- 

 vium was proved in a boring by the Public Works Department, the 

 statement that the grade of the Kinta River is increasing cannot 

 be accepted. 



Ordinary denudation in the higher parts of the rivers and depo- 

 sition of alluvium in the valleys not only appear to explain the 

 presence of the limestone-hills and the clays at their foot, but also 

 offer an immediate explanation of the numerous horizontal grooves 



1 ' The Geology & Mining Industry of the Kinta District' 1913, p. 18. 



2 W. R. Jones, ' The Geology & Mining Industry of Ulu & Kuala Selangor ' 

 now in the hands of the Government Printer, Kuala Lumpur, F.M.S. 



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

 1913, p. 49. 



