158 Lieut. J. B. Scrivenor — Origin of Clays and 



been to lessen the objections to the glacial hypothesis put forward 

 by myself, but at the same time it still remains the only explanation 

 that meets the facts in a way that can be called at all satisfactory. 

 It may be that long acquaintance with the subject has made me see 

 difficulties in the way of other explanations Avhere in fact no 

 difficulties exist, and my position regarding the question is some- 

 what akin to that of a doctor versed in tropical medicine who once 

 informed me that the result of many years study of the etiology of 

 heri-beri was that he felt he could raise fatal objections to any theory 

 that had been proposed. I have not seen sufficient reason as yet, 

 however, to change my views on the subject of these clays and 

 boulder-clays. Certain sections to be noted later militate against 

 a glacial origin, but the evidence of these deposits, including those 

 showing bedding at Gopeng, being older than the granite of tlie Main 

 Kauge is stronger than it was before. In the following paragraphs 

 I will attempt to give briefly a statement of the points for and 

 against all possible explanations of the peculiarities observed in 

 these important sources of tin-ore. 



It will be convenient to consider first the deposits that show no 

 bedding. These occur both on the west and on the east of the 

 Kinta River, and are especially well developed in the vicinity of 

 Siputeh and Pusing. The problem regarding them may be stated 

 thus : Are they the result of bedded rocks being broken up and 

 completely disorganized owing to the limestone underneath them 

 being dissolved away and so producing a general sinking movement 

 in the overlying material ; or were they originally laid down as 

 uubedded clays with irregularly distributed boulders? 



When work was commenced in Kinta the former of these two 

 explanations commended itself, and I think that anyone examining 

 the evidence cursorily would come to the same conclusion. In 

 a paper on the tourmaline-corundum rocks of Kinta (Quart. Journ. 

 Geol. Soc, Ixxvi, p. 448, 1910) I gave as my opinion that they were 

 derived from rocks associated with schists over limestone, probably 

 chert and silicified limestone, and I may also remark in passing that 

 on p. 438 I referred to the corundum found in the " alluvium " at 

 Pulai and elseAvhere. 



At that time, however, it was thought that there were two 

 occurrences of these rocks known to be in situ, i.e. in the position 

 where they were originally deposited before alteration, but in one 

 case mining operations proved this not to be the case, while in the 

 other the mass of rock, close to the Siputeh bridle-path from Batu 

 Gajah, might have been a huge boulder. It is now completely 

 hidden by raining silt. 



Bedding that is a division of a mass of rock into clearly defined 

 strata of more or less different composition has never been seen in 

 these clays, but in a few cases a faint trace of lamination has been 

 seen. This, however, might be the eff'ect of pressure on unstratified 

 clay. The tourmaline-corundum rocks are hard, the clays are soft. 

 What is required to prove that the former are derived from a con- 

 tinuous bed or beds intercalated among softer beds is a section 

 showing some sign of it, and as yet no such section has been found. 



