158 ME. J. B. SCRIVENOR ON [Juue I912, 



that is, no boulders of tourmaline-corundum rocks have been found 

 on the east, and no pure corundum boulders have been found on 

 the west side of the valley. 



The manner in which the corundum boulders are massed together 

 in a small area (at the Tekka mines and at Pulai) suggests that 

 the}^ were dropped from melting ice, and occupy at present the same 

 position in the clays as that which they occupied when so dropped. 

 Supposing, then, that there should prove to be an extension of the 

 Gopeng Beds across the valley to the west side, it would be possible 

 to account for the absence of corundum boulders on the west by 

 supposing them to have been carried over that area by ice without 

 any being dropped ; and a further possibility would suggest itself 

 of the tourmaline-corundum rocks having been in part brought 

 from a distant source by ice. Whether this is so I am not prepared 

 to say yet, but it must be mentioned here that Mr. W. M. Currie, 

 the General Manager of the Fusing group of Mines, to whom 1 am 

 indebted for much information, expressed an opinion some time 

 ago that the soft clayey masses over the limestone, which I described 

 as much-weathered schists (Q. J. G. S. vol. Ixvi, 1910, p. 438), 

 strongly resemble glacial clays. If Mr. Currie is correct in thinking 

 that they are of glacial origin, then the angular masses of tourma- 

 line-corundum rock found in such clayey ground may be regarded 

 as erratic boulders, instead of remnants of a once-continuous bed 

 (op. cit. p. 439). Sections lately exposed by miners show that I 

 may have been mistaken in considering any of these rocks to be 

 171 situ. 



(12) Conclusion. 



The main points of this paper may be summarized by sketching 

 briefly the probable course of events in the earth's crust in this 

 particular region, as indicated by the available evidence in the 

 neighbourhood of Gopeng. 



In Carboniferous times a large tract of land, Gondwanaland, 

 existed some way to the west of a sea occupying the site of the 

 present Malay Peninsula, and in this sea calcareous beds were 

 deposited. 



The coast-line of Gondwanaland advanced eastwards, and glaciers 

 coming down from the highlands, after traversing rocks carryings 

 tin-ore, deposited above the limestone a mass of detritus, partly 

 stratified, in which tin-ore, tourmaline-granite, tourmaline-schists, 

 etc., are common. 



Conditions changed, and above the glacial detritus shallow-water 

 beds of clay and sandstone were deposited, and also further 

 thicknesses of rocks, now denuded away, which had the effect then 

 of making the relative position of the limestone, the glacial beds, 

 and the shallow-water clays and sands very deep in the earth's 

 crust. 



Lateral pressure and heat caused the three members of the series 

 of rocks with which we are concerned to be bent, folded, and altered, 

 so as to form part of the western limb of an anticlinorium, the rocks 



