Vol. 68.] THE GOPENa BEDS OF KINTA. 159 



being now crystalline limestone, glacial detritus, and phyllites and 

 quartzites. 



At the same time a granitic magma was being urged upwards 

 from below the limestone by entangled gases, and the upward 

 pressure led to the break-up of the anticlinorium, one huge block 

 falling bodily into the magma (' magmatic stoping '), and allowing 

 the granite to rise up and to form the material from which the 

 main range of the Peninsula was carved later. West of this main 

 fracture there were subsidiary fractures that had the effect of 

 faulting down the glacial detritus against blocks of crystalline lime- 

 stone. At the same time the glacial beds, already tin-bearing, were 

 further enriched in tin-ore where they were invaded by the granite 

 magma. 



The granite magma cooled and solidified, cementing together the 

 remains of the anticlinorium. Denudation gradually worked down 

 to the shattered arch and the granite, and carved out the present 

 physical features : the main mass ®f granite standing out in relief 

 as the main range of the Peninsula, and the preference of the 

 streams for the phyllites and quartzites and glacial beds leaving the 

 limestone blocks as hills bounded by fault-faces. Thus an old 

 Gondwanaland tin-field, after having been buried in the earth's 

 crust during more than the whole of the Mesozoic Era, is once 

 more on the surface and is yielding up its mineral wealth to 

 commerce ; whereas, when these deposits were first formed, the ore 

 lay unheeded in a glacial waste pre-dating by many centuries the 

 birth of primitive man. 



Although interesting side issues suggest themselves for dis- 

 cussion in connexion with the Gopeng Beds,' such, for instance, as 

 their precise mode of deposition, and the abundance of alumina in 

 a pre-Carboniferous magma, indicated by the quantity of pure 

 corundum, and perhaps by the tourmaline-corundum rocks also, I 

 have left such questions for the future, in order to make this paper 

 as short as possible while emphasizing the more important points. 

 There is, however, one matter that I might mention here. If, as 

 I believe to have been the case, huge masses of limestone fell away 

 into the granite magma during a process of magmatic stoping, 

 would not one expect to find support for the hypothesis in the 

 mineral and chemical composition of the granite ? Unfortunately, 

 no series of systematic analyses of the granite has been made as 

 yet. But it is significant that, considering the mass as a whole, 

 hornblende is one of the mineral constituents ; that in some places, 

 as for instance on the Pahang road near Kuala Kubu, hornblende 

 is abundant ; and that a plagioclase felspar is nearly always found 

 in thin sections. 



Appendix. 



[Owing to the fact that this paper on the Gopeng Beds reached 

 England too late for reading at the final meeting of the Session 

 1910-1911, it will not be read until November. At the time of 



I 



