The Gopeng Beds of Kinta. 205 



The Gopeng Beds, consisting of clays and boulder-clays with 

 some stratified drift, are of glacial origin. This is proved by the 

 inclusion of large boulders in the clay, by the physical condition of 

 the components of the clays and their distribution, and by the striking 

 resemblance of the beds as a whole to Pleistocene glacial detritus. 



The nature of the beds is considered to be sufficient proof of 

 glacial origin, but it is admitted that no boulders have been found 

 showing striation due to ice-action, nor has any glaciated rock- 

 surface been found. Such evidence, however, can hardly be 

 expected, because the boulders are all more or less decomposed 

 owing to the great power of the ground-water in removing silica ; 

 and, if the limestone ever presented the features of a glaciated 

 surface, it has been so much modified by solution owing to the 

 action of ground-water since then, that all traces of those features 

 must have disappeared. Large unweathered boulders of corundum 

 are present in some of the beds, but their hardness would make the 

 appearance of ice-scratches improbable. 



Unfortunately, the pale and uniform colouring of the bulk of the 

 clays and boulder-clays makes it hard to obtain photographs showing 

 clearly the resemblance to Pleistone glacial deposits. A number 

 of photographs is submitted, however, that will, it is hoped, do 

 something towards this. The petrology of the Gopeng Beds is 

 described in detail. The most interesting point revealed is that the 

 ice from which the detritus was derived passed over a stanniferous 

 granite-mass, and in consequence the Gopeng Beds carry tin-ore 

 throughout, though sometimes in very small quantities. This tin-ore 

 is an original constituent of the beds, but they have been further 

 enriched by tin-ore derived from the Mesozoic granite at their 

 junction with the granite and in the neighbourhood oi veins from 

 the granite that have risen through the limestone. 



The faulting in the Gopeng neighbourhood, the general structure 

 of the country, and the age and origin of the Gopeng Beds are 

 discussed in detail. Tie Gopeng Beds are considered to be the 

 equivalent in time of the Talchir boulder-beds of Orissa ; but a 

 penological similarity is wanting, because the Gopeng Beds were 

 derived from a mass of stanniferous granite the position of wnich 

 is at present unknown. 



November 22nd, 1911.— Prof. W. W. Watts, Sc.D., LL.D., M.Sc, 

 F.R.S., President, in the Chair. 



The following communications were read : — 



1. ' Petrological Notes on Guernsey, Herm, Sark, and Alderney. 

 By Prof. T. G. Bonney, Sc.D., LL.D., P.R.S., P.G.S., and the 

 Rev. Edwin Hill, M.A., P.G.S. 



The authors returned to these islands, after an interval of 

 nineteen years, in order to give futher study to the relations of 

 the igneous masses and especially of certain dyke-rocks. As they 

 had themselves suspected in 1891, and as Mr. J. Parkinson had 

 announced in 1907, the old distinction between diorite and syenite 

 could not be maintained ; but there existed, especially in Guernsey 



