148 MR. J. B. scRivENOR 01^ [June 191 2, 



individual boulders. On the other hand, boulders may be few and 

 far between in one bed, as at Pulai. The big boulder, just 

 mentioned as having been found at the J^ew Gopeng lline, was 

 in a bed with very few large boulders. There were one or two 

 tourmaline-rock boulders weighing about 10 lbs. each near by, but 

 the clay did not contain many others of any sort. 



The outline of the boulders varies considerably, although for the 

 most part they show rounded edges. Generally speaking, the 

 angularity increases with size. All, with the exception of those 

 of corundum, show signs of recent weathering on the surface. 



The granite-boulders are remarkable — in that they are nearly 

 always bounded by two flat surfaces, and have a roughly oval or 

 circular outline. The best example of this is a boulder found 

 recently on the Tekka property, washed out of dark red clay. It 

 is nearly circular, and has a maximum diameter of 7 inches. Its 

 thickness is roughly 1| inches, and the two surfaces are quite flat, 

 although roughened by weathering. The condition of boulders such 

 as these, when seen in situ, shows that they are not ' cores ' repre- 

 senting the remains of larger weathered blocks, but that when they 

 became embedded in the clay they already had their present form. 

 The flat surfaces are suggestive of the boulders having been ground 

 down by ice-action. 



The sand in the clays is angular, and distinct from sand that has 

 been worn down in a river-bed, but the edges of the grains are 

 generally rounded off. 



The form of the corundum boulders is noteworthy. Those 

 occurring on the Tekka property, where they have been found in 

 one bed only so far and in a restricted portion of that bed, al- 

 though in great numbers, are angular and in some cases exceed 

 80 lbs. in weight. At Pulai also, where the tin-workings are 

 littered with them, the bigger boalders are angular; bat, both at 

 Tekka and at Pulai, the smaller pieces separated from the tin-ore 

 during the final dressing are often beautifull}' rounded. 



The corundum at Pulai sometimes occurs also in the form of 

 flat tabular masses, suggesting that it was originally a veinstone. 

 Occasionally, the tourmaline-rock boulders are similar in form. 



(5) The Intrusive Veins and the Junction with 

 the Mesozoic Grranite. 



In several localities on the Gopeng mines large veins of Avhite 

 kaolin and of kaolin and quartz can be seen cutting the Gopeng 

 Beds. A very good section has been exposed for a long time on the 

 Kinta Tin-Mines land, showing a sharp junction with deeply stained 

 boulder-clay on either side, and the termination of the vein in a 

 thin stringer above. On the Gopeng Mining Company's land, I 

 have seen an excellent section of a vein with a breccia of kaolin and 

 deep red clay at the margin. A deep red staining of the clays 

 and boulder-clays is usual, but not universal, at the margin of these 

 yeins. 



