226 STREAM TIN DEPOSITS OF PERAK. 



These are stratified. If you examine those which are not far from 

 the gaol, you will perceive in them a singular ribbon-like structure. 

 There are lines varying between red. yellow, white and dark slaty 

 blue. In some places, traces of quartz veins may be seen. The 

 strata are twisted and crumpled into curves and folds. Now, I re- 

 gard this as a very ancient formation, and which once probably 

 covered the granite. The latter rock has been pushed through it, 

 and this is why we find it principally at the base and the sides of 

 the range. Probably the granite itself has been formed from this 

 rock. It has been melted into its present crystalline form. But 

 the clays contain more iron than the granite does. They have 

 been much changed by their contact with the granite, and some 

 portions of the formation have been converted into what geologists 

 call " gneiss." I fear I cannot explain these terms to you now in 

 the time at my disposal. 



There is one thing about these clays which must strike ob- 

 servers, and that is their fiery red colour. This is due to per-oxide 

 of iron or rust of iron. In these countries such a rock is called 

 "laterite." Though the term is applied to many different kinds of 

 rock, in fact any red stone or clay, I am now referring to only one 

 kind, which is that derived from the paleozoic or ancient formation 

 which lies above the granite. 1 wish to add also that, wheu not 

 affected by much oxidation or rusting, these clays are blue instead 

 of red. 



These paleozoic clays give us a clue to the age of the tin. It 

 tells us that the metal occurs here as it does in other parts of the 

 world, that is, in connexion with the oldest granites. These paleo- 

 zoic clays are probably Ordovecian, or amongst the oldest of the 

 stratified series known to geologists. Usually such clays or slates 

 have been much altered by the changes to which they have been 

 subjected in their long histo^. 



From the great extent in which these clays appear throughout 

 the Malayan Peninsula we may conclude they they once covered 

 the whole of it before the granite burst through. But before this 

 took place, the strata were much twisted and altered owing to 

 heat, pressure and movements of the earth's crust. 



There are excellent sections of this formation in the cliffs 

 around New Harbour, Singapore, and again where the new road 

 cuts through the hills on which Fort Palmer is built. The east 

 side of Port Canning also at Singapore shows an outcrop of the 

 same rock with regular strata dipping to the westward and a sur- 

 prising variety of colouring. At Tanjong Kling near Malacca the 

 fiery red rocks, more property termed Limonite instead of Laterite 



