1186 GEOLOGY AND PHYSICAL GEOGRAPHY OF THE STATE OF PBRAK, 



and the marks of former stratification can be traced in the granite. 

 There are occasional bands or veins of quartz and felspar, but no 

 true metalliferous vein has as yet been discovered. 



The stream tin which has been found so abundantly at the foot 

 of some portions of this range has been derived from the granite, in 

 which it was scattered or disseminated in small crystals. Probably 

 the tin was nearly confined to the upper part of the granite, 

 especially at its junction with the paleozoic rock. Libei'ated in the 

 gradual weathering of the stone it has been swept down into the 

 valleys and flats by the almost continuous rainfall. The gravitation 

 of the particles has performed the necesssary sifting. As the tin 

 is found in the lowest strata it may owe this position to three 

 causes. 1. Gravitation facilitated by the repeated washing and 

 sifting to which stream beds ai'e subject, and the heaviness of tin 

 ore. 2. A greater richness in the upper granite at its junction 

 with the paleozoic clays. 3. Stream tin gradually sinking through 

 the strata. 



Tin ore is not universally scattered through the matrix of the 

 granite in its upper jjortions, but it must be so to a very large extent, 

 considering the wide spread character of stream tin deposits in 

 Perak. It may be regai-ded as a very good indication of the 

 existence of stream tin where there is evidence of another foi-mation, 

 such as the Ordovecian clays or the limestone. In cases where the 

 overlying formation has been denuded away the red clay is a good 

 indication. My reason for this opinion is that all metalliferous 

 formations are richest at the junction of a different deposit. Thus 

 when the upper formation has been denuded away the upper 

 portion of the granite has been veiy rich in tin. All my 

 experience in Australia has forced these conclusions upon me. 



It should also be borne in mind that the gradual wearing away 

 and denudation of the granite has reduced the slope of the 

 mountain at the foot and gradually converted it into a plain. But 

 time was when the uptui-ned paleozoic rock presented steep and 

 jagged edges to the sides of the hills. These acted as ripple tables 

 in which the tin was caught and accumulated. It was not until 

 the drift had silted up within reach of these rocks and reduced all 

 to a plain that light sands would accumulate upon them. 



