BY THE REV. J. E. TENISON-WOODS, F.G.S., F.L.S., &C. 1185 



will stain a large mass of earth. As a rule the latei'ites of the 

 drift are derived from the paleozoic clays but they are sometimes 

 due to the surface decomposition of granite. In one instance in 

 the Kinta Valley this red deposit is caused by the erosion of a 

 basaltic dyke of a recent tertiary age. 



An important question arises in connection with these paleozoic 

 clays which are found to contain on the surface a little tin 

 combined with rounded grains of iron. The question is how far 

 they may have been the original matrix of the tin sand. If we 

 regard the granite as only a more highly metamorphosed portion 

 of these rocks they may be considered as stanniferous. My 

 opinion is that they are an upper formation lying on the granite, 

 and contain a little tin. 



A more important question is whether the clays derived from 

 this rock may always be considered as a true " bottom." For 

 stream tin I should say decidedly yes. There can be no tertiary 

 drift between this formation and the granite. But I am not so 

 sure that in these loose clays stream tin may not sink to a certain 

 depth and be found a little below the first level. At the junction 

 of the paleozoic clay with the granite it is consistent with 

 experience to expect to find granular tin in small pockets or veins. 

 These deposits would be local. It is an open question whether 

 they would repay a search for them. The paleozoic clay is only a 

 few feet in thickness and rests directly upon the granite, so there 

 would be no great expense in testing the question. In looking 

 for a second bottom for stream tin, as the ore would have to sink 

 through soft sandstone or into very loose clay, any search beyond 

 a few feet would be useless. 



Granite Rocks. 



The whole of the Thaiping Range and a good deal of the rock 

 underlying the stream tin is a coarse blueish or grey granite, con- 

 taining but little mica, large crystals of orthoclase felspar, with 

 schorl, cassiterite, tungstates of iron (wolfram), fluor spar, manga- 

 nese, and titanif erous iron imbedded in a quartzose paste. It is 

 clearly a metamorphic rock, as many portions are still schistose, 



