1847. j including Notices of Sumatra, the Malay Peninsula, §-c. 677 



the former in their fluid or viscous state as having been the immediate 

 agents of the volcanic and mechanical forces to which the latter have 

 been subjected, or we may consider the former as the product of the 

 first plutonic action beneath this region ; the latter as sedimentary rocks 

 subsequently accumulated [over them] during a period of quiescence, 

 and their fracture, upheaval, and alteration as the effects of a new 

 excitement to activity in the plutonic sea below, in which the old 

 plutonic crust, with its sedimentary covering, was broken and upheaved, 

 and ferruginous or ferro-siliceous gases copiously emitted through the 

 lines of fracture. On either supposition the ferruginous character of 

 the emissions would be accounted for, because the upper granites, 

 &c. contain much iron in their hornblende, and whether the mass below 

 the granite crust, had remained in its fluid state during the deposit of 

 the sedimentary rocks, or had been wholly solidified and subsequently 

 melted down anew, the gases given off from it, when vents were formed, 

 would probably preserve the same character as those given off from its 

 original surface before any granitic crust had been formed. I cannot 

 stop now to explain how the prevailing plutonic theories, as applied to 

 the phenomena of the district, seemed, at the time when the paper 

 first mentioned was written, to require the adoption of the opinion that 

 the granites, &c. were in existence when the volcanic action took place. 

 Even under the influence of these theories I considered the point as 

 very doubtful, and, although it involved consequences irreconcileable 

 with these theories, I ventured to hazard the conjecture that the upper 

 hypogene rocks had been the immediate agents of the changes. The 

 examination of Pulo l/bin shook my faith in these theories as expounded 

 by some of their principal advocates, and the conjecture assumed a 

 high degree of probability. Latterly I had all but embraced it, but 

 still suspended its complete adoption in the hope that I would discover 

 some phenomenon amounting to ocular proof of its truth. 



I have only another point to advert to before I come to Malacca. 

 If you have taken any interest in Indian Geology, you arc doubtless 

 acquainted with the rock called laterite which prevails so largely in 

 southern India, and is also found in Bengal, &c, and which, to this day, 

 remains the most fertile subject of discord amongst Indian Geologists, 

 although the general opinion appears of late to have settled down in 

 favor of its being a sedimentary deposit. In the paper first alluded to in 



