520 On the Local and Relative Geology of Singapore, [June, 



ferruginous gases, &c, had been emitted. The action of these gases on 

 the rocks had, amongst other transformations, produced laterite. The 

 paper was written under the impression that the formation of plutonic 

 rocks and plutonic action in sedimentary rocks were confined to deep 

 subterranean levels (see the writings of Mr. Lyell and other English geo- 

 logists). Hence it seemed necessary to believe that the superficial igneous 

 action with which the paper was mainly concerned, was wholly unconnect- 

 ed with the granitic and other plutonic rocks of the district ; subsequent 

 investigation of some of the best developments of these led to the con- 

 viction that the Tartarean theory was inapplicable to them at least, 

 The disturbed sedimentary rocks were re-examined free from the bias 

 of that theory, and it then appeared, that, while the evidence in favour 

 of the metamorphic origin of the laterites, &c, was so strong and 

 varied that it might be now recorded as a demonstrated fact ; there were 

 no apparent obstacles to the reception of the simple hypothesis that 

 they were caused by plutonic agency, and that the plutonie rocks of 

 the districts were themselves the agents of the alteration or the effects 

 of one and the same hypogene agency. This hypothesis embraces at 

 once the whole region of elevation in which Singapore is situated, with 

 all the plutonic, volcanic and metamorphic phenomena which it exhi- 

 bits. It refers the whole to one cause operating throughout a long 

 period of time, and which has not yet entirely ceased to operate, as the 

 volcanic emissions of Sumatra and the vibrations of the whole region, 

 from time to time, and the thermal springs of Sumatra and the Penin- 

 sula, constantly testify to us. This cause is the existence of an internal 

 plutonic intumescence, or nucleus, which has slowly swollen up, fractur- 

 ing the sedimentary strata, saturating and seaming them with its 

 exhalations, and as it forced itself up beneath them and through the 

 gorges and fissures, at once upheaving them and feeding on their 

 substance, till, in many places, it pressed and eat through them to the 

 refrigerating surface, and rose, congealing, into the air or sea. It is 

 this latter circumstance that distinguishes the region from all those 

 which have been observed by European geologists, and it is this singu- 

 larly high level which the plutonic reduction has reached that explains 

 the extraordinary appearances which the unreduced superficial rocks 

 have so often assumed. The metamorphosed rocks of Europe evinced a 

 deep subterranean saturation with plutonic exhalations, and European 



