1847.] including Notices of Sumatra, the Malay Peninsula, fyc. 533 



Such a comparatively small portion of Singapore has yet in any 

 way been laid bare, and of the accessible parts, with certain ex- 

 ceptions, so little is open to inspection save the mere surface, that had 

 my examination of the most favourable localities of the latter been much 

 more minute and careful than it has been, I should still have hesitated 

 to combine the results into any general hypothesis. But as such an 

 hypothesis has been forced upon me while following up my inquiries, 

 and no facts have hitherto been noticed to which it is irreconcileable, 

 I shall endeavour to explain it, leaving to future observations to build 

 it into a theory, or reject it as a fancy. And as I shall proceed in sub- 

 sequent papers to furnish detailed accounts of different localities, the 

 reader will be enabled to draw his own conclusions. 



The general direction of the elevatory force to which the hills or 

 Singapore aud the neighbouring Islands owe their origin, was from W. 

 by S. to E. by N. since their dip is generally in or near that direction. 

 Although the undulations or upheavings had this general tendency, the 

 causes to which they were due must have been of a somewhat irregular 



phism which the matter of most of the elevated land has suffered from that cause. May I 

 venture to suggest that the hypothesis which isdevelopedin this paper for Singapore might, 

 if applied to the laterite of India, perhaps explain its origin, and, in doing so, to a certain 

 extent also reconcile the conflicting opinions that have been maintained regarding it. 

 All that I have read of the great laterite formations of the south of India, and which ex- 

 tend to the heart of Bengal, where they are described by Dr. Buchanan, leads to the 

 conclusion that they do not consist of purely volcanic, sedimentary or decomposed matter, 

 but what I have termed semi-volcanic. The same formation is found at Malacca and 

 analogous deposits at Singapore, and both inseparably associated and evidently contem- 

 poraneous with altered rocks of the kind previously noticed. If we conceive an area 

 with trap, granite, sandstone, shale, &c. exposed at the surface (in the atmosphere or in 

 the sea) and partly decomposed or disintegrated, to be subjected to a peculiar species of 

 minor volcanic action like that which is described in this paper (the distinctive •phenome- 

 non probably of one and the same geological epoch) the result would be that, with the 

 occasional exception of matter ejected from no great depth, and some dykes and veins, 

 the previous soft surface rocks would be merely altered or metamorphosed by heat and 

 impregnated with iron, derived perhaps from the basaltic and other ferriferous rocks 

 through which the discharged steam, gases, and water had passed in their ascent. Whe- 

 ther the action took place under or above the sea would be determined by the presence 

 or absence of the ordinary marks of oceanic denudation. 



When clays strongly ferruginous, and soft from saturation with water, are dried, the 

 iron previously held in solution by the water is deposited between the particles and cements 

 them into a hard compact rock. Hence the induration of laterite clays on exposure to 

 the atmosphere. 



