﻿1851.] 



LOGAN GEOLOGY OF SINGAPORE. 



343 



lization from fusion *, and that the whole series of nether-formed 

 rocks, volcanic and plutonic, may be produced in both modes. It is 

 probable also that wherever an electro-chemical action is so intense as 

 to generate the granitic and other highly crystalline forms, it emanates 

 from a lower region where the heat is so great as to cause fluidity^ . 



Remarks on the accompanying Geological Map%. 



The basis is the Chart made from the Surveys of Mr. Thomson 

 and Captain Congalton, published in 1846. The rivers, creeks, and 

 alluvial tracts of Singapore I have added from later and unpublished 

 surveys by Mr. Thomson, which he has kindly allowed me to use ; 

 and from the same source I took the great majority of the additions 

 and corrections of the names of localities. The insulation of Tan- 

 jong Surat and the rough outline of the estuary of the river Johor 

 above it are merely from my own observations, and not from a survey. 

 The coast of Batam has not been surveyed. A general outline with 

 some blanks appears on the published chart. These blanks and the 

 names of localities § I have filled in from my own observation, as well 

 as the names of islands to the west of it from P. Blakang Padang to 

 P. Kapal. The Silat Batu Haji I copied roughly from a Dutch chart. 

 The orthography of the Malayan names, which has hitherto varied 

 greatly, has been corrected in accordance with the system which I 

 have lately adopted in the 'Journal of the Indian Archipelago,' as the 

 most simple, uniform, and accurate which occurred to me, after giving 

 much consideration to the subject. 



The geological colouring is entirely from my own observations, with 

 the exception of Pulo Pisang||, Gunong Pulai*j[, the islets to the N.W. 

 of the Krimuns (Carimons), a few places on the coast of the main- 

 land in the Silat Tambrau, the south coast of the S.E. part of Johor 

 from Tanjong Stapah to Point Romania, the islets and rocks off that 

 Point, and the coast of Bintang with the islets and rocks off it, all 

 which are from information, and partly from specimens, given me by 



* In the crystallization of a molten rock the same electro-chemical action may 

 operate. The process must be greatly similar in both cases. The electro-chemical 

 force segregates minerals and gives a symmetrical structure in spite of the solid 

 form of the rock in the one case, and in spite of its fluid form in the other. The 

 solid form tends to keep each particle of the matter of the rock in the place where 

 it has been deposited, the fluid form tends to keep them all mixed up indiscrimi- 

 nately. The electro-chemical agencies of plutonic regeneration perform their office 

 unshackled by either kind of resistance. 



f Fusion is perhaps not necessary to account for plutonic intumescence and the 

 consequent elevation, rupture, and inclination of superincumbent strata. If gra- 

 nitic crystallization is always attended with expansion (see the " Rocks of P.Ubin," 

 /. c. p. 38), the amount in a vast plutonic mass like that of the Hindu-Chinese and 

 Malayan Peninsulas, Sumatra, and Borneo, with all the inequalities of degree to 

 which the process is evidently subject, might be sufficient to account for the con- 

 dition in which the sedimentary remnants are now found resting on it. 



% The lithographed Map, PI. XVIII., is reduced from the original map coloured 

 by the Author. 



§ Few names except those referred to in the paper appear in the reduced map. 

 || See p. 318, note. Not included in the accompanying Map. 

 f G. Pulai (2152 feet high) lies N.W. by W. of S. Sakodai, beyond the limits 

 of the map. It forms part of a tract of " Crystalline rocks" running N.W.-S.E. 



