32 



■ 

 of that grand series of plutonie rocks which , like the volcanic , have undergone the action 



of heat, and which consist of alternate layers of quartz, felspar, mica and other mine- 

 rals" (l). The origin of this series of rocks is one of the great debateable questions of geo- 

 logy. As in so many other instances , both of physical and metaphysical questions, where 

 an array of probabiliües can be advanced on each side , both parties may be in the right 

 and both in the wrong; or rather, nature, capacious and multiplex while harmonious, 

 can embrace and assimilate the ideas of both. If we limit our views to India , we can 

 hardly deny an identity of origin to granite and gneiss. Upon the question generally I sh all 

 not enter , but it may help us to a better understanding of Pulo Ubin , if some facts , 

 gathered from the papers of Indian geologists , be here placed side by side with those local 

 facts wilh which they appear to be connected by some general law. Dr. Voysey, one of the 

 earliest and ablest labourers in the field, remarked, in 1823, — » up to the present time I 

 am inclined to think that both the granite and gneiss of India are contemporaneous , as 

 they are perpetually passing into each other and have the same subordinate rocks. I think 

 it probable they owe their difFerence of structure to a different mode of consolidation (2)." 

 Dr. Bughanatt Hamilton's recently published report on the Eastern Districts of Bengal confirms 

 Dr. Votsey's view, and suggests still more important considerations bearing on the geology 

 of the Malay Peninsula and its Arehipelagoes. In reading it I was struck with several 

 features of the hill ranges of Bengal which strongly reminded me of those of Singapore. 

 I have been ted to think that the same relation subsists between these hills and the great 

 mountain ranges behind them , — between the lower hill ranges on both sides of the Pe- 

 ninsula of Southern India and the central mountains , — between the hills on the flanks 

 of the Sumatra chain and the chain itself, — between the hills along the coasts of the 

 Malay Peninsula and the mountain groups of the interiour; — and between the hill 

 ranges and the mountains of Australia. Some remarkable characteristics are com- 

 mon to all these hill ranges and groups , and every addition to our knowledge serves to 

 confirm my impression that they must be referred to one geological era and one peculiar 

 plutonie or volcanic action operating over a region of great extent, in which Southern Africa, 

 India, the Malay Peninsula, a large portion of the Eastern Archipelago and Australia, 

 are included. It would require a separate paper to bring together the facts that have induced 

 -and confirmed this impression. I wilL here only notice some circumstances mentioned by 

 Dr. Bughawan corroborative of Dr. Voysey's view, and bearing on the structure of the Pulo 

 Ubin rocks. The miiierals of what Dr. Bughanaw terms the southern central division of 

 Bhagulpore consist , in general , of aggregate rocks composed of felspar or schorl intermix- 

 ed with quartz and sometimes with mica , and disposed in vertical strata running easterly 

 and westerly. The quartz is not only found as a portion of the aggregate, but in parallel 

 layers alternalmg with it , and even in whole strata. » In some of the strata the compo- 

 nent parts were pretty uniformly scattered, thus forming granite*, according as they contain- 





(1) DARwrB on volcanic Islands p. 72. 



(2) Brewster's Edinburgh Journal of Science vol. X p. 375. 



