﻿420 MR. J. B. SCRIVENOR ON THE ROCKS OF [Aug. I9IO, 



17. The Rocks of Pulatj Ubin and Pulatt Nanas (Singapore). 

 By John Brooke Scrivenor, II. A., F.G.S., Geologist to the 

 Federated Malay States Government, and formerly of H.M. 

 Geological Survey of the United Kingdom. (Read December 1st, 



1909.) 



Contents. 



Page 



I. Introduction 420 



II. Pulau Ubin 422 



III. Pulau Nanas 427 



IV. The Relations of the Pulau Nanas Granite Fragments and 

 the Pulau Ubin Normal Granite to the Granite Masses 



of the Archipelago 428 



Y. The Relations of the Pulau Ubin Rocks 431 



YI. Conclusion 433 



I. Introduction. 



In the January number of the ' Geological Magazine' for 1909 1 

 a short note of mine appeared on the igneous rocks of Singapore, 

 giving the results of observations made on occasional visits to 

 Singapore from the Malay States during the years 1904 to 1908. 

 iNot many weeks after the paper had been despatched, a further 

 opportunity presented itself of visiting some of the localities men- 

 tioned; and, as perhaps has happened to others, I found that the 

 fresh information available in the quarries was so extensive and so 

 significant that my remarks in the note mentioned appeared very 

 meagre. It proved too late, however, to withdraw the paper, and 

 therefore the following remarks mast be considered in some sense 

 supplementary to those in the earlier paper ; but, at the same time, 

 they embody other new information that will, I think, be found to 

 be of considerable interest to those who have studied the geology 

 of the East Indies. 



My object in the present paper is to describe the granite of 

 Pulau Ubin, veins of rhombic pyroxene-bearing rocks traversing 

 this granite, as well as ' basic masses ' in the granite of the same 

 island ; also to describe fragments of granite in tuffs on Pulau 

 Nanas, and to show that these are derived from a granite mass 

 distinct from and much older than that forming Pulau Ubin, and 

 therefore also older than the tin-bearing granite that now forms 

 the backbone of the Peninsula. Further, the mutual relations of 

 the granite, the veins, and the basic masses on Pulau Ubin, and 

 their relation to rocks in the Archipelago, will be discussed. 



So far as previous literature is concerned, it is unnecessary to 

 do more than note J. R. Logan's paper mentioned in my earlier 



1 ' Note on the Igneous Rocks of Singapore, with Special Reference to the 

 Granite & Associated Rocks carrying Rhombic Pyroxene ' Geol. Mag. dec. v, 

 vol. vi (1909) pp. 17-22. 



