1847.] including Notices of Sumatra, the Malay Peninsula, fyc. 675 



try. The hills around it are principally arenaceous. The arenaceous 

 band however on the N. W. of the plain merely skirts it. Beyond 

 this band (and succeeding the sandstone ranges to the N. E. of the 

 shale tract first noticed) a broad zone of clayey hills, of which the 

 boundaries are irregular, but which may be from 3 to 4 miles in breadth, 

 stretches through the heart of the Island to Bvikit Timah, and thence 

 across to the Salat Tambroli or old strait of Singapore behind the 

 Island. The tract to the S. W. of this, stretching from the parallel 

 of the S. W. boundary of the shale band to the S. W. point of the 

 Island (Tanjong Gul), is composed principally of sandstone and shale, 

 but granitic bases and ranges also occur. The great clay tract I believe 

 to consist in large measure of decomposed hypogene rocks, — sienitic 

 and granitic chiefly, (it has only however been partially examined or 

 laid open). Blocks of these rocks are seen at the surface in some of 

 the hills, and the sections made by roads so exactly resemble decom- 

 posed crystalline rocks that I have no doubt that the whole of the clay 

 hills are at bottom hypogene rocks. Their structure and composition 

 I believe to be very variable. This tract is continued over a consider- 

 able part of the rest of the Island to the N. E., but a large tract of 

 sandstone (accompanied by a very little shale) stretches into it. The 

 coast boundary of this tract is a line of about 4 miles, extending along 

 the south eastern shore of the Island from Siglap to beyond Tanah 

 Mera Besar (the Bed cliffs). It insulates the granitic N. E. projecting 

 portion of the Island at Changy, embraces the northern coast from the 

 inner extremity of this promontory to the inner extremity of that of 

 Piingal, and then proceeds inland. The line of its junction on the N. 

 W. with the granitic tract that surrounds it I have not yet ascertained, 

 but it is probably irregular. On the S. W. it connects itself with the 

 arenaceous band surrounding the plain previously mentioned, and, 

 indeed, forms the larger portion of the boundary of the plain. It 

 then stretches inland for some distance, having the S. E. projection of 

 the great granite tract interposed between it and the arenaceous and 

 shaley bands, first above noticed. P. Ubin is entirely hypogene, varying 

 from granitic to compact types. Hornblende is largely developed. 

 The structure of the rocks is highly curious and interesting. I have 

 given much attention to this Island, and in the beginning of September 

 last sent a full account of it, and of the geological views to which it 



