522 On the Local and Relative Geology of Singapore, [June, 



Before entering on a detailed account of the mineralogical features of 

 Singapore, it Mali be convenient to bring into a preliminary paper some 

 discussions of a theoretical nature, which, if not thus separated from 

 the former, might, in the sequel, occasion frequent interruptions and 

 some confusion. A brief sketch of the topography of the Island will 

 suffice as a basis for the remarks which follow it. 



The Island is of an irregular figure, when correctly laid down, (for 

 the published maps, with the exception of Mr. Thomson's, are very in- 

 correct,) resembling a bat, the head being at Tanjong Sinoko, in the old 

 strait, the tail at Tullah Blanga, or rather Blakan Mati, — the western 

 wing being fully expanded and the eastern a little retracted. Its great- 

 est length from Pulo Campong or Point Macalister, on the west, to Tan- 

 jong Changai on the east, i. e. between the tips of the wings, is 21 

 miles. Its greatest breadth from T. Sinoko to T. Blangah coast, i. e. 

 from the head to the tail, is 12 miles. Its superficial extent is roughly 

 calculated at 200 square miles. 



The town of Singapore, to start from the best known point, is situ- 

 ated at the south-western extremity of a flat alluvial tract, of which the 

 greatest length in a straight line near the sea-beach is about 6 miles, and 

 the greatest breadth inland about 1\ miles. Three well marked depo- 

 sits occur in this flat. A stiff clay of a greyish hue, becoming in some 

 places darker and even blackish ; a whitish, greyish or yellowish sand ; 

 and a vegetable deposit, consisting, where most recent, of fragments of 

 wood or masses of aquatic plants more or less decomposed, and, where 

 older, of a soft peaty matter passing into a black mud. The mode in 

 which these beds have been deposited will be described hereafter. The 

 west side of this plain is marked by low rounded hillocks, separated by 

 openings on the same level as the plain. On following these in a north- 

 westerly direction, the former are found to be the extremities of dis- 

 tinct ranges of hills, and the latter the mouths of valleys between them, 

 the principal extending about six miles inland. The largest valley, 

 along which there is a public road, terminates a little to the south of a 

 group of hills called Bukit Temah, the summit of which is 530 feet 

 above the level of the sea, and the highest point in the Island. From 

 this group the valley and the stream which drains it borrow their name. 

 The coast of Singapore to the S. W. of this valley also follows a N. 

 W. direction. The intervening space is occupied towards the sea by a 



