﻿316 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 25, 



with red in various degrees, in isolated or connected ramifying blotches 

 or in parallel curvilinear streaks. Fresh sections exhibit various tints 

 of red, lilac, purple, yellow, &c. Pure white streaks and zones also 

 occur frequently, exhibiting a kind of irregular, broken reticulation. It 

 is sometimes altogether of a dark red hue. "When this is the case, 

 masses of a half-decomposed iron-rock are generally found in it ; and 

 in most localities, where cuttings have been made, a similar rock 

 occurs here and there in dykes and ramifying veins. On the sides of 

 these veins laminse of a red colour are sometimes seen, either parallel 

 to the vein, radiating from points in it, or forming systems of concen- 

 tric lines. The iron-rock is also found either strewed over the surface 

 in amorphous cellular blocks and small pebbles, or below the surface, 

 at depths varying from a few inches to a few feet, in layers of similar 

 pebbles. With these pebbles others of jaspideous and porcellanous 

 rock are frequently intermixed, and veins or strings of the latter are 

 found in the deeper sections or in the half-decomposed crumbling 

 granite which in a few localities is exposed at the surface. In some 

 places patches of a vesicular jaspideous rock are frequent in the de- 

 composed mass. These are sometimes considerably ferruginous. 

 Fragments of semi-decomposed syenite and granite, ferruginous in 

 different degrees, are common. When highly ferruginous, they are 

 more or less vesicular, and the only unchanged constituent of the 

 solid rock is the quartz. Even this is sometimes penetrated by the 

 iron. The upper soil, or that which has been completely subjected 

 to atmospherical action, is a clay with a greasy lustre, but often in- 

 clining to a dry friable appearance, in colour generally yellowish 

 brown, but with lighter and darker hues in particular localities. In 

 many hills it is highly ferruginous and of a deep red colour. This, 

 with the smaller proportion of quartz, distinguishes it from the granitic 

 clays of Pinang higher up on the west coast. 



The easily accessible localities where ferruginous blocks are most 

 exposed are the hills along the boundary between the plutonic and 

 sedimentary tracts near Singapore Town, such as Mount Victoria 

 (58)*, SriMenanti (39), the hills connecting it with Mount Zion 

 (38), the hill forming the extreme S.W. point of the granitic tract 

 (33), the western hill of Dr. Oxley's nutmeg-plantation (36), Cairn 

 Hill (50), the coast of the mainland from Tanjong Tanguloh to Pulo 

 Nanas (at Tanjong Passier Mera and near S. Tukong), &c. 



The sandstone and shale surround the plutonic tract on the W. 

 and S., being found occupying the space to the N.W. of it up to the 

 Old Strait, rising in the hills near Singapore Town to the S.E. of it, 

 and, lastly, forming, with a great predominance of sandstone, grit, 

 and conglomerate, all the eastern portion of the island, with the ex- 

 ception of the hills at Changgei. At several places there is much 

 ferruginous rock, as in the hills running south from the Mosque in 

 the town to Tanjong Malang, and continued in the reefs off that 

 point. On the opposite side of the flat of the Singapore River, and 

 where the very same line, prolonged to the north, crosses the two 

 bifurcations of the Tanglin Range, we find a considerable development 

 * The figures refer to those on the map. 



