- 'Physical Geography of the Malayan Peninsula'
Source: Nature, December 18, 1884, pp. 152-4
As some remarks of mine on the mountain system of the Malayan peninsula have already appeared in NATURE, perhaps the following summary of the results of ten months' explorations in the State of Perak will be interesting.
The State of Perak is comprised between the sea (Straits of Malacca) and the main central chain which runs along the centre of the peninsula. Its boundaries are, roughly: north, the River Krian; south, River Bernam; west, the ocean; east, the main central chain.
The geology may be briefly described as consisting of —
(1). an immense granite formation, rising into extremely sharp and precipitous parallel ridges having nearly a meridional direction. This granite passes frequently into slates and schists. The prevailing colour is blue.
(2). A Palaeozoic formation of slates, mottled sandstones, and clays, forming outliers or detached portions. It is found most abundantly at the foot of the ranges, whence it usually dips away conformably to the slopes of the hills and mountains. It has evidently been subject to great denudation.
(3). Limestone in detached outliers, or isolated hills of precipitous character, showing much denudation. It is stratified or crystalline. No fossils have been found yet, but is probably of Palaeozoic age. From its wide extension throughout Perak, where it crops out in so many places, it may have once covered the whole of the granite and Palaeozoic clays.
(4). Drifts and alluvium from the ancient streams and river beds. These are formed of the material from all the preceding deposits. All the tin deposits in the country are in these drifts. The ore occurs in a manner very similar to the alluvial gold in Australia, that is to say, in "leads," which are the ancient or modern river beds.
Above these alluvial deposits there is the usual alluvial surface soil, for the most part supporting a very dense vegetation.
The tin deposits hitherto formed are all stream tin. No lodes have yet been worked, though there are some in the mountains round the sources of the Perak River. The ore is almost always cassiterite in small abraded crystals. It is of a peculiar blackish-gray or brown aspect. Any person with a little experience would be able to distinguish between tin sand from Australia and that of Perak. The former is rather rich in gems, such as sapphires, rubies, hyacinths, garnets, topazes, and zircons. I [End Page 137] have never seen any in Perak; but there is a good deal of fluorspar, tourmaline, and less frequently wolfram.
The most of the workings are on the western slopes at the foot of the mountains. I cannot recall any instances of mines on the eastern slopes, but the wash or drift seems to have been greater on that side.
The matrix of the tin seems to be in the upper part of the granite at its junction with the Palaeozoic clays. In the lower part of the clay there is also a small quantity of tin.
In the drift the tin is always found in nearly the lowest levels, lying in one or two strata from one foot to five feet thick. It is mingled with fine drift sand and gravel. Its position is, I think, due to the repeated sifting and washing it has been subject to in the stream bed. But as it is generally covered by from ten to thirty feet of material destitute of tin, the inference is that only one part of the granite was very rich in the metal.
The stream tin deposits lie upon (1) kaolin clay, or partly decomposed granite; (2) granite; (3) Palaeozoic sandstones and clays. In the latter case the stream has come from the denudation of a portion of the same strata on the tipper slopes of the hills.
On the highest granite ridges, or those above 5000 feet, there is found a distinct vegetation. Three or four of the genera are Australian (Melalenca, Leptospermum, podocarpus, Leucopogon), and two of the species (Leptospremum and Leucopogon) are common Australian forms. Similar facts have been observed in Borneo, but I have not heard that they had...