TIN MINING IN PERAK. ; Ig 
CHAPTER: sue 
SKETCH OF THE GEOLOGY OF PERAK. 
There are many interesting problems involved in the geology of the 
State which, unfortunately, at the present time there is insufficient 
data to solve; but leaving these debatable matters out of the question, 
the broad facts are very simple. There are in reality only four forma- 
tions represented. These are—firstly, the granitic rocks; secondly, a 
large series of beds of gneiss, quartzite, schist, and sandstone, overlaid 
in many places by thick beds of crystalline limestone; thirdly, small 
sheets of trap-rock, and fourthly, river gravels and other quaternary 
deposits. The granites are of many varieties, and also, in all proba- 
bility, of several different geological periods.* 
The series of quartzites, schists and limestones are of great age, but 
as no fossils have ever been found in any of them, nothing definite can 
be stated as to their exact chronological position. Their lithological 
characteristics, and the total absence of all organic remains, point to the 
PALehecan Period. + The failure to discover signs of life in them is, of 
course, merely negative evidence, and the finding of a single fossil ou 
at once upset it. However, until this happens they may be conveniently 
classed as Laurentian. It is at present impossible to form anything 
approaching an accurate estimate of the thickness of this extensive 
series, but it is probable that it is somewhere between 4,000 and 5,000 
feet. Unconformability has been noticed between the limestones and the 
beds beneath, but whether this is sufficient to separate them, or not, is a 
matter for future investigation. 
In some places, on the top of the limestone, are small patches of 
heavy black trap, often vesicular in texture. It is evidently now only a 
remnant of what it once was, and is represented in many places by only 
a few scattered fragments; but the time which has elapsed since the 
deposition of the limestone is so great as to allow any amount of denu- 
dation to have taken place. It is a question whether the crystalline 
character of the limestones is not due to their having been flooded by a 
thick layer of incandescent trap. 
The quaternary beds consist of old valley-gravels, newer clays, sands, 
peats and gravels, and, near the coast, fluviatile and marine deposits. 
They are composed of the detritus of the granitic and Laurentian for- 
mations, with, of course, a certain amount of organic matter, and, in 
Kinta, some slight admixture of decomposed trap-rock. 
The interval of time represented by the position of the ancient 
archzan rocks and the modern alluvial beds lying on top of them is so 
immense that the question of what took place in Perak during all. those 
countless ages naturally arises; but it can only be determined by a very 
much wider range of observations than have yet been made, extending 
* The Rey. J. E. Tenison Woods expresses the opinion that the granite of the Bubu- 
Hijau-Inas range is a metamorphic sedimentary rock. (Vol. [X., Part 4, of the Proceedings 
of the Linnean Society of New South Wales.) - 
+ See the paper on “The Black Limestone at Kamuning,” Perak Musewm Notes, 
No. 1., pp. 28-29. __ 
