And geology of the malay peninsula. 
101 
When we ascend the valley of the Johore river, which gives a par¬ 
tial longitunal section, the same phenomena are presented. We first 
meet with sedimentary rocks, in some places very highly ironmasked. 
Then low granitic bosses are seen extending over a considerable 
i[ 
tract. Higher up aqueous strata recur, and then granite appears 
again. 
In a zone of such length the plutonic rocks might be expected to 
vary greatly. But in fact this variation takes place within very nar¬ 
row limits. In the short range of Pinang, for instance, the granite 1 
changes its character as we proceed from north to south, having at 
first a great predominance of quartz and felspar with a general 
coarseness and uniformity of granulation, and then losing this unifor¬ 
mity, assuming a larger proportion of mica, acquiring in many places 
hornblende and schorl, varying in composition, and, in texture, be¬ 
coming, in some bosses, as fine as fine grained sandstone. In much 
smaller ranges at the southern extremity of the Peninsula, the rock 
may be seen changing from highly crystalline and large grained gra¬ 
nite and syenite through greenstone to types almost purely felspathic. 
Porphyries, claystones, and other rocks of the volcanic class also 
occur adjacent to granites, and are evidently contemporaneous with 
them. Very well developed large grained granite appears in the low 
hills, entirely composing them, or forming patches in tracts approach¬ 
ing to volcanic types; but several instances which we have observed 
seem to indicate that in the bulky mountain masses the rock is generally 
more uniform and highly crystalline than in the smaller bosses, whe¬ 
ther these occur in immediate contact with the mountain ftanks or at 
a distance from them in apparent isolation amongst sedimentary 
rocks. 
The granites of the southern part of the Peninsula are generally 
hornblendie, and often to such a degree that the soils which they 
yield are of a dark red hue. 
The structure of the plutonic rocks of Johore is sometimes as re¬ 
markable as their rapid graduation from plutonic to volcanic types. 
Well crystallized ternary and quaternary granites exhibit an unequi¬ 
vocal laminar arrangement, tly lamime being spherical, cuboidal. 
