628 
MOUNTAINS OF CEYLON AND WESTERN GHAUTS. 
We have thus given an abstract of Dr. 
Benza’s paper and shall resume our notice 
of it in our next. 
We proceed to give an abstract of the 
next article by Capt. Allardyce. 
The circumstance most remarkable in 
the INDIAN GRANITE FORMATION 
is perhaps the great prevalence of that kind 
of rock called primitive trap, greenstone, 
or hornblende rock ;* * it does not form, 
as in other countries, patches of limited 
extent, but surrounds and intersects the 
whole peninsula ; it seems to have its regu- 
lar place among the granitic strata, with 
which it is confluent at the line of junction, 
passing gradually from green to red and 
white felspar rocks : it generally cuts off 
and terminates all the other granites. Pos- 
sessing this character, it may be considered 
the oldest rock here unfolded in the gra- 
nitic series ; for if the primitive mountains 
are the subverted fragments of a formerly 
horizontal crust, which all observation and 
experience tend to prove, then, according to 
the laws of subversion that prevail in the 
more recent formations, the stratum found 
encompassing the others will be that which 
was earliest formed and originally under- 
most in the series. 
The primitive trap, together with its as- 
sociate the small-grained sienitic granite, is 
by far the most extensive and continuous of 
the Indian rocksf. On the western coast 
♦ The Palaveram rock is a good example of 
the primitive trap: being nearly allied to 
sienitic granite, it appears to be sometimes 
distinguished by the same name ; it has been 
called also primitive greenstone, hornblende 
rock, and gneiss when distinctly stratified. 
The composition is, in most cases, at least two 
thirds felspar, of a bottle green colour, or 
usually some shade of green, which changes to 
a light sandstone hue in decomposition; mica, 
quartz, garnet, hornblende, and schorl also 
occur, but in minor proportions, the essential 
ingredient being felspar. In the western 
Ghauts near Goa this trap consists of a paste 
of bluish grey felsiiar with scarcely any other 
ingredient, perhaps the distinguishing mark 
of trap that will apply most generally is its 
difiference in texture from granite ; the one 
being a compact vitrious paste, the other a 
more freely granulated compound.-.in this 
sense the term is here used, for any defini- 
tion founded on origin or manner of eruption 
will not hold good with regard to the primi- 
tive traps. 
+ If sienitic granites are to be distinguished 
by the presence of hornblende, it will be found 
that, according to the present unlimited appli- 
it seems to extend uninteruptedly from Surat 
to Cape Comorin, or rather to Ceylon, for 
the mountains there appear to be of the same 
character as the western Ghauts, and are 
besides nearly on the same line. From 
Ootacamund to the N. E., at least as far as 
Madras, this rock extends in full character; 
but does not constitute the mass of the 
eastern Ghauts at Nakanary, which in this 
respect differs from the western chain. The 
mountains of the Northern Circars are said 
to form a very continuous and well-defined 
range of trap hills, but elsewhere in the line 
of eastern Ghauts, or between Salem and the 
Kistnah, the strata appear to be of various 
kinds. Connecting the western Ghauts at 
Surat with the eastern at Balasore or Ram- 
ghur, is the Vyndiah range also of this trap : 
so that the trap or green felspar rock appears 
to surround the peninsula on every side. 
Numerous similar and smaller chains cross 
the interior, generally in a direction S. W. 
and N. E. Travelling westward from Pala- 
veram, where green felspar prevails, we do 
not again meet with the same rock until 
reaching the western Ghauts on the opposite 
coast. The identity of the Palaveram rock 
with that of the western Ghauts, the dis- 
similarity of the eastern range at Nakanary, 
and the non-occurrence of the green granite 
in the intermediate space, are circumstances 
indicative of a particular arrangement. 
The direction of stratification at Oota- 
camund, on all the hills near the canton- 
ment, is W. S. W.* at Trichinopoly the 
same, and at Nakanary not very different. 
The lines of stratification cross the Ghauts 
diagonally at Nakanary, or, perhaps more 
cation of the word, there is scarcely a granite 
in this part of India that might not be included 
as sienitic : but, if we regard them simj)ly as 
intermediate between granite and trap, it is 
better at present, for the sake of perspicuity, 
to drop the dubious term sienitic granite, and 
pass on to the trap, which will include the 
granites next to it having a close texture and 
vitrious aspect. 
• An exception to this occurs on the north 
side of the cantonment where the direction of 
a piece of gneiss or rather trap more strati- 
fied than usual runs N. and S. and has fallen 
besides to an angle of 45'^., the dip being to 
the westward. This fragment includes at 
least three small hills, the convexity and ex- 
foliation of which have the usual direction 
with regard to the horizon, and are not influ- 
enced by tbe oblique position of the rock. 
