412 
THE TROPICAL AGRICULTURIST 
[Dec. 2, 1901. 
rann;es from a yellow to a r jd brown. There are 
also a few grains of pyrifco^. Bfowii micx o^-cur.s 
ia obher speciinans . Ttie.se darker minerals consti- 
tute the greater part of tlie rock. The rert of the 
slide is made up of clear and colourless pla'^io- 
clase, with wall-marked twins and extinction- 
angles of 11- dg. to 17 dg. (agreeino; with olicjo- 
clase) on either side of the trace of the plane of 
composition. 
A thin section, cut from a soecimen showiug 
the contact between the ' Band' and tlie mass of 
limestone Vifhich appears to be included in it, 
exhibits points of interest. The aspect of the 
' Band' is greatly altered. It is fine grained, 
rather pink in colour, and discloses no distinctive 
minerals when e.\-amined by the naked eye. The 
lime stone is not so coarse as in the cutting nearer 
LTkawela, biifc is crowded with green inalacolites. 
At the junction exists a line of flark minerals. 
Under t'lie microscope the ' Band ' is represented 
by a tine-grained aggregate of calciteand malacolite, 
t3he latter preponderating, the former interstitial. 
The smaller grains of malacolite are full of in- 
clu'iions, perhaps of a carbonate. Tlie limestoea 
consists of plates of dolomibic calcice,* and is 
exceptionally rich in malacolite, thus resembling 
the rock on the oth-jr side of the junction, 
except that the carbonates predominate over 
tlie ma'afjolite, and the whole is coarser. The last- 
named mineral becomes mora plentiful as we ap- 
proach the boundary, and is also serpsntinized along 
cracks and edgis; while near the junction many 
grains are converted into yellow and green ser- 
pentine. The line of demarcation between t-he 
two rock^ consists of greenish and yellow serpen- 
tine, whithout definite for a and showing but few 
traces of its origin from .nalacolite. 
A secund contact-section, cut from another speci- 
men a couple of yards or so away, unfortunately 
gives but little information about the composition 
of the ' Band ' near the junction. We find the 
same serpsntinized ziae ; and the line of demarca- 
tion between the two rocks is not strongly marked, 
so that it is diffieult to say where one begins and 
the other ends. Tnis section is, however, note- 
worthy for the grains of spinel embedded in the 
serpentine-zone. There is some iron-oxide, possibly 
of the nature of a residue, and a few small flakes 
of reddish-brown mica, almost colourless for vibra- 
tions normal to the basal plane. Tlie spinel is of 
a dull sage-green, considerably cracked, and occurs 
in rounde l subangular grains up to •025 inch in 
diameter. 
Perhaps some monticellite may be present, as 
well as malacolite. The limestone 12 inches from 
the junction contains abundant grains ot mala- 
colite, fresh and not serpentinized, and a few 
plates of slighty-coloured augite. The dolomitic 
calcite here and in the cuttings to the south 
often has a veriniculated structure, owing 
to the presence of threads of a colourless mineral 
with an exceedingly low index of refraction and 
apparently no action on polarized light.f Very 
rarely we find a few flakes of yellow-brown 
mica, and still less frequently a grain of spinel. 
* The rock effervesces sharply with cold hydrooh- 
loric acid. S^e Bull. Soc. Min. France, vol. xii (1889) 
p. 'o'A6, wh'jre tha presence of both caloite iind doloimte 
are recorded by M. L;»,ci'oix. 
f An identical sfcrueture is described and frsjured by 
M' Livcroix in ;ho dijloinite o£ these rocks ; see Bull. 
Soc. Min, France, vol. xii (1889) pp 337-38 and tig. 60. 
Pri?ms of pale blue apatite are common, ranging 
up to 07 inch in length When detached entirely 
from the rock and examined in polarized light 
we find them to l)e strongly dichroic (pale blue 
to pale claret-red; * 
A specimen of the ' Baud' distinguished by the 
presence of large brown plates of micx. 1 to 
inches across, deserves a few words. The rock is 
much lighter in colour than normal specimens. 
A thin section shows that there are three primary 
miner ils and one secondary — the former are mala- 
colice, mica, and spinel, the last named brownish 
hornblende. This replaces the malacolite com- 
pletely in many places t- It is yello vish-brown 
for vibrations parallel to the prismatic cleavage, 
and possesses a fairly strong absorption. Tlie 
mica includes plates of the iiornblenrle, and ex- 
tends its irresrular eilges amongst the hornblende- 
erystaU. It is bro vuish-red for vibrations parallel 
to the basal plane, and pile straw at right 
angles to this direction. The mica also encloses 
small grains of green spinel, which make only the 
faintest attempt at an idiomorphic outline. The 
same mineral occurj embedded in the malacolite, 
and occasionally forms conspicuous aggregates 
which measure 'l incli across. Tlie malacolite- 
grains are closely packed togpther, cracked, and 
rather stained. Very commonly the hornblende 
and mica contain a large number of small rounde I 
greenish inclusions, with a high refractive index 
They are so minute that their double refraction 
cannot be sifely estimated, but it seems that 
a reijular gradation can be traced from them to 
indubitable grains of spinel, and it may b inferred 
that they are that mineral. 
The laterite exposures found alternating with 
those of the limestone must originally have been 
represented by a crystalline rock of some such 
type as that described from the west of Kandy 
or from the neighbiurhood of liandarawella. X 
Accordingly we find the less difficulty in corre- 
lating the small rock-mass termed the 'Bind' 
with those between Nuwara Eliya and Hakgala, 
which it closely resembles. The presence of 
crystalline limestone above and below this ' Bind' 
and the way in which it partially encloses a mass 
of tlie former are unaccountable by any explana- 
tion other than that of intrusion. § 
IV. HORN'IJLRNDl!; AND PYROXENE-GEANULITES. 
(a) The Neighboukhood o? B.\ndarawel- 
LA. — In the quarry on the hillside above the 
station we find a garnet-bearing hornblende- 
felspar-quartz rock with a vary granulitic struc- 
ture (specificgravity=2 76). Itis often well binded, 
* See A. K. Coomara-Swamy Quart. Journ. Geol. 
Soc. vol. Ivi (1900) p 600 : Lacroix, Bull. Soc. Min. 
France, vol. xii (1839) p. 339 ; and G. Barrington 
Brow" and J. W. Jurld, Phil. I'rana. Roy. Soc. vol. 
clxxxvii <1896) A, p. 212. 
t So'ae iron must be present in the original 
minsral. 
Decomposition in situ seems to be the true ex- 
planiitiou o£ the formation of this type of soil in 
Ceylon. 
§ I am of opinion that the peculiar mineralogico,! 
composition of the two rooks described above, namely, 
the representative of the ' Band ' at the junction witii 
the limestone, and the m ilaoolite-mica-spiael rock, 
may be beat accounted for on the hyhothesis that, 
local incorporation of the limsstone accompanied the 
intrusion. 
