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the strata on a rather large scale, or faults exist which were not obvious
during tlie rapid survey, the Kalva-Ranganbetta quartzites underlie all the
beds to the northward of it. Another series of overlying quartzites is shown
to the north-north-west of Kalva-Ranganbetta ; but the relation between it
and the upper beds just described could not be determined without a much
more close examination of the district, more especially as the space between
the two sets of outcrops is very largely and closely covered by spreads of
regur. The chloritic schists offer no specially interesting features, and
they are not, as a rule, well seen, e.xcept on the slopes of the hills, the
general face of the country being much obscured by red or l^lack soil, which,
both of them, occur in great thickness.

Iloniiali Gold-Jield. — One remaining point of great interest is the large
number of important quartz veins, or reefs, which traverse the belt of
chloritic rocks overlying the Kalva-Ranganbetta quartzites. They are the
source of the gold occurring in the thick red soil which covers the whole
face of the low-lying country, and which has been washed for gold, certainly
for several generations past, by several families of Jalgars residing at
Palavanhalli. The gold is so generally distributed through the red soil that



42 GEOLOGY

it is clear that many of the reefs must be auriferous, and the quantity found
is sufficient to justify strong hopes that a profitable mining industry may be
developed by working the richer reefs. Several of the series of reefs close
to Devi Kop, a little village 2>\ miles east-south-east of the Kalva-Rangan-
betta, had been carefully and deeply prospected at the time of my visit by
Mr. Henry Prideaux, M.E., and in one case certainly with very marked
success. The quartz in this case was found very rich in gold, which was
visible in grains and scales scattered pretty freely through the mass. The
quartz in many parts had a quasi-brecciated structure with films and plates
of blue-green chlorite occurring along cracks in the mass. Near the surface
the chlorite, with which were associated small inclusions of pyrites, had
often weathered into a rusty-brown mass. The reef which at the time of
my visit was regarded as the most promising, and to which the name of
Turnbull's reef had been given, is one of a series of three that can be traced
with some breaks for a distance of six miles nearly parallel with the great
quartzite ridge of the Kalva-Ranganbetta, the true strike of the reef being
from N. 40° W. to S. 40° E. Another important set of three reefs having
the same strike occurs about half a mile north of the first series, but they
are not visible for such a long distance, their north-western course being
covered by the thick spread of cotton soil. To the south-east they, or at
least one of them, can be traced across theNyamti nullah, which divides the
gold-field in two. Out-crops of vein-quartz in a line with a south-easterly
extension of this set of reefs are to be seen north and east of Palavanhalli.
Numerous other quartz reefs having the same strike occur in the south-
eastern half of the gold-field, £'.^., a set of four, rather more than a mile north-
east of Palavanhalli, and several others to the north of Dasarhalli and south
of Kuntra. A few reefs were also noticed whose strike was different from
those above referred to. They represent two other systems of fissures, the
one running N. 5° E. to S. S"" W. ; the other, W. 5° N. to E. 5° S. Several
of both these series are of very promising appearance, the " back of the
lode " bearing considerable resemblance to that of Turnbull's reef. The
greater number of the reefs in the Honnali gold-field are well-marked
examples of these fissure veins.

During my stay at Devi Kop, I watched the results of many washings
both of crushed quartz and of the red soil taken from many localities and
various levels. The great majority were highly satisfactory. The Jalgars,
or local gold-washers, seeni to be a fairly prosperous set of men, so their
earnings must be fairly remunerative. They confine their attention,
as far as I could ascertain, pretty generally to the high-lying red soil banks,
between Devi Kop and the Nyamti nullah. The head Jalgar, a very
intelligent old man and dexterous gold-washer, informed me that the best
day's work he had ever done was the finding of a small pocket in the gneiss
which contained about Rs. 80 of gold in small grains and scales. I
gathered from him that he had not found anything beyond the size of a
''pepite." The position of these auriferous banks near Devi Kop would
admit of hydraulic mining over a considerable area by a system of dams and
channels to bring water from the Nyamti nullah, but the question of the



KOLAR GOLD-FIELD 43

profitableness of such an undertaking could only be decided by an expert
after careful examination and more numerous trials by washing.

Kolar Gold-Jield. — The schistose band, which bears within its limits the
Kolar gold-field, forms an elongated synclinal fold which in parts rises
somewhat over the general level of the surrounding granitoid country. The
dip of the rocks forming the basement of the schistose band, and therefore
tlic boundaries of the synclinal fold, is easily traced on both sides ; not so,
however, is the dip of the uppermost members of the group, for all the beds
exposed in the centre of the band have been much altered by great pressure,
which has superinduced an irregular slaty cleavage to a great extent. This,
combined with extensive minute jointing, has so greatly altered the original
texture of the rocks that they have assumed to a very great extent a highly
trappoid appearance. The lines of bedding are completely obliterated, and
it was impossible to decide from the sections I saw whether the central axis
of the synclinal represents one great acute fold, or a series of minor ones in
small Vandykes. The great petrological similarity of the strata forming the
upper (central) part of the synclinal makes the decipherment of this
difficulty all the greater. The sections I saw in the several shafts being
sunk at tlie time of my visit threw no light on the subject ; it is possible,
however, that a closer study of these sections would go far to enable this
point to be decided.

The succession of formations seen from west to east, after leaving
General Beresford's bungalow at Ajipalli on the road from Bowringpet rail-
way station to the gold-field, is micaceous gneiss (resting on the granitoid
gneiss), chloritic gneiss, micaceous schist, ha^matitic quartzite, and
chloritic schist, on which rests a great thickness of hornblendic schists,
which, as just mentioned, are highly altered, and have their planes
of bedding almost entirely effaced by the pressure and crumpling they have
undergone. The eastern side of the fold shows near the village of Urigam
well-bedded schists — dipping west from 50° to 60" and resting finally on the
granitoid rocks. The western side of the gold-field is very clearly demar-
cated by a well-marked ridge of hitmatitic quartzite which culminates in
the Walagamada Trigonometrical Station hill, from the top of which the
majority of the mines can be seen. The bedding is often vertical and
highly contorted in places. The texture varies from highly jaspideous
quartzite to a schisty sandstone. The hard jaspideous variety generally
shows distinct laminic of brown haematite, alternating with purely siliceous
laminit, generally of white or whitish-drab colour. It is only here and there,
and over very trifling areas, that the ferruginous element ever assumes
the character of red haematite. The beauty of the " Vandykes " and
complicated crumpling and brecciations of this rock in the Walagamada
Konda is very remarkable. The thickness of the hicmatitic band is very
considerable, and it forms the most striking feature of the western side of
the gold-field. On the eastern side of the gold-field the haematite quartzite
is much less well developed and exposed, excepting in the south-eastern
part of the gold-field where it occurs in thick beds forming the main mass of
the Yerra Konda Trignomctrical Station hill. Here the dip is about 60°



44 GEOLOGY

westerly, and affords one of llie clearest proofs of the synclinal character of the
schist band. To the southward the hicmatitic beds appear to coalesce, the
synclinal being pinched together, but I had no opportunity of following up
the eastern boundary of the schistose band. The western boundary is a
very conspicuous feature, a bold rocky ridge running up into the lofty
Malapan Betta peak, the highest summit in this part of the country.
South of Malapan IJetta the hiematitic beds appear to lose their importance
and no longer form the most striking feature of the schistose band, and
micaceous and chloritic beds abound. Owing to the great extent of jungle
and the rugged character of the country, their general relations were not to
be made out completely in the short time at my disposal. The beds run
south into the Salem District, and probably occupy the valley lying east and
north-east of Krishnagiri and, not improbably, extend on towards and past
Darampuri. A subsidiary ridge of lower elevation, which branches off from
the western side of Malapan Betta westward and then trends south-west
and finally south-south-west, also consists of schistose beds of similar
character, amongst which a hi'ematitic quartzite is the most conspicuous.
The relation of these latter beds to the Kolar gold-field synclinal fold is
quite problematical, but it is very probable that several important faults
have caused great dislocation of the strata first along the boundaries of
the main synclinal fold. The stratigraphy of the several spurs radiating
from Malapan Konda is very complicated and interesting and well worthy
of careful consideration.

The auriferous quartz reefs which have attracted so much attention lie in
the broader part of the synclinal fold north of the railway. None of any
importance were seen by me in the tract south of Malapan Betta. The
intermediate tract I had no opportunity of examining closely, but I did not
hear of the existence there of any of interest or importance. The reefs
make very little show on the surface as a rule ; in many cases, indeed, the
whole back of the reef, or lodes, has been removed during the mining opera-
tions of the old native miners, whose workings were on a rather large scale
considering the means they had at command. Much also of the surface is
masked by scrub jungle, or by a thick coating of soil, often a local black
humus. The reefs are so very inconspicuous that I have not attempted to
show them on the map. Their run is north and south with a few degrees
variation either east or west. The hade of the reefs is westerly in most
cases, as far as they have been tested by the shafts sunk. The angle they
make with the horizon is a very high one, on the average not less than from
85° to 87°. Much has been said about the reefs in the Kolar not being true
fissure veins, but I was unable to find any good reason for promulgating this
view, and several iiiining engineers of high standing and great experience,
as Messrs. Bell Davies, Raynor St. Stephen, and other practical miners well
acquainted with the locality, have no hesitation about calling them '' fissure
veins " or " lodes." The quartz composing the reefs is a bluish or greyish-
black diaphanous or semi-diaphanous rock, and remarkably free from
sulphides (pyrites, galena, &c.) of any kind. The gold found is very pure
and of good colour. Several washings of crushed vein stuff were made in



TRAVERSE NOTES 45

my presence at the Utigam and Kolar mines with really satisfactory results,
the quantity of gold obtained being very appreciable. The samples operated
on were not picked ones.

The principal new mines now in progress formaline stretching from south
to north on the eastern side of an imaginary axis drawn along the centre of
the synclinal fold, and this line coincides with that followed by the '*' old
men," many of whose abandoned workings are being extended to greater
depth than they had the power of attaining to without steam-pumping
machinery.

Numerous large dykes of dioritic trap are met with traversing the gneissic
rocks of this region. One set of them runs north and south with a variation
of about 5° east or west. The other runs nearly east and west. The
presence of these dykes will offer formidable obstacles to the mining works
in some places, and it will probably be found that the intrusion of these great
igneous masses has added considerably to the metamorphism of the schistose
beds along the lines they traverse. As already mentioned, the schists are most
highly altered along the central axis of the synclinal fold, and the largest of
the north and south dykes shows a very little to the east of the synclinal axis.

The Kolar schistose band is the only one as to the exact stratigraphical
relation of which to the granitoid gneiss any positively conclusive evidence
had been obtained ; but there is reason to believe that at least three of the
schistose bands to the westward of it, viz., those of Sundur, near Bellary, of
Dambal-Chiknayakanhalli, and of Dharwar-Shimoga, are similarly super-
imposed on the granitoid rocks. Whether the superposition is a conform-
able or an unconformable one, is a point that has yet to be determined by
further investigation ; at the Kolar gold-field, however, the relation between
the schistose synclinal and the underlying granite gneiss appears to be one
of distinct conformity. The Hospet end of the Sundur schist band certainly
presents every appearance of being the acute extremity of a synclinal basin.
The south-eastern extension of this band is as yet unknown, but there is
good reason to expect a considerable extension of it to the south-eastward of
Bellary.

The remarkable length of the Dambal-Chiknayakanhalli and Dharwar-
.Shimoga bands precludes the idea that they can be each a simple synclinal
fold, rather may they be expected to prove a succession of synclinal and
anticlinal in dchelon, with their contact boundaries not unfrequently coin-
ciding with faults. The geographical position of these great bands confirms
and amplifies the evidences to the fact which 1 specially pointed out in my
Memoir' on the East Coast from latitude 15° N. northward to Masulipatam,
that the Peninsula of India had been greatly affected by tremendous lateral
forces acting mainly from east to west and thrusting up the gneissic rocks
into huge folds. These great foldings have undergone extensive denudation,
and the softer schistose beds especially have been entirely removed from
large tracts of country which they must have formerly covered, if any of the
bands now remaining really represent (as they in all probability do) portions
of once continuous formations.

' Memoirs, " Geological Survey of India," \'ul. X\T.



46 GEOLOGY

The schistose hands having only been mapped at different points, their
general width, as shown on the annexed sketch map, is only hypothetical,
and it is very possible that at intermediate points they may either spread out
•or narrow considerably. Their relation to the schistose gneissics of the
Carnatic Proper has yet to be made clear, and it is not at all unlikely that a
third subdivision will have to be recognized in the crystalline rocks of South
India — a subdivision which will include the rocks of a character intermediate
between the typically schistose rocks and the typically granitoid rocks of
Mysore and the South Mahratta country, namely, the massive gneissics of
the Carnatic, in which the ferruginous beds are magnetic, not ha^matitic.



From Report on Auriferous Tracts in Mysore [in 1887), f>y the same.

These tracts lie widely scattered, but may be conveniently grouped (for
the purpose of description) in three groups corresponding to the three
principal divisions of the great Auriferous rock series' which traverses
Mysore in great bands in a generally north-north-westerly direction, and
forms such important features in the geological structure of the table-land.
These three groups may be appropriately termed the Central, the West-
Central, and the IVestern groups ; the Eastern group being formed by the
Kolar gold-field {see above, p. 43). The central group belongs to the
Dambal-Chiknayakanhalli band of my former paper : and the western group
to the Dharwar-Shimoga band of the same. The west-central group
includes a number of small outlying strips of schistose rocks, some, if not
all, of which are of the same geological age as the great schist bands lying
to the east and west.

{Xanjangi'id to Jagali'ir.)

Central Group. — The rocks seen at Holgere, 7 miles south-west of Nan-
jangiid, are very gneissic in their general aspect, but they are very badly
seen on the top of the ridge where the old workings are situated, and it is
possible the hornblendic beds there occurring may belong to a very narrow
strip of the auriferous schists (Dharwars), an outlier of them in fact, and
probably faulted in along the strike of the underlying gneissic rocks. The

1 Rocks of the same geological age as the auriferous rocks of Mysore occur largely
in other parts of South India, both north, east, and south-west of Mysore, and to
classify such a widely-developed system, it was necessary to have a collective name
for them. The name of Dhaiivar rocks was therefore given by me to these rocks,
on the usual principles of geological nomenclature, namely, for their having been
first recognized as a separate system after the study of their representatives in the
Collect orate of Dharwar (Bombay Presidency), where they occur ver)- largely and
typically, and underlie the important town of Dharwar. The use of this name in this
report has, however, been deprecated on the plea that it might lead to confusion in
the minds of readers unfamiliar with South Indian geography. I have therefore
avoided using it wherever this was possible, but geologists who may peruse my report
will understand that the alternative terms which I have used, "Auriferous" or
" Schistose rock series," really mean formations of the Dharwar age.



AURIFEROUS TRACTS 47

quartz reefs licre seen are small and coincide in direction with the nortli-to-
soiith strike of the country rock, or deviate a httle (3°-5") to the east-of-
north. The quartz exposed in the principal old working is highly ferrugin-
ous, being full of scales and films of impure haematite (specular iron), but
contains no pyrites or other sulphides. North of the old working the reef
is cut off by r. broad band of a highly decomposed granite rock containing
much pink felspar. The country between Holgere and Mysore is composed
of micaceous gneiss with a few bands of hornblendic schist and potstone,
with no quartz reefs of any importance, and the small show of gold obtained
by Mr. Lavelle from washings in the Kadkole nullahs must have come from
veins too small in size to be worth mining. I could not trace any connec-
tion between the Holgere auriferous rocks and the great Chiknayakanhalli
band, the former must therefore be considered as a mere small outlier, if
they are really of Dharwar age. The line of high ground commencing on
the north bank of the Kdveri river near Shettihalli consists mainly of
quartzites and hornblendic schists belonging to the Dharwar series and
forming a narrow band (from 2 to 3 miles in width), which extends north-
ward, widening very gradually as it is followed up. A number of small
quartz veins occurs running in the direction of the strike of the beds, here
nearly due north and south. The quartz is very white and "hungry-look-
ing," and very few minerals are to be found in it. Those noted were blackish-
greenish mica and a white decomposing felspar, the former not infrequently
in distinct six-sided prisms. These included minerals show but very rarely
and at wide intervals, but here and there become numerous and convert the
vein into a true granite, a rock in which gold very rarely occurs in any
quantity. Fragments of good-looking blue quartz were noticed scattered
about ihe surface to the south-west of Siddapur village, but on tracing them
up to their true source they were found to be derived from typical granite
veins. As far as surface indications go, this tract appears a very unpromis-
ing one, and quite undeserving of consideration when so many really pro-
mising tracts remain as yet unprospected. The course of the extension of
the Chiknayakanhalli schist band south of the Kdvcri is yet undetermined,
but as seen from the top of the Karigatta Trigonometrical Station, it appears
to go southward, passing east of the granitoid mass of Chamundi hill ;
unfortunately want of time prevented my determining this point, which is one
of considerable interest geologically. Hoimabctta is a hill lying a mile and
a half south by west of Ndgamangala, and forming the central part of an
outlier of the auriferous series on the western side of the Chiknayakanhalli
band. The mass of the hill consists of hornblendic schist overlaid by
chloritic schists. A washing made in the small nullah draining the north-
east face of the hill just within the eastern boundary of the auriferous rocks
gave a good show of gold of medium size and excellent colour. I noted one
large bluish quartz reef on the high north spur of the hill which struck me
as worthy of being tested in depth. At present merely the back of the lode
is exposed, and but to a very small depth, so it is impossible to test the
real quality of the stone. This reef runs through the chloritic schists.
Giri^i:;uiida forms the northern extremity of the outlier, and shows chloritic



48 GEOLOGY

and lioinljlcndic schists, extensions of the Ilonnabetta beds. The rid^e of
the Giiigudda is traversed by a pale green dioritic (?) trap. The north end
of the outher dies away rapidly northward of Girigudda, and disappears
northward of the nullah. A careful washing in the small stream draining
the east side of Girigudda, at a spot about a quarter of a mile eastward of
the hill, gave a fair show of medium fine gold. The presence of trap rock
among the schists is a favourable indication for the presence of gold. The
whole outlier, which extends 7 miles from Girigudda southward to Maradipur,
with a width of a little more th m a mile across Honnabetta hill, is deserving
of very close examination, and the reefs of being prospected to some depth.
About 2 miles north of Girigudda and within the gneissic area lies Hnlmnn-
dibcfta, a low hill on the ridge of which occur several fine reefs which are
being tested in depth by the Mysore Concessions Gold Company. The
question— Are the quartz reefs occurring in the gneissic rock profitably
auriferous as well as those occurring in the Dharwar series ? (to which all the
important gold-yielding reefs at present known unquestionably belong) —
will doubtless ere long receive a definite answer from the results of these
deep prospectings, and I sincerely trust it will be a very favourable one, as,
if so, many other reefs of great size and beauty running through the gneissic
series may probably also prove to be gold-yielding. Much of the quartz
turned out at Hulmandibetta is good-looking, bluish in colour, contains
some pyrites, and encourages the hope that it will prove auriferous at
depths not reached by superficial weather action. Haliibetta, a large hill
some three miles north of Nagamangala, has been reported auriferous, but the
statement is highly improbable, the whole mass of the hill except the southern-
most extremity consisting of granitic gneiss. A band of schistose rock extends
from the southern spurs southward for a couple of miles till hidden by the
alluvium of the Ndgamangala stream. Large reefs of quartz were noted on
either side of Haltibetta ; they are very unpromising, the quartz being very
white and free from included minerals. In miners' parlance, they are very
hungry-looking. At Kalijiganhalli the old native workings occupy a con-
siderable area on which old dumps stood thickly, showing that a large
amount of washing had been done. A very good show of gold was obtained
by washing the dumps, but no reefs, large enough to be worth mining, could
be found. Further south, however, fine reefs are to be seen pretty
numerously, running north and south in the strike of the chloritic schists.'
A narrow strip of very typical auriferous schists crosses the road a mile and
a half west of the bridge over the Shimsha on the Hassan-Bangalore road,
and may be seen stretching away north and south to a considerable distance,



Online LibraryB. Lewis (Benjamin Lewis) RiceMysore: a gazetteer compiled for government (Volume 1) → online text (page 7 of 98)