August i, 1888.I THE TROPICAL AGRICULTURIST. 129 
"ALL ABOUT GOLD." 
In view of the present activity in " prospecting " 
for gold in Ceylon, the latest number receiv d of 
the " Becoiiiis or THE Geological Survey of 
India Vol. XXI, Paht 2, 1888, " is of special 
interest locally. The list of articles in this part is 
as follows : — 
Award of the SVoIlaston Gold Medal, Geological So- 
ciety of Loudon, 1881, The Dharwar System, the Chief 
Auriferous rock scries in South India, by It. B. Foote, 
r-i a. s., Superintendent, Geological Survey of India, 
(with map). Notes on the Igneous rocks of the dis- 
tricts of Baipur and Ualaghat, Central Provinces, by 
Pramatha Nath Bose, B. Sc., i. g. s., Deputy Superin- 
tendent, Geological Survey of India, (with a plate). 
Beport on the Sangar Marg and Mehowgala Coal- 
lields, Kashmir, by Tom. D. LaTouche, b. a., Geo- 
logical Survey of India (with one plate). 
The number has for frontispiece a portrait 
of Mr. Medlicott in the shape of a " photo etch- 
ing " exeoutcd in the office of the Survey of India. 
Mr. Medlicott joined the Geological Survey of India 
in 185-4 and did good work for a third of a century, 
in the face of difficulties and hardships. In 
presenting the medal the President said : — 
During the last eleven years you havo occupied 
the important and responsible position of Director 
of tho Indian Survey ; and it is to your adminis- 
trative ability in thHt position that we owe many of 
the vuluablo results obtained by that Survey in recent 
years ; more especially aro we indebted to you, nnd to 
our Si cretary, Dr. Blanford, for that useful Compen- 
dium of Indian Geology which has now become indis- 
pensable to all students of our science, 
It is, however, Mr. Foote's paper on the Dharwar Sys- 
tem, the chief auriferous rock series in South India, 
that is interesting to us hero in Ceylon, now that pro- 
specting for gold is exciting special attention. It 
appears that, as the result of extended examina- 
tion, the Dharwar rocks havo been separated from 
the gneissic system (the prevalent system in Ceylon) 
amongst which they were formerly reckoned. Mr, 
Foote explains the geological reasons :— 
The Dharwar rocks form a very well marked series 
(or system), consisting mainly of Schistose rocks 
(hornblendic, chloritic and argillitic) with associated, 
more or less hnmatitia quartzites and numerous con- 
temporaneous trap flows. In many parts of the areas 
occupied by these rocks occur quartz reefs and veins 
which aro auriferous, indeed all tho more important 
auriferous tracts as yet known in South India lie within 
such areas, and hence the rocks composing them have 
come to be called the auriferous series. The Kolar 
gold field unquestionably occurs in an outlying band 
of the Dharwar system, and bo also the Honnabetta, 
Chicknayakanhalli, Kotemaradi, Honnamaradi, Ilalc- 
kal gndda, Malibennnr, Chiranhalli, Ilommhatti auri- 
ferous tracts and the Honnali gold field (Kudri 
kouda and Talvanhalli) in Mysore, and the Dambal 
gold field, in Dharwar District, which occur in one 
or other of tho great bands. The majority, if not 
all the fifteen outlying auriferous localities, forming 
the west central group of my Mysore Beport are 
also situated on detached areas or outliers of tho 
Dharwars. The namo chosen for this great series 
of rocks, " the Dharwars, " was selected on well 
recognized principles of geological nomenclature, from 
the district in which the separation into a distinct 
and separate system of the Schistose recks was first 
rccoguizod. Till then they had been grouped as part 
of the great South Indian Gneissic system Tho 
necessity for such separation was pointed out by mo 
in my memoir on the South Mahratta country 
(Memoirs, Geological Survey of India, Vol. All, 1876), 
but I waited for fnrthor evidence of tho stratigraphical 
relation of tho Schistoso series to the tar more 
cryBtnllino gnoissics, and this was obtained during 
my travorso across Mysore in 1881, and by an ex- 
amination of tho rocks in the Sandal and Bellary hill 
in 1HS1-h.->. The Schistose rocks are very largely and 
clearly developod in Dharwar District, aud the well 
known towu o( Dharwar stands on them. All things 
17 
considered, no othi r local name seemed to havo so 
many points in its favour and the name of Dharwar 
was therefore given to the schistose, or aurifcrjus 
rock system. 
The occurrence of the Dharwar rocks over tho 
face of the gneissic systems in such remarkable bauds, 
or portions of bauds, is a feature which at once ar- 
rests the attention and demanls explanation. The 
explanation is tbat-*he Dharwars, as now seen, aro 
the remains of a great sendimentary series which 
covered a very largo area in what now forms the 
peninsula of India. The periods of sendimentary 
deposition were interrupted by poriods of volcanic 
activity during which great Hows of contempora- 
neous trap were poured out. Many such flows were 
formed in different parts of the Dharwar area, as 
in that which now forms the Sandnr and Bellary 
hills, and further to the south-west the hills suuth of 
Chilaldrug and tho Bababudcn mountains. TheDhar- 
war rocks were at a very remote geological period 
exposed to vast lateral pressure, by which they were 
crumpled into great folds, which wore then exposed 
to great denuding action, and largely eroded. Tnis 
took place anterior to the deposition of theKadapa 
and Kaladgi basins, which belong to the upper transi- 
tion group. Both basins were deposited unconform- 
ably on the upturned, aud greatly contorted and 
eroded beds of tho Dharwar system. The groat 
jaspery haematite beds of the Dharwar system fur- 
nished the bright coloured jasper pebbles which are 
so striking a feature in the basement aud other 
conglomerates of the Kadapi system. The forcer 
which caused the great crumpling of the Dharwar 
rocks had, of necessity, also much effect on the 
underlying gneissic rocks, and in various places in- 
duced a parallelism of folds which gives locally great 
semblance of conformability. The section of the gneiss 
rocks exposed south of the southern end of the Sandur 
tract, shows the gneiss to have been affected by an 
anterior process of crushing from pressure, acting in a 
more or less east and west direction. This is note- 
worthy, as it shows that the peninsula was affected at 
no less than four periods by great, approximately east 
to west or west to east, thursts ; the two just noted, 
and two later ones, by which tho Kadapa and Karuul 
rocks were respectively crumpled up into the great 
foldings they now show. Of these, the last would seem 
to have been the least energetic. 
The auriferous region of Southern India would seem, 
therefore, to have been exposed, within compara- 
tively recent periods of geologic time, to volcanic dis- 
turbances, of which our gneissic rocks, so far as we 
know, show no traces ? But for the settlement of 
a'l such questions weought to have a geological survey 
of the island. 
There is a note on laterite believed to be the 
result of weathering on the surface portions of 
the primitive rocks which is interesting to us in 
Ceylon where so much of our gneiss rock has 
undergone or is undergoing the process of change : — 
Note. — A special feature demanding notice in the 
western half of the Sbirnoga inlier, and still more 
striking over the gneissic tract of the Dharwars near 
Anantapur is the development of lateritic rock which 
covers the surface almost ubiquitously and to con- 
siderable depth, rendering it extremely difficult to 
find any outcrop si the underlying older rock. I 
have not attempted to show the laterite on my map 
separately from the gneiss on which it mainly lie*, 
as my brief visit to this north-west cornor of Mysore 
did not afford mo time to determine the relationship 
between the roc ks. I did not see enough ot the late- 
rite to feel satisfied as to its being of true detrital 
origin or merely a product of weathering, as is much 
of the laterite on the southern parts of the Deccan 
trap described iu my South Mahratta Beport (Me- 
moirs, Geological Survey of India, Vol. XII., 187t3). The 
laterite which 1 am (so far as my observation goes 
up to the present) inclined to regard as formed by 
weath< r actio. i, constitutes a nearly unform cover to 
tho whole country, whether it be flat or hilly, with 
a generally pale, rodditsh, more or less clayey surface 
which affords but little uouriobinout to vegetation . 
