1919.] The Sixth Indian Science Congress. elxxvii 
Hitherto we have dipnusoet the origin and relationships 
Sibi anes may be designated the normal 
Archaean rocks. 
B 
India we have another set of formations, which extends 
southwards into the hill masses of Southern India and Ceylon. 
This peculiar and abnormal set of formations may be 
designated the Eastern Ghats facies of the Archaean and com- 
prises the charnockite series of Holland, the khandalite series 
of T. L. Walker, and a series of garnetiferous biotite-gneisses. 
Last winter I had occasion to tour Orissa in search of mica 
through country much of which is still geologically unsurveyed. 
As one result of this tour, I was led to discover the existence 
of what may prove to be a very SOE geologival boundary 
or line. Its approximate position, as judged from my own 
to the south of Sambalpur, as far as a point to the north of 
Borasambar. South of this line practically all the rocks are 
garnetiferous, consistin gneisses, of 
the garnetiferous schists and gneisses comprising the khondalite 
series and the hybrid Bezwada gneiss, and of basic members of 
the charnockite series, sometimes but not always garnetiferous. 
No rth of this line we have normal non-garnetiferous gneisses an 
s and normal Dharwar sediments with basic epidioritic 
i be 
tion of the line (or zone) separating the normally garnetiferous 
formations from the normally non-garnetiferous formations, 
and to determine to what extent the difference between these 
two facies of Archaean formations is due to original differences 
of composition and to what extent to differences of dynamic or 
thermal history; but we may convenience refer to the two 
es of Archaean formations in 
Chota Nagpur or nor- rere as te Chota Nagpur facies or 
pee ee ee Ae ae ae Eastern Ghats facies or 
= vely. 
In discussing now the ore- acetely of the Archaean in India, 
I propose to confine my attention to those found in the no 
or Chota Nagpur type of Archaeans, except for a brief refer- 
ence to the ore-deposits of the Eastern Ghats type at the end. 
In view of the foregoing discussion on the origin and 
ao he ule rmal relationships the aang of ae 
pete gpcsoenataeentene aang t of Archaeans in India, 
wot ai rary Rt may Sak the following general 
classification :— 
(1) Oldest gneisses and granites—not yet certainly identi- 
fied. 
