40 
Records of the Geological Survey of India, 
[VOL. VI. 
VI.— Metamorphic Rocks. 
The metamorphic rooks surrounding the Bisrampur coal-field are separable into two 
groups, chiefly by their respective lithological characters. But 
their occurrence here, as well as in other parts of Chota Nagpur, 
is accompanied by certain geological features, which render it probable that they really belong 
to two different periods. 
The types of the former group are coarse granitic gneisses with variable amounts of 
visible foliation. Of the latter the types are slates, quartzites, 
T ' pes ' and hornblendics. Instances occur however where individual beds, 
lithologically undistinguishable from the latter, are geologically inseparable from beds be¬ 
longing undoubtedly to the former. 
VII. —Granitic Gneiss Sekies. 
The east and west range of hills south of Partabpiir, which bounds the coal-measure 
rocks on the north, consists of coarse granitic gneisses and schists which are exposed in 
section in the Mahan, Banki, and Rehr rivers ; in the Banki section, however, there are also 
some quartzites, to which allusion will be made again further on. 
On the east face of the field, granitic and porphyritie gneisses are again met with near 
Ara, where they occupy a zone about three miles wide. South of 
Trap-Uke hornblenditb. these a peculiar group of trap-like hornblendic rocks form the 
high ground near Parsa. At first I was strongly inclined to believe these to be trappean, 
and only relinquished this opinion on finding traces of foliation in some of the sections 
exposed in the streams on the top of the hill. These rocks continue to the Bank south of 
Sonpur. 
The spurs from the high ground east of Bisrampur are formed of granitic gneisses with 
Spu rs . occasional schistose, hornblendic, and quartzose bands. 
South-west of Bisrampur and south of the Pilka hills, there is an area occupied by 
metamorpliics, which consist chiefly of granitic gneisses. These extend southwards to the 
Main pat through Lukanpur. 
On the west of the field the section of the metamorphic rocks in the Rehr commences 
with quartzites of rather uncertain affinities; these are followed 
by granitic rocks, which continue—occasionally including schistose 
or slaty beds—up to Jhilmilli. 
Section in Rehr 
VIII.— Quartzite and Slate Series. 
North of the faulted boundary where it crosses the Banki, there is a thickness of 
several hundred feet of quartzites and slates, which present a 
somewhat very unusual appearance. Granite veins or dykes 
which are ordinarily confined to the gneissose rocks, in this case pass across into the 
quartzites, and appear to have been the cause of the disrupted and tilted condition ot 
the beds. In some cases fragments seem to have been torn off from the main mass and 
are enveloped in the granite. Accompanying this disturbance 
the slates are much hardened, and the faces are lustrous with 
crystals of actinolite. 
On the eastern side of the field, rather more than half the length of the boundary 
runs between Talchirs, quartzites, slates and schists. The extreme irregularity of the surface 
Section in Banki. 
Rocks hardened. 
