RECORDS 
OF THE 
GEOLOGICAL SURVEY OF INDIA. 
Part 2.] 1873. [May. 
Name. 
Position and boundaries. 
The Bisrampuk Coal-field, by V. Ball, m. a., Geological Survey of India. 
The above name being that of the capital town has been given to an area of coal- 
measure rocks which is situated in the eastern portion of the 
comparatively low-lying ground of Central Sirguja. On the 
north and east the limits of the original basin of deposit are 
defined by, in the former case, a ridge of low hills composed of metamorpbic rocks, and in 
the latter by the flanks of a plateau formed of the same rocks. This plateau rises from 1,000 
to 1,800 feet above the generally elevated country of Western Chota Nagpur; thus forming 
a step or barrier between Lohardugga and Central Sirguja. 
In some cases the ancient valleys and indentations in these bounding walls of the basin 
are occupied by prolongations from the rocks of the Talehlr formation, which, as they crop 
out on all sides, probably underlie the coal measures throughout. Instances occur, notably 
one, where spurs from the metamorphics penetrate into the area now occupied by the coal 
measures. With these exceptions the latter lie within well defined boundaries, which, to a 
comparatively small extent only, have been affected by faults. On the south and west the 
case is very different. The original boundaries of the coal measures are far removed from the 
present limits; and broken and semi-detached extensions of the sedimentary rocks, especially 
the Talchirs, connect the Bisramptir field with other coal-fields, which, however, for all practical 
purposes are, and for purposes of description maybe, most conveniently regarded as distinct. 
The coal measures whose limits have been thus defined occupy an area of about 400 
Area square miles, throughout which, except in the river hods or their 
immediate neighbourhood and on a few small hills, no rocks are 
exposed : a considerable covering of alluvium concealing all. To such an extent is this the 
case that a traveller might pass over the Bisrampur and Partabpur road for twenty-two miles 
without seeing a single outcrop of Barakars, save at two or three of the river crossings. 
The level of this area falls gradually from south to north, Bisrampur at the south-east 
_ . corner being 1,943 and Kiunra on the northern boundary 1,747 
teet above the sea level. 
The drainage of the eastern three-fourths of the field is effected by the Mahan river 
and its tributaries. The waters of the remainder are carried directly into the Rehr by the 
Pasang and other smaller tributaries. Tbe Mahan itself joins the Rehr at a point a few 
miles to the north-west of the field, in its course traversing a channel deeply cut in the above 
mentioned barrier of metamorphic rocks which bounds the field on the north. This fact, if 
others were wanting, affords evidence of the immense denudation 
which has taken place. But in the isolated Pilka hill, formed of 
the upper sandstones which rest on the southern boundary of the field, there is a remnant 
Denudation. 
