PART 4 .] 
103 
Ball: Raigarh and Hingir Coal-field. 
In the present account the coal-measure rocks which occupy the valley of the Mand 
and stretch thence to Korba are not described, as they have not been fully examined, 
lliey extend over a considerable area and contain many seams of coal. 
I. —General Geology. 
The rocks which occur within and in the vicinity of the coal-field belong to the follow- 
iug series and groups :— 
Metamorphic Series. 
Vindhyan 
Talchir 
Damuda „ 
Barakar Group. 
Upper sandstones or Hingir Group. 
Laterite. 
The rocks of the metamorphic and Vindhyan series, which surround and underlie the 
coal-field, are not described at present, as the examination of them has been limited to the 
immediate vicinity of the field, and no general exploration of them has been yet attempted. 
The Talchir series does not in this area attain any great thickness. Probably 250 feet 
is its maximum, but this estimate, in the absence of reliable data, is, it must be admitted, 
purely conjectural. 
The rocks constituting the Barakar group are, I believe, of much less thickness than in 
the Damuda valley coal-fields; but there are no sections which would justify any definite 
statement. 
The upper sandstones, for which the temporary and local name of Hingir group is used 
without prejudice to their future relegation under one of the titles used for similar rock 
elsewhere, may in places exceed 1,000 feet, but that is, I believe, a fair average. It has been 
arrived at from the measurement of horizontal beds from the level of the Barakars to the 
tops of the highest hills. 
The thickness of the laterite seldom exceeds 60 feet. Generally it is much less. 
II. —Talchir Series. 
Within the area under description, the rocks which belong to the Talchir series do not 
anywhere attain any very great importance either as regards their thickness or the area 
occupied. As to the amount of the former, only an approximate and very rough estimate 
has been offered, no measurable section being exposed. Of evidence of faulting alone the 
boundaries, except in the case to be hereafter mentioned, there is none. On the whole, it 
would appear that the representatives of this series merely occupy originally shallow and 
more or less detached depressions in the metamorphic rocks, and before any marked disturb¬ 
ance. or denudation took place, were covered up and overlapped in most instances by the 
Barakars. One well marked case, at least, occurs, however, where Talchirs are immediately 
superposed by the upper sandstones, no trace of intervening Barakars being found. 
In their lithological characters the Talchirs of this area conform closely to the well- 
known types, as will be seen from the following detailed descriptions. 
For purposes of reference it will be convenient to refer to the several areas of Talchir 
rocks which occur along the margin of the coal-field by the names of the principal villages or 
rivers withm their limits. Thus denominated they would stand under the following heads 
Sasun—Eemra. This area occupies an irregular strip of country which stretches from 
a tew miles east of Sasun* westwards to beyond Eemra, in all for a distance of about 
twenty miles, and with a breadth of from three to six miles. 
* Sasun is about eight miles north of Sambalpur. 
