500 Scientific Proceedings, Royal Dublin Society. 
fragments, carbonaceous and other shales, and coal. Except in 
some of the eastern fields of the Damuda Valley series, this group 
includes all the valuable coal of Peninsular India. 
The thickness attains its maximum in the Jeriah coal field 
where it is estimated to be 3,800 feet. In the Ranigunj field it is 
2,000 feet ; in most of the other fields it is much less. 
TRONSTONE SHALE Group.—This group, consisting of bands of 
ironstones, running through gray and black (carbonaceous) shales, 
overlies the Barakar group with general conformity. It is only 
found in the Damuda Valley fields, wholly disappearing further 
west. 
In the Bokaro field it attains its maximum thickness of 1,500 
feet. 
RANIGUNJ (KAMTHI) Group.—The Ranigunj group consists of 
sandstones which are fine grained and often calcareous, carbona- 
ceous shales and coal. The coal is generally of better quality and 
more uniform in composition and in the thickness of seams than is 
that of the Barakar group. In the easternmost field of the Damuda 
Valley series, namely, the Ranigunj which has given the name to 
the group, the principal coal seams which are worked belong 
to this group. In-the more western fields, it steadily thins out, 
the coal becoming of less and less importance. 
In the central fields of the peninsula it is very much changed 
in lithological characters and is so greatly increased in thickness 
amounting to from 5,00U to 6,000 feet, that the true identity 
with it of these latter deposits which constitute the so-called 
Kamthi group is established only by general geological relations 
aided by fossil evidence. 
The rocks of the Kamthi group are largely made up of coarse 
sandstones and conglomerates in which there is a prevailing red- 
dish colour due to the amount of iron always present. Coal rarely 
occurs as a member of this group ; its importance is insignificant. 
For fuller accounts of the lithological characters and fossil con- 
tents of the above beds I must refer the reader to Mr. Blanford’s 
account of them in the manual of the Geology of India. 
The groups of the upper Gondwanas do not contain workable 
coal, but their presence in the several fields covering and sometimes 
wholly concealing the coal-measures confers on them indirectly a 
considerable economic importance. 
