THE DATVIUDA SERIES. 29 



The foregoing" paragraph terminates the enumeration of the known 

 outcrops of coal in the Barakar group. A look at the map will show 

 that there are large areas in which no seams are indicated. This fact 

 does not imply the absence of coal throughout those areas, but merely 

 the want of surface evidence which, in other parts of the field, is afforded 

 by outcrops. I believe the coal to be nearly constant in its horizon ; 

 and therefore when we have made ourselves acquainted with one clear 

 section, it will not be difiieult for us to feel our way in searching for coal 

 even where there are no signs of it at the surface. 



During my survey of the field, I was not able to collect very reliable 

 data for estimating the thickness of the Barakars. There are several 

 instances of the local exaggeration of particular rocks : one, such as 

 the occurrence of the ferriferous shales east of Koilan, and another 

 the excessive development of the pebble beds at the base alono- the 

 southern boundary. Near Loharsi on the Damuda, they form cliffs 

 exceeding 60 and 70 feet in height. Allowing then, for what may be 

 termed irregularities, a fair average estimate would give the Barakars a 

 thickness of between 1,500 and 1,600 feet. In the Raniganj field they 

 are said to be 2,000 feet, whilst in the Jherria they are more than 

 3,000 feet. 



One of the changes in the mineral aspect of the sandstones of 

 this group is the great accession of iron. In many instances the 

 bottom grits and sandstones are so altered in appearance that they 

 resemble the rocks of the upper Panchets, and considering the o^eat 

 weight that must necessarily be given to lithological evidence, where 

 palseontology fails, it is difiieult, in some cases, to determine correctly 

 which series we are dealing with. 



This accession of iron is a very fortunate circumstance. It has 

 materially affected the industry of the district, and compensated largely 

 for the non-adaptability of the group, as a whole, for ao-ricultural 

 purposes. 



( 313 ) 



