14 GRIESBACIl : HAMKOLA AND TATAPANI COAL-FIELDS. 



Talchirs. 



The oTound covered by the beds of the Talchir formation is not of 



g-reat extent in the Tatapani coal-field, though 



rocks belonging to this series are seen wherever 



the boundaries of the Gondwana basin are natural. The largest area 



covered by these rocks is to be found along the eastern extremity of the 



field, cropping out from beneath the Barakars in a belt of varying width 



of from half a mile to three miles, extending from Tatapani to near 



Gumharia. 



I have generally found them forming irregular beds and filling 



up hollows in the metamorphic rocks, which 



Lithoiogy. j^^^^^ ^^^ ^^^^^ exposed through the Talchirs by 



denudation. The base bed is usually a reddish-brown and olive-coloured 

 greenish shale of marly character, breaking into small angular pieces, 

 being jointed in three directions. Light coloured, fine-grained sand- 

 stones, with occasional pebbles, generally overlie these shales, and are 

 followed by the Talchir conglomerate ; this series is often repeated several 

 times by faulting, but the whole complex of beds may attain a total 

 thickness of not more than 900 feet. The bedding is most irregular and 

 the dip rolling ; the beds themselves are of very uneven thickness, thin- 

 Bin«- out often at a few yards distance, and again thickening rapidly. 



This is especially the case with the fine-grained sandstones found 

 alternating with, and replacing, the boulder bed and 

 Boulders. shales. Pebbles and boulders, from the size of a 



pea to enormous blocks from 30 to 40 feet in diameter, are seemingly 

 disseminated throughout all beds of this formation. These boulders 

 were evidently deposited from above in a fine silty matrix, and it is im- 

 possible to detect a regular or even deposition in this bed. Many of the 

 boulders, of elongated shape, are standing perfectly upright in the matrix, 

 and seem to have dropped from above into the fine clay. 



The latter is usually of a bluish or olive-green tint, but occasionally 

 dark red or brownish silts prevail, as, for instance, in the Talchirs of 



( ua ) 



