GENERAL GEOLOGY OF THE AllEA. 



15 



South Rewah, a continuation of the Ramkola-Tatapani field. This variety 

 is then often mottled, and lumps and clunchy masses of the greenish 

 clay are inclosed in the red silt. 



Such is shown in the beautiful exposures of Talehirs near Kandia, and, 

 in fact, in all the nullahs cutting- through these beds in that part of the 

 coal-field. I have shown it in fig. 2 of Plate II. We find there rounded 

 and angular blocks of gneiss, hornblendic rock, quartzites and tourma- 

 line oranite along with pebbles, and blocks of red quartz sandstone of 

 Vindhyan type enclosed in the silt and also in the shales. In fact, 

 throughout the Talchir beds, even in the fine, silty, greenish sandstone, 

 pebbles are disseminated more or less. 



There are also the usual intercalated masses of fine-grained, yellowish 

 green sandstone, with occasional strings of pebbles 



San one. ^^^ wovn boulders; they are almost invariably 



thick-bedded and often pass into either the shales or the boulder-bed, 

 as, for instance, near Mitgain, where I noticed a thick mass of unusually 

 hard sandstone with pebble strings, passing into fine-grained bright- 

 coloured sandstone of the usual character. 



The sketch, fig. 1, Plate II, represents this mass of Talchir sand- 

 stone near Mitgain, where it suddenly swells to a considerable thick- 

 ness, and is denuded into enormous pot-holes all along the course of the 

 nullah. Nearly everywhere the exposed portions of Talehirs are much 

 denuded, and generally only form a thin layer over the underlying 

 Denuded surface of metamorphics. This denudation seems partly, at 

 Talehirs. least, to have taken place during pre-Barakar 



times, since I found at one place, in the detached mass near Dongardih, 

 a denuded surface of Talehirs presenting old pot-holes filled by thinly 

 laminated bluish-grey Barakar shales. Several of these pot-holes with 

 their contents are now traversed and cut through by the present 

 stream, which forms new pot-holes exposing sections of the old erosions 

 with their shaly contents. 



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