Chap. IV. § 1.] the damuda series. 41 



of those places ? and also how far the different sub-divisions are repre- 

 sented elsewhere. 



The unconformity, if it exists, is evidently of small amount, for the 

 general strike and dip of the three series is the same. But this 

 is also the case with the Talchir beds which have been shown to 

 underlie the Damuda rocks so unconformably as to be probably 

 over-lapped to the extent of 500' feet, within a distance of less than 

 10 miles. 



No clear evidence of the unconformity of the upper series of sand- 



TT , , . stones and coals upon the ironstone shales has been 



Upper beds conforma- l 



ble on ironstones. me |. w ith. ^he same strata appear to be in con- 



tact throughout, the uppermost bed of the ironstone measures being a 

 somewhat sandy, black shale, and the lowest of the upper series being- 

 thin bedded sandstones, with nodular hard bands. It is true that these 

 may both belong to the upper series, but the lower of them appears 

 to pass down into the ordinary carbonaceous shale of the ironstone 

 series. It is, however, difficult in abed in which sections showing 

 the dip accurately are as rare as they are in the carbonaceous shales, to 

 decide this point. 



But at the base of the ironstones there is better evidence of uncon- 

 Ironstones unconform- formi <7- At the first glance at the map it would 

 able on lower beds. almost appear as if a great over-lap of the lower 



Damuda group took place towards the East, the area occupied by 

 them being so much broader to the "West of the Barakar. They may 

 perhaps thicken somewhat to the Westward, but if so, the increase is 

 due to the greater vertical development of the rocks composing them, 

 and not to their being overlapped to the East, nor to their having 

 been denuded to any great extent before the deposition of the iron 

 shales. Mainly, however, the appearance is due to the higher dips 

 to the' East, and to the lower beds being cut out by faults alono- the 

 boundary. 



