50 HtJGHES. — KARANPURA COAL-FIELDS. 



graphical conformity of the contact beds of either series, to permit its 

 readily to admit the probability of a sudden alteration from the 

 climatal conditions necessarily involved in any ice theory to those which 

 have been considered essential for the growth of that vegetation to which 

 coal owes its origin. 



It seems more in consonance with the stratigraphical and palseon- 

 tological evidence to allow that the three formations have been accu- 

 mulated under almost similar conditions ; and as there can be little doubt 

 that the Damiida and Panchet series are essentially fresh water deposits, 

 the Talchirs may be classed in the same category. . 



Admitting then their fresh water origin, we have to determine 

 whether they be fluviatile, lacustrine, or estuarine deposits. .In the 

 sandstones of the Damiida and those of the Panchet series, we have 

 evidences of current action resembling those which may be seen in the 

 valley deposits of our Indian rivers. 



The Talchir differs from the Damtida and Panchet series, in that 

 its strata are more uniformly fine grained, and seem to indicate more 

 tranquil conditions of deposition. If we turn again, however, to our 

 great river alluvial accumulations, we find that the features of the 

 Talchir period are reproduced. 



The extent and thickness of the needle shales are equalled by the 

 recent deposits of our rivers ; and with regard to the boulder bed, 

 there are examples of it to be met with. One which I noticed was 

 in the Wardha river coal-field, near Wargaon. The extent exposed 

 was not much, but it was enough to see the possibility of such a deposit 

 occurring in a river formation, in order to conceive its greater extension. 



Limitation of deposition.— Lf we turn to a geological map of Lower 

 Bengal, we find that the coal-fields of the upper Damudaal, most without 

 exception, occupy the low lying ground, limited by the elevated table- 

 lands of Hazaribagh and Chota-Nagpur, The I'tkhuri occupies the low 

 ground fronting the northern scarp of the Hazaribagh plateau, and the 



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