TALCHEER COAL FIELD. 81 



A few words as to the much questioned age of these coal-bearing 

 strata (the middle, Damoodah, group of the Orissa 



Age of the beds of 



the Middle or Damoodah. district) may be useful. Their supposed equivalents 



Group. 



have, by Dr. Carter and Messrs. Hunter and Hislop, 

 been included in one great group, which they refer to the Oolitic period. 



It will be remembered that the three groups established in the district 

 under consideration (Talcheer) correspond in a remarkable degree to the 

 groups at Nagpur, as described by Messrs. Hislop and Hunter (Nos. 1 

 and 2 of comparative table, p. 75.) But between these beds they find and 

 describe others which they call the " Mangcdi shales." These are 

 fossiliferous, but " contain scarcely any organic remains common to the 

 " inferior layers about Nagpur." 



Now there is strong evidence, although not absolute certainty, that 

 these Mangali shales are not older than the "argillaceous sandstone" 

 which Mr. Hislop has shown to be the equivalent of the coal-bearing 

 rocks (Damoodah group) of Bengal. They are found immediately under- 

 lying the upper beds, and in geographical position between points where 

 these upper beds rest unconformably upon the " argillaceous sandstone." 



The great unconformity between the middle and upper group (Damoo- 

 dah and Mahadewa beds) indicates very clearly a considerable lapse of time, 

 so far as the Talcheer district is concerned. During this time it is possible 

 that the Mangali shales were deposited, either locally or jDerhaps more gene- 

 rally, in which latter case they may well have been removed by the extreme 

 denudation which has evidently been in active operation in the district. 



If then this speculation be admitted (nothing less than a detailed 

 examination in the field can establish or disprove it), and the 

 Mangali shales be supposed to afford the representative of the time 

 indicated by the great break in the continuity of the series in Talcheer, 

 the remarkable distinctness of the fossil contents of these shales becomes 

 of most important significance. We have already quoted Mr. Hislop's 

 statement, that in few respects do these organic remains agree with 

 those from the " argillaceous sandstone" and other beds. But they differ 



M 



