THE DAMtJDA SERIES. 13 



The ironstone shales diminish rapidly in thickness from east to 

 west, and they do not_, as far as present researches prove, occur to the 

 west of the Karanpura area. 



The unconformity of overlap exists as a ground for separating the 

 groups ; but in addition there is, from a purely economic point of view, 

 a good reason for establishing a sub-division of the series. Coal is only 

 found in the upper and lower groups : the ironstone shales being devoid, 

 of anything more advanced towards the condition of coal than car- 

 bonaceous shale. 



In Bengal, the Damuda series has not yielded any remnant of a 

 fauna upon which to found data as to its age. 



In the Central Provinces, however, an ArcJiegosaums was exhumed 

 and it will help to determine the place which this series occupies in the 

 chronological history of the formation of the existing earth^s crust. 



The absence or paucity of a fauna is not peculiar to the TalcMr and 

 Pamuda series. Other formations are as badly, or nearly as badly, off. 

 The Vindhyans, exceeding ten thousand feet in thickness, have yielded 

 no well-authenticated animal remains. The lower Panchets, which im- 

 mediately overlie the Damudas, have furnished only a small store whilst 



the upper Panchets, and their representatives in 

 Paucity of animal re- 

 mains in the older form- S. Hewah, the Central Provinces, and south of 

 ations. 



the Nerbudda valley, and, again, the ' Jabalpur^ 



beds, are almost without a fauna. Indeed, throughout India generally, 

 leaving out of consideration the formations of the Himalayas and 

 salt range, none of the older series of rocks are really fossiliferous. 



It is impossible to assert what the cause of this extraordinary 

 poverty was, but the fact of this poverty must be held to prove, that the 

 conditions under which these different formations were deposited, were 

 unfavorable, either to the development of animal life, or to the pre- 

 servation of animal remains. 



( ^97 ) 



