354 



On the róchs bftlie Damúda group: 



[No. 4, 



The rocks of the Rániganj field and their approximate thickness in 

 feet, are, in descending order, 



C Upper Panchits, ... ... 500 



1. — Panchit group, 



2. — Damúda group, 

 3. — Talchir group, 



(. Lower Panchits, 

 /■ Rániganj series, 

 ,. < Iron stones, .. 

 v. Lower Damúdas, 



1,500 

 5,000 

 1,500 

 2,000 

 800 



11,300 



Of these beds the Damúda group alone contains coal. This, 

 énormous thickness of beds is cut off on the south by a fault, the 

 downthrow of wliieh cannot he less than 10,000 to 11,000 feet. 



The lowest or Talchir group, first separated in 1S56 from observa- 

 tions in Orissa, consists of a series of fine sandstones and mudstones, 

 frequently of a peculiar greenish colour, and becoming coarser 

 towards the top, while towards the base they are commonly com-r 

 posed of the finest silt, in which there oceur, in patches, gneiss 

 boulders of énormous size, some having been measured as much as 

 15 feet in diameter. It is most difncult to account for so anomalous 

 an oceurrence as that of these huge blocks in the finest mud, for any 

 current which could roll or even move the former would necessarily 

 sweep away the latter, and although such a phenomenon appears 

 absurd in India, judging from the climate of the present day, the 

 action of ice, probably of the form known as ground ice, appears to be 

 the only geological agent which can account for all the circumstances, 

 by explaining the transport of the boulders. 



The Talchir group had not undergone a very great amount of de- 

 nudation, prior to the deposition of the Damúda rocks. It is, however, 

 completely overlapped in the eastern portion of the Eánigánj field, 

 although well developed in the west. Very few fossils have as yet 

 been obtained from these beds, those found are entirely plants, and 

 shew distinctions from Damúda forms. 



Beds belonging to the Talchir group have now been discovered in 

 Orissa, in Central India, in Beerbhoom, where they oceur in numer- 

 ous scattered patches, and in one or two places on the west side of the 



