18 HUGHES. — KARANPURA COAL-FIELDS, 



boundary of the true Ironstone-shales g-roup. By going south, however, 

 from Nappo, a series of ferriferous shales are met with, many of which 

 have the concretionary structure of the Ironstone group. The discovery 

 of these beds added doubt to those which first assailed me, as to the 

 propriety of placing the tiger^s-paw sandstones amongst the Barakars ; 

 for, my first notion on observing the ferriferous shales was that they 

 belonged .to the true Ironstones j and I do not think this idea would 

 have been dispelled, had I not fortunately been able to trace the tiger^s- 

 paw sandstones, into connection with the strike of the upper beds of 

 the sandstones of Luriinga hill, and thus prove that the ferriferous 

 shales were an intercalated band. 



Accepting these shales as a datum line, from which to calculate the 

 thickness of the Barakar group, it will be found that a much greater 

 accumulation of strata exists south of Nappo, than along the line of 

 section from Luninga to that village. The tiger''s-paw sandstones 

 increase in depth as they extend southward in the direction of Pa'tra, 

 and the grits and sandstones below the ferriferous shales maintain the 

 same horizon which they exhibit in the Lurunga hill ; so that leaving 

 out of consideration the ferriferous shales, there is an augmentation in 

 the thickness of the group. This fact points to a certain amount of 

 unconformity in the Barakars, and the existence of great banks of 

 sand during the period of deposition. And the intercalation of the 

 ferriferous shales proves the synchronous accumulation of material 

 charged with ferruginous matter, and of that which composes the 

 ordinary sandstones and shales of the group. 



It is very possible that the range of metamorphic hills north of 

 Ango was a limiting shore of deposition towards which the currents 

 set, and then being deflected there, the material tliat they carried was 

 thrown down, forming a disproportionate accumulation of rock debris. 



The tiger^s-paw sandstones do not occur in any part of the field 

 other than between Nappo and Patra. They form in this locality the 



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