146 HANIGANJ COAL FIELD. [CHAP. VIII. 



In many instances, the traps, instead of forming vertical dykes, 

 Trap intruded horizon- nave intruded themselves between the planes of 

 * J ' stratification, or have traversed an easily yielding 



bed, such as coal. This is especially the case in the Lower Damudas, 

 and is, indeed, almost distinctive of the traps there occurring. It is best 

 seen in the area already referred to, extending for a considerable distance 

 in an Eastern and "Western direction, near the North boundary of the 

 field, and parallel to it, and which was mapped by Mr. Williams as a 

 ridge of intrusive trap, extending from Etiapora to beyond Samdi. The 

 trap becomes noticeable, in fact, near Churalia, North of which village 

 two runs of interstratified traps occur. A little further "West, North 

 of Madanpur, Kapista, &c., a long ridge of low hills occurs, which forms, 

 for some distance, the Northern boundary of the field. This consists of 

 two or three runs of trap, and of the sandstone hardened by it. The 

 great North-west and South-east fault, which runs between Aliptir 

 and Etiapora, and has a down-throw to the North-east, throws the out- 

 crop of these traps and sandstones for some miles to the South. They 

 are seen at Etiapora, and abound from thence in the ridge of ground 

 on which stand the villages of Bila, Amelia, Mohanpur, Pahargora, 

 Samdi, &c. ; the little hill of Muktochandi is a mass of intrusive trap. 

 Again to the West of the West branch of Nunia these traps stretch 

 across through Dandarbad and Sabtinpur. They are less conspicuous 

 near the Barakar and West of it. 



These dykes alter and harden the sandstones with which they come 



in contact to a great extent, more than their size, 

 Effect on the rocks. 



tor they are seldom oi any thickness, would 



lead any one to anticipate. But their principal effect is upon the 



coal beds. In describing the enormous deposits of fossil fuel which 



occur in the Lower Damudas, the great injury done by the traps 



occurring associated with them was repeatedly referred to. Seam after 



seam is found traversed by these dykes, which permeate the coal in the 



