Chap. IX.] faults. 149 



there are two series of dykes in the Raniganj field, the older one of 

 which is of Damuda, possibly of Lower Damuda age, and the newer of 

 the same period as the Rajmahal group. 



The older or Damuda dykes are almost invariably decomposed and 

 soft, forming a red or yellow stone ; they consist of fine grained trap, 

 frequently vesicular. 



Besides regular dykes, there are a few local outbursts of trap. This 



is the case with several small hills North and 



Local outbursts of 



trap. North-east of Afzalpur; they, however, being 



confined to the gneiss, may be of older date. One, known as Maluncha 

 Hill, near Nala, in Kundit Kuraya, is the largest. Within the area of 

 the field, the most noticeable is Muktochandi Hill, which, however, is of 

 no great size. Two small masses occur, one beneath the barracks at 

 Raniganj, and another a little to the West of them, while a third is seen 

 about half a mile South-west of Parassia village. The last-named is 

 amygdaloidal, and contains agate. These outbursts are, doubtless, of the 

 same age as the dykes, from which they merely differ in greater 

 breadth. That at Muktochandi Hill, near Samdi, and a smaller one in 

 the village of Pahargora, may, perhaps, be of the same age as the neigh- 

 boring horizontal dykes, which appear to have some connexion with 

 them, but it is equally probable that they belong to the newer series. 



Chapter IX. — Faults. 



Much of the most important information which has been accumu- 

 lated concerning faults has already been stated in the preceding 

 section. Very much remains to be ascertained upon this subject which 

 can only be thoroughly understood, when far greater facilities exist 

 for examining the various strata than is now the case. This is 



