Chap. IV. § 2.] lower damuda group. 59 



for more than a few hundred yards, and the quality of the coal may 

 (and in general does) vary within even shorter distances. An admira- 

 ble example is seen in the Ktidia stream, at the bend diie South of 

 Nirsha, and near the village of Sampur. Here a 13 feet seam of coal 

 is seen, within 50 yards, to split into two, and the lower seam to change 

 into sandy shale. 300 yards from the place where it was first seen, a seam 

 apparently identical, but only 7 feet thick, is found ; and this is certainly 

 not an extreme case. Many seams of considerable thickness seem to 

 disappear entirely within a shorter distance. 



Of course, in a region where no mine of any size exists, it is im- 



T , -.. „ , possible to say whether there are exceptions to 

 Irregularity of coal *■ J L 



seams - this rule or not. The most extensive workings 



that have ever been made in the beds of the Lower Damuda group, 

 within the Raniganj field, have never been more than galleries driven 

 in from the out-crop, and these have probably in no case reached for 

 100 yards in distance, nor to a depth of 50 feet from the surface. The 

 quality of the coal is, in many cases, admirable ; the best yet procured 

 in the Damuda field is said to have come from the mines West of the 

 Barakar.* The assertion, however, so frequently made, that coal 

 suitable for coking purposes has been procured from Chanch, Kumar- 

 dhubi, and other places, has never been satisfactorily proved, and is 

 certainly incorrect in the case of Chanch. 



One circumstance which seriously interferes with the seams of the 

 Lower Damuda group is the frequency with which 

 they are injured by trap dykes. These ramify, for 

 great distances, and in a most peculiar manner, through many of the 

 seams, converting the coal into a hard, dense, shaley substance, appa- 

 rently an impure authracite, which is frequently most beautifully 

 columnar. 



* The coal of Sirsol, Nimcha, and some other seams near Raniganj is probably equal to 

 any yet found West of the Barakar. 



