±o mallet: coal-fields of the naga hills. 



Disa7ig group. 

 Throug-hout the length of ground examined, or from the Namchik 

 to the Disai (andj probably, considerably further in both directions) the 

 general dip of the rocks is towards the axis of the range ; seldom at 

 low angles, generally at moderate or high ones. Occasionally it is 

 reversed at a high inclination. In the low hills east of Jaipur, known as 

 the Tipam range, we have an ascendinor section of the rocks in their 

 normal order, viz., coal-measures, Tipam and Diking groups ; but else- 

 where the structure is less simple, the newer beds being juxtaposed to 

 the older in a way that can only be explained by inversion or faulting. 

 The evidence in favor of the latter view will be more conveniently dis- 

 cussed further on (p. 33). It is here only necessary to point out that, 

 throughout a large portion of the area examined, the older groups are 

 found towards the interior of the hills, and the newer nearer the plains. 



To the south of the Tipam and coal- bearing strata, we find an ex- 

 tensive development of shales and sandstones, which I have provisionally 

 called the ' Disang group ,■* one of the best sections I obtained of them 

 being in the river of that name. They include — 



b. — Naogaon sandstone. "^ 



a. — Grey shales. 



About a mile north of Naogaon the Tipam sandstones dip at 60°, 

 and then, with a sharply defined (faulted) junction, splintery grey shales 

 come in, which are somewhat contorted, and dip rather irregularly at 



feet in thickness, with a dip of 5°. The coal is brownish-black, with dark brown streak ; 

 breaks with a conchoidal fracture ; does not soil the fingers, and contains disseminated 

 grains of reddish-yellow resin. An assay gave the following result : — 



Hygroscopic water ... ... ... .. ... lO'O 



Volatile matter (exclusive of water) ... ... ... 29'2 



Fixed carbon ... ... ... ... ... 28-6 



Ash ... ... .., ... ... ... 32-2 



The coal does not cake and leaves a white ash. 



( ^86 ) 



