IV. The Jaipur Field. 



From an economic point of view, or with, reference to water car- 

 riage, the Jaipur field is naturally divisible into 

 two sections — ^the northern or Dihing-, and the 



southern or Disang — but it is one geologically, the measures being 



continuous between these rivers. 



The coal-bearing strata extend as a narrow fringe along the western 

 edge of the Tipam hills, dipping at high angles (seldom less than 30" 

 or 40°, and sometimes nearly vertical) beneath the Tipam sandstones. 

 The boundary passes along the skirt of the hills, so that only the upper- 

 most part of the measures is visible at the surface. The remainder is 

 sunk below the alluvium level. The most northerly coal rocks known 

 as yet are at Tipam tea garden, about three miles north-east of Jaipur. 

 There can be little doubt that they extend further on — not improbably as 

 far as the end of the range — below the Sub-Himalayan beds, as is, indeed, 

 indicated by the numerous ' pimgs ' existent along the edge of the hills. 

 But whether they rise above the alluvium level or not is undetermined. 

 Between the Dihing and Disang the measures are visible in every nalla, 

 and also close to Boruarchali, but on the path from Halua to Kulun 

 Mutun they do not appear, the Sub-Himalayan strata being there in 

 contact with the alluvium. On the northern side of Gujua Ting, a low 

 detached ridge near the debouchure of the Teok from the hiUs, they are 

 again apparent, in the same relation to the Tipam beds as further east, 

 and this outcrop, eight miles south-west of Boruarchali, may be regarded 

 as an outlier of the Jaipur field. Coal is also said to occur at the base 

 of the hills in the Deodubi, a tributary of the Teok south-west of Kanu- 

 gaon, but, owing to heavy rains and the consequent flooding of the 

 stream, the bed of which forms the only path, it was impossible to 

 approach the place at the time I was in the vicinity. In the Borjaa, a 



( 314 ) 



