ECONOMIC GEOLOGY. 85 



rapids. None of these, however, are of a dangerous character, nor would 

 they present any great difiiculty to regular navigation.'^ The distance 

 by land from the Makum field to the river at Dibrugarh, by the route 

 considered most advisable by the Government of Assam, is about 63 

 miles. 



In the neighbourhood of Jaipur it is only a small part of the 



measures that appear above the alluvium level, and 

 Jaipur. 1 n 1 1 f. 1 • 



nearly all the coal yet found is of the kind that is 



crumbly at the outcrop. But as the measures cross the Dihing, the coal 



could be raised close to the river bank, and the distance down-stream to 



the Brahmaputra is only 82 miles; the Dihing being the largest and 



most navigable stream between Dibrugarh and Jorhat. The Jaipur coal 



also has the advantage of being situated below the rapids. The distance 



to the Brahmaputra, along the line of the present road, is about 40 miles. 



In the neighbourhood of the Disang, the measures are somewhat 

 more fully exposed, although the greater part of 

 them are below the alluvium level. Some of the 

 coal is of the best quality and the measures cross the river. But as far 

 as Kumar's ghat, 8 miles below the coal, there are numerous rapids, and 

 the river is practically unnavigable in the dry season,t so that it would 



* For more than 20 miles below the mouth of the Tirap, the river has the same charac- 

 ter as below Jaipur, namely, a wide sandy chaimel with steep alluvial banks ; and the 

 quantity of water is nearly the same, the only affluent of any importance being the Namsang. 

 Then the river enters the gorge of the Tipam range, and for 1 1 miles flows between very 

 low jungle-clad hills. In this part of its course, between reaches of deep water, there are 

 several rapids, but none of them are bad ones, nor is the current unmanageably swift. The 

 water flows over coarse shingle, and the channel is free from rocks. On the 25th of De- 

 cember, when the river is almost at its lowest, Mr. Goad and I descended the stream from 

 Makum to Jaipur, and found a minimum depth of 2 feet in the central part of the rapids, 

 which is as much as can always be depended on in the sandy parts of the river above and 

 below the gorge. At the latter end of March I found between Namsang and Jaipur a 

 minimum depth of 3 feet. 



t On the 1st of January I went down about half-way in a dug-out of the smallest 

 size. At several of the rapids the boatmen were obliged to get out and help the almost 

 empty boat over the shingle. 



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