alluvium. 5 



2. Alluvium. 



Any observations^ however incomplete, that may help in discussing 

 the question of the great fluviatile formations of the plains are worthy of 

 record. In a nearly central position in the plains of Lower Bengal, 

 extending in a northerly direction from Dacca for about sixty miles, 

 there is an extensive terrace of earthy deposits known as the Madhoprir 

 jungle. It is raised some forty or fifty feet over the general level of the 

 surrounding deltaic deposits. This ground has never been closely ex- 

 amined, but various conjectures have been made to account for it. 

 Mr. Fergusson, in his description of the delta of the Ganges,* considers it 

 to be an area of special upheaval. This view was never supported by 

 suflScient evidence ; and those acquainted with the geology of the country 

 had long since connected this ground with similar areas elsewhere 

 having the same relation to the actual river deposits. Some observations 

 I have made this year will bring this connection much nearer home. 

 The northern extremity of the Madhopur jungle is about thirty miles 

 distant from the base of the Gkro hills, and all round the base of these 

 hills on the west there is a terrace of old alluvial deposits. It occurs 

 close in to the hills, where more or less protected by the spurs ; and it 

 presents an abrupt edge overlooking the present alluvial surface. It 

 could hardly be questioned that this ledge is a part of the same deposits 

 as those forming the Madhopur area — all being the remnants of a much 

 more advanced delta than the present one — and that the phenomenon 

 which produced the change was much more general than that assigned 

 by Mr. Fergusson. 



The removal of these older deposits has been so general, and their 

 elevation above the present surface of deposition is so considerable, that 

 it would not be possible to bring the facts within the range of the simple 

 process of delta-formation— -of those changes which take place in the 

 course of a delta-forming river owing to the partial distribution and 

 * Quar. Jour. Geol. Soc, London, VoL XIX, p. 321, 1863. 



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