1838.] On the Indian Coal Fields. 65 



VIII. — On the difference of level in Indian Coal fields, and the causes 

 to which this may be ascribed. By J. McClelland Esq. Secre- 

 tary to the Committee for investigating the Coal and Mineral re- 

 sources of India. 

 [Extracted with permission from the Committee's Reports now under publication.] 

 Before proceeding to notice the information which has been published 

 or reported to government regarding the various coal fields, it will be 

 desirable to offer a few observations on the geological features of that 

 portion of India in which they occur, more especially beyond the Gan- 

 ges. 



The face of the country rises gradually as We cross the plains on the 

 western side of the Hoogley towards the range of hills, at the base of 

 which the coal field of Burdwan is situated ; this is proved by the fol- 

 lowing fact noticed by the late Mr. Jones, namely, that at Omptah, 

 twenty-two miles due west of Calcutta, and the same distance from the 

 sea as that city, the tides in the Damuda derived from the estuary of 

 the Hoogley rise but ten inches during the springs of June, ebbing 

 and flowing only half an hour*. In Calcutta on the other hand there 

 is a difference of seventeen feet between high and low water during the 

 same springs-)-, from which we may perhaps infer, that the plain in this 

 direction ascends nine inches per mile for the distance of twenty-two 

 miles from the Hoogley ; beyond this, the surface is known to rise 

 more rapidly throughout the extent of sixty or seventy miles to the foot 

 of the hills, which is the cause of those violent floods that render the 

 navigation of the Damuda so difficult J . 



* We should think the facts here noted prove rather the two places to be on 

 the same level. As far as the tide reaches, the average of high and low water will 

 be very nearly the level of the sea, unless there is a considerable flow of water from 

 above, which is less the case in the Damuda than in the Hoogley. The lift de- 

 pends on the body of water, depth, and configuration of the channel, and the 

 Damuda only gets an offset from the Hoogley tidal supply. The height of the 

 surface of the land may be safely measured from the average of high and low 

 water mark. See a paper on this subject by Captain T. Prinsep, Gl. Sci. 

 Vol. II.— Ed. 



f See Kyd's Tables, Asiatic Res. 1829. 



X Mr. Jones states that the Damuda river is open from the middle of June 

 to the end of September for boats of 300 maunds burden, from Omptah to the 

 situation at which the coal is raised, and that each boat is capable during this 

 period of passing five times between these situations. It is necessary, when from 

 a slight cessation of rain the river is perceived to fall, to haul the boat on the 

 highest practicable ground, and there await the succeeding flood, which sets in 

 with so much impetuosity as to overwhelm whatever may happen to be in its 

 course. 



K 



