1868.] Proceedings of the Asiatic Society. 231 



That portion of the river's bed which lies low. has. in the 

 rainy season, a deep channel of the river flowing over it. A deep 

 channel, as a rule, has a rapid current, and consequently the only 

 deposit which can be formed is of sand, as mud would be swept away 

 by the stream. After, by deposits of sands for a few years, the bed 

 has been raised, it is in the rains only covered by a shallow, and 

 therefore a slow stream, and under such circumstances, the deposit 

 of earthy particles is possible, and a muddy deposit is formed rapidly. 

 I have myself seen in a small bay of back water of the river, out of 

 the current, a deposit of about five feet thick of fine sand and earth 

 formed in a few days. 



It may be remarked that the river's bank on the concave side of 

 a curve is always precipitous, as the destructive scooping action of 

 the current destroys a slope, and hollows and undermines the bank. 

 On the other hand, the bank on the convex side of the curve is 

 always gently sloping, formed recently by gradual accretions of sand, 

 at the part near the river, and of earth on the upper portions, where 

 in the rains the current runs with little force. 



The bank on the concave side may be permanent or non-permanent, 

 but the river's bank on the convex side is always non-permanent* 

 because formed by recent deposits and containing no kunkur. Though 

 non-permanent in its character, the convex bank is safe and lasting 

 from its situation, and from its immunity from the action of the 

 current. The Benares Railway Station is built on a portion of the 

 bank, non-permanent in character, but safe from its convexity ; while 

 the cities of Benares and Mirzapoor are built on portions of the concave 

 bank, permanent in character, but exposed to the destructive influence 

 of a current. 



A large mass of kunkur deposit has a remarkable power of 

 resisting the destructive influence of current. The kunkur bank 

 at Adilpoora within the Sooltanpoor Cantonment, nearly opposite 

 to Chunar, has for years stood unharmed by a most violent 

 current. 



The investigation of the law of changes in the river's bank, is of 

 some practical importance in connection with the navigation of the 

 river, as it is always desirable to have some foreknowledge of changes 



