Vol. I, No. 9.] The Geology of the Gangetic Plain. 231 
eee ENS): 
District, I have marked in on a map of the district the limits of 
the “ Khadir.” 
I may say that in some places the limit of the “ Khadir” is 
exceedingly plain, whereas in other places it is not at all so plain 
.to the eye. 
However, by tracing the line from one curve which is well 
defined and following slight indications, it is almost always pos- 
sible to follow the line till it reaches another point where the 
indications are again quite unmistakeable. 
In the Ghazipur district the only part where, in my opinion, 
the line is really doubtful, is the western edge of the island of old 
alluvium opposite the confluence of the Ganges and Karmnasa. 
Both the northern and the southern edges of that island are 
extremely well defined as far west as a line drawn north and 
south just west of Birpur; but the western edge is very ill- 
defined. 
In my opinion, two causes have united to create this diffi- 
culty. The first is the proximity of the deep stream of the Gan- 
ges within comparatively recent years, which has led to a great. 
accumulation of water-borne material; and the second is the prox- 
imity to the west of the boundary of a large sandy tract whence 
a considerable amount of material has probably been blown by 
the strong west winds which prevail during the early part of the 
hot weather. 
It is clear that at any particular time each bank of the river 
must have concave bends alternating with convex bends. Ceniri- 
fugal force throws the current against the concave bends and 
away from the convex bends. LHrosion, therefore, only takes place 
at the concave bends, and this is the reason why the edge of the 
““Khadir,” as delineated on the map, does not contain any convex 
bends. 
The fact that these concave bends, which form the limits of 
the “ Khadir,” are not connected by convex bends, but cut each 
other at various angles, proves that no two adjacent bends could 
have been made at the same time. ; 
The width and shape of the “ Khadir” opposite the town of 
Ghazipur show that there must have been many complete altera- 
tions in the course of the river. 
Between each of the alterations in the course of the river, 
indicated by the indentations in the edge of the “ Khadir,” a very 
long period must have elapsed. 
Although the vagaries of the Ganges are proverbial, it must 
be borne in mind that, whenever the river impinges on the old 
alluvium, the process of denudation is very slow. 
In the new alluvium the river often cuts away three or four 
hundred feet in a year, but in the old alluvium, whenever the 
river impinges on reefs of kunkar, there is practically no denudation. 
Even where the river impinges directly on the stiffish clay 
(without any kwnkar reefs to protect it), which is the prevail- 
ing soil in the Ghazipur district, the denudation, as will be shown 
later, does not exceed ten feet in the year. 
