PART 4<.] Center: Note on Bch or Alkali Soils and Saline Well waters. 265 
and like conditions of soil prevail, similar efflorescences are developed. In the 
dry pampas of South America they consist chiefly of sodium sulphate with some 
common salt; in the Siberian steppes, of sulphate of magnesia along with 
suljjhate of soda and common salt. They are likewise found in the Russian 
steppes and the Tibetan plateaus. 
24. The Khadar, or low-lying river valley, cut out by recent erosion from the 
old alluvial plain, usually shows little or no saline accumulation on the surface 
and none in the underground water. Hero the cii'cumstances are all different. 
In fact the river occupies the line of natoal drainage of the countiy, and its 
deposits are parallel to the lino of slope. Accoi’dingly, the water percolating 
from the river forms a subterranean stream, gi’avitating down the river-course 
and accompanying the main stream. Its extent depends on the permeability 
and arrangement of the strata and the resistance of the porous beds along wliich 
it moves. In the beds of dry nullahs this gravitating water may bo met on 
digging in the dry channels. If the underground water were stagnant, remain¬ 
ing long in soakago contact with the water-bed, it would become more or less 
saline, whereas it is found to resemble the river water filtered, though of course 
it has taken up some ingredients from the earth, chiefly more carbonate of lime. 
In two cases in which I examined the water in beds of dry nullahs, I found it 
much loss saline than that of the surrounding plain. In the Khadar land the 
water lies near the surface, and may bo within the reach of cajpillary evapora¬ 
tion, which w'ould produce efflorescences, as it often does to some extent. Bat 
in consequence of the occasional w'ashing by floods, and of the underground 
circulation I have described, there is no permanent accumulation either on the 
surface or in the ground-water. 
25. One of the most interesting and important cases is that in which the 
Accumulation by eva- ground water lies close to the surface within the reach 
poration from a sliallow of capillary evaporation, thus furnishing an unlimited 
water table. Supply of offloresconco. The enquiry made by the 
Aligarh Committee chiefly referred to this instance. It was considered that the 
ground-water level had been raised by percolation from the canal, assisted by 
hydrostatic pressure, in consequence of the canal being above the level of the 
country. Other causes assigned for the rise were the obstruction to surface 
drainage by canal and railway embankments acting as bunds, and the practice 
of profuse irrigation in flooding. All these w'ould lead to an increased body of 
water sinking into the ground, carrying earth salts in solution to be again 
brought uji by capillary evaporation from the shallow water table. It is very 
important to be able to estimate how much is due to each of these agencies, as on 
the decision of this point would depend the remedial measures to be applied, 
such as the lowering the level of the canals, their realignment on the high Bhan- 
gar land instead of on the lower ground, the restriction of profuse irrigation, the 
relieving of the sui-face drainage, and the establishment of artificial sub-soil 
drainage. I am unable to enter into the merits of these most interesting points 
because I have never had an oppoihunity of making observations on an area 
where this mode of generation of iv'h was going on to a serious extent. The 
only portions of country 1 have seen in which the ground-water lies very near 
