266 
Records of the Geological Stmey of India. 
[vOL. XIII. 
tlie stii-faco are the plains adjoining the liills and the Kliadar lands or river 
valleys. In tlie former tire rainfall is more jilentiful, the slope of the surface and 
deep strata are better, there is more moisture in the air, and therefore less eva¬ 
poration. All these tend to prevent accumulation of salt below and efflorescence 
above. In the latter the washing of the surface by the floods mid better subter¬ 
ranean drainage may account for the want of accumulation. In the parts of the 
Ihiri Doab Canal which I have seen, the ground-water lies at a depth that is 
totally out of the range of cajiillary action, and the strata consisting of alternat¬ 
ing clays and sands are so imjienotrable that percolation can have little effect on 
the water level. Captain Ottley informs me that on the Bari Doab and Ujjper 
Sutlej Inundation Canals the curves of the rise and fall of the well waters 
markedly follow those of the rainfall and do not appear to be affected by irriga¬ 
tion. I did not find any marked difference in the water levels of the wells near 
and at a distance from the canal about Lahore. A still better proof was that the 
salinity of the wells was not altered by proximity to the canal. If percolation to 
any extent existed, the wells close to the canal ought to be fresher than those at 
a distance. In the part of Lahore occupied by the railway station and barracks 
the ground-water is salt. At the end of the hot weather I found that a well a 
few yards from the canal contained as much salt as others far off. After the 
rains the same well waters wore found to be so diluted as to contain less than 
one-half of the fomier amounts. The depth from which capillary evaporation 
can take place is also a question that ought to be investigated by observation 
and experiment, hluch of course depends on the porosity of the soil, but in the 
most favourable cases one would fancy, from the known laws of capillary force, 
that the action would only be through a few feet, unless assisted by hydrostatic 
prossui'o. At the village of Baoli, on the Western Jumna Canal, where the 
roh action is very jironouncod, the deiith from the surface of the ground to the 
■water table (as shown by measurements of an unused well) is 8 feet. It is said 
that befoi-e the Western Jumna Canal was ro-opened in 1819, the water in wells 
about the part lay at a depth of 00 to 70 cubits, and this tradition appears to be 
confirmed by inspection of the records of other wells which had been sunk to as 
much as 110 feet, and in which now there are 02 feet of water. On the banks 
of water-courses and canals about Lahore in salt soils one often observes two 
lines of efflorescouce, one a few feet above the water level at the upper limit of 
capillary soakage, and another some distance from the surface, at the base of the 
surface percolation. As regards the rise in the well water levels said to bo 
caused by canals, it "would be necessary to have accui'ate information as to what 
those levels were before the canals wore made. Probably no accurate record was 
made before the earlier canals were started, as attention -was not directed to the 
point. 
2(3. There are last to bo noticed some other modes of distribution and accu- 
Otlicr modes of accu- mulation of alkali salts. Irrigation by flooding and 
mulatioii. allowing the water to dry on the soil, unless it is very 
permeable, of necessity leads to production of .salt. Aot only doe.s the irrigat¬ 
ing- water contain salt which it depo.sit.s as an elUorosceuce, but it also promotes 
further decomposition in the soil. The amount of rob in ordinary canal water 
