PART 2.] 
Blanford: Water-bearing strata, Surat. 
51 
for believing that Surat has shared in this movement, and that the plains of south-eastern 
Guzerat have been raised above the sea-level at no very distant geological date. 
Such being the geological nature and origin of the alluvial formations which cover the 
country, it may be inferred that more or less salt must originally have been left in the 
soil, and that the occurrence of saline impurities at present will depend upon whether they 
have been removed by the percolation of rain water—whether, in short, they have been 
washed out—since the deposits were formed. If other conditions remain similar, it is 
reasonable to anticipate that the salt would be removed more completely from those strata 
which have been raised to a greater height above the sea and from the more permeable beds 
because the first, owing to their elevation, and the second, in consequence of their porosity! 
have been traversed to a greater extent by water seeking a lower level. It is also probable 
that elevation has been gradual, and, if this has been the case, it is evident that the surface 
deposits at a greater height above the sea have been first raised, and have consequently been 
longer subjected to the action of sweet water. But these more elevated portions of the 
plains are farther from the sea, and consequently it appears probable that the amount of salt in 
the alluvial deposits diminishes gradually in passing from the lower ground on the sea board to 
the higher inland plains, the presence or absence of saline impurities also depending on the 
more or less porous nature of the beds ; or, which is the same thing, the proportion of sand 
and gravel to clay in their composition. Moreover, as the beds thin out within short dis¬ 
tances, and the intercalation of sandy and gravelly layers with the less pervious argillaceous 
strata is variable, much irregularity in the extent to which the water is impregnated with 
salt may be anticipated. If the brackishness of the water depended directly on the perme¬ 
ability of the beds, we should expect that the wells yielding the largest supply of water 
would be the least impregnated with salt, and although this does not appear to be universally 
the case, some instances in its favor have come to my knowledge in the town of Surat, but 
the amount of salt in each instance is much complicated by peculiarities in the course taken 
by the water in reaching the well from the surface, and the beds it passes through during 
the process of percolation. 
So far as I am aware, this theory of the mode in which the alluvial deposits of Guzerat 
have been formed, and of the distribution of beds containing brackish water, agrees with 
observed facts. With the important exception to which I shall presently refer, and which 
I can, I think, explain, of certain perfectly sweet wells close to the sea, the water found near 
the coast is more or less salt, whilst that obtained in the higher portions of the plains away 
from the sea is sweeter; but there is much irregularity. I have dwelt at some length on the 
theory by which I account for the brackishness of the well water, because it is upon the 
correctness of this theory that the conclusions formed depend; because, by explaining my 
views fully, I afford an opportunity to the civil officers and engineers of the district to 
test and confirm or refute them, and because, in one instance at least, I have found theories 
put forward which appear to me erroneous. 
There are two circumstances at least which appear at first sight to be opposed to the 
views above expressed. One of these is the occurrence, already alluded to, of sweet water in 
wells close to the coast. I was only able to investigate one instance ; this is at some bunga¬ 
lows between the villages of Dumas and Bhimpur, just south of the mouth of the Tapti 
river, and about ten miles from Surat. At and around Surat city, on the road between Surat 
and Dumas, and in the village of Dumas itself, every well which I tried, and so far as I could 
learn, every well existing, is more or less brackish, some being sufficiently pure for use, whilst 
others contain water much too salt for either drinking purposes or irrigation. But at 
the bungalows just mentioned, which are within less than half a mile of the sea, the 
water in the wells is perfectly sweet. Now, the bungalows stand on hills of blown sand ; 
the village about a mile away is on black soil. The wells at the bungalows are very shallow, 
