48 
assumed that the bore at the Chartham Asylum touched the Gault. 
Mr. Whitaker places the bottom of the bore at that horizon. From 
the specimens I-have seen at the Canterbury Waterworks, | doubt if 
they quite reached the Gault. There seems also to be a slight 
synclinal of the Thanet beds in the valley of the Stour east of 
Canterbury—the Isle of Thanet being on an anticlinal. 
It would seem as if the Lower Greensand in this neighbourhood 
cannot be reckoned upon asa source of water-supply, firstly, because 
the water is not good, and secondly, because there is no high land 
of this formation to receive the rainfall, nor is it certain that it 
would be met with in any thickness east of Dover.’ 
The slight anticlinal ridge of the Thanet Chalk has yielded water 
for the present supply of Ramsgate, Margate, and Broadstairs ; but 
in dry seasons the supply has not equalled the demand, and supple- 
mentary wells have been sunk ; these, however, all derive their supply 
from the exceedingly porous beds of the Upper Chalk, the wells not 
reaching much below the sea-level, about which point the line of 
saturation of the Chalk is there reached. From the fact that one of 
these, the Southwood Waterworks near Ramsgate, became brackish 
from the influx of sea-water, the engineers of these waterworks 
appear to have been afraid to sink deeper in the Chalk. It is pro- 
verbially foolish to prophesy unless you know; but I would 
venture to suggest that the future water-supply of Thanet must be 
sought for in a well reaching down nearly to the Gault. For though 
there is every appearance that the whole depth of the Chalk strata of 
Kent are to be found here (the Thanet beds reposing on the higher 
beds at Margate, St. Peter’s, and Broadstairs), yet there should be 
no difficulty in piercing the Chalk, and I should expect an unlimited 
supply of good water would be found in the Lower Chalk. Should 
such be the case, there would be no danger of its being contaminated 
with sea-water, if a site were chosen not too near the sea, or 
directly in a line of fault. If the stratum pierced was in a state of 
saturation, there would be no reason to fear that sea-water would 
replace the fresh. 
One great advantage of the water derived from deep Chalk strata 
is its great purity, the only drawback being its exceeding hardness, 
from the presence of bicarbonate of lime; this may, however, be got 
rid of by adopting the admirable method employed at Canterbury, of 
passing lime water in certain proportions into the fresh pumped 
water, which, uniting with the excess of acid in the bicarbonate of lime 
in solution, precipitates it as an impalpable powder, and at the same 
time killing all organic impurities and precipitating them with the 
lime. 
It now only remains for me to explain the supplementary section 
1 See section in Mr. Whitaker’s paper, Quart. Journ. Geol. Soc. vol. xlii. p. 36. 
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