47 
Greensand is bad, being largely impregnated with iron. I have very 
few data relating to the wells of this district, which is, however, 
of little importance in the general survey of the water supply. 
Mr. W. Whitaker, B.A.Lond., Assoc. Inst. 0.E., F.G.S., of H.M. 
Geological Survey, has kindly placed at my disposal some well- 
sections not before published, chiefly that of the Herne Bay Water- 
works at Ford and the Whitstable Waterworks, which are in the 
Tertiary area north of Canterbury. But it is not certain from these 
data whether the water is derived from the Thanet Beds or the ~ 
Chalk. In the case of Whitstable, at a height of 48 feet above 
Ordnance Datum, the well, 400 feet deep, pierced the London Clay 
at 69 feet, the Tertiaries at 240 ft., and penetrated the Chalk 160 feet. 
The water-level is stated to be 35 feet down, and the yield 220 
thousand gallons daily. And in the case of Ford, reaching a total 
depth of 260 feet, piercing the Lower Tertiaries at 110 feet, and 
penetrating the Chalk 50 feet—the water-level standing 26 feet 
down. From which facts it seems that the Chalk in both cases was 
the source of the supply. 
The well-sections in the Isle of Thanet, which have (with the 
exception of one at Mr. Cobb’s Brewery, Margate) been sunk but 
little below the sea-level, have only yielded water at about that 
level. In the case of Mr. Cobb’s well, which reached a depth of 
317 feet, no spring was met with. Artesian wells at Minster at 
a low level, piercing the Thanet Bed to some 20 feet or so into the 
Chalk, yielded water springs flowing to the surface. 
The permeability of the Chalk in Kent was shown some years 
ago by an old member of vur Society, Mr. Bland, of Sittingbourne, 
in some tables which he published showing how one well was 
influenced by another, and how they all fluctuated with the rainfall 
of the seasons. Mr. Prestwich has in his memoirs! made use of it, 
and I am indebted to the Rev. C. J. Wimberley, of Sibertswold 
Vicarage, for a copy of this interesting paper. His conclusions with 
respect to the permeability of the Chalk have been corroborated in 
all the observations I have made, and the truth cannot be too often 
repeated to those who are engaged or interested in sanitary matters. 
It must be of the first importance to consider this in relation to the 
sewage and health of towns. Sewage matter will contaminate a 
large area of Chalk, if precautions are not taken. 
The section I have made would show how regularly the lower 
beds dip towards Canterbury ; but if I had continued the section to 
Whitstable nearly in the same line, it would be apparent that the 
Gault must rise, or there would be an enormous thickness of Chalk 
to be accounted for had the Gault continued at the same dip. It is 
1 «The Water-bearing Strata of the Country round London,’’ and ‘‘ Manual of 
Geology.” 
