THE CHALK WATER SUPPLY OF YORKSHIRE. 35 
must escape beneath the surface, through and along beds of drift 
sand and gravel, which exist in the vale of Pickering, in places at 
the base of the chalk. This underground outflow, like that on the 
surface, chiefly makes its way to the river Derwent. 
Great and frequent as are the changes in the height of the 
water-line along the zone of out-cropping chalk, and the 
consequent variation of the outflow from the springs, the author 
believes that no amount of pumping or prolonged absence of 
rain would entirely stop the flow of a few of the main springs, or 
cause the water in the chalk to sink far below the sea level. For 
as after excessive rainfalls the mass of water in the chalk becomes 
of sufficient weight to force its way into the ocean, it is manifest 
that should the water-line in the chalk sink below a certain point 
through prolonged drought, or excessive pumping, and thus 
diminish the pressure seawards to a mininum, the flow would 
be reversed, and the water of the ocean would then prevail, and 
would force its way into the chalk, and thus prevent the sub- 
terranean water-line from falling below that of the sea. Mr. W. 
Oldham, of Cottingham, writes that “the first well he had to do 
with was one made for Mr. Hawkins about fifty-six years ago,* 
at or about the site of the entrance to the Albert Dock at Hull. 
The chalk was reached at r10 feet below the surface of the land, 
and was penetrated 22 feet, giving a total of 132 feet, when a good 
supply of drinkable water was found. And for some two or three 
weeks prior to connecting the pump to the pipe inserted, it was 
observed that the surface level of the water in the tube was always 
on the same level with the water of the Humber, whether high or 
low tide. In bores made at Hessle, Anlaby, and Springhead the 
same phenomenon takes place. In 1846 a pipe was put down at 
Sunk Island for the Commissioners of Woods and Forests, to the 
depth of 330 feet, by Messrs. Easton and Amos of London, but 
failed in obtaining pure water free from salt. They reached the 
chalk at about 110 feet, and bored 220 feet into it.” 
And Mr. Villiers, of Beverley, writes, on the roth April, 1877, 
“We went through the chalk in Hull at 615 feet. We always 
find under the chalk one kind of stiff blue clay, very dry. In 
Hull and all over Sunk Island the water from the chalk, if from 
deep bores is salt, but in the interior of Holderness the water 
contains very little salt. There is a little salt found at Hornsea, 
but it soon pumps off. At Hull and at Sunk Island it is no better 
for pumping. The freshest water I ever found in Hull is from a 
bore 95 feet deep, and there is another bore twenty yards from it 
300 feet deep, which contains twenty per cent. more salt. Both 
* 7.é., about 1823. 
