drainage of the Mendip Hills is focused on a series of large springs
along the foot of the Mendips. These generally occur at the lowest
points in the Carboniferous Limestone or the overlying Triassic Dolomitic
The links between the stream sinks on the Mendip plateau and the
springs has been proved by many experiments using a series of different ‘tracers’ including
chaff, ink, copper sulphate, fluorescent dyes and optical brighteners
(the chemical which makes your clothes appear whiter than white).
of the spring water can also give an indication of its source. For
example, springs with a very high calcium carbonate content are often
fed by a diffuse input rather than point sources such as stream sinks.