Date and Time
Bath Royal Literary and Scientific Institution, 16-18 Queen Square, Bath BA1 2HN
Several models have been proposed for the origin of the Bath Hot Springs, but the one that best fits the evidence of the water’s chemistry and the general geology of the area is that the spring water derives from rainfall on the Mendip Hills, ca. 20 km south of Bath. Alternative views include a northerly source, originally proposed by William Smith, or water circulation within deep-seated “fracture-zones”.
Without clear knowledge of the water’s origin it is difficult to ensure the spring’s protection from effects such as water abstraction from deep quarries, should these be sited in strata that are hydraulically connected to the spring. The hydrochemical, geological and geophysical evidence will be reviewed and some of the different hypotheses tested by means of a simple groundwater model.
The conclusion of the modelling study is that it is highly unlikely that much of the spring’s flow derives from the north, and that most probably comes from the Carboniferous Limestone outcrops of the Mendip Hills having passed beneath the North Somerset Coalfield at depths of greater than 2.5 km.
The Bath Hot Springs and the group of cooler thermal springs at Hotwells, Bristol, are best understood as outlets for thermal water formed where the rim of the Bath-Bristol basin has been cut or brought close to the surface by the cutting of the Avon valley. The implications for protection of the Hot Springs and the aspects that require further research will be discussed.
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