The Geology of the Hot Springs at Bath Spa, Somerset

According to legend and the historian Geoffrey of Monmouth (Historia Regum Brittaniae, 1136), the hot springs at Bath were discovered in the 9th century BC by Bladud, a Celtic prince who was so disfigured by leprosy that he became a wandering swineherd so that his people would not have to look upon his disfigurement. When he chanced upon the springs and noticed that the sores on his pigs were healed by their waters, he cured himself. He went on to become a great king who founded the city of Bath, learned to fly and sired King Lear. Later historians noted that Mesolithic remains and Iron Age coins, probably votive offerings, have been found adjacent to the springs (Cunliffe, 1983). However, the documented history of the springs did not begin until the Romans built the magnificent baths that now lie at the heart of the Bath Spa World Heritage Site. The extent of their walled city remained little changed until the end of medieval times (Figure 1). Like most hot springs, those at Bath have been considered since time immemorial as magical by some and medicinally valuable by many more. King Bladud reputedly built a temple there dedicated to the Celtic goddess Sul (hence the Roman name Aquae Sulis) who was associated with medicine and fertility. Not all medicine is efficacious. The pool formed by the King’s Spring is the richest source in Britain of Roman ‘curse tablets’, requests to the goddess by victims of theft to afflict unpleasant, sometimes fatal, ailments on the presumed thief. In the 18th century it was claimed that the hot springs could cure complaints as diverse as piles, sciatica, migraine and sterility, and that they were especially efficacious for rheumatic and skin problems. One result of this was that the first national hospital in Britain, the Royal Mineral Water Hospital, was founded in Bath in 1738 to treat those who could not afford private treatment (Rolls, 1991). The discovery in 1903 of significant concentrations of radium salts in the spa waters led to the belief, at least temporarily, that this was the active beneficial ingredient and a ‘radium inhalitorium’ Gallois, R.W. 2006. The geology of the hot springs at Bath Spa, Somerset. Geoscience in south-west England, 11, 168-173.