Travelling around on motorways can be very stressful these days and most people find a landmark a useful aid to marking their progress. One of ours is the radio station near Droitwich with its big masts visible for miles around. It was appropriate that it was a radio programme on BBC 4 that started an enquiry about the town, it's past as a Spa and the local geology --"Mapping the Town" with Julian Richards touring around uncovering the ancient salt industry and its later attempts to become a Spa resort.
 

Here is a map of the Droitwich area. And here is the place in Google Earth. You can get Google Earth here.

Production of salt from the brine springs along the valley had a long tradition and the installation of furnaces for speedier drying was recorded back in A.D.816. Since then the many bore holes, wells and evidence of quite severe subsidence problems have produced a landscape we usually associate more with the salt producing areas in Cheshire. In Droitwich the underground brine streams were found to be confined to a very specific corridor of land about 6 miles long by only 300 yards wide, the latter detail confirmed from drillings made in the search for new sites.

Once pumping began and as surface flows were lost, the main High Street was found to be sited over the course of the brine stream and evidence of continual repairs to buildings and changing of the road level can be clearly seen as you walk along today. Roof eaves, door and window frames and sills are all at strange angles and some buildings have notices on them now warning of dangerous conditions.

It was in the mid 19th century that the fashion for brine bathing started in Germany and the benefits of a "sea-air" climate especially for people with breathing problems was noted. One Sir Charles Hastings, a doctor who was an early BMA president made the suggestion to the local Salt Company that they could use some of their production to run a salt water bathing spa. Local traders were persuaded to invest in the venture and in 1836 a small building with a classical style facade imitating grander projects in places such as Bath, Leamington and Cheltenham was opened.

For the next hundred years or so the fortunes of the Spa and its assorted buildings waxed and waned. As our friends in Bath are only too well aware, building and maintaining a Spa facility can be very expensive!!. In the Spa a temperature of 85/95 F. was used for most treatments with a higher 106 F. for lumbago and sciatica. Cold brine was put in first followed by pure boiling water and then the correct level was reached by adding cold water. As the brine was very strong direct heating just blocked the plumbing system with salt.

Most of the first visitors came from the local area. An attempt to raise more money for expansion in the 1850's failed and while a private building was completed the continuing shortage of accommodation for visitors in what was otherwise a very poor town with only the salt works for employment always made any new venture very precarious. In 1852 the local people sent a petition to the Salt Company about the smoke pollution from the works, that, together with poor drainage and sewerage in the streets, and a dirty canal did little to help with attempts to attract sick people for treatment. Some visitors stayed in Worcester and commuted to the baths. Nearby Malvern was developing a centre in a much more pleasant surroundings and when the railway reached Droitwich one enterprising Hotel owner had special wagons made to ship the salt to Malvern.

The new salt works at Stoke drew workers away from Droitwich leaving few people to staff what few hotels were being opened. A Cheshire Salt baron John Corbett sold up there just before Parliament were due to make a law to compel companies to compensate people for subsidence damage and moved to Droitwich to try to improve the facilities. He did make a lot of improvements both for the local people and the visitors but money was always short and it was a constant battle to make the salt works and the Spa live side by side. During the last war the Hotels were taken over for military purposes and the Baths were passed around by various hospitals and health authorities. Now run by the Worcestershire Clinic, Droitwich is one of only three saline spas, the others being in Switzerland and Northern Italy. It is open to members of the public.
 

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All this, however, is only half the story. To find some geological information on this very compact area required a rummage through the local reference section in the Droitwich Library. There a copy of an entry to the Quarterly Journal of the G.S. from around 1884 dealt with the Droitwich Brine Springs and Saliferous Marls by a C. Parkinson. Droitwich is situated in a deep depression in the lower Trias and Permian rock which has infilled with Upper Keuper marls. The Red Marls in this sequence are where the brine springs are found and long time extraction causing subsidence and damage very closely mirrors the course of the narrow buried stream. Drilling has also confirmed the width to be around the 300 yards already mentioned.

North East of the town the ridges of the Clent and Lickey Hills are Permian rocks which dip to the south under New Red Sandstone of Trias age towards Bromsgrove. Lower Keuper sandstones also have a dip to the south and the Upper Keuper marls occupy a fault bound trough with Droitwich at the lower part. The total drop from the Lickey Hills is around 800'.

A small stream, the Salwarpe, rising in the Hills, runs through the town. In 1779 a well through the Red Marls and bands of gypsum broke through into a brine stream about 2ft deep at a depth of 80ft and the pressure was so great that, as it broke the surface, two workmen were killed in the flood. When the new works were started at Stoke around 1820 the brine was pumped from 800 - 1000ft at Stoke and around 210 - 220ft at Droitwich.

Various larger cavities were found along the course of the stream which had obviously once been pockets of salt. A 15ft bed of very hard sandstone marks the bottom of the stream at the Droitwich end though other beds of salt were thought to be lower down again.

The rock salt was mined at Stoke until the brine steam broke through at about 800' and after that only the brine could be used. The water source to maintain such a constant pressure and strength of brine was believed by the writer to be coming from the Bunter Sandstones around the Lickey Hills and the elevation of the latter plays its part in the mechanics of the system. Droitwich brine is a concentration at 38-40 per cent which is not far from the saturation point of common salt of 42%. The Dead Sea is around 25 p.c. Stoke works had iron casing to the well so no surface flow diluted the stream.

One suggestion for the general setting for the formation of the deposits is a lagoonal area with some connection to the sea, further north at that time in the area now the Cheshire Basin. Another possibly was for a similar area to that of the present Great Salt Lake of America. It is now known that in Cheshire and Shropshire two periods of salt deposition occurred, one each in the Lower and Upper Keuper beds with a break ranging between 300 - 600m in some area of middle Marl. The general climate of the time was arid and hot which produced the evaporite sequences over a large area from Cheshire to the Trent. At the present time the Keuper Marl is now being eroded again and in places such as the Charnwood area the buried Triassic levels are shown to have been very steep in places.

There is obviously a lot more to the story than I have included in the above but it was interesting to "dig around" for the information. We ended the day with a dip - on the briney - in the Baths. This is the best way to express the feeling and this is probably the nearest I shall get to sample the Dead Sea experience!. Any one who wants to visit should book a session first if possible as it a popular place with the locals which at long last is what the whole venture was intended to achieve.

References:- Droitwich Spa by Cora Weaver. Pub. Spas Research Fellowship. ISBN 0 9536711 00.
The Droitwich Brine-springs and Saliferous Marls. C Parkinson F.G.S. Q.J.G.S. Pub date c 1884.
British Regional Geology. Central England Pub. H.MSO. ISBN 0 11 880088 4