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This website is now an archive of the restoration and should only be used as a resource. Please visit the Lion Salt Works website for the most up-to-date information.



Welcome to the Lion Salt Works blog

The Lion Salt Works is a historic brine salt making site that is being restored and transformed into a unique heritage attraction. Led by Cheshire West and Chester Council, this £8million project will see the site reborn as a fascinating destination for tourists, day visitors and families and a valued resource for local communities, businesses and heritage interest groups.

Located in the village of Marston, close to the town of Northwich, the site lies adjacent to the Trent and Mersey Canal and is close to the historic Anderton Boat Lift. A substantial part of the site is a Scheduled Monument.

Restoration work has now started on the site, with an expected opening in spring 2015. The Lion Salt Works is currently closed to the public.

Thursday, 16 May 2013

How to....extract brine from the ground


Salt has been produced in the Cheshire Area for over 2000 years. This was a as a result of Cheshire’s unusual geology which resulted in the formation of large salt deposits located beneath the ground.

Geology

The Cheshire Basin between the hills of the Delamere Forest and the Staffordshire and Derbyshire border once formed a large basin fed by the sea to the north. As the land levels to the north rose, this area was cut off from the sea but was occasionally inundated with sea water at high tides forming a large salt lake. Sedimentation and evaporation led to deposits of salt forming between layers of soft sedimentary rock known as marlstone.

The Cheshire salt-beds lie in the red or Triassic Keuper marls in a kind of basin comparable with an elongated saucer with its longest axis lying in a nearly north and south direction. The best-known and most important beds of rock salt are about the centre of this basin, in the neighbourhoods of Northwich and Winsford located below what is now the level of the sea.

Two beds of rock salt exist in Northwich an upper and lower bed. These beds spread from the Northwich town centre in the Baron Quay’s area to the north-east of Marston in an area around two miles in diameter. Each bed is from 25.6 to 27.4m (84 to 90 feet) in thickness at Marston and Wincham, divided from each other by 9 to 10m (30 to 33 feet) of marl and marlstone. For example salt was located at Neumann’s Mine between 60 feet and 144 feet below Ordnance Datum in the upper bed and 174 feet and 258 feet in the lower bed. The bottom part of the lower bed was found uniformly to be the best quality.

Brine Springs

The surface of the upper bed was impermeable and an underground stream of water would flow across it. Where this stream of water came close to the ground surface, at locations on the side of the Weaver or Wheelock valleys the water would emerge as a brine spring. The springs would look like most other springs, a small pool of water bubbling from the ground within shallow valley locations. The difference was within the water itself which would have been saline.

These became the first locations for salt making in the Prehistoric and Roman periods. Brine springs denote the locations of the Cheshire Salt towns of Northwich, Winsford, Middlewich and Nantwich.

Salt Mining

In the 17th century the first of a series of mines were begun in the Northwich region. A bed of rock salt was discovered in 1670 by the Smith-Barry family when they were searching for coal on the Marbury Estate, near Marston. This is believed to be the first mine sunk for rock salt into the upper bed of salt at around 50 feet below the surface. This resulted in the excavation of a number of ‘top rock’ mines around Northwich. The early top rock mines resulted in subsidence in the area.

By 1779 investigation below the upper bed of rock salt resulted in the discovery at the Marston Mine of a lower bed of salt at a depth of around 150 feet. This was also mined for a number of years until it began to be exhausted around 1850. During the 19th century the mines of the Northwich district began to collapse and subsidence was widespread.

Wild Brine Extraction

Wild brine extraction or brine ‘tapping’ had been carried on since the 17th century. This involved the sinking of a shaft to natural brine streams below the ground that ran over the upper bed of salt. This was then extracted and used to make salt by the open pan salt process.

The exhaustion of the mined rock salt supplies resulted in a rapid expansion of the wild brine extraction techniques. This was aided by more efficient pumps that allowed the brine to be pumped from both the upper and lower beds. The process of brine-tapping involved the sinking of a shaft to the brine stream, a dangerous occupation. AK Calvert describes the process;

In sinking to many of the springs, the supply of brine, when cut into, was so copious that the sinkers had to flee for their lives, ascending the shaft among the brine, and having no opportunity of seeing what was underneath.

The brine was subsequently pumped out of the ground to supply the salt works based at the surface. By the late-19th century brine shafts and traditional open pan salt works dominated the area around Northwich many controlled by the monopolistic Salt Union.

As the rock salt mines closed they were inundated with water creating vast underground reservoirs of brine. These were increasingly tapped for brine and it became increasingly common to deliberately flood the mines to provide new sources of brine. The erosion of the sides of the mine by the brine streams led to more and more mines collapsing and subsidence was widespread in the Northwich area. This can be seen by the large flashes that dominate the salt-making landscape.

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