250 to 200 million years ago, during the Triassic era, much of Britain was a shallow inland sea surrounded by desert. Close to the equator the climate was hot and dry, the scientific term is arid. Seawater moved inland creating a chain of shallow salt marshes. Across the Cheshire Basin the evaporting water created huge deposits of rock salt.
Today the huge salt layers are only 50m below the surface, in the area of the ground water. Salt is continually soluted, creating brine springs.
Since before Roman times people have been extracting and trading this salt. Historically they used the natural brine which was evaporated with fire. Archaeologists found lead salt pans used to extract the salt from the brine during Roman times.
The salt deposits had an incalculable effect on the region's history and development. Until today Cheshire is the only place in Britain where salt is produced on a large scale. Nevertheless, calling Northwich the salt capital of the world is a little arrogant.