Rock salt, however, was discovered by accident in 1670 when a local dynasty at Marbury near Northwich were looking for coal. It was mined extensively around Northwich and Winsford but scant attention was paid to the consequences of water dissolving underground salt deposits. The area is now pock-marked with flashes as a result of mines collapsing.
Buildings erected after this date were built with a timber frame equipped with jacking points. In the event of subsidence the building could be jacked up and wedged into position.
The building here must be rare in that the first floor is older than the ground floor.
After jacking it up, a whole new floor was built underneath.
The Bridge Inn used to be next to the Town Bridge. In the 19th century it was jacked up and moved 185ft to its new location: it weighed 55 tons.
The same principle has been applied more recently using steel girders to form a rigid foundation to hold the house together. In the event of subsidence the house should not collapse but tip like a Lego model.
This area between Chester and Wrexham was also mined for coal, iron ore and lead although all activity has ceased long ago.
At Gresford the mining disaster of 1934 in which 266 miners died was only one factor in the decline of these industries.
A memorial to those men now stands on the site of the colliery
Nearby at Bersham was the iron works where John Iron Mad Wilkinson perfected his revolutionary technique of boring out canons from solid iron.
These proved their accuracy in the American War of Independance.
In later years the iron was put to more mundane uses.
At the Minera lead processing plant much of the original equipment has been preserved or restored.
This is an open-access site with an informations centre open at certain times. Walking around amongst the machinery an impression of how the processes were carried out is much clearer than looking at books.This contraption is effectively a large sieve in a bath of water. By bumping the sieve up and down by means of the arms small lumps of lead ore could be separated from the other rock due to its considerable weight.This was known as a Jig and the operator was a Jigger.
On our way back at the end of a very busy day some of us made a detour to Chester as we remembered passing some interesting industrial buildings near the canal as we left there by boat.
A mill - now converted to offices....
....but which used to look like this.......
......A cylindrical water tower currently being restored......
.....a Napoleonic lead shot tower also being restored........
......and a row of cottages which face the canal. This is unusual as they generally face away from the canal.
What a weekend!