SALT and Subsidence in Northwich and Marston was the topic by Colin Edmondson.
Colin explained the relationship between the natural brine streams near the surface and the rock salt beds below. Pumping the brine allowed fresh water to percolate across the top of the rock salt bed towards the pumps, creating valleys deep underground, eventually causing subsidence.
Most of the area under Northwich and Marston was used for salt extraction and the consequences are well-known. He showed many buildings sinking and at bizarre angles, prior to destruction or abandonment.
To counter the problem a style of building using timber framing on a raft was devised. This proved effective in allowing buildings to be jacked up to a new level.
Next meeting is on March 11 in the Gladstone Club, Northwich.
Paul Shackcloth will talk about Locomotives of the Lancashire and Yorkshire Railway.
For details contact Paul Tench on 07790 486 735.
David Hawkes
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