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March 25th 2021
From Subterranean Norwich to Highland Wymondham
Matt Williams
Thirty-six members enjoyed a fascinating visual presentation via Zoom by Matt Williams, whose talk was entitled “From Subterranean Norwich to Highland Wymondham.” Mr. Williams, a noted engineering geologist and historian, as well as now a cycling instructor, considered the geography and geology of Norwich and its surrounds. Quoting the reference in Noel Coward’s play Private Lives to “very flat Norfolk”, Mr. Williams commented that when cycling around Greater Norwich he noticed it was full of ups and downs with some quite steep slopes.
There are some survey benchmarks affixed to walls indicating heights above sea level. Colegate at only 3.83 metres above sea level contrasts with Gas Hill, 43 metres high at the top and the steepest point, which affords a fine panoramic view taking in the city’s two cathedrals and showing how low the middle of Norwich really is. At the top of the tower of St. George’s Church, Colegate, which is 26 metres up, there is a fine view in the opposite direction.
The highest point in the county is at Sheringham and the lowest at Bishopsgate in the city. The River Wensum is only one metre above sea level in the city, whereas at Fakenham it is 35 metres above sea level. Norwich is at the head of the estuary and at New Mills the river becomes tidal so it is navigable as far as the city. Wymondham Market Place by comparison is 42.6 metres above sea level.
Discussing the different soil layers under the city, which include sand, crag and a considerable amount of chalk, the speaker mentioning the phrase “Norwich is built on porridge!” In contrast Wymondham is built on a plateau over boulder clay and gravel. In Norwich there are extensive chalk pit workings with tunnels, the chalk having being used for centuries for making lime mortar once used in building.
Discussing the different soil layers under the city, which include sand, crag and a considerable amount of chalk, the speaker mentioning the phrase “Norwich is built on porridge!” In contrast Wymondham is built on a plateau over boulder clay and gravel. In Norwich there are extensive chalk pit workings with tunnels, the chalk having being used for centuries for making lime mortar once used in building.
A map of underground Norwich revealed the extent of the chalk workings. There were ones, now filled with concrete, under the Roman Catholic Church and Earlham Road. There is chalk below such thoroughfares as Earlham Road, Pottergate, Rosary Road and Barrack Street. Norwich City’s former football ground, The Nest, was built on a chalk quarry off Rosary Road.
Underground features which can be found in the city include cellars, undercrofts, crypts, ice houses, kilns, sewers, air raid shelters and tunnels. In 1824 there were extensive vaults under the hill by St. Giles Gate, while August will see the 150th anniversary of Norwich’s first sewer. There are stories that there are tunnels connecting various buildings, but maybe they are merely legend, although there is one between the Castle and the Shirehall. Perhaps it seems Norwich has been built on holes!
In March 1988 a double - decker bus fell down a hole in Earlham Road when a Medieval chalk mine collapsed – and it made news round the world! There have been other incidents, for example in 1936 when three homes fell into a deep sinkhole in Merton Road. Mr. Williams had referred to his talk at the beginning as a roller coaster and he literally covered a lot of ground!
Kevin Hurn, who was in the chair, thanked him for an informative and interesting presentation.
Report by Philip Yaxley
