Careful Where You Walk

Petrea asked yesterday if I'd actually seen any of the old chalk mine workings that make living in Norwich so much fun and that I brought up in the last post.

Well, yes, I have. I spent several years surveying them as a kind of side project when I worked in Norwich many moons ago. The surveys were carried out when it was realised that only about ten percent of the old mines and chalk pits had been measured (not counting the ones we didn't know about until we almost fell in the buggers - see later in the post) and the council's Building Regulations department operated mostly on guesswork.

 Anyhoo, the result of all the work was this book, the blockbuster publishing sensation that was "Subsidence In Norwich," a tantalising pot-pourri of maps, statistics and geology that would make a spiffy stocking filler for the whole family at Christmas (if it wasn't so prohibitively expensive).

ISBN 0-11-752868-4 if you really feel you cannot live without a copy.

 Here are some of the photographs from the book. First up is the back of a house at the top of Kett's Hill. The woman who lived there had just left her kitchen when a hole opened up right where she'd been standing and ate the back of her house. The pit went right down to river level about 80 feet down.

 And here's the infamous bus in a hole incident.

 These things (the sink holes, not the bus) are caused when water finds its way down to the old chalk workings and gradually leaches out all the chalk, usually leaving a pit some twenty feet in diameter and anything up to 200 feet deep.

 The chalk workings themselves were dug from Roman times, expanded greatly in the 1200s and then usually used as storage in the mediæval city until most of them had their entrances blocked up and were forgotten about.

Until Norwich started falling into them.

 Here's an old map from the 1820s of the workings under Earlham Road, right next to the Roman Catholic Cathedral, which is probably still standing solely due to the power of prayer.
You can see the plan of the Cathedral outlined on the left of the map.

These workings were used (and lived in - very Dickensian) up until Victorian times and actually have street names.

 More fun.

I actually found one of these stupid holes by accident.

I was surveying an old house on Ber Street at the top of the cliff and found some pretty scary cracks in the back of the building. Walking out across the back yard I thought it sounded hollow underfoot (it was paved with Victorian bricks) and the word "oops" popped into my head.

Calling in the Structural Engineer we found to our horror that once a few bricks had been removed the whole yard fell 180 feet down a sink hole, taking the back of the house with it.
Yikes!

This is the kind of thing that happens. You can see soil has fallen in to this old chalk mine. Luckily, this one is under Eaton Park golf course so it merely resulted in some new landscaping once it had all been filled in.

So there you have it.

Mind where you put your feet.