Report - - Report - Mines of Essex: Cymbeline's Gold Mine (Thurrock) - May 2022 | Mines and Quarries | 28DaysLater.co.uk

Report - Report - Mines of Essex: Cymbeline's Gold Mine (Thurrock) - May 2022


Enthusiastic Idiot
28DL Full Member
This report is a bit history heavy and report/pic light.

The History Stuff

Cymbeline: (also known as Cunobeline "Strong Dog", or Cunobelinus) was "King of the Britons" roughly AD 9 - AD 40 as a client-king of the Roman Empire (outer Roman Empire was run kind of like a franchise model). Most notable due to the large number of coins discovered bearing his head/name. See: https://en.wikipedia.org/wiki/Cunobeline

Gold: Chemical element with the symbol Au (from Latin: aurum) and atomic number 79, making it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile metal in a pure form with absolutely no ******* chance of being discovered in Essex. See: https://en.wikipedia.org/wiki/Gold

Essex isn't a county people associate with underground mining. There are many examples of aggregate, sand, brick clay and in a few locations chalk, exploited opencast. CANUK even own a licence for hydrocarbon exploitation at Little Chishill close to the border with Cambridgeshire, with exploration wells drilled by BP in 1966. But no commercially viable sources of oil/gas have been discovered to date. See https://www2.bgs.ac.uk/mineralsuk/download/england/essexMap.pdf

I'm not a geologist so correct me as needed. South Essex is dominated by a load of stuff dumped by the bottom edge of glaciers after a series of glacial events which is why it's a great area for various sand and gravel works. One example and I've seen it myself is an approx. 1 ton boulder outside a visitor centre in South West Essex which was found in a nearby gravel pit. The boulder is a very specific rock type and without doubt it definitely originated on the Whin Sill in County Durham before it was found buried in an Essex gravel works. Incidentally massive blocks are very occasionally carried by glaciers. This transport mechanism explains a natural occurrence of large lumps of rock from Presli Hills, Wales - being found in Wiltshire, especially when you look at the map of directions and limits of glaciation! So maybe Stonehenge builders didn't need the help of aliens to transport the heel-stone rock for them after all..? but that's a whole different report ;) See: https://brian-mountainman.blogspot.com/2012/04/chunk-of-whin-sill-in-london.html

Underneath that alluvium cover (sands/gravel/lots of clay/similar cr*p) are layers of "sand". This is "Thanet Sand" and isn't a rock-hard sandstone but isn't sand like on a beach, think of it more as a very wimpy soft rock than being "sand". Underneath the Thanet Sand is chalk - lots of chalk, a massive body of chalk.

However... in South West Essex there is a long history of small scale underground mining going back to at least as far as Roman times. Mining in the Kent and Essex area was described in some detail by Pliny the Elder in AD 70 and how chalk was spread on Clay fields at 8 tonnes per acre and how long one application lasted on the fields. This loaming process was to "sweeten" the soils. He says of the mining process:

"...the chalk is sought from a deep place, wells being frequently sunk to 100ft, narrowed at the mouth, the vein spreading out within as in mines. This is the kind most used in Britain. It lasts for 80 years and there is no instance of anyone who has put it on twice in his lifetime..."

It is also reasonable to believe that there were underground sand mines in Essex in the past, but as far as I know, none exist today. Until surfaced roads became common, cart wheels would sink in the mud so transporting sand, chalk, gravel, brick clay or any heavy materials for even a short distance was undesirable, so many small mines existed supplying their immediate areas.

Cymbeline's Gold Mines
The exact history and dating and even purpose of what's known as Cymbeline's Gold mines is speculative and different explanations have fallen in and out of favour. Around the time of Henry IV (1367-1413) there was a widespread belief that the large number of deep shafts in the ground at Hangman's Wood in Thurrock were the remains of Cymbeline's Gold mines and the secret of his wealth and fame. If anything is to be learnt from mining history, it's that wild stories of hidden wealth always originate from someone pulling some kind of scam. The who and what for that scam/story is unknown, but we know that there were a *lot* of holes in the ground, at least 70 and that they were ancient and of unknown use/origin during by the late 1300s. The assumption is due to the numbers of them, they must be made over a period of time and worked much earlier than the 1300s for their use to be forgotten by then. Perhaps Roman times and probably not later than 1200s. Quite likely they are >1,000 years old.

They used to be a local curiosity with The Essex Field Club exploring then in 1887 when 15 shafts were explored also a trip by a Scout group in the 1970s (before health and safety! https://www.thurrockgazette.co.uk/news/10375980.were-going-underground/). Many were badly capped by throwing a tree stump into the top of shaft and covering with earth, so now the stumps rotted there are many left plugged with just earth! many have collapsed and the dene holes remaining aren't particularly stable. There are maybe 5 still existing on that site? but only 3 remaining known to have open shafts. In 1985 Hangman's Woods Dene Holes and surround were classified as SSSI due to their importance to brown long eared bats, Natterer's bats and Daubenton's bats and they are left open but securely fenced off.

In theory you can apply for permission to enter them, but due to health and safety whatnot I don't fancy your chances of going with permission unless you are doing some official bat survey (don't visit any site where bats are suspected during October to April hibernation period, don't disturb bats!) As far as I can tell, this site has had very few visits since 1985 apart from a KURG survey around then and some bat monitoring on a few occasions since.

Dene Holes versus Chalk Wells
Generally, people use the term Dene hole to refer to a narrow vertical shaft (maybe 3 foot diameter) that descends between 30-90 deep to underground chambers that radiate from the shaft base, arranged a bit like clover leaves (double trefoil). In *theory* great care was taken that adjacent holes didn't break into each other to help maintain pillars to support the cavities/stalls otherwise it would be even more unstable - this wasn't the experience of my report. The shafts have scoops in the "sand" like a staircase and back-and-footing using the scoops was the miners' method to enter/exit. These are thought to have all been constructed much between Roman times (or earlier) up to the 1300s. There aren't any real artefacts or way to date them, some appear to have antler pick marks in roof (not from metal tools) but exact dating is speculation.

Chalk Wells are a much wider shaft, without any steps/scoops leading down to a bell shaped widening at the base. These are made much later and thought to all be after 1700 and the last known example was made between 1904-1908 in Kent. Entrance and exit was to be raised/lowered in a basket with rope. These were generally for extraction of chalk to burn for lime.

Based on this distinction the holes in Hangman's wood are Dene Holes, not Chalk Wells.


Diagram taken from subbrit (linked below)

What were the Dene holes for?
Cult of Mithras altars, smugglers' hoard, grain stores, royal gold mine, flint source (many don't have the right kind of flint, for flint use), hiding places, underground housing - all have been given as explanations and none seem very likely. The only plausible explanation is mining chalk for loaming nearby fields, as historically documented by Pliny the Elder. But never let common sense get in the way of a good story. Rather than some chalk mine I'm describing my exploration of "Cymbeline's Gold Mines", so much classier!

Diagrams, explanations and further reading on Dene holes see:



Enthusiastic Idiot
28DL Full Member
The Explore

Hangman's Woods, Thurrock, Essex. A sunny mid week afternoon. Again this was a half-day off work midweek where I didn't tell the Mrs (she hates me exploring) and I was on my own, another "bunking off school" trip :)

The Park


There is a bridal path through the woods that follows the path of an old road. Note the unusually tall security fencing (the world's sharpest topped 3 metre "W" palisade fence, a real trouser ripper) , with a second layer of ordinary height older palisade fence inside that too.

In total there are 3 fenced off areas like this, with a third one a short way to the left of this pic behind some bushes about 15m? away. Due to the council grass cutting man eyeing me with great suspicion and driving his ride-on mower up and down exactly where I wanted to be, I ended up exploring the close by 3rd site not pictured here.

The Hole
Now I'm not sure how or why the perspective is like this in the (sorry slightly blurred) photo , because what is, is a fairly large hole, much more than the 3 fot diameter at the bottom of a very steeply sided funnel. I I slip at this point I'd be going down that hole and I'm actually on a rope and Petzl stop to go down to rig it.

I don't know why, but for whatever reason I have this really bad feeling that today is unlucky and I shouldn't be here. If this was very local I'd just have gone home. Something about the site made didn't make feel a happy bunny, no idea why. Note the Altair 4x gas detector clipped just above my chest ascender. Soon to be lowered down the hole on rope with a floodlight too so I can see down it before I go


I was going to re-belay on the tree at the top of the hole, but half was dead and half alive and when I thumped it with my fist i'm sure I could feel the ground just uphill shudder so I decided the fence and smaller tree just back from top was enough and to leave the bigger tree alone. It is in soft sandy clay and a bit undercut by subsidence. No idea about roots, it could be solid or about to fall, I've no idea. While pondering rigging to the tree there was a lot of squawking of a small bird. I looked and its young must have fallen from the nest onto the slope near but out of my reach, each time it moved it tumbled a bit further towards the hole, the mother cheeping frantically the whole time. Down it went, this seemed a bad omen. The shaft itself was very soft and much wider than 3ft and not at all round or regular, it looked very eroded and was maybe 25m deep.


a huge cone of previous collapse and rotting stuff is at the bottom of the hole. As I was unclipping my stop and looking at the gas meter a very slow moving squirrel limped away from me deeper in, as I didn't know the air and not wearing gloves I didn't grab it, I think the poor thing was already too dehydrated to survive and it escaped me into a small tunnel and was gone. The place smelled like things died there.

As I was standing there I could feel a constant light rain of sand and small stones, looking up the shaft it wasn't clear where it came from, but I must have disturbed stuff so no problem. I still felt a sense of doom and I was putting that out of my mind.

Fresh fall

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Enthusiastic Idiot
28DL Full Member
Well... if you like holes full of rotting junk, this is the place for you



I had slightly low oxygen but alarm not sounding, a bit of LEL reading (methane?) but no alarm sounding, it smelled bad, didn't feel "fresh" but the air seemed within safe limits, the meter did vibrate now and again, presumably to make me look at it, but nothing too concerning and no alarms. I wasn't greatly happy about the "rain" of sand and occasional stone showers in the shaft, because nothing was disturbing it as far as I could see, so what was moving?

One section the builders had excavated too high and broken through the chalf up into the compressed sand above. So the roof was sand not rock... great :(. Or maybe that's just the collapse process, not sure. Not so great either way


Note the kids ride on toy car in the background of the pic above

What I wasn't expecting was that there were crawl tunnels deliberately created between Dene holes so you can explore between them. This is the one the dying squirrel walked down in slow motion away from me

Typical chamber/stall with the tomb of the unknown squirrel at rear

Another squeeze tunnel to the Stacked Blocks chamber in a different dene hole again. this is not a full belly crawl/squeeze but is tighter than just easy hands knees

At this point as I was about to crawl through to the stacked blocks I heard a load of stones and **** come tumbling down the entrance shaft
That was it, call me a "wuss" (which my boss did when I mentioned the explore to him), maybe I was being soft in the head that day, but the feeling of impending doom was already growing stronger, my spider senses were tingling - and the latest stone shower/fall was enough. That was it I was getting out. I put my pantin on my left wellie and practically ran the rope out of there.

Maybe I'll go back trying a different shaft, I'd love to explore the stacked block chamber and see a load of other chambers and crawl tunnels, but that day I wasn't feeling it. Oh.. but on the bright side, not a single bat in sight. This trip may be a "collectors item" and not appeal to many others. Certainly many others have been before me and will go after, but unless you live locally I'm not sure it'll attract big crowds.

So In summary, yes Essex has underground mines, probably who knows.... some very ancient ones at that. See them before they collapse.
RIP Mr Squirrel

Down and beyond

The true source of englands wealth is coal
Regular User
Absolutely cracking stuff tom fair play mate hope to see ya soon :thumb their is some cracking geology going on


28DL Full Member
28DL Full Member
Awesome. Heard there were some caves in those woods but never thought they were so spacious. Me and my explorer buddy are local, if you decide to return, we will be glad to be on safety duty at the top, don't think I would like to venture down that hole myself.

Calamity Jane

i see beauty in the unloved, places & things
Regular User
Fair play, solo again. Another lot close to me. I hate those fences, because I cant climb them lol. Nice images. Lots of info here. I've seen the dene hole in Darenth woods, but never been able to go down it.


Enthusiastic Idiot
28DL Full Member
That’s fantastic! I’ve always wanted to go down them but been a bit nervous as my dad fell down them at 14
Really?? Hope he's OK, depending which shaft that's a long way down, some may have been partly collapsed or plugged and be less, but if he'd taken a full depth fall he'd be one lucky guy survive that.

I rigged at top with a shorter bit of blue climbing rope, but for the shaft drop I used a semi static. It was 60m orange with halfway marked in black, I was maybe 5m short of the halfway marker to reach bottom. So I reckon the main drop (not inc the funnel of earth at top) was about 25m/80 foot.


28DL Full Member
28DL Full Member
You got some balls doing that on your own il give you that! You really should let someone know what your doing if your going alone just in case as you never know. Nice report mate I enjoy reading about something new :thumb


Enthusiastic Idiot
28DL Full Member
Thanks Doozer. Yeah.. although I've been down places with no call out (3 times this year for example :( ), I never like doing that! This one I had text my daughter with a Google maps pin and what I was doing with a time I should be out. Then I let her know when I got back to car and instructions to delete all texts/evidence afterwards. Gotta set call out when underground, especially solo trips. I had asked a couple of mates about coming down Dene holes but whatever date I suggested seemed to be the same day they were washing their hair, amazing unlucky coincidence I guess, so it was another solo.


Enthusiastic Idiot
28DL Full Member
Awesome. Heard there were some caves in those woods but never thought they were so spacious. Me and my explorer buddy are local, if you decide to return, we will be glad to be on safety duty at the top, don't think I would like to venture down that hole myself.
The 2 layers of fence act as a good safety to stop anyone fiddling with rope while you're down there, but if you're local you should consider making a trip down them yourself some time. But... stay safe!
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