The Dangers of Mine-Exploring
This document represents my particular opinion as to the most common dangers encountered whilst exploring disused mine workings. They are listed in order of probability, not severity (as the resulting scenario in all cases is death, I deem the severity equally spread).
It is very important to state that the dangers here are by no means exhaustive, purely the matter of personal opinion, not necessarily accurate, and should never be used as the basis for any safety training. I'm not a qualified cave rescue technician or instructor, and if anything said here contradicts with what a qualified professional tells you, take the latter as the truth and please then inform me of my mistake.
Dangers Encountered
1: Falling
Falling I would consider by far and away the most likely cause of death to any explorer of old mine workings. Vertical drops of alarming height abound everywhere in practically all mines. Like all dangers, they represent the greatest risk to the unwary and inexperienced; as such individuals will not always be aware when a risk of falling is present.
- Falling Through a False Floor
False floors might sound like something from an Indiana Jones movie but they are real, abundant, and highly dangerous. False floors are frequently (but not exclusively) found in metal mines. They were installed into the mines to provide a bridge across usually a stope as it is worked deeper and deeper, to maintain access to tunnels on the other side. False floors are made from timber, and then overlaid with the same dirt and gravel that covers the floor of the tunnels. False floors may have been pretty solid when installed, but 100-200 years or more of damp rot will cause them to weaken greatly.
The primary danger of false floors is that it's usually very hard to know you're standing on one because the floor looks and feels exactly the same as normal tunnels through solid rock. You won't be able to tell where the solid rock ends and the false floor begins, nor when it becomes solid rock again, as it really is seamless in appearance. Below the false floor, which might be less than an inch thick of rotten timber, will typically be an awful vertical drop of potentially hundreds of feet.
Even more dangerous are false floors that are submerged slightly below water. For instance, you may enter a mine tunnel that has, say, six inches of water on the floor throughout it's length. You would stomp along the tunnel in Wellington boots but be completely unaware that you've crossed from solid rock to a false floor. When covered by water, they are even harder to detect and more rotten than normal. Below these floors again will be a deep stope but obviously this time a flooded one. If you fall through carrying heavy kit, you'll probably sink right to the bottom and drown. Even if you can swim against it and come up, you'll most likely come back up to the false floor at different point to the hole you made falling in, and you'll be trapped in exactly the same way as one is trapped falling through ice on a lake. There will be no daylight streaming though the hole, in fact it'll all be pitch black especially as your headlamp will now not be working either. In this unfortunate scenario, all you can do is try to feel for the hole before your air runs out, though frankly the odds of surviving this situation are not very good at all.
The picture on the right shows a false floor that has half-collapsed. As you can see from the remaining half of the floor, it looks just like any other floor in a perfectly normal tunnel, and had it been intact, there would be virtually nothing to suggest the floor was false. The collapsed portion reveals the stope below is flooded to probably a great depth, right up to the false-floor. The false floor is not very thick and its strength seriously limited.
The two defences the mine-explorer has against false floors are detection and protection. If you're in a metal mine, you must remain alert to the danger of false floors and look for tell-tale signs to indicate that you are on one. For instance, if it becomes clear that you are in a stope rather than a normal tunnel, because (usually) the roof will suddenly go higher, or the rock walls become deeply stained with mineral deposits, then is it reasonable to assume that you could be standing on a false floor. If at any point in the mine you look up and see a false floor above you (there are obvious from below, of course) then you must assume that you yourself could be standing on one. Remember that in a stope only one floor is not false and that is the very bottom one. Unless you're very deep in the mine, assume the bottom of the stope is way below you.
If you do discover that you've accidentally walked out onto a false floor, the correct procedure of course is to get off it. If you realise you're mostly across one, and have to decide to get off it by either continuing to the end or backtracking, my opinion is that it is still best to backtrack even though it is further. My reasoning for this is that the floor you've covered has held your weight once and didn't collapse. The shorter stretch ahead may contain a weak point which you have not tested with your weight. When retreating, try to stand in your own footprints and go lightly as one might cross a minefield.
The correct way to cross a false floor is belayed from a partner who is firmly anchored and braced for a sudden jolt. The explorer crossing should have ascenders or prussic knots on hand so that if s/he falls through, s/he is able to get back up the rope to safety.
- Falling Down a Shaft
Shafts are found in mines of all types and there are not many mines that don't have at least one. A shaft is a tunnel that is completely (or very nearly) vertical. They were used to raise men and mineral, carry pipes, provide ventilation, or seek deeper veins to work. The top of the shaft (the ‘Collar') might be on the surface leading down into the mine, or within the mine itself, leading down to lower workings. Shafts often have doorways into their sides at various points in their length leading to workings.
The vertical extent of even the shortest shaft is enough to kill anyone who falls down it and so they should always been treated with respect. The longest continuous shaft in the U.K. is 1.1 kilometres, or just over two and a half times the height of the worlds tallest skyscraper.
Shafts are not normally very dangerous as they can usually be seen at a safe distance, though frequently the mine-explorer will need to use shafts as a means of travel in the mine (to get into it for instance). While abseiling down or prussiking up a shaft, correct use and mechanical health of all equipment involved is of paramount importance, as mistakes in a vertical environment can quickly result in a fatal fall.
- Falling off a bridge
Many mines, especially Slate mines, contain timber bridges spanning workings below. Through time, many have collapsed though some still remain, albeit in a dubious condition. Often, routes through the mines require the crossing of these bridges where obviously a risk becomes present of either falling off it, or falling through it. When crossing bridges, rope protection should always be used.
- Other Falling
There are plenty of other kinds of vertical drops within mine workings (chambers in slate mines, for instance), and all should be approached cautiously and using rope protection.
2: Drowning
Most mines contain sections of flooded workings, which can sometimes be many hundreds (even thousands) of feet deep. Falling into deep water isn't fatal of course but failing to get out of it in time is. This section doesn't require much further explanation than what it covered in the Falling section, the only difference being you've fallen into deep water rather than rock and therefore are liable to die by drowning instead of injury from impact. Falling into water (if the fall is not too great) does give you a second chance if you're a good swimmer and are able get yourself out of the water and rescued. There are however two other ways to drown in a mine without falling into water.
- Getting Caught by Flash Flooding
When a caver enters a cave system s/he must always pay great attention to weather conditions. Many cavers have drowned in caves from sudden rain occurring outside, resulting in the passages themselves filling with water.
Mines on the other hand are rarely affected by weather conditions in this way, and entering a mine on a rainy day is not considered an unsafe practice, whereas entering a cave could be suicide.
None the less, it can still happen, some sections of some mines are prone to flooding with sudden outbursts of rain. The best way to protect yourself against this danger is to know the mine you are in and find out from other explorers and guides any information relating to this.
- Releasing Flooding Water Above You
It is not uncommon in mine workings to have a section flooded in an isolated manner, with access possible underneath the water into lower workings. It is also not uncommon that that miners dammed and consequently flooded small unwanted sections in order to provide a water source.
It is a very unlikely danger but you should be aware of the risk of releasing any water above you, by fiddling with timber dams or similar. This could result in drowning in a sudden unexpected influx of water or being swept off some great drop. If you find something that looks like a dam, it is best to leave it alone, particularly if you're not sure if it still holds back deep water or not.
3: Killed by Ghosts
Is this for real? Ghosts a danger? In a sense: yes, I think they are. First off, this isn't a column claiming the existence or non-existence of ghosts. I've never seen one or spoken to anyone who has (though I've read witness statements about 'presences' in mines). Personally I don't believe in ghosts to be honest but whether you do or don't, that's not what I'm here to prove either way as it is irrelevant. What is relevant however is the reaction of the human mind to environments that it is not comfortable in and how this in turn affects the actions and decisions of the mine-explorer.
The primitive human mind with an instinct for survival gets scared when sensing danger. Being scared causes the chemical hormone called Adrenaline to be released into the blood stream which acts like a turbo-boost. The heart beats faster, reaction times shorten, and running speeds increase, thereby providing the human with a temporary burst of energy to assist in dealing with the danger.
Going back to our native environment, certain scenarios cause us to get scared. One is the dark. Humans are vulnerable to attack in the dark as our eyes are not built for it. When the sun goes down, we instinctively look for a safe and secure environment to remain until the sun comes back. Even sitting in our own house in darkness can be scary.
Another is being alone. Humans are safer in packs, like a pack of wolves, monkeys, sheep or whatever. A group is less likely to be attacked, and is more able to fend off an attack. If there are 10 of you running from a tiger it is statistically less likely you'll be the one that gets eaten. So being alone will always make you more scared than being in a group.
Another is being in an unfamiliar environment. Being somewhere you know well is far less concerning than being somewhere you don't, like in a foreign city. If a danger pops up you'll deal with it better if you are familiar with where you are.
So if you combine all three: being alone deep in a pitch black unfamiliar mine your brain will naturally be making you quite scared. Every distant drip sound will make you stop and listen, and even the slightest thing will make you jump. You might even feel childish and stupid for feeling scared but you won't be able to help it, it's simply a natural reaction to the environment. However, care has to be taken not to let this lead to panic and unrational behaviour.
There are many things that could push you from being scared into a state of panic:
- Getting lost
- Your lighting suddenly failing or weakening unexpectedly
- A sudden unfamiliar noise
- Thinking you heard a sudden unfamiliar noise
- Unusual shadows or reflections catching your eye
- A sudden realisation how far you are from daylight
…and more. “Did I just see something move up ahead? I'm sure something moved. No that's silly. Or is it? Must have just been a reflection. Then again I heard something odd earlier...”
Passing a point in a mine where you remember that a miner came to a grisly end in an unfortunate accident is also never a pleasant experience.
If you do or don't believe in ghosts, monsters etc it doesn't matter because here in the mine it's not actually the ghosts or monsters that threaten your safety, only your own fear of them. Panic can cause you to suddenly run or try to get out of the mine as quickly as you can or stop thinking in a sensible and safe manner. You might run over an edge, or hit your head, or trip and fall. You might faint and come round hours later with your batteries flat. If your heart is weak and you're really panicking you may even suffer a heart attack – and you're a long way from help in a disused mine.
So, to conclude, yes it is possible to get yourself killed in a mine that has done nothing to harm you, in effect causing you to kill yourself through irrational thinking and fear of a danger that just isn't there. This is why I think Ghosts do deserve a place on any list of dangers in a mine.
In terms of prevention, you can't do anything about the darkness nor the fact that it's unfamiliar (if it is) but it is certainly true to say you're much safer in a group than alone. You're far less likely to panic and get scared in a group, even if it's just two of you. There are also many other safety reasons why it's best to explore in a group but I won't list them here. If you do go into a mine on your own (as admittedly I often do) your best defence is an understanding of your fear and enough self control that if you do feel yourself starting to panic, you can calm yourself down. Try to get your breathing back under control. Rest, have a drink and tell yourself that you're perfectly safe and that you need to stay calm in control.
Getting lost in a mine is a very unpleasant experience but it's important to keep telling yourself that you'll regain your route if you just search long enough. Mines are not infinite in size and like any maze, getting out just takes time. You have lots of batteries with you? You know you can and will keep wandering until you find the way and it really can't be that far.
If you find yourself with no light, because your main lamp batteries fail and all your backups mysteriously don't work either, firstly feel silly for somehow getting in this situation and then sit where you are and wait for rescue. You did tell someone where you were going and when you'd be back? If not, feel even sillier but still sit where you are and wait for rescue. Unless you know for absolute sure you're in a straight tunnel to the exit and definitely facing the correct way, don't ever try and crawl out of a mine with no light, it's extremely dangerous and if you sit tight someone will eventually miss and come looking for you. Hopefully.
4: Bad Air
Most mines were built in such a way that a natural airflow occurs to replenish the air. Shafts and adits were placed in various positions to create ventilation and air circulation. Often this was aided with large fans and water-blast. However, not all the workings received good ventilation and today, many of the ventilation shafts and adits could be sealed preventing air movement. Some tunnels might be blocked. The fans will not be working anymore. Therefore the air might not be replenishing itself as it should. Bad air might build up making breathing difficult or impossible.
- Black Damp
Miners of old used the generic term Black Damp for gases such as Caron Monoxide and Carbon Dioxide which dilute the Oxygen present in the air. You need Oxygen to breathe of course so any reduction in the available Oxygen to you is a bad thing. Even a small reduction in the percentage Oxygen present can be a serious risk.
Black Damp can build up form gasses seeping into the workings, from breathing too much in an area with no replenishment, from a fire or from other causes. Being alert for this is always very important and if you feel unusually tired, out of breath or sleepy then suspect Black Damp immediately and retreat out of the mine.
This is true even if you've been there many times before. Maybe someone had a bonfire near there recently which caused a big build up of Black Damp. It always amazes me how many people have bonfires in mines, even in cramped tunnels with little ventilation. Nothing burns Oxygen like a smouldering fire and the bad air can hang heavy for weeks.
I know a story where one night a lightning storm struck the power lines to a mine causing an electrical overload deep underground and a small fire broke out in the switchbox. This soon burnt itself out, but a couple of days later two miners entered the area and I believe both died very suddenly from Carbon Monoxide poisoning, the gas still hanging in the air from the fire. So fires underground are not something to encourage and you must remain aware that someone else may have lit one recently.
It is believed that if you suspect Black Damp you should strike a match, the theory being that if it burns dimly or won't light at all, then the Oxygen is very weak and therefore you must be in Black Damp. My opinion is this technique isn't much use because you're in danger long before the Oxygen gets low enough to visibly affect the striking of a match. Also, if it's not Black Damp but Fire Damp (below) then you won't want to be striking any matches. If you suspect Black Damp enough to consider testing for it with a match – you should already be making your way out.
- Fire Damp
Even worse than Black Damp is Fire Damp. Fire damp is an explosive gas (Methane?) usually found in coal mines as it seeps out of the coal seams. Coal mines needed massive amounts of ventilation to flush out the Fire Damp which constantly filled the workings. Huge volumes were blown up to the surface; sometimes portions of it were harnessed and supplied to the coal-mining towns as a household fuel (Coal-Gas).
Tens of thousands of miners in the U.K. have been tragically killed in coal mines because of explosions underground from Fire Damp. When exploring a disused coal mine, great care has to be taken for areas saturated with this suffocating, explosive gas as it's killed more people than anything else in British mining history*. Generally speaking you only find Fire Damp in coal mines, but sometimes other types of mines cut through small coal seams or oily shale searching for other minerals, releasing (comparatively) small amounts Fire Damp and causing fatal explosions. With these small seams, the issuing gas probably died off quickly but ground movement could always release another burst so even if you're in a lead mine don't entirely rule out the possibility.
5: Roof Collapses
What the layman might consider the greatest danger to the mine-explorer I would personally put way down on the list of things likely to kill you. Sections of roofs in mine workings do collapse sometimes on their own accord, be it in a chamber or a tunnel. If you're under it when it decides to go you'll be killed of course. Still, I would consider the probability pretty small of you being under that precise spot at that precise time when the roof that has been there for hundreds of years suddenly decides to go. I do honestly think you're more likely to be killed on the roads driving to the mine than actually killed in the mine from a spontaneous roof fall.
That statement though only relates to chance roof falls you had no effect upon. Far more likely is the roof falling on you because of your presence in the mine. The thing to always remember in a mine is that you never know how close the roof above you is to collapsing. It might be right on the very brink of collapse, relatively speaking. On a scale of hundreds of years, this would mean it's within a few weeks of its collapse, so the thing to do is not provoke it. When looking up at a chamber roof, remember that the last time anyone inspected it for safety was an unqualified rockman clinging to an 80 foot long ladder with only a feeble candle in his hand, probably over a hundred years ago.
Shouting in mines is to be avoided. So is fiddling with support beams. Pushing rocks over drops is very silly indeed, as is anything that makes a loud noise or a shockwave of any kind. I do know of one story where a group of mine explorers were whooping about in a chamber, and caused a car-sized boulder to fall from the roof which landed right next to them. Nobody was hurt that time, but it was very close and a lesson to us all.
You wouldn't want to be in a mine with an earthquake. Should you be unfortunate enough for this to happen, my advice is to leave immediately and not go in any mine for weeks.
Whether you cause it or not roof falls can and do happen and anyone in an old mine should be alert for the danger. Something to always look for is coming across other, recent roof falls. This could be indicated by a fresh looking pile of rubble, particularly if it's dusty, or with sharp edges, or a lighter colour than the general grey of the surrounding rock. If you come across an area where this is evident the roof could still be very unstable and a careful retreat is strongly recommended.
6: Radon Gas
Radon Gas is only a recent discovery and was completely unknown to the miners of yore. It is a form of radiation present in all rock underground and is stronger in some areas than others. Prolonged exposure to high levels of it can (as I understand it) increase the risks of developing cancer. Study is still being undertaken on the subject but evidence suggests that it poses little risk to the mine-explorer or caver, neither of whom is likely to ever receive enough dosage to pose a health risk. Individuals who work underground a lot (especially in a high Radon area) such as caving instructors or miners ought to make themselves aware of the danger and investigate if it is likely to cause them any problems.
*Footnote 28/8/05: No, it would seem I was wrong to say explosions from Firedamp were the no.1 killer in Coal Mines. They attracted the most attention because when they occurred they were extremely serious and could kill hundreds of men and boys below ground in one go. Checking though some official statistics for all coal mines in the U.K., more miners died over an average year through being crushed by roof-fall than explosions. Coal mines were awful for unstable roofs and the statistics are very sobering as to the number of men and boys killed this way. I also found it shocking how many coal miners were killed in transport related accidents, e.g., lifts in shafts falling or hitting beams, trains derailing etc. Hundreds of men and boys lost their lives every year due to being killed by their conveyance.