In the early stages of mining operations, test shafts are often sunk from 50 to 100 feet deep through loose material overlying bed rock. These shafts can be concealed by brush and grass. They are dangerous to anyone who might step into them.

Entering abandoned mines or tunnels is more dangerous than standing in the middle of a rush-hour freeway. Old shafts can be deceptively deep. Decomposed rock, at the top of the shaft, and adjacent tunnels can cave-in suddenly.

Timbers are used to support the mine’s roof and walls. Wood used underground may dry-rot faster than surface timber because moisture and humid air are often found under the surface. Timbers in abandoned mines are usually decayed. This danger is not apparent because the timber looks very old. Other timber, although in good condition, becomes loose and will fall with the slightest touch. A particular area may give the appearance of being a well timbered mine opening to the inexperienced observer and can give a sense of security, when in fact, the timber can barely support its own weight. There is the constant danger of brushing against a timber and causing the entire area to collapse.

Entrance to, or exit from, underground- workings is often by ladders. Ladders are usually built of lightweight material that quickly rots.

The ladders in most abandoned mines are unsafe because rungs are often missing or broken. Some will fail under minimal weight. It is impossible to climb down a ladder and examine each rung before placing weight upon it.

There is no safe way for a trespasser to determine the condition of a ladder.

Unsupported Roof and Walls

Many underground passageways, tunnels, drifts, slopes, and other working places do not need timber support during mining operations. When the mine has been deserted, these conditions change with time. The weight of the earth overhead is constantly pressing down and squeezing the roof and walls. There is no sure way of knowing when water and air may cause the rock to loosen and fall.

Bad Air (Lack of Oxygen or the Presence of Deadly Gases)

The normal atmosphere we breathe is composed of several gases. Oxygen, an important part of normal atmosphere, is the only gas that will support life. Mine atmosphere or mine air maybe contaminated with gases that are poisonous and may displace the necessary oxygen to support life.

Minerals and decaying timbers use up oxygen. Carbon dioxide is given off by decaying timbers. Some gases are also released from rocks and decaying vegetable matter. In active mines, it is necessary to keep fresh air coming in from the outside to ventilate the places where miners are working. When mines are deserted, air no longer may be circulating or air passages maybe completely blocked by fallen rock or timber. In many abandoned mines, no fresh air is present below the surface. Persons have lost their lives even in shallow pits and wells because of bad air. Some abandoned mines also contain explosive gases which are easily ignited.

Do-not disturb pools of water. They may contain dissolved poisonous gases that are released by walking in the water.

Underground Holes and Shafts (Covered and Uncovered)

Underground holes and shafts may be manmade or caused by caving ground. Shafts and abandoned holes are dangerous. Persons falling into underground holes may plunge hundreds of feet to their death. These holes, when covered, can be more dangerous than open holes because the cover may be rotten or broken.

Mine shafts are deceptive because there is little or no light in a dark hole. The feeling of height and normal reaction to “pull back” is not evident in most persons. People who hesitate to look over the side of a tall building show no fear when looking into a mine shaft. Remember — a fall down a mine shaft is just like falling from a tall building.

Water

All abandoned mine water should be considered unfit for drinking. it is frequently contaminated with chemicals and other refuse.

Underground lakes, reservoirs, pools, and sumps are very common in abandoned mines. Sometimes the water surface, when covered with fine dust, may look like solid ground.

When water is standing or flowing, it is usually impossible to see the bottom and there is always the danger of stepping into a winze or other deep hole. Many tunnels have water standing in deep pools or holes concealed in the floor. Pools of water also are common at the bottom of shafts. It is impossible to estimate the depth of the water. A false step can lead to drowning.

Underground Fires

Underground fires pose three important dangers by:

• Consuming oxygen
  
  
• Liberating dangerous gases
  and
  
• Spreading throughout a mine

All fires consume oxygen. The flames goes out when the oxygen is gone. But the danger point to human life has, by that time, already passed.

Mine fires liberate dangerous gases, including deadly carbon monoxide. It is an odorless, colorless, tasteless gas. Small amounts of carbon monoxide can kill.

Fires can spread through a mine and cut off escape routes.

Abandoned Explosives

Explosives and blasting caps deteriorate “with age and become very dangerous. A slight jar, excessive heat, or just handling may set them off and may cause a serious injury or fatality.

Do not handle explosives or blasting caps.

Dangerous Animals and Insects

Mines and caves are cool in summer and warm in winter, generally offer a good food supply, and often furnish shelter for snakes, spiders, scorpions, insects, and other dangerous animals. Any protected hole or ledge is a natural habitat for snakes. This is a particular danger in shallow shafts.

Danger of Becoming Lost or Trapped

Old mines and caves contain a complex network of underground passages. Lost persons have died from exhaustion, thirst, hunger, exposure, slips and falls.

Posting Signs

Open holes, unfenced tunnels and closed mining operations often have no warning signs of any kind. Signs or fences should be placed around the open areas to warn people against trespassing and to keep people out of abandoned mine properties. These areas are extremely dangerous and should be avoided at all times.