For the more information about the geologic resources of the National Park Service, please visit http://www.nature.nps.gov/geology/.
Hazards — Stay Out and Stay Alive!
Occasionally, adventurous people enter abandoned mines and wells. Some are injured or do not make it out because they fell victim to one or more of the many hazards associated with abandoned mineral sites:
Many abandoned mines become flooded. The most common cause of death in abandoned mines nationally is drowning in water-filled quarries and pits due to the presence of rock ledges, old machinery, and other hazards that may be hidden beneath the water's surface. The water can be deceptively deep and dangerously cold; and steep, unstable, slippery walls make exiting these features extremely difficult. In underground mines, shallow water can conceal sharp objects, drop-offs, and other hazards.
Vertical Mine Openings
Falling into vertical underground mine openings is the second most common cause of death and injury in abandoned mines. Darkness, loose debris, and false floors can hide vertical openings. Weathered rock at the edge of an opening can break away and slide into the hole under the weight of a person.
Deadly Gases and Oxygen Deficiency
Lethal concentrations of carbon monoxide, carbon dioxide, methane, hydrogen sulfide, and other gasses can accumulate in underground passages. Pockets of still air with extremely low oxygen levels can be encountered. By the time persons feel ill, they are no longer able to react.
Mines can cave in at any time! The effects of blasting and weathering destabilize once-competent bedrock through time.
Support timbers, ladders, cabins, pump jacks, tanks, and other related structures may seem safe but can easily crumble under a person's weight. Do not be fooled by appearances!
Unused or misfired explosives are deadly. Because old explosives become unstable, minimal vibrations from a touch or footfall can trigger an explosion.
The vertical and near-vertical edges of open pits and quarries are called "highwalls." These highwalls can be unstable and prone to collapse. Do not climb near or on highwalls.
Mud pits once used for oil and gas operations can contain hazardous materials and may be the consistency of quicksand.
Some of the materials that were mined, such as uranium and thorium, are radioactive. Because the effects of radiation exposure are cumulative throughout a lifetime, exposure from mines can be harmful to humans, wildlife, and plants.
Designed for the Short-Term
Mines were constructed and maintained to be safe only while they were in operation. When the miners departed in search of more lucrative deposits, they often left vertical openings uncovered and removed the ventilation and water-pumping systems. Support structures, timbers, and ore pillars were removed or left to rot, leaving the mines much less stable than when they were operating. Modern laws and regulations require miners to leave properties in a safe condition, but this was not the case in past decades.
Mines Are Not CavesCaves are formed naturally over thousands or even millions of years. Mines, in contrast, are developed in a comparatively short time, often in inherently unstable structures such as faults, through blasting, which fractures and destabilizes the wall and roof rocks. Most underground mines do not have natural ventilation and consequently can have lethal air traps. Even experienced cavers can die exploring mines.
Underground mine rescues are extremely hazardous. Mine rescue teams, despite their extensive training, are at significant risk every time they enter an abandoned mine. When people decide to enter an abandoned mine, they not only risk their own life, but the lives of those who might be called to rescue them when they get lost or injured underground. The tragic and unfortunate reality is that many mine rescues turn into body recoveries.
Last Updated: February 27, 2013