Do not enter where you see signs such as
"Caving Ground" or "Mine shaft."
Posted on the World Wide Web by Michigan Technological University
Michigan Mining Engineering Department
based on materials from the Mine Safety and Health Administration (MSHA)
booklet "Abandoned Mines." The information about abandoned mines in Michigan
has been provided by the Mineral Technology Research Group taken in part from the Michigan
Department of Natural Resources funded project on abandoned underground mines.
Educational use of this material is encouraged.
Click Here for a recent summary of the Michigan
Underground Mine project that is appended to this report.
Dr. Allan M. Johnson, Director, Mineral Technology Research Group,
Department of Mining Engineering, Michigan Technological University.
Abandoned Mines, Quarries and Cave-ins have claimed the lives of many adults and
children over the years. Some fatalities have occurred in Michigan. There were several
mining areas in Michigan. Some of the mines were opened in the 1840s and were closed and
abandoned over 100 years ago.
While many mine operators have taken precautions to fill in and secure abandoned mine
areas, many old mines were opened and then abandoned long before any consideration was
given for making the areas safe after ore extraction was completed. Michigan has many
mines that were opened up in the 1840s. There are very limited records of the locations of
shafts. Also it may not be known how near the surface these undermined areas are or how
extensive the mine voids may be.
People enter abandoned mines for a variety of reasons, ranging from curiosity to
vandalism. Those who seek these pastimes often meet with sorrow and misfortune. Many young
people (as well as adults) have been killed or injured while attempting to satisfy a
desire to explore old mines, caves, and open pits.
Any old mine can be a death trap. Trespassers not only violate the law but they risk
their lives and the lives of others.
Probably the greatest number of accidents around mines occur to children. Public
schools in mining districts should teach children about the dangers that exist around
these old abandoned mines.
Fences and "No Trespassing" signs may not stop children from venturing into a
mine or mining area. Fences or signs may be obscured or hidden by trees and bushes, or
covered by deep snow, or the fences or warning signs may not have been maintained. Thus,
children or adults may venture innocently into an area that has old cave-ins and shafts.
The increasing use of snowmobiles and all-terrain vehicles, such as four-wheelers,
traveling into forested areas makes possible the accidental discovery of an abandoned mine
area. People should remain on marked trails.
Another factor is that unknown or unrecorded old mine workings may have caved-in and
authorities and present owners may not be aware of the new cave-ins. This has happened in
some of the oldest mined areas. In areas where mining is known to have taken place in the
1800s, such as parts of Michigan, openings such as pits or crevices should always be
avoided. Children should be warned to stay away from such openings. The counties where
mines were opened in the 1800s and have been closed and abandoned over a hundred years ago
in some cases include: Keweenaw, Houghton, Ontonagon, Baraga, Marquette, Gogebic, Iron,
and Dickinson, all in the upper peninsula.
Many open pits exist in mining areas. Pit walls may be unstable and landslides may
occur at any time. There may be overhanging edges on pit walls that could collapse when a
person stands on them. The walls of the pit may be steep. Persons have drowned in the
water in these pits because the water may be deep all around the pit with no ledge or
place to hold on to. Diving into a pit is dangerous because there may be rocks just below
the water surface. People have fallen to their death from the top of a pit or have been
struck by falling rock when inside a pit. Stay away from open pits, quarries and gravel
Mine shafts may be vertical, as straight down, or inclined at an angle from nearly
vertical(90 degrees) to being nearly level (adits). Many shafts are 55 degrees or 35
degrees, or 26 degrees. In Michigan all types occur. Open mine shafts are especially
dangerous. The rock or soil around the shaft may be unstable and the shaft timbers may be
rotten. Do not walk anywhere near a shaft opening. When you see an area enclosed fully or
just partly with old fence posts with wire or fence attached---even if the fence and posts
have fallen down---stay way from the area. Be suspicious. It may be a shaft opening. It is
possible that a new cave-in or subsidence may have just taken place--and you are the first
person to find it. You will have no idea how much undermining or caving may have taken
place. The whole area may be ready and waiting to cave into the shaft or other mine which
may be hundreds of feet deep. You may be on "thin ice" ----So stay away.
Adits, unlike shafts, are openings into a mine that are level or nearly level like a
tunnel. These tunnels may be dangerous because rocks can fall from overhead. There may be
holes in the tunnel called winzes that drop straight down hundreds of feet. Old boards or
timbers over these winzes may obscure them and may not support your weight.
The ground area around abandoned mine openings and pits can be weak and cave-in without
warning. Because there are old mines from the mid 1800s in Michigan, mine timbers or
pillars may have taken all of these 150 years to finally fail and cause a cave-in. A minor
disturbance, such as vibrations caused by walking or or any noise, like speaking, may be
just enough to cause an area to cave in under the surface or a hollowed out area to open
up to the surface. In some cases, people have fallen into a cave-in and survived only to
die from starvation, suffocation or drowning.
In some cases, old explosives left behind have been discovered in mining areas. Never
handle anything that may be an explosive.
Mining properties may have lakes or ponds in pits or reservoirs for mine operations.
These water bodies are not for swimming, they may have steep banks, water may be very deep
and cold. There may be underwater obstructions such as rocks or mining equipment. Cave-ins
may have water in the bottom with steep sides and no place to hold on to.
A shaft that is sunk downward in a tunnel or adit is called a winze. In many old mines
winzes were sunk in the floors of the adit or tunnel and then boarded over. The winze may
look like a puddle. But it may be a deep opening that is filled with water.
A surface area may be hollow underneath: it may be undermined by stopes or large
caverns from mined-out areas underground. In old mine areas, these caverns may have been
caving in slowly over the years. The hollowed area may have been slowly climbing higher
towards the surface. The depth of ground over these caverns may have decreased. New cracks
and crevices may be visible. If there are surface features of a former mine, such as
shafts or adits, fences or signs, there may be shallow under-mined areas nearby. This is
another reason to stay away from the area.
You should never go underground into an old mine opening. If you do fall or slide into
the underground area by accident, the following are some of the underground dangers.
Timbers were used to support a mine roof and walls. Wood may take a while to rot, but
eventually the wood rots and decays. It may even appear solid, but it may be rotten and
soft. You may step on a timber or board that may collapse or fall to pieces. It may be
covering a deep hole. Even good timbers may be loose and fall with the slightest touch. An
area may appear well-timbered and supported, when, in fact, it cannot support its own
weight. There is a danger of brushing against a timber and causing an entire area to
Ladders may be present in an underground area. They may be rotten wood, or just some of
the rungs may be rotted.
UNSUPPORTED ROOF AND WALLS
Many underground passageways, tunnels, drifts, adits, stopes and other underground
areas do not have timbers to support them. When the mine has been deserted, the strength
of the walls and roof may have deteriorated. The weight of overburden has been pressing
down and squeezing the roof and walls. There is no way of knowing when the exact time has
come for the rock to loosen and fall.
Minerals and decaying timber may have caused a build up of gases or a lack of oxygen. A
lit match may cause a flammable gas like methane to explode or you may become tired and
dizzy from lack of good air. When mines were operating, the ventilation with good air was
very important. Abandoned mines usually have no ventilation to get rid of bad air. In some
cases people have lost their lives in pits because of bad air in the confined space. Also,
sound may not travel as far in an underground mine.
Cave-ins underground may occur at any time. This may cause an air blast to travel
through the mine. Water may also be blasted out of a water-filled part of the mine into a
UNDERGROUND HOLES AND SHAFTS
Underground holes and vertical openings may be part of the mining operation, such as
winzes or shafts between levels, or shafts from adits into deeper areas. Some holes were
made as chutes for dumping rock into a deeper area of the mine. Some may be old
ventilation shafts. Or holes may be caused by caving ground into deeper mined areas
underneath. Persons falling into a hole underground may fall hundreds of feet to their
death, or fall into a water-filled part of the old mine. These holes may be covered by
rotten timbers that will collapse when stepped on or they may look like a puddle of water.
Underground areas are dangerous because of the darkness. You may have light, but it may
not be bright enough or you may lose your light. Mine shafts are deceptive because there
is little or no light in a dark hole. When coming up to a deep hole, you may not sense the
feeling of height and perspective as you would when looking over the edge of a tall
building or a cliff, so you may not feel the normal reaction to "pull back" from
the edge of a deep hole.
A great danger in an old mine is that water over a hole may even be covered with dust
and look like solid ground. It is usually impossible to see the bottom of water, standing
water or flowing water. Even in a level adit, water may conceal a winze or chute or deep
hole that is straight down. An underground area may even be dry while mined areas overhead
are full of water. A sudden cave-in may allow hundreds of feet of water from levels above
to rush into the dry area. Some mines had wooden dams to keep water from one part of the
mine out of another part. These dams could break at any time. All abandoned mine water
should be considered unfit for drinking.
In some cases a fire may occur in an abandoned mine. Never strike a match or start a
fire in an old mine. There may be no ventilation, odorless explosive or flammable gas may
be present. Even if that is not the case, a fire could deplete limited oxygen, liberate
dangerous gases and spread through the mine, cutting off any escape.
While explosives may be discovered in surface areas, it is also possible to stumble
onto explosives underground. Any disturbance may set off explosives after decades of
sitting in an abandoned mine.
DANGEROUS ANIMALS AND INSECTS
Though many old mines in other parts of the country may have snakes, scorpions, and
spiders, in Michigan it is possible to stir up a black bear residing in an old adit or
mine opening. Bears are known to occupy some adits. You cannot predict what a bear will do
in a confined space. Bats usually occupy abandoned mines. Bats will try to avoid you, but
they may startle you.
MAZE OF A MINE
Underground areas, such as adits, drifts and levels are often in a maze of passages.
Persons have died in the maze of an old mine from exhaustion, thirst, hunger, and exposure
as well as from slips and falls. Some mines in Michigan have many miles of passages.
Do not enter where you see signs such as "Caving Ground" or "Mine
Do not cross fences. Be suspicious of any location where old rotten fence posts and
rusty barbed wire is found. There were hundreds of mines in Michigan that were opened and
operated as early as the 1840s that have been closed and abandoned for over a hundred
years. While the state of Michigan has provided for mine inspectors in counties where
mining has occurred and currently has issued a contract to Michigan Technological
University for a program to finding old mine shafts and workings, some are still unknown