Plain English
What is actually down there
| Word | What it means |
|---|---|
| Adit | A tunnel driven in from a hillside, flat enough to walk into. Not a hole you fall down, but a way into workings that can run a long way back. |
| Shaft | A hole straight down. This is the one that opens at the surface years later and swallows a car or a garden. |
| Portal | The mouth of a tunnel. The doorway, in other words. |
| Seam | A layer of coal, lying flat like a sheet in a cake. Coal is taken seam by seam. |
| Vein | A sheet of ore in rock, usually tilted rather than flat. Gold, silver and copper come out of veins. |
| Overburden | Everything above the working: the rock and the soil between the old mine and your garden. Shallow overburden is what makes a collapse reach the surface. |
| Room and pillar | The common way coal was taken out. Rooms are emptied and pillars of coal are left standing to hold the roof up. When pillars crumble, or were taken later on purpose, the roof comes down and the ground above sinks. |
| Longwall | A machine takes the whole seam in one pass and the roof is let down behind it on purpose. The sinking is planned, it happens quickly and it is usually a wide shallow dish rather than a hole. |
| Stope | The open space left behind where ore was cut out. |
| Tailings and spoil | The waste rock and ground up leftovers, usually in piles or ponds at the surface. |
| Mine pool | A worked out mine that has filled up with water. |
Plain English
What people see at the surface
| Word | What it means |
|---|---|
| Subsidence | The ground sinking because something under it gave way. It can be a slow dish over acres or a hole that opens overnight. |
| Sinkhole | A hole that opens at the surface. Over an old mine it is usually a shaft or a shallow working collapsing. In limestone country it happens with no mine involved at all, which is why a hole is not proof of a mine. |
| Undermined | There are old workings under the property. The word a state office will use in a letter. |
| Acid mine drainage | Orange or rust coloured water running out of an old working or a pile of waste rock. A sign of old workings nearby, and a water problem of its own. |
Plain English
The records and the offices
| Word | What it means |
|---|---|
| Mine map | The plan the company drew of what it actually dug, room by room. The only document that shows where the workings run, and the thing worth asking for. |
| Certified, and the certification date | The day a mine map was signed off as a true record of the workings. Anything dug after that day is not on the map. |
| Topographic sheet, or quadrangle | A survey map of one rectangle of the country, drawn and redrawn over a century. Surveyors marked the mine openings they could see, which is where a lot of our records come from. |
| Mapped feature | A hole a surveyor drew on one of those sheets. Nobody catalogued it as a mine, so all that is known is that it was there on that date. |
| Producer, past producer, prospect, occurrence | The four words the federal catalogue uses for how far a site ever got: working now, worked once, dug at and given up, and no more than a mineral seen in the ground. |
| Abandoned mine land, or AML | The state programme that closes dangerous old mines and fills open shafts, paid for by a fee on coal. The office to telephone about an open hole. |
| National Mine Map Repository | The federal archive in Pittsburgh holding more than 275,000 maps of closed and abandoned mines, searched for you on request. |
| MSHA | The federal mine safety agency. It covers mines that are working today, not the ones that closed before anyone was counting. |
| MRDS and USMIN | The two federal files our counts come from. The first is a catalogue of mineral sites with what came out of them. The second is the file of mine openings and holes that surveyors drew on the topographic sheets. |
The one to watch
If you only learn one of them
Learn what an underground opening is. A gravel pit or a quarry is a hole in the open air and you can see all of it. A shaft or an adit is a way into workings that carry on underground, out of sight, and that is the kind that can still take a garden down years later.
Our map counts the two separately for that reason, and the state offices do the same.
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Before you rely on any of this
The mine information here is for general information only. Old mine records can be incomplete, outdated or wrong, and finding nothing here does not mean there is nothing there. Check with the mine map office named here before you rely on it, and have a qualified engineer look at any ground you are worried about. PublicRecordCenter.com assumes no responsibility or liability for any errors, omissions, or consequences arising from the use of this information.