Mining shaped much of the American West and parts of the East, and USGS maps recorded it in detail. Crossed picks, small Xs, and half-black squares mark mines, pits, and prospects. Many are long abandoned. These symbols are a treasure map for history buffs and a hazard warning for everyone else.
What does the crossed pickaxe symbol mean on a topo map?
Crossed picks mark a quarry or open-pit mine. A half-black square is a mine shaft, a line ending in a Y is a mine tunnel or cave entrance, and a small X is a prospect, a test pit or exploratory digging. Treat all of them as hazards.
IN THIS GUIDE
Mines, pits, and caves · Mine waste and disturbed ground · Power lines and pipelines · Exploring mining country safely · FAQ
Mines, pits, and caves
Larger pits and quarries are outlined to scale. Small ones get a point symbol.
Quarry or open pit mine
Crossed picks: a quarry or open-pit mine, active or abandoned. Expect sheer walls.
Gravel, sand, clay, or borrow pit
Crossed shovels: a gravel, sand, or clay pit, or a borrow pit dug for road fill.
Mine shaft
A square split diagonally, half black: a vertical mine shaft. Old shafts can be hidden by brush or rotten boards, and a fall can be fatal.
Mine tunnel or cave entrance
A line ending in a Y: a horizontal mine tunnel (an adit) or a natural cave entrance, usually labeled with its name.
Prospect
A small X: a prospect, meaning a test pit, trench, or small digging. Clusters of Xs often show where a mining district once boomed.
Mine waste and disturbed ground
Waste rock and tailings are often the most visible trace of an old mine.
Tailings
A tan tint or swirled pattern, or an outline labeled Tailings: finely crushed waste left over from processing ore. It can contain heavy metals.
Mine dump
A tan tint or pattern: piles of waste rock, usually right next to a shaft or tunnel.
Former disposal site or mine
A tan tint: a former mine or disposal site, often reclaimed.
Power lines and pipelines
Utility lines cut long, straight corridors across the land, which makes them easy landmarks.
Power transmission line; pole; tower
A thin line with dots for poles and small squares for towers: an electric transmission line. The cleared corridor beneath it is easy to spot from a ridge.
Telephone line
A dashed line, often labeled Telephone.
Aboveground pipeline
A solid line: an aboveground pipeline for oil, gas, or water.
Underground pipeline
A dashed line labeled Pipeline: a buried pipeline, usually marked on the ground by signs and a cleared strip.
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- Stay out, stay alive. Never enter an old mine. Bad air, rotten timbers, and hidden shafts kill explorers every year.
- Respect cave closures. Many caves are closed to protect bats from white-nose syndrome or require permits. Check with the land manager.
- Use historic maps for history. Older maps often show mines, mills, and camps that later editions dropped, which is perfect for finding ghost towns.
- Utility corridors make good handrails. Power lines run straight and are easy to see, but don't count on a usable trail beneath them.
PUT IT TO USE
See these symbols on a real map
Frequently asked questions
What's the difference between a mine shaft and a mine tunnel on a topo map?
A mine shaft is vertical and shown as a half-black square. A mine tunnel, or adit, goes into a hillside horizontally and is shown as a line ending in a Y.
Are mines on topo maps still active?
Some are, but many are abandoned. The map doesn't say which. Assume any mine site may be private property and dangerous.
How are caves shown on a topo map?
Cave entrances use the same symbol as mine tunnels, a line ending in a Y, usually with the cave's name.
What does a small X mean on a topo map?
On its own, a small X is a prospect: a test pit or small mine digging. An X with a number next to it is a spot elevation.
MORE SYMBOL GUIDES
Vegetation & Surface Symbols: What Green Means on a Topo Map · Building, Campground & Landmark Symbols on Topo Maps · Road, Trail & Railroad Symbols on Topo Maps
← Back to all USGS map symbols
Symbol artwork from the U.S. Geological Survey Topographic Map Symbols brochure (public domain).