SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/scout-contours-never-cross

Why do contour lines on a topo map never cross each other?

Each line is one exact elevation, and one spot cannot be two heights.

  1. One spot can't sit at two elevations at once ✔
  2. Mapmakers erase the crossings to keep maps neat
  3. They do cross wherever two trails meet

Why: A contour line marks one exact height. If two lines crossed, the crossing point would have two different elevations at once, which is impossible.

Huh, didn't know that: Narrower intermediate contours between the wide index contours fill in the shape of the land.

The dad joke
Two contour lines met at a party. They kept their distance.
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Sources

  1. USGS: Topographic Map Symbols https://pubs.usgs.gov/gip/TopographicMapSymbols/topomapsymbols.pdf

Test yourself in the game

Outdoors & CampingOn a topographic map, what does a contour line connect?Outdoors & CampingContour lines on your map are packed very close together. What does that mean?Outdoors & CampingWhat is the contour interval on a topographic map?

That's stuff everyone should know.