A topo map's core feature is contour lines — each one connects points of equal elevation. Learning to read their spacing tells you the shape of terrain before you ever see it.
- Lines close together = steep terrain. Lines far apart = gentle slope or flat ground.
- Concentric closed loops = a hill or peak (check the elevation numbers to know if you're reading a summit or a depression — depressions are marked with tick marks pointing inward, called hachures).
- V-shapes pointing uphill = a valley or drainage, often where water — and potentially a stream — runs.
- V-shapes pointing downhill = a ridge or spur.
The contour interval (stated in the map legend, e.g. "40 ft") tells you the elevation change between each line — count lines between two points and multiply by the interval to get elevation gain.
Cross-reference contour shape with the map's other symbols (blue lines for water, green shading for forest cover) to build a full mental picture of terrain before you commit to a route — especially useful for spotting cliffs, avoiding unnecessary elevation gain, and finding water sources.