Understanding topographic maps

Once you know how to read a topo map, you can tell the shape of a hill just by looking carefully at the map and thinking.

Vertical distances on a map

What do all those curves mean on a topo map?

On a topographic map, lines (actually curves; they're not usually straight) connect places that have the same elevation, or height above sea level. If one of these lines were painted on a hill and you walked along it, you would stay at the same elevation. You wouldn't go up or down, though you would probably turn right and left.

Some of the curves have numbers marked; these tell you the elevation of all places along that curve. The lines with numbers are usually darker or thicker than the other lines.

How can you tell what elevations the other curves have? Somewhere on the map is information about the contour interval. A "contour" is a curve on a surface, including the curves on our hill. Interval means the distance between two contours. In this case, it's the vertical distance between two contours. So if one curve as elevation 800 m, and the contour interval is 10 m, the next higher contour has elevation 810 m, and the next lower contour haion 810 m, and the next lower contour has elevation 790 m.

Horizontal distances on a map

To tell how you far you would have to travel to get from one point to another, use the scale of the map.

Here is project involving making a model of a hill from a topo map to help you learn to read topo maps.

Here are some questions about steepness on topo maps to help you check your understanding.