Reading Contour Lines on a Topographic Map
Contour lines turn a flat sheet of paper into a picture of the land's shape. Each line connects points of equal elevation. With some practice you can see steep climbs, gentle valleys and likely water sources before you leave home.
Spacing and steepness
The contour interval, printed in the map legend, is the elevation difference between neighboring lines. Lines close together mean steep ground; lines far apart mean gentle slopes. Lines that merge or nearly touch can indicate cliffs.
Index contours are drawn thicker and labeled with elevations, which makes counting easier.
Valleys, ridges and peaks
Contours form V or U shapes where they cross valleys and ridges. In a valley or stream drainage, the point of the V faces uphill, upstream. On a ridge, the point faces downhill. Closed loops mark hills and summits, with the smallest loop at the top.
Saddles, the low points between two summits, appear as an hourglass shape between two sets of closed loops.
Practice by comparing a map with a familiar local hill; seeing how the lines match the real slopes builds intuition quickly.
Using contours to plan
Count the lines a route crosses to estimate total climbing, and look for long stretches of closely spaced lines that will slow you down. Gentle benches and saddles often make good rest points or campsites.
Compare the map with the terrain often during a hike; it builds the skill faster than any book.