How to Read Topography

Reading a topographic map may take some adjustment because it is not the same as reading a conventional road map. Topographic maps are two dimensions that represent three dimensions. The third dimension is represented with lines that show the elevations and contours of a particular region. Contours usually represent valleys, hills, mountains, and rivers. When you can read and understand these contour lines, you will have a three-dimensional spatial representation of the geological formations represented on the map.

Difficulty: Moderately Easy

Instructions

1. Read the contour lines. A single contour line is of equal elevation all the way along it. Some maps will note the elevation on each contour line. You can use these elevations to figure out how many feet of elevation change are between each contour line. For example, if one line is 100 feet and the next line above it is 150 feet you know the space between each line is a change in elevation of 50 feet. How close the contour lines are to one another represents how steep this region is. If lines converge, this represents a cliff. If lines are widely spaced, then this represents a gentle slope.

2. Notice the loops that are produced by the contour lines. As a general rule of thumb, the inside of a contour line represents uphill while the outside of a contour line represents downhill.

3. A topographic map should have a base elevation on the map legend. Always read this elevation in the map key. If the base elevation is 4000 feet, then a line that reads 200 actually represents 4200 feet in total elevation.

4. Make sure you understand negative numbers. Any negative numbers on a topographic map represent that this region is below the base level of elevation on your map.

References

• Pictures of Topo Maps
• Topography Definition