Why Are Contour Lines Important on Topographic Maps?

Understanding Contour Lines

Contour lines are imaginary lines that connect points of equal elevation on a topographic map. They are typically represented by solid lines, and the spacing between them indicates the steepness of the terrain. A closer spacing between lines indicates a steeper slope, while a wider spacing indicates a gentler slope. For example, a contour interval of 20 feet between lines means that every line represents a 20-foot change in elevation.

Reading Contour Lines for Navigation

When reading contour lines for navigation, it’s essential to understand the direction of slope and the shape of the terrain. This can be done by looking for the shape of the contour lines and the direction of the arrows that indicate the direction of slope. For example, if the contour lines are forming a “V” shape, it indicates a steeper slope, while a “U” shape indicates a gentler slope. By understanding the direction of slope and the shape of the terrain, you can make more informed decisions about which route to take.

Using Contour Lines with a Compass

When using a compass, it’s essential to take into account the declination, which is the difference between magnetic north and true north. This can be found on the map or by consulting a declination chart. Once you’ve accounted for declination, you can use the contour lines to help you navigate. For example, if you’re trying to find a peak that’s marked on the map, you can use the contour lines to help you identify the direction of the peak and navigate towards it. By combining contour lines with declination and compass readings, you can make more accurate navigation decisions and avoid getting lost.