Quick Answer
Understanding contour lines is crucial for predicting elevation changes and navigating terrain. Contours help you visualize the landscape, identify potential hazards, and make informed decisions about route planning and shelter selection. Accurate interpretation of contour lines can be a matter of life and death in wilderness survival situations.
Understanding Contour Lines
Contour lines are imaginary lines on a map that connect points of equal elevation. The contour interval, or the distance between each contour line, indicates the change in elevation between adjacent lines. For example, a contour interval of 20 feet means that the elevation changes 20 feet between each contour line.
Reading Contour Lines
To read contour lines effectively, start by identifying the contour interval on the map legend. Look for the smallest contour interval, which is usually denoted by a label such as “20 ft” or “10 m”. Then, locate a contour line on the map and measure the distance between it and the next contour line. Multiply this distance by the contour interval to determine the elevation change between the two lines. For instance, if the contour interval is 20 feet and the distance between two contour lines is 1 inch, the elevation change is 40 feet (20 feet x 2 inches).
Scaling Contour Lines
To accurately measure distances and elevation changes, it’s essential to understand the map scale. The map scale is usually denoted by a ratio, such as 1:24,000 or 1:50,000. This ratio means that 1 unit on the map represents 24,000 or 50,000 units in real life. To measure distances, use a ruler or straightedge to draw a line along the contour lines between two points. Then, use the map scale to convert the distance from inches to miles or kilometers. For example, if the map scale is 1:24,000 and the distance between two points is 2 inches, the actual distance is approximately 48,000 feet or 9.2 miles.
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