Quick Answer
Contour lines on a map reveal the steepness of terrain by representing the shape and elevation of the land. A dense cluster of contour lines indicates a steep slope, while widely spaced lines suggest a gentler slope. The closer the contour lines, the steeper the terrain.
Understanding Contour Lines
Contour lines are imaginary lines on a map that connect points of equal elevation. They are used to represent the shape and elevation of the land, helping navigation and understanding terrain steepness. The distance between contour lines represents the difference in elevation between them. For example, a contour line interval of 20 feet (6 meters) means that each line represents a 20-foot (6-meter) change in elevation.
Reading Contour Lines for Terrain Steepness
To read contour lines for terrain steepness, focus on the spacing between lines. A dense cluster of contour lines (less than 100 feet or 30 meters apart) indicates a steep slope. Conversely, widely spaced lines (more than 500 feet or 150 meters apart) suggest a gentler slope. Additionally, look for contour lines that converge, indicating a steep slope. If contour lines are parallel, the terrain is relatively flat.
Techniques for Using Contour Lines
When navigating with a map, use contour lines to identify potential hazards such as steep cliffs, gorges, and water sources. To estimate the steepness of a slope, measure the distance between contour lines and compare it to the contour line interval. For example, if the contour line interval is 20 feet (6 meters) and the distance between lines is 60 feet (18 meters), the slope is approximately 3 times steeper than the contour line interval. This technique helps you anticipate terrain difficulties and plan your route accordingly.
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