What are contour lines?

Contour lines are lines drawn on a map that connect points of equal elevation above a given level, such as sea level. They are used in topographic maps to represent the three-dimensional shape of the terrain in a two-dimensional format. Here are some key features of contour lines: 1. **Elevation Representation**: Each contour line represents a specific elevation. For example, a contour line labeled "100" indicates that all points along that line are at an elevation of 100 units above sea level. 2. **Spacing**: The distance between contour lines indicates the steepness of the terrain. Closely spaced lines indicate steep slopes, while widely spaced lines indicate gentle slopes. 3. **Closed Loops**: Contour lines often form closed loops. If the elevation increases as you move inward, the loop represents a hill or a mountain. If the elevation decreases, it represents a depression or a valley. 4. **Index Contours**: Some contour lines are thicker and labeled with their elevation, known as index contours. These help to make the map easier to read. 5. **No Crossings**: Contour lines never cross each other, as this would imply that a single point has two different elevations, which is not possible. Contour lines are essential for understanding the topography of an area, aiding in navigation, land use planning, and various scientific applications.