* Contour lines connect points of equal elevation. Imagine a landscape sliced by a series of horizontal planes. Each plane intersects the land at a specific elevation, and the contour line traces that intersection.
* Closely spaced contour lines indicate steep slopes. When the elevation changes rapidly over a short distance, the contour lines will be close together.
* Widely spaced contour lines indicate gentle slopes. When the elevation changes slowly over a longer distance, the contour lines will be farther apart.
* Contour lines never cross. If they did, it would mean that two different elevations exist at the same point, which is impossible.
* Contour lines follow the terrain. They bend, curve, and even close in on themselves to accurately represent the shape of the land.
Here are some additional details:
* Contour intervals: The difference in elevation between two adjacent contour lines is called the contour interval. This value is typically printed on the map and helps you understand the scale of the slope. For example, a contour interval of 10 feet means that each contour line represents a 10-foot change in elevation.
* Depressions: Contour lines can also be used to depict depressions in the landscape. These are shown with hachures, which are short, perpendicular lines that point uphill.
* Hilltops and valleys: Contour lines form closed loops around hilltops, and the lines that point uphill are called "spur lines." Contour lines that point downhill form a "V" shape where they converge at the lowest point of a valley.
By understanding how contour lines represent elevation and slope, you can interpret the topography of a landscape and make informed decisions about navigation, planning, and development.
