Elevation and dept
Elevation and depth
Contours are one of several common methods used to denote elevation or altitude and depth on maps. From these contours, a sense of the generalterrain can be determined. They are used at a variety of scales, from large-scale engineering drawings and architectural plans, through topographic mapsup to continental-scale maps.
"Contour line" is the most common usage in cartography, but isobath for underwater depths on bathymetric maps and isohypse for elevations are also used. The process of drawing isohypse contour lines on a map is called isopletion].
In cartography, a contour interval is any space between contour lines, representing a difference in elevation between the lines. When calculated as a ratio against the map scale, a sense of the hilliness of the terrain can be derived.