<P> A contour line ( also isocline , isopleth , isarithm , or equipotential curve ) of a function of two variables is a curve along which the function has a constant value , so that the curve joins points of equal value . It is a plane section of the three - dimensional graph of the function f ( x , y ) parallel to the x , y plane . In cartography , a contour line ( often just called a `` contour '' ) joins points of equal elevation ( height ) above a given level , such as mean sea level . A contour map is a map illustrated with contour lines , for example a topographic map , which thus shows valleys and hills , and the steepness or gentleness of slopes . The contour interval of a contour map is the difference in elevation between successive contour lines . </P>
<P> A contour line ( also isocline , isopleth , isarithm , or equipotential curve ) of a function of two variables is a curve along which the function has a constant value , so that the curve joins points of equal value . It is a plane section of the three - dimensional graph of the function f ( x , y ) parallel to the x , y plane . In cartography , a contour line ( often just called a `` contour '' ) joins points of equal elevation ( height ) above a given level , such as mean sea level . A contour map is a map illustrated with contour lines , for example a topographic map , which thus shows valleys and hills , and the steepness or gentleness of slopes . The contour interval of a contour map is the difference in elevation between successive contour lines . </P>
the lines that join points of equal elevation above the mean sea level are known by what name
the lines that join points of equal elevation above the mean sea level are known by what name
contour line
contour line