<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 line joining points of equal elevation is known as
the line joining points of equal elevation is known as
contour line
contour line