How do contour lines show elevation, slope, and relief?

A contour line is a line of 'equal height': every point on a contour is the same height above sea level.

The closer any two contour lines are the steeper the hill is: and the further apart they are the move level the ground.

If a group of contour lines suddenly move to form a V shape then the hill either has a promontory sticking out from it or a valley in it.

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