What are contour lines?
A contour line connects points of equal elevation on a topographic map.
Definition and processes
Core concept The difference between adjacent lines is the contour interval, stated on the map. Closely spaced contours show steeper slopes; wider spacing means gentler terrain. How it is studied Contour patterns reveal valleys, ridges and hills. A terrain profile plots line elevations against distance; the lines themselves do not physically exist on the land.
Applications and caveats
Why it matters Contouring helps plan walking routes and roads and assess drainage and flooding. Scale and interval limit the landforms a map can show. Common misunderstandings Closely packed lines alone do not mean a hill is higher; they indicate slope. Read labeled contours and the reference level for absolute elevation.