# Contour lines

1. Jan 2021
1 von 6

### Contour lines

• 1. Contour Lines
• 2. Contour Lines •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 of slopes.
• 3. Contour Lines •The ability to understand the shape of the ground from a map is a useful skill to learn. •The height and shape of the ground is shown on 1:25 000 scale maps by brown contour lines. •A contour is a line drawn on a map that joins points of equal height above sea level. •1:25 000 scale maps the interval between contours is usually 5 metres, although in mountainous regions it may well be 10 metres.
• 4. Contour Lines •The diagram shows the link between the shape of a hill and the contours representing it on a map. •Another way of thinking about contour lines is as a tide mark left by the sea as the tide goes out, leaving a line every 5 metres.
• 5. Contour Lines • To make topographic maps easier to read, every fifth contour line is an index contour. • Because it's impractical to mark the elevation of every contour line on the map, the index contour lines are the only ones labelled. • The index contours are a darker or wider brown line in comparison to the regular contour lines. • You'll see the elevations marked on the index contour lines only. • To determine elevations, pay attention to the amount of space in between lines. • If the contours are close together, you're looking at a steep slope. • If the contours have wide spaces in between (or aren't there at all) the terrain is relatively flat.
• 6. Contour Lines • Ordnance Survey maps use contour lines to join points of equal height together. • Understanding contours is a very useful navigation skill because you can identify the lay of the land and landscape features as they appear on the ground. • They tell you whether the ground is flat, hilly or steep, and whether a route will be a gentle easy walk or a hard uphill slog.