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.