Contour Interval and Steep Ground

Relief information on a map legend

This pictures shows you the symbols on a map legend that relate to relief. The legend tells you what contour interval is used, what the spot heights look like, etc. (c) Copyright Ordnance Survey Ireland

Relief information on a map legend

Relief information on a map legend

This pictures shows you the symbols on a map legend that relate to relief. The legend tells you what contour interval is used, what the spot heights look like, etc. (c) Copyright Ordnance Survey Ireland

Enlarge image

At the bottom of your Discovery Series map you will find information about relief.

This tells us that the paler colour contour lines are all 10m apart and that the darker colour contour lines are all 50m apart. These darker contour lines have the height indicated on them.

Contour Intervals explained

This picture shows how every fifth countour line is a darker colour. This makes it easier to count the contour lines when they are closely spaced, and so get an accurate picture of the landscape. (c) Copyright Ordnance Survey Ireland

Contour Intervals explained

Contour Intervals explained

This picture shows how every fifth countour line is a darker colour. This makes it easier to count the contour lines when they are closely spaced, and so get an accurate picture of the landscape. (c) Copyright Ordnance Survey Ireland

Enlarge image

For example, look at the darker contour lines on Luggala or Fancy Mountain.

Note how they increase from 400m above sea level to 450m and then 500m.

They are increasing by 50m each time.

If you count the paler lines between the 400m and the 450m contour lines you will see there are four and they represent, 410m, 420m, 430m and 440m which brings us to the next 450m darker contour line.

Contour Lines close together

Example of contour lines as shown on a map. The example is Scarr mountain in Wicklow, which has quite steep sides - hence the contour lines are are close together. (c) Copyright Ordnance Survey Ireland

Contour Lines close together

Contour Lines close together

Example of contour lines as shown on a map. The example is Scarr mountain in Wicklow, which has quite steep sides - hence the contour lines are are close together. (c) Copyright Ordnance Survey Ireland

Enlarge image

Contour lines on maps give us much useful information.

In this section of map, note how close together the contour lines are on the outlined area of Scarr Mountain.

This means that the ground here is steep.

Wider spaced contour lines to indicate less steep ground

Example of wider spaced contour lines to indicate less steep ground on a section of map. (c) Copyright Ordnance Survey Ireland

Wider spaced contour lines to indicate less steep ground

Wider spaced contour lines to indicate less steep ground

Example of wider spaced contour lines to indicate less steep ground on a section of map. (c) Copyright Ordnance Survey Ireland

Enlarge image

In this example the contour lines in the highlighted area are further apart.

This means that the ground is less steep.

Can you spot other less steep areas on the rest of the map?

What sort of ground would you expect to find between the points marked Rock Art and Oldbridge on this map?

How a cliff is shown on a map

Example of how a cliff is shown on a map.The cliff shown is on Luggala in the Wicklow Mountains.The contour lines are very close together. (c) Copyright Ordnance Survey Ireland

How a cliff is shown on a map

How a cliff is shown on a map

Example of how a cliff is shown on a map.The cliff shown is on Luggala in the Wicklow Mountains.The contour lines are very close together. (c) Copyright Ordnance Survey Ireland

Enlarge image

Contour lines which are very close together indicate that there is a very steep section such as a cliff in that area and that extra care should be taken especially in conditions of poor visibility such as fog or mist.