Quality Mountain Days
 
                                                                 & Advanced workshops


Things to remember about Contours

In 1:50000 OS maps the contour lines are 10m apart (the vertical interval).

In 1:25000 OS maps the contour lines are either 5m apart (lowland areas) or 10m apart (high ground).

In Harvey maps the contour lines are 15m apart.

In all three of these types every 5th contour line is thicker - the index contour.

Contour lines are hard to read if you are using a red light at night to preserve night vision. 

In OS maps & Harvey maps the top of the number in a contour line will be uphill. This helps to distinguish valleys from spurs.


Slopes

The closer the contour lines the steeper the ground.

Steeper ground:


 


Less steep ground:



 

A slope that is steeper at the top than at the bottom is called a concave slope. Contours are closer at the top than the bottom of the slope.

 

A slope that is steeper at the bottom than at the top is called a convex slope. These can be dangerous to descend as you may not be
able to tell - without the map - that the slope wil become too steep to walk down. Contours are more widely spaced at the top than at the bottom of the slope.

 

A slope steeper than 30 degrees will usually require hands to climb and care to descent.

A 30 degree slope has 6 index contours per 500m (1 cm on 1:50000 and 2cm on 1:25000).







Important: Participation Statement

Climbing, hillwalking and mountaineering are activities with a danger of personal injury or death.
Participants in these activities should be aware of and accept these risks and be responsible for their own actions and involvement.


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