Virtual course: Control #11

This is where this virtual trail orienteering starts to get technical! As a foot orienteer you will be familiar with some rock faces being marked on the map and some not. The IOF recommended minimum for the height of a mapped rock face is 1m. This means that a tapering height rock face is only mapped where its height exceeds 1m. Such a rock face appears longer in the terrain than on the map. This is generally of little significance in foot orienteering but is much more important in trail orienteering.

Consider the example in the photograph. The control description has no flag position information in Column G. The default position is therefore the rock face foot at the middle point of its mapped length. At first sight this appears to be marked by Flag B.

However, using the size of the marker flags as a guide (30cm square), it can be seen that the right hand flag marks the point where the rock face height falls below 1m. The mid point between this and the left hand end (which is over 1m) is Flag A – the correct answer.

Solution: Flag A.