Flagstone walls are a common feature of the Caithness landscape. The rocks of this area are mostly sandstones and they split easily into slabs. At one time flagstones were being exported to pave the streets of cities all over the world.
The flags also make good wind-proof walls if they are set upright in the ground.
Sadly, they are being replaced with modern wire fencing and many, like this one, are falling into disrepair.