A fence near the Indian River, Keene, Ontario
Different examples of split rail fences are seen all over Ontario. They were very practical and less work than building stone walls to enclose tracts of land especially on properties where the there was more wood than stone.
The traditional two post method isn't used in cases where the ground is too rocky, or the bedrock too close to the surface to dig post holes.
The tripod becomes the support for the rails to wedge down onto (or hang from with wires). Sometimes the tripod was four posted (quadpod?) for greater strength.
While the tripods create good vertical support than are still susceptible to sliding or even tipping. To prevent this, heavy rocks are sometimes placed on the upper "V"crotch of each tripod to add extra weight and cause the feet of the tripod to spread even more, creating a wider stable base.
It is interesting that even where there is a lot of wood available and wooden fencing has been chosen over stone fencing, rocks still play an important role.