Borgundaberget is a typical table mountain, characterised by a number of Cambro-Silurian layers with a protective dolerite cap on top. The plateau itself is essentially flat and marked by smaller drops and steep slopes to the west, north, and east. The plateau is covered by old broadleaf woodland very rich in dead wood. Birch, aspen, and goat willow dominates, but there is also spruce, whitebeam, wild cherry, ash, oak, rowan, pine, elm, and wild apple. There is a very rich wood fungi flora with several red-listed species tied to the naturally dead wood. Hazel grows in abundance across most of the area.
The rocky escarpments have high natural values tied to the woodland ecosystems with their partially very old trees. In some parts of the escarpments, the boulders are continually wetted by moisture and water, enabling thick moss to spread out over the stones and tree trunks.