These Grinding Grooves have been made in a fine grained sand stone rock.
They are unusual because they are under an overhang with no pools of water close by.
During wet weather, water from the top of Mt Bungin drips over the edge of the overhang.
There are a number of overhangs in the region with a grinding groove close by an overhang.
Kanangra Tops (Dunphy)
Kanangra-Boyd National Park (NSW)