At 10.2 kilometres in from the turnoff from the Outback Hwy into Parachilna Gorge, the geological boundary between Precambrian period and Cambrian period sediments can be sighted.
To the south of the road, a prominent outcrop of Rawnsley Quartzite marks the Precambrian layer. At the base of the western slope can be found the Precambrian / Cambrian boundary.
Ripple marks in the quartzite can be seen at the geological boundary.
