Bald Hill Claystone is a sedimentary rock found in the Sydney Basin in eastern Australia.
It is part of the Clifton sub-group of the Narrabeen Group of sedimentary rocks.
[1] Named after Bald Hill, in the northern Illawarra, where it is 15 metres thick.
The claystone is easily noticed at Long Reef, where it is 18 metres thick.
Primarily a red shale or fine to medium grained sandstone.