| Wombarra Claystone | |
| Period: | Triassic & Permian |
| Age: | late Permian to early Triassic |
| Type: | Geological formation |
| Otherlithology: | quartz-lithic sandstone |
| Unitof: | Narrabeen Group |
| Underlies: | Scarborough Sandstone |
| Overlies: | Bulli Coal |
| Thickness: | up to 30m (100feet) |
| Region: | New South Wales |
| Extent: | Sydney Basin |
| Namedfor: | Wombarra, New South Wales |
| Location Ts: | Illawarra |
| Country Ts: | Australia |
Wombarra Claystone is a geologic formation in the Sydney Basin in eastern Australia. Commonly seen in the Illawarra region, this stratum is up to 30 metres thick. Formed in the late Permian to the early Triassic, it is part of the Narrabeen Group of sedimentary rocks. This formation includes grey shale, and minor quartz-lithic sandstone.[1] [2]