Griman Creek Formation
| Griman Creek Formation | |
|---|---|
| Stratigraphic range: late Albian-early-mid Cenomanian ~ | |
| Type | Geological formation |
| Unit of | Rolling Downs Group |
| Sub-units | Coocoran Claystone & Wallangulla Sandstone Members |
| Underlies | Unconformity with Oligo-Miocene Cumborah Gravel |
| Overlies | Surat Siltstone, Wallumbilla Formation |
| Thickness | Up to 345 m (1,132 ft) |
| Lithology | |
| Primary | Sandstone, siltstone, mudstone |
| Other | Conglomerate, coal |
| Location | |
| Coordinates | 29°24′S 147°42′E / 29.4°S 147.7°E |
| Approximate paleocoordinates | 64°24′S 134°54′E / 64.4°S 134.9°E |
| Region | Queensland New South Wales |
| Country | Australia |
| Extent | Surat Basin |
| Type section | |
| Named for | Griman Creek |
| Named by | Reiser |
| Year defined | 1970 |
The Griman Creek Formation is a geological formation in northern New South Wales and southern Queensland, Australia whose strata date back to the Albian-Cenomanian stages of the mid-Cretaceous. It is most notable being a major source of opal, found near the town of Lightning Ridge, New South Wales. Alongside the opal opalised fossils are also found, including those of dinosaurs and primitive monotremes.