Griman Creek Formation

Griman Creek Formation
Stratigraphic range: late Albian-early-mid Cenomanian ~106–98 Ma PreꞒ Ꞓ O S D C P T J K Pg N
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 / -29.4; 147.7
Approximate paleocoordinates	64°24′S 134°54′E / 64.4°S 134.9°E / -64.4; 134.9
Region	Queensland  New South Wales
Country	Australia
Extent	Surat Basin
Type section
Named for	Griman Creek
Named by	Reiser
Year defined	1970
Griman Creek Formation (Australia)

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.^[1] 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.^[2]