It is the lowermost unit in the Marree Subgroup, overlying the Cadna-owie Formation and is overlain by the Coorikiana Sandstone. The formation dates to the Aptian to Albian stages of the Early Cretaceous.[3] The Bulldog Shale is composed of finely laminatedcarbonaceous and pyritic mudstone and claystone beds. Weathering has caused heavy leaching and bleaching in some regions of the Bulldog Shale, including those around Coober Pedy, so that the rocks are white or multicolored. These horizons contain rich opal deposits. Horizons without this bleaching are primarily composed of organic-rich shale. Gypsum, in addition to carbonatelimestoneconcretions rich in fossils are common in these unbleached shaly horizons.[4]
B. P. Kear. 2007. A juvenile pliosauroid plesiosaur (Reptilia: Sauropterygia) from the Lower Cretaceous of South Australia. Journal of Paleontology 81(1):154-162
R. E. Molnar. 1991. Fossil reptiles in Australia. In P. Vickers-Rich, J. M. Monaghan, R. F. Baird, & T. H. Rich (eds.), Vertebrate Paleontology of Australasia 605-702
R. E. Molnar. 1980. Australian late Mesozoic continental tetrapods: some implications. Mémoires de la Société Géologique de France, Nouvelle Série 139:131-143