| Marl Slate Formation | |
| Type: | Formation |
| Period: | Lopingian |
| Prilithology: | Dolomite |
| Region: | England |
| Country: | United Kingdom |
| Underlies: | Raisby Formation, Cadeby Formation |
| Overlies: | Yellow Sands Formation or unconformity with Carboniferous Coal Measures |
| Thickness: | To 5.48 metres |
The Marl Slate Formation is a geological formation in England. Despite its name, it is mostly dolomite rock.[1] The Marl Slate Formation was formed about 273 to 259 million years ago, during the Guadalupian and Lopingian epochs of the late Permian period of the Earth's geological history.[1] This formation is part of the Zechstein Group of rocks, and is equivalent to the Kupferschiefer of Germany.[1] The Marl Slate Formation contains fossils including the conodont Mesogondolella britannica and the dorypterid fishes Dorypterus and Lekanichthys,[2] as well as the gliding reptile Weigeltisaurus[3] and terrestrial reptile Protorosaurus[4] The Marl Slate Formation outcrops in County Durham and Yorkshire in north-east England.[1]