Marl Slate Formation

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]