Marl Slate Formation

The Marl Slate Formation is a geological formation in England. Despite its name, it is mostly dolomite rock. 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. This formation is part of the Zechstein Group of rocks. The Marl Slate Formation contains fossils including the conodont "Mesogondolella britannica" and the dorypterid fishes "Dorypterus" and "Lekanichthys". The Marl Slate Formation outcrops in north-east England, for example in Yorkshire. 