These dark, fossiliferous Mudstones were deposited in slow moving water associated with sedimentary basins & continental shelves. They are rich in carbon which makes them almost black. This is typical of an anoxic, reducing environment such as deep water or stagnant conditions where carbon rich material would remain unoxidised during subsequent deposition & diagenesis. These examples are from the Jurassic strata of the Yorkshire Coast. They contain fossil bivalves, ammonites, belemnites & bioturbation traces. Some are pyritised which is another indicator of the anaerobic environment of deposition. Specimens are provided in labelled card trays.