Hashiura Group
Geology
Formations: Arato (2), Aratozaki (2)
Lithologies: "shale" (2), sandstone (4), conglomerate (2)
Paleoenvironments: marine indet. (4)
Age range: base of the Early/Lower Bajocian to the top of the Oxfordian or 170.90000 to 154.80000 Ma