And when this was a level ocean floor, the shells of clams and crustaceans and things settled down over the millennia and formed a cemented layer, which is called a hard-pan layer.

远古时期这里是平坦的海底，蛤蜊和甲壳类动物的壳经过几千年的沉淀，形成了一个胶结层，而这被称为硬盘层。