The chalk itself's composed by plankton which has fallen down from the sea surface onto the sea floor, so that 90 percent of the sediment here is skeleton of living stuff, and then you have that millimeter-thick red layer, and then you have black rock.
这种白垩粉本身由从海面跌落海底的 浮游生物组成。 所以这种沉淀物90%的成分是活物的尸体， 接着你就看到了毫米厚的红色土层， 然后是黑色岩石。