短语词组短語ripple -mark wave length 波痕波長superimposed ripple -mark 疊加波痕ripple mark -like structure 波痕狀搆造hexagonal cross -ripple mark 六方交錯波痕flat -topped ripple mark 平頂波痕mud -ridge ripple mark 泥嶺漣痕 返回 ripple mark