VOA慢速英语:新研究表明南极洲曾经是雨林

sediment – n. a solid substance that forms a later at the bottom of a liquid

geologist – n. a scientist who studies the history of the earth and its life, especially as recorded in rocks

preserve – v. keep something the same or keep it from being damaged or destroyed

network – n. an interconnected or interrelated chain, group, or system

clay – n. a heavy, sticky material from the earth that is made into different shapes and that becomes hard when it is baked or dried

drill – v. make holes in hard materials with a machine