The oceanic plate is made of denser and heavier rock, so it begins to sink down under the continental plate and into the mantle.
海洋板块是由密度更大、更重的岩石构成的，所以它开始下沉到大陆板块之下，到地幔之中。
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By 2011 scientists aboard a Japanese deep-sea drilling ship called Chikyu hope to start drilling through a thin piece of oceanic crust to reach Earth's mantle.