If an oceanfloor tectonic plate meets the edge of a continent and they push against each other, the heavier one sinks down and goes under the other one.
如果一个海底构造板块与大陆边缘接触并相互挤压，较重的板块下沉到另一个的下面。
2
It all began in 1977 with the exploration of hydrothermal vents on the oceanfloor.
一切始于1977年的一次海底上深海热泉的探索。
3
More and more of this plate, the oceanfloor, would go down under the continent into the mantle.