Question

inside the earth at the mid ocean ridge, where it then formed into new crust on the ocean floor. gradually it was pushed away on either side as more molten rock continued pushing up from behind it. hess called his great discovery ______. the mariana trench plate drift sea floor spreading the atlantic volcanic swarm

Explanation:

Hess's discovery related to the formation of new oceanic crust at mid - ocean ridges and its movement is known as Sea Floor Spreading. The Mariana Trench is a deep - sea trench, Plate Drift is an incorrect term (the correct term is Plate Tectonics), and The Atlantic Volcanic Swarm is not related to this discovery.

Answer:

Sea Floor Spreading