Answer:
Several types of evidence supported Hess's theory of sea-floor spreading: eruptions of molten material, magnetic stripes in the rock of the ocean floor, and the ages of the rocks themselves.
Step-by-step explanation:
Sea-floor spreading occurs when the sea floor spreads apart along divergent boundaries and forms the mid-ocean ridge. Magma is pushed up through cracks in the crust along the mid-ocean ridge. As the magma is thrust up and hardens it forms new crust and the ocean floor on both sides of the mid-ocean ridge move outward.