Seafloor spreading is the process by which new oceanic crust is created at mid-ocean ridges and moves away from the ridge crest. It is a key component of the theory of plate tectonics, which describes the large-scale movement of Earth's lithosphere.

The theory of continental drift was proposed by Alfred Wegener in 1912. It suggests that the continents have moved over time and were once part of a single landmass called Pangaea. Wegener's theory was based on evidence such as the fit of the continents, the distribution of fossils, and the similarity of geological structures on different continents.

Seafloor spreading provides strong support for the theory of continental drift. The rocks on the ocean floor are younger near the mid-ocean ridges and older farther away. This pattern is consistent with the idea that new ocean floor is being created at the ridges and is moving away from them. The movement of the ocean floor also explains why the continents are moving. As new ocean floor is created, it pushes the continents apart.

Seafloor spreading and the theory of continental drift have revolutionized our understanding of Earth's history and dynamics. They have shown that the Earth is a dynamic planet that is constantly changing.