What are the evidence of sea-floor spreading?

Fossils of the Mesosaurs, an ancient freshwater reptile found in South America and Africa, indicate that the two continents could have once been one solid continent that drifted apart. Evidence for seafloor spreading has come from fossils in South America and Africa and magnetic minerals on the ocean floor. Most basalt magmas contain abundant molten iron. As magma starts to harden into rock, iron-rich minerals solidify first.

Their crystals are pulled into alignment the Earth’s magnetic field. Once the basalt cools completely into solid rock, the alignment of the iron minerals is fixed. There are a series of invisible magnetic stripes of normal and reversed polarity in the sea floor. The pattern reflects the creation and spreading of oceanic crust along the mid-oceanic ridges.