What did the evidence for seafloor spreading mean?

• A. It provided an explanation for Wegener's continental drift idea and it led to plate tectonics
• B. It disproved continental drift
• C. It showed continents are fixed
• D. It indicated isotropic mantle

Answer: (A)

Seafloor spreading provides a mechanism for moving the continents and the foundation for plate tectonics. The idea that new oceanic crust is created at mid-ocean ridges and then moves outward as rock cools explains how large pieces of the lithosphere could drift apart over geological time. Magnetic stripes on the seafloor, symmetric about the ridges and recording reversals, show that oceanic crust is being pushed away from the ridges as it forms, while older crust is found farther from them. This pattern aligns with a world of moving tectonic plates, on which continents ride, which is exactly how Wegener’s idea of continental drift fits into a broader, testable framework. So this evidence didn’t disprove drift; it provided the mechanism and the broader theory—plate tectonics—that makes continental movement understandable. It also isn’t about continents being fixed, and it isn’t about isotropic mantle.