Who proposed the theory of seafloor spreading?

Harry Hess proposed the theory of seafloor spreading, which is a fundamental concept in plate tectonics. He introduced this idea during the early 1960s, suggesting that new oceanic crust is formed at mid-ocean ridges and then gradually moves away from the ridge, effectively explaining how continents drift apart.

Hess's work built upon previous research and directly contributed to our understanding of the ocean floor and the processes that shape it. His research integrated concepts of mantle convection and the movement of tectonic plates, providing a clear mechanism for the continuous renewal of oceanic crust and the dynamic nature of Earth's surface.

In contrast, the other individuals mentioned each contributed to different aspects of geology and plate tectonics. Arthur Holmes focused on radioactive dating and the theory of continental drift, Alfred Wegener is known for proposing the theory of continental drift, suggesting the continents were once joined (Pangaea) but did not specifically explain the mechanisms like seafloor spreading, and J. Tuzo Wilson introduced the concept of transform faults and helped further the understanding of plate dynamics but did not propose seafloor spreading. Hence, Hess’s specific contribution is recognized as the initiation of the seafloor spreading theory.