The hypothesis that was a significant contribution to the understanding of plate tectonics and provided a mechanism for how continents move and interact with each other is seafloor spreading.
Seafloor spreading is the process by which new oceanic crust is formed at mid-ocean ridges and gradually moves away from the ridge, allowing the continents to drift apart. This mechanism explains how the Earth's lithosphere is divided into tectonic plates that float on the semi-fluid asthenosphere beneath them. As the seafloor spreads, it also helps to account for the movement of continents and contributes to the understanding of various geological phenomena, such as earthquakes and volcanic activity, occurring along plate boundaries.
This concept was integral in developing the broader theory of plate tectonics, which describes the large-scale motions of plates and their interactions.