Final answer:
Robert Dietz and Harry Hess made significant contributions to the theory of seafloor spreading, which provided the mechanism for Alfred Wegener's continental drift, leading to widespread acceptance of plate tectonics.
Step-by-step explanation:
Robert Dietz and Harry Hess were pivotal figures in developing the theory of seafloor spreading. In the 1960s, building upon the foundational ideas of continental drift postulated by Alfred Wegener, Harry Hess proposed that new ocean crust is created at mid-ocean ridges and spreads outwards.
This was a crucial element in understanding the mechanism of Wegener's continental drift, which lacked a convincing explanation for the movement of continents.
Robert Dietz also contributed to this theory by coining the term 'seafloor spreading' and was part of the research that supported these concepts, bringing together observational evidence like magnetic anomalies on the ocean floor that matched on opposite sides of the ridges.
However, it wasn't until technological advancements, such as deep-sea drilling which revealed symmetrical bands of rock of alternating magnetic polarity on either side of the mid-ocean ridges, that the theory gained widespread acceptance amongst the scientific community.