Final answer:
Many scientists rejected Wegener's hypothesis of continental drift because he did not have a clear mechanism to explain the process. However, with advancements in geology, oceanography, and geophysics, the mechanism of plate tectonics was developed and Wegener's hypothesis became widely accepted.
Step-by-step explanation:
Wegener's suggestion of continental drift was initially rejected by many scientists because he lacked a clear mechanism to explain how solid continents could drift over thousands of miles. Scientists in his time were skeptical and needed more evidence that would fit with their understanding of nature. It wasn't until decades later, with further progress in fields like geology, oceanography, and geophysics, that the mechanism of plate tectonics was developed and Wegener's hypothesis gained widespread acceptance.