Final answer:
Wegener's continental drift theory was dismissed due to the lack of a mechanism explaining the movement of continents, considered too speculative at the time. With advancements in plate tectonics during the 1960s, his ideas were vindicated and became foundational in geoscience.
Step-by-step explanation:
Alfred Wegener's idea of continental drift was initially dismissed by the geosciences community due to a lack of a plausible mechanism to explain how continents could move over thousands of miles. Wegener had proposed that continents were once joined in a supercontinent named Pangaea, based on evidence such as the jigsaw-like fit of continental coastlines, fossil similarities across oceans, and geological formations extending across separate continents. However, without a clear and acceptable physical explanation for the process, most scientists at the time found the idea too revolutionary and speculative.
It wasn't until advancements in plate tectonics theory during the 1960s that Wegener's ideas became the foundation of our modern understanding of a dynamic Earth, changing how the geosciences perceived continental movement and interactions.