Final answer:
Early 20th century geologists strongly disagreed with Wegener's continental drift theory due to the absence of a clear mechanism, despite his extensive evidence. It was only after the development of plate tectonics that his hypothesis was validated.
Step-by-step explanation:
Geologists from the early 20th century strongly disagreed with Alfred Wegener's proposal of continental drift. Wegener conceived the idea of continental drift by noticing the congruence in the shapes of continents, and after thorough research, he published his findings in 1915. Despite presenting extensive evidence, such as the similarities between fossils in South America and Africa which implied past continental connections, he was unable to provide a solid mechanism to explain how continents could move, leading to skepticism and rejection from the scientific community of his time.
Wegener continued his research despite the resistance and was appointed to a professorship in meteorology and geophysics. However, it was not until the development of the theory of plate tectonics several decades later that the mechanism behind continental drift was understood, validating Wegener's hypothesis and establishing it as a fundamental principle of geology.