Final answer:
Wegener's theory of continental drift lacked a mechanism for how continents moved, leading to skepticism among scientists. Advances in geology and the discovery of plate tectonics in the 1960s provided the necessary evidence and mechanism, leading to the acceptance of Wegener's idea.
Step-by-step explanation:
The major weakness of Alfred Wegener's theory of continental drift was that he was unable to provide a convincing mechanism to explain how the continents moved. Despite presenting compelling evidence, such as congruent continental shapes, fossil correlations across separated continents, and evidence of past climates (paleoclimate data), Wegener's theory did not gain acceptance because it lacked an explanation for the force that could shift large landmasses over the Earth's surface. Scientists remained skeptical, adhering to the methodology of requiring robust evidence and a clear mechanism that aligns with established knowledge.
It was not until the development of the theory of plate tectonics in the 1960s—thanks to advancements in the fields of geology, oceanography, and geophysics—that scientists discovered the mechanism behind Wegener's theory, which involved rigid tectonic plates moving over the semi-fluid asthenosphere below them. Evidence such as the discovery of the mid-ocean ridge and the process of sea-floor spreading played crucial roles in explaining how continents could drift, thus validating Wegener's initial concept of a dynamic Earth.