Final answer:
The main weakness of Wegener's continental drift theory was its lack of a plausible mechanism and insufficient empirical evidence.
Step-by-step explanation:
Alfred Wegener's continental drift theory, proposed in 1912, articulated the idea that the continents once formed a single landmass, broke up, and drifted to their present locations. The main weakness of the theory was its lack of a plausible mechanism. While Wegener suggested the continents pushed through the ocean crust, present-day understanding based on tectonic plates is contrary to this. Additionally, Wegener's continental drift theory was not able to provide sufficient empirical evidence to support its claims, leading to skepticism in the scientific community. Due to these weaknesses, it was only with the emergence of the plate tectonic theory in the 1960s that the idea of moving continents became widely accepted.
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