Question

why was Alfred Wegners theory not accepted

Answer 1

When it was proposed, there was no mechanism described that could move the continents. Following World War II, more information was gathered that showed the oceanic crust was much newer than continental crust and that spreading was driven from ridges in the middle of the ocean crust. Furthermore, more seismic data showed that the oceanic crust was also destroyed, thus the surface of the earth was of approximately constant size.

Answer 2

Alfred Wegners theory was not accepted because he had no mechanism to drive the movement of the continents.