When was plate tectonics discovered?

I think it was in 1912 that Alfred Wegner, from Germany, proposed the idea of continental drift and followed up on this idea in 1915 with his book "The Origin of Continents and Oceans". The established scientific community scoffed at the theory since there was no way to confirm such ideas at the time.

In the 1920's, English Geologist Artur Holmes proposed that the continental seams, or junctions, lay at the bottom of the oceans. Again, unconfirmable at the time.

Sometime in the mid 1950's the discovery of variable magnetic field directions, in rocks of different ages, became the first evidence that crust plates did move about. That discovery led to the acceptance of Wegner and Holmes work and the main stream scientific community jumped on the plate tectonics band wagon.

Deep sea research in the 60's aided in the development of Plate Tectonics and by the end of the 60's, as we were landing on the moon, the Theory of Plate Tectonics became universally accepted.