Our transcription: The earliest Earth was vigorously convecting as it tried to get rid of heat.
The surface of the Earth at that time would have had some stiffness to it because it was colder, but as time went on that surface layer became thicker and still more stiff.
We see this process even taking place today in lava lakes, for example, on The Big Island of Hawaii.
The stiff surface layer of the Earth becomes so stiff that it breaks up into plates, and so we expect as part of the convection process of the Earth that the surface becomes a set of mobile plates, which are able to be continually created and recycled within the Earth, and this process is now known as plate tectonics.
In the earliest Earth, it must have had some similar behavior, perhaps more complicated, perhaps more dynamic, perhaps more plates, but the plate tectonic process that we now see as the guiding principle of so much of geologic evolution had its beginning right in the early history of Earth.