HAD STARTED WHEN THE PLATE TECTONICS? earth mysteries of the earth

7. HAD STARTED WHEN THE PLATE TECTONICS?

Thin plates of hardened crust flying on the Earth's surface are responsible for the beautiful sunsets and mountain of violent volcanic eruptions. Yet geologists do not know yet when the engine of plate tectonics is party. Most of the evidence has been destroyed. Only a handful of tiny mineral grains called zircons survived for 4.4 billion years, and scientists tell the story of the first continental rocks that already existed. But the evidence for plate tectonics is controversial. And geologists still wonder how it originated the continental crust.