The Earth’s oldest surface layer forming continents, termed its crust, is approximately 4 billion years old and is comprised of 25–50km-thick volcanic rocks known as basalts. Originally, scientists thought that one complete lithospheric crust covered the entire planet, compared to the individual plates we see today which were believed to have only begun formation 1 billion years later. However, attitudes towards this hypothesis are being challenged.
Click here for original story, Plate tectonics 4 billion years ago may have helped initiate life on Earth
Source: Phys.org