Older parts of the surface slide under newer plates to be recycled in the Earth’s core.
Coincidentally, this is the same age as the rest of the planets in the Solar System, as well as the Sun.
At some point in the early history of Earth, a planetoid the size of Mars crashed into our planet.
The resulting collision sent debris into orbit that eventually became the Moon.
Small particles of dust collected together into larger and larger objects – pebbles, rocks, boulders, etc – until there were many planetoids in the Solar System.
These planetoids collided together and eventually enough came together to become Earth-sized.
Of course, it’s not a coincidence; the Sun and the planets all formed together from a diffuse cloud of hydrogen billions of years ago.
In the early Solar System, all of the planets formed in the solar nebula; the remnants left over from the formation of the Sun.
How do scientists know Earth is 4.54 billion years old?
It’s actually difficult to tell from the surface of the planet alone, since plate tectonics constantly reshape its surface.