Question

With the oldest rock on Earth be at the outer edges of oceanic crust

Answer 1

The oldest rocks on Earth are not typically found at the outer edges of oceanic crust, but rather in continental crust. The oldest known rocks are found in areas known as cratons, which are stable portions of the continental crust. The oldest intact rock formations are found in places like the Acasta Gneiss in Canada, which is about 4.031 billion years old, and the Nuvvuagittuq Greenstone Belt, also in Canada, which may be up to 4.28 billion years old.

Oceanic crust, which is formed at mid-ocean ridges and continually recycled through subduction at tectonic plate boundaries, is generally younger than continental crust. The oldest oceanic crust is found near subduction zones, but even that is typically only around 200 million years old. This is due to the constant renewal process of the ocean floor, which is subject to seafloor spreading and tectonic activity.

In summary, the oldest rocks are located in continental regions, while oceanic crust is predominantly much younger.