How would the age of the oldest rocks on the continents compare with the age of oldest rocks on the seafloor?

1 Answer
Feb 11, 2017

The oldest sedimentary layers on the continents are much older than the oldest sediments in the ocean.


The ocean sediments accumulate as the ocean plate move away from the mid ocean ridges at the divergent boundaries The oldest ocean sediments are destroyed at the convergent boundaries where the subduction zones push the ocean sediments back into the mantle.

The sedimentary and igneous rocks on the continents are preserved at the convergent boundaries as the continental plates are lifted up over the sub ducting ocean plates. So there are rock layers on the continents that are much older than any existing ocean layers.

The question is how did the ocean layers on the continents get there with no evidence of deformation. Shallow seas on the continents with underlaying granite plates, does not seem to explain the very thick sedimentary layers on the continents.