Here's a breakdown:

* Plate tectonics: The theory that the Earth's outer layer (the lithosphere) is made up of large plates that move and interact with each other.

* Divergent boundaries: The areas where these plates move apart from each other.

* Splitting apart: As plates move apart, the crust thins and eventually fractures.

This process is responsible for:

* Mid-ocean ridges: Underwater mountain ranges where new oceanic crust is formed.

* Rift valleys: Areas on land where the crust has been pulled apart, creating valleys and volcanoes.

* Seafloor spreading: The process of new oceanic crust being created at mid-ocean ridges.

So, while "splitting apart" isn't the specific geological term, divergent plate tectonics accurately describes the process.