Despite the likely increased volcanism and existence of many smaller tectonic "platelets," it has been suggested that between 4.4 and 4.3 Ga (billion year), the Earth was a water world, with little if any continental crust, an extremely turbulent atmosphere and a hydrosphere subject to intense ultraviolet (UV) light, from a T Tauri stage Sun, cosmic radiation and continued bolide impacts.
The Hadean environment would have been highly hazardous to modern life.
These gaps represent a missing period in our relative time scale.
An angular unconformity occurs when rocks are tilted, then eroded and then new sediment is deposited on top.
It happened last and we know that because all of the other layers had to have been there before the Earth faulted.