The geologic time scale (GTS) is a system of chronological dating
that relates geological strata (stratigraphy) to time. It is used by
geologists, paleontologists, and other Earth scientists to describe the
timing and relationships of events that have occurred during Earth's
history.
Bombardment
The Late Heavy Bombardment (abbreviated LHB and also known as the
lunar cataclysm) is an event thought to have occurred approximately 4.1
to 3.8 billion years (Ga) ago, at a time corresponding to the Neohadean
and Eoarchean eras on Earth.
Layers of the Earth
The internal structure of the Earth is layered in spherical shells: an outer
silicate solid crust, a highly viscous asthenosphere and mantle, a liquid outer
core that is much less viscous than the mantle, and a solid inner core