Noachian
Noachian is a geological period and system of the Moon. It is the earliest of the four periods of the Lunar geologic timescale, following the pre-Nectarian and preceding the Eratosthenian. The Noachian epoch is defined as the time during which the youngest large impact basins formed. Its beginning is marked by the formation of the Mare Imbrium basin, and its end is defined by the formation of the Oceanus Procellarum basin. This period is characterized by intense bombardment by asteroids and comets, leading to the formation of many of the Moon's large impact craters and basins.
The Noachian period is estimated to have lasted from approximately 4.1 billion to 3.8 billion years ago.
The term "Noachian" is derived from Noah, the biblical figure associated with a great flood, reflecting the