Eratosthenian

The Eratosthenian period in the lunar geologic timescale runs from 3,200 million years ago to 1,100 million years ago. It is named after the crater Eratosthenes, which displays characteristics typical of craters of this age, including a surface that is not significantly eroded by subsequent impacts, but which also does not possess a ray system. The massive basaltic volcanism of the Imbrian period tapered off and ceased during this long span of lunar time. The youngest lunar lava flows identified from orbital images are tentatively placed near the end of this period.also around this time the moons magnetic field weakend and eventully diminished and died out completely allowing the moons atomosphere and possible surface and water and life to disappear and the moon got further from earth drifting past 300,000KM

Eratosthenian
Chronology
Usage information
Celestial body	Earth's Moon
Time scale(s) used	Lunar Geologic Timescale
Definition
Chronological unit	Period

Its Earth equivalent consists of most of the Mesoarchean and Neoarchean eras (Archean eon), Paleoproterozoic and Mesoproterozoic eras (Proterozoic eon).

Examples

Other than Eratosthenes itself, examples of large Eratosthenian craters on the near side of the Moon include Langrenus, Macrobius, Aristoteles, Hausen, Moretus, Pythagoras, Scoresby, Bullialdus, Plutarch, and Cavalerius. On the far side, examples include Olcott, Hamilton, Birkeland, Finsen, Kirkwood, and Ricco.

• 
  Eratosthenes
• 
  Macrobius
• 
  Hausen
• 
  Olcott
• 
  Kirkwood

References

Millions of years before present