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Geologic time scales for Mercury, Moon, Mars, Venus, and Earth

Geologic time scales for Mercury, Moon, Mars, Venus, and Earth
Geologic time scales for Mercury, Moon, Mars, Venus, and Earth The geologic histories of terrestrial planets are divided into time periods based on key events in each planet's history. For all but Earth, the time period boundaries are based on major impact or volcanic events. They are tied to specific chronological years based on crater counting, but for places other than Earth and the Moon, there is a lot of uncertainty about absolute ages of each geologic era. Jean-Pierre williams