An Etymological Dictionary of Astronomy and Astrophysics
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The current geologic era on Mars that began around 2 billion to 3 billion years ago. It is characterized by lower geologic activity such as volcanism and only occasional releases of underground water. A dry environment with a very thin atmosphere in which water can only exist as a solid or a gas, not as a liquid. → Noachian era; → Hesperian era.

Named for the young lava-covered plains called Amazonia Planitia. → era.