The Eridania basin of southern Mars is believed to have held a sea about 3.7 billion years ago, with seafloor deposits likely resulting from underwater hydrothermal activity. This graphic shows estimated depths of water in that ancient sea. | NASA/JPL-Caltech/MSSS

Well-Preserved Hydrothermal Deposits on Mars Offer a Window Into Early Earth

Data from the Red Planet shows that conditions in the Eridania basin of Mars once resembled those on Earth when life first emerged billions of years ago.

This view of a portion of the Eridania region of southern Mars shows fractured, dismembered blocks of deep-basin deposits that have been surrounded and partially buried by younger volcanic deposits. | NASA/JPL-Caltech/MSSS
This diagram illustrates an interpretation for the origin of some deposits in the Eridania basin of southern Mars as resulting from seafloor hydrothermal activity more than 3 billion years ago. | NASA