Oceans on Mars formed 300 million years earlier than first thought, according to a new study.
Research suggests the planet’s water systems appeared after a series of massive volcanic eruptions permanently altered the planet’s surface around 4 billion years ago.
The formation of Mars’s oceans was linked to the violent rise of Tharsis, a 3,000-mile- (5,000km)-wide string of volcanoes that make up the solar system’s largest volcanic system.
Tharsis likely spewed gases into the atmosphere that created a global warming or greenhouse effect, which allowed liquid water to exist on the planet.
Nearly a third of the surface of Mars was covered by oceans of liquid water early in the planet’s geological history, but how they formed has largely remained a mystery.
To explore how the planet’s ancient shorelines changed over time, researchers at the University of California, Berkeley, examined images from early Mars orbiter missions.
Previously researchers believed Mars’s oceans appeared long after Tharsis formed during a huge outpouring of lava from the planet’s surface 3.7 billion years ago.
But a new model proposes that the oceans formed at the same time or even hundreds of millions of years before the volcanic system sprung to life.
After they appeared, these vast water systems evolved together, shaping the climate history of Mars, researchers said.
Study lead author and UC Berkeley scientist Dr Michael Manga said: ‘The assumption was that Tharsis formed quickly and early, rather than gradually, and that the oceans came later.
‘We’re saying that the oceans predate and accompany the lava outpourings that made Tharsis.
‘Volcanoes may be important in creating the conditions for Mars to be wet.’
Eruptions triggered by the volcanic system also created channels that allowed underground water to reach the surface and fill the northern plains, Dr Manga said.
Shoreline-like features seen on Mars hint that oceans may once have filled the red planet’s northern lowlands.
Dr Manga told MailOnline: ‘The elevations of the shorelines vary by several kilometres over the lengths of the shorelines.
‘This is unexpected because a shoreline should follow a constant line of elevation, or sea level. We were looking for an explanation on what could have deformed the shorelines since their formation.’
The team suggest that the oceans formed with a constant line of elevation but were later deformed by the appearance of Tharsis.
The growing volcano would have depressed the land and deformed the shoreline over time, which could explain the irregular heights of some shorelines.
Older shorelines, such as those created by the planet’s Arabia ocean, show these deformations, while bodies of water that formed after Tharsis, such as Deuteronilus, do not show these changes, the team said.
Dr Manga told MailOnline: ‘Loading from the formation of the Tharsis volcanoes changes the shape of the planet, so a shoreline that formed before a portion of the Tharsis volcanoes would be deformed by any subsequent loads from later growth.
‘The present day elevation changes of the shorelines suggest the younger Deuteronilus shoreline formed during the late stages of Tharsis, and the older Arabia shoreline formed before or during the early stages of Tharsis.’
