By studying massive ancient waterfalls on Mars, researchers from the University of Hull have identified two different Martian ocean levels within the same record.
These levels are more than 1,000m in elevation apart – meaning in the past Mars would have experienced huge fluctuations in its ocean levels.
The research shows oceans on Mars may have existed for a long time, expanding our understanding of how long Mars was a wet planet and how its water cycle may have fluctuated.
Researchers discovered knickpoints - or sharp changes in Martian river channels, like massive waterfalls on Earth – that occurred at the same elevation across the planet, showing that the rivers once flowed into oceans at the same level.
On Mars, these waterfall like knickpoints are massive – 100’s of meters in height, with some more than 5km wide.
By comparison, the Niagara falls are 60m high and up to 1km wide.
Using satellite data from Mars and computer modelling, scientists showed that these knickpoints occurring at the same elevation could not have been by chance – so must have been due to the same base or ocean level.
Tom Coulthard, Professor of Physical Geography at the University of Hull, said: “There are existing records of large oceans covering nearly half of the Northern hemisphere of Mars – which has implications for whether life sustaining conditions could have once been found there.
“But records of past oceans are based on separate geological evidence of shorelines and from old deltas of rivers draining into the oceans.
“We undertook an analysis of all major channel systems on Mars and detected sharp changes in elevation which exhibit a striking resemblance with terrestrial fluvial features, commonly termed ‘knickpoints’.
“We observed common elevations of Martian knickpoints in twelve separate channel systems draining into the Martian Northern lowlands. Numerical modeling showed that the common elevations of some of these knickpoints were not random.
“As the knickpoints are spread across the planet, we suggest that these Martian knickpoints were formed in response toa common base level or ocean level. Thus, they potentially represent a record of past ocean levels and channel activity on Mars.”