The surface of Mars was shaped by fast and furious floods from overflowing craters, a new study suggests.
While river erosion on Earth is usually a slow process, on the red planet massive floods from overflowing crater lakes had a big role in shaping the Martian surface.
They carved deep chasms and moved vast amounts of sediment, according to the research.
The study found that the floods, which probably lasted mere weeks, eroded more than enough sediment to completely fill Lake Superior and Lake Ontario – among the largest lakes on Earth.
Lead author Tim Goudge, an assistant professor at the University of Texas Jackson School of Geosciences, said: ‘If we think about how sediment was being moved across the landscape on ancient Mars, lake breach floods were a really important process globally.
‘And this is a bit of a surprising result because they’ve been thought of as one-off anomalies for so long.’
Crater lakes were common on Mars billions of years ago when the planet had liquid water on its surface.
While some craters could hold a small sea’s worth of water, when the water became too much to hold, it would breach the edge of the crater, causing catastrophic flooding that carved river valleys in its wake.
A 2019 study led by Prof Goudge determined that these events happened rapidly.
Images taken by satellites orbiting Mars have allowed scientists to study the remains of breached Martian crater lakes.
However, the crater lakes and their river valleys have mostly been studied on an individual basis.
Researchers say this is the first study to investigate how the 262 breached lakes across the red planet shaped the Martian surface as a whole.
The scientists compared the depth, length and volume of different valley types and found that river valleys formed by crater lake breaches punch far above their weight – eroding away nearly a quarter of the planet’s river valley volume despite making up only 3% of total valley length.
Co-author Alexander Morgan, a research scientist at the US-based Planetary Science Institute, said: ‘This discrepancy is accounted for by the fact that outlet canyons are significantly deeper than other valleys.’
At 559ft (170.5 metres), the median depth of a breach river valley is more than twice that of other river valleys created more gradually over time, which have a median depth of about 254ft (77.5 metres).
The researchers suggest that although the chasms appeared in a geologic instant, they may have had a lasting effect on the surrounding landscape.
The breaches scoured canyons so deep they may have influenced the formation of other nearby river valleys, the study suggests.
This is a potential alternative explanation for unique Martian river valley topography that is usually attributed to climate, researchers say.
The study published in Nature was funded by Nasa.
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