Valleys on Mars' Barren Surface Carved by Huge Floods Billions of Years Ago

Massive floods from overflowing and rupturing lakes carved deep chasms into the face of Mars during its ancient history, according to new research.

The research, led by scientists at the University of Texas (UT) at Austin, could grant insights into how the now dry network of river valleys formed across the Martian surface.

Published in the journal Nature, the findings indicate that this flooding shaped the Red Planet's geological features up until around 3.5 to 3.7 billion years ago when the planet's liquid water began to disappear.

The authors of the study, including lead author and assistant professor at the UT Jackson School of Geosciences Tim Goudge, said in a UT press release that though the floods lasted just weeks they would erode more sediment than would be needed to completely fill Lake Superior and Lake Ontario.

This means that while river erosion is usually a slow process here on Earth, it proceeded much faster billions of years ago on the Martian surface.

"When you fill [the craters] with water, it's a lot of stored energy there to be released," Goudge said in the press release. "It makes sense that Mars might tip, in this case, toward being shaped by catastrophism more than the Earth."

Water-holding craters were common when Mars had liquid water on its surface and some of these structures on the surface of the planet are large enough to hold a small sea's worth of water

When the water was too much for the craters to hold, they would breach and cause catastrophic flooding carving out river beds. Earlier research published in Geology and also authored by Goudge suggested these flooding events happened rapidly.

One example of such a breach river basin is Loire Vallis, a nearly 435-mile-long channel that is as wide as 62 miles at certain points and is often referred to by scientists as "the Grand Canyon of Mars."

While the idea of flooding on Mars carving out river basins may have been explored in the past, what is new here is the revelation of the global reach such occurrences would have had and the long-term effect on how the surface of Mars looks today.

"If we think about how sediment was being moved across the landscape on ancient Mars, lake breach floods were a really important process globally," said Goudge. "And this is a bit of a surprising result because they've been thought of as one-off anomalies for so long."

The team was able to make this more widescale discovery by using images collected by remote sensing satellites observing Mars which allowed them to study the breached craters.

Mars' Grand Canyon
An image of Loire Vallis, referred to as "the Grand Canyon of Mars." New research suggests that crater breach events like the one that created Loire Vallis may have played a major role in shaping the surface of Mars. GSFC/JPL/ASU./NASA

Although breached lakes had been studied on an individual basis in the past, this was the first time scientists had considered how 234 breached lakes, with a single outlet through which water burst free across Mars, could have worked as a whole to alter the planet's surface.

The researchers found that river valleys formed by crater breaches were significantly deeper than those formed in other forms of water flow. Valleys formed after breaches accounted for about 25 percent of Mars' total river valley volume even though they only account for 3 percent of total valley length.

The team said that the average depth of the breach river valley was around 560 feet, while the depth of valleys formed in other ways was just around 254 feet. This indicates that breach valleys carved out rock and sediment rapidly, while other valleys formed slowly over time.

The formation of river valleys through crater breach could have created canyons deep enough to have had a major knock-on effect on surrounding valleys, too. According to the team, this could mean that the Martian climate had less of an effect on river valley topography across the Red Planet's surface than previously believed.

"It's been known for a while that a few select Martian valleys were formed from lake overflow flooding, but our study is the first global analysis," said paper co-author and Planetary Science Institute research scientist Alexander Morgan in a press release from the organization. "Previous work has argued that differences between valley networks on Mars and river valleys on Earth are evidence that Martian features formed by processes other than surface water, such as groundwater or glacial erosion.

"Our results show that many Martian valleys are in fact more analogous to catastrophic floods on Earth, such as those that shaped the northwest United States at the end of the last glacial period."

A stock image of Mars. New research suggests that billions of years ago floods from burst lakes carved deep valley's into the planet's surface. StockByM/Getty