Floods sculpt the surface of Mars | Astronomy.com

Catastrophic floods

More than 3.5 billion years ago, water flowed freely over the surface of Mars, forming lakes and seas. New research shows that these lakes may have overflowed and burst along their flanks, causing floods so severe that they have dug canyons on the Martian surface in the space of just a few weeks.

This new research suggests that the floods could have shaped and dramatically changed the Martian landscape and, potentially, other planets that also lack plate tectonics, said Tim Goudge, lead author and postdoctoral researcher in a statement.

"These pierced lakes are quite common and some of them are quite large, others of the size of the Caspian Sea. So we think that this type of catastrophic overflow flooding and rapid incision of exit canyons was probably very important on the surface of Mars early on, "Goudge said in his release.

A geological evolution

Today, the Martian surface has more than 200 paleolakes, or ancient lakes that have either shrunk or disappeared with changing conditions. The floods caused by these paleolakes have left many paths dug by the running waters called exit canyons.

For more than 25 years, Goudge said in an email, scientists are aware of these paleolakes and canyons. "These paleolakes have long been one of the most compelling proofs that Mars has known a time during which fluid liquid water has altered the surface," added Goudge. But it is only now, with this study, that scientists have shown that these canyons were quickly cut by single floods instead of being gradually formed.

The researchers came to this conclusion by studying high-resolution photos of Mars taken by NASA's Mars Reconnaissance Orbiter satellite. "By examining the topography of the exit canyons, we were able to show that the size of the outlet is highly correlated with the amount of water that would have been drained from the basin during a flood, which best corresponds to their rapid formation. (in the geological sense) through a single large flood, "said Goudge.

The team is still working to understand how fast and severe these floods have been, "said Goudge. But "some preliminary work suggests [the outlet canyons] can be trained in a few weeks to a few months, "he added.

Mr. Goudge also had some idea of ​​what these catastrophic floods might have looked like: "The floods would have been very rich in sediment, with the risk of moving large rocks far downstream, and they might even have taken the form of something more typical river. "