A colored topographical image showing river valleys on Mars. The outlet canyon Loire Vallis (white line) formed from the overflow of a lake in Parana Basin (outlined in white). Black lines indicate other river valleys formed by processes other than lake overflows. Background is colored Mars Orbiter Laser Altimeter-derived topography over a Thermal Emission Imaging System image mosaic. Image is approximately 650 kilometers across. Credit: NASA/GSFC/ JPL ASU
On Earth, river erosion is usually a slow-going process. But on 
The remains of a former crater lake on Mars surrounded by other smaller craters. The large outlet canyon in the upper left formed during a crater breach event. Credit: Goudge et al.
Crater lakes were common on Mars billions of years ago when the Red Planet had liquid water on its surface. Some craters could hold a small sea’s worth of water. But 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 Goudge determined that these events happened rapidly.
Remote sensing 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, Goudge said. This is the first study to investigate how the 262 breached lakes across the Red Planet shaped the Martian surface as a whole.
The research entailed reviewing a preexisting catalog of river valleys on Mars and classifying the valleys into two categories: valleys that got their start at a crater’s edge, which indicates they formed during a lake breach flood, and valleys that formed elsewhere on the landscape, which suggests a more gradual formation over time.
A global map of Mars showing river valleys around the Red Planet. River valleys formed by crater lake breaches are in white. River valleys that formed gradually over time are in black. Credit: Goudge et al.
From there, the scientists compared the depth, length, and volume of the different valley types and found that river valleys…
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