Billions of years ago, the surface of Mars was dotted with massive lakes created when impact craters slowly filled with water. Eventually, many of the lakes burst their bounds, leading to catastrophic floods that gouged canyons into the surrounding landscape.
These short but deep channels may have played an unexpectedly important role in shaping the Red Planet’s topography, scientists reported this week in Nature. The researchers compared satellite imagery of valleys created by overflowing craters and more gradual river erosion across Mars and found that canyons associated with crater lakes accounted for nearly a quarter of the total volume of the valleys. The findings highlight key differences in the processes that have influenced the landscapes of Earth and Mars and have implications for understanding our neighbor’s past habitability.
“They aren’t just one-offs that we can mostly ignore at a global scale,” Timothy Goudge, a planetary scientist at the University of Texas at Austin and co-author of the study. “Recognizing that this is a global process helps inform the way we should think about how Mars’s surface evolved.”
During early, soggier chapters of Mars’s history, crater lakes could reach hundreds of kilometers across, comparable in size to small Earthly seas such as the Caspian. Many of these lakes ultimately became so full that water would spill over the rim of the crater, wearing it down and allowing still more water to escape. In other cases, the flooding began when the immense pressure from all the water stored in the crater ruptured the rim.