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Mysterious gullies on Mars appear to have been carved by burrowing CO₂ ice blocks
https://phys.org/news/2025-10-mysterious-gullies-mars-burrowing-ice.html
Mars dune with gullies in the Matara crater. The erratic course is probably due to disturbances such as wind ridges in the sand bed, sending the blocks in a different direction each time. Pits at the bottom of the slope mark the end of the process. Credit: Image taken by HiRISE (ESP_030528_1300_RED), NASA/JPL/University of Arizona.
Also see n2doc's "Mysterious New Gully Spotted on Mars" - https://www.democraticunderground.com/122828045
Did life really exist on Mars after all? Unfortunately, there is no conclusive evidence for this yet. Nevertheless, it would seem that some form of life was the driving force behind the mysterious Martian dune gullies. Earth scientist Dr. Lonneke Roelofs from Utrecht University has investigated how these gullies were formed. In a test setup, she observed that blocks of CO2 ice "dug" these gullies in a unique way.
"It felt like I was watching the sandworms in the film Dune," Roelofs says. Her findings are published in Geophysical Research Letters.
Other researchers had previously suspected that these blocks could play a role in the formation of the gullies. Roelofs has now proven this by having CO2 ice blocks actually dig those gullies in an experiment—a phenomenon that we do not know here on Earth and that had never been observed by anyone before.
Sublimation
Ice forms on the dunes during the Martian winter when it is minus 120 degrees Celsius. At the end of winter, the dune slopes heat up and blocks of ice break off, some of which are up to a meter long. Due to the thin atmosphere and the large temperature difference between the warm dune sand and the ice, the bottom side of the ice immediately turns into gas, a process referred to as sublimation. As a kilo of gas requires far more space than the same weight of ice, the ice explodes, so to speak.
"In our simulation, I saw how this high gas pressure blasts away the sand around the block in all directions," says Roelofs. As a result, the block digs itself into the slope and becomes trapped in a hollow surrounded by small ridges of settled sand. "However, the sublimation process continues, and so the sand keeps on being blasted in all directions."
. . .
"It felt like I was watching the sandworms in the film Dune," Roelofs says. Her findings are published in Geophysical Research Letters.
Other researchers had previously suspected that these blocks could play a role in the formation of the gullies. Roelofs has now proven this by having CO2 ice blocks actually dig those gullies in an experiment—a phenomenon that we do not know here on Earth and that had never been observed by anyone before.
Sublimation
Ice forms on the dunes during the Martian winter when it is minus 120 degrees Celsius. At the end of winter, the dune slopes heat up and blocks of ice break off, some of which are up to a meter long. Due to the thin atmosphere and the large temperature difference between the warm dune sand and the ice, the bottom side of the ice immediately turns into gas, a process referred to as sublimation. As a kilo of gas requires far more space than the same weight of ice, the ice explodes, so to speak.
"In our simulation, I saw how this high gas pressure blasts away the sand around the block in all directions," says Roelofs. As a result, the block digs itself into the slope and becomes trapped in a hollow surrounded by small ridges of settled sand. "However, the sublimation process continues, and so the sand keeps on being blasted in all directions."
. . .