Within certain Martian dune formations, features known as linear dune gullies are observed. Despite their name, these chasms frequently exhibit a highly serpentine course. Previously, the prevailing hypothesis attributed their genesis to debris flow events facilitated by liquid water. However, contemporary analysis of orbital imagery reveals their active formation during the local spring season, driven by a process involving carbon dioxide ice. This ice coalesces on Martian dunes during the Martian winter and detaches from the dune crests at the onset of spring. Through novel laboratory simulations conducted within a Mars-simulating chamber, planetary scientists affiliated with Utrecht University, Le Mans Université, Nantes Université, Institut de Planétologie et d’Astrophysique de Grenoble, and The Open University have demonstrated that linear dune gullies originate from blocs of carbon dioxide ice. These icy masses either slide or burrow into the sandy inclines of the dunes, propelling themselves downslope by forcefully expelling the surrounding granular material. This erosive mechanism is propelled by potent gas currents generated by the sublimation of the carbon dioxide ice as it transitions into gaseous carbon dioxide. Whereas sliding blocks of carbon dioxide ice account for the superficial channels, burrowing carbon dioxide ice is responsible for the excavation of the profound, sinuous ravines on the Martian dunes.
Two examples of Martian dunes with linear dune gullies: (a) linear dune gullies on a dune field in Galle crater; (b) linear dune gullies on a dune field in an unnamed crater in the center of Hellas Planitia. Image credit: Roelofs et al., doi: 10.1029/2024GL112860.
Linear dune gullies represent distinctive and intriguing geological formations situated on dune fields within the mid-latitudes of the planet Mars.
These parallel channels, which frequently deviate from their eponymous description to exhibit pronounced sinuosity, are characterized by sharp bends, confined origin points, well-defined marginal embankments, and terminal depressions, and lack terrestrial counterparts.
They are differentiated from the archetypal gully landforms observed on steep Martian and terrestrial slopes. These classical gullies comprise an erosional alcove, a channel, and a depositional apron, and generally surpass linear dune gullies in scale.
“Our experimental simulations vividly illustrated the phenomenon of high gas pressure forcefully expelling sand from the vicinity of the ice block in all directions,” remarked Lonneke Roelofs, a researcher at Utrecht University and the principal author of the investigation.
“Consequently, the ice block excavates its way into the slope, becoming lodged within a depression demarcated by nascent ridges of deposited sand.”
“The sublimation process, however, persists, leading to a continuous outward projection of sand.”
“Through this ongoing mechanism, the ice block gradually descends, leaving behind an elongated, deep gully flanked by subtle sand formations on either side.”
“This precisely mirrors the morphology of gullies identified on the Red Planet.”
In their scholarly pursuit, Dr. Roelofs and her esteemed colleagues synthesized laboratory investigations, which involved deploying blocks of carbon dioxide ice onto sandy inclines under Martian atmospheric conditions, with direct observations of linear dune gullies on the extensive dune formations within Russell crater.
“We explored a range of parameters by replicating dune slopes with varying degrees of steepness,”
“The carbon dioxide ice block was released from the apex of the slope, and its subsequent behavior was meticulously documented.”
“Upon identifying the optimal slope inclination, definitive results were achieved. The carbon dioxide ice block initiated a downward traversal into the slope, behaving analogously to a subterranean mole or the formidable sandworms depicted in the fictional narrative ‘Dune.’ The process was remarkably visually striking.”
“But how, precisely, do these icy formations originate? The blocks of carbon dioxide ice develop on the desert dunes situated in the central regions of Mars’ southern hemisphere.”
“During the winter months, a stratum of carbon dioxide ice blankets the entirety of the dune field, sometimes reaching a thickness of up to 70 centimeters! With the advent of spring, this ice begins to warm and sublimate.”
“The residual segments of this ice are concentrated on the shaded aspects of the dune crests, and it is from these locations that the blocks detach when ambient temperatures ascend sufficiently.”
“Upon reaching the base of the slope and ceasing their movement, the ice continues its sublimation until all carbon dioxide has dissipated. The residual feature is a void within the sand at the dune’s foot.”
This groundbreaking research was officially disseminated on October 8 in the esteemed journal Geophysical Research Letters.
_____
Lonneke Roelofs et al. 2025. Sliding and Burrowing Blocks of CO2 Create Sinuous ‘Linear Dune Gullies’ on Martian Dunes by Explosive Sublimation-Induced Particle Transport. Geophysical Research Letters 52 (19): e2024GL112860; doi: 10.1029/2024GL112860
