A canyon system slashing across Mars outscales the Grand Canyon by an order of magnitude and exposes a planet that was once anything but static. Known as Valles Marineris, this fracture zone stretches for thousands of kilometers and dives several kilometers deep, turning the apparent desert into a geological archive.
Valles Marineris formed where the Martian crust was pulled apart under intense tectonic extension, creating rift-like troughs that mirror continental breakups on Earth. Nearby volcanic provinces loaded the lithosphere, altering stress fields and accelerating faulting. The result is a complex of interconnected chasms, landslides, and layered walls that record cycles of uplift, collapse, and sediment transport rather than a single catastrophic event.
Orbital imaging and spectrometry now point to fluvial erosion and possibly subsurface ice as secondary sculptors. Channels feeding into the canyon, hydrated minerals, and stratified deposits indicate that liquid water once moved through parts of the system, assisted by mass wasting and aeolian transport. The canyon’s sheer scale reflects low Martian gravity, thin atmosphere, and long-lived internal heat, which together slowed isostatic rebound and erosion. From orbit, Mars still looks dry and inert; down in Valles Marineris, its crust preserves the entropy increase of a world that once reshaped itself.
