The Valles Marineris is a system of canyons stretching approximately 4,000 kilometres along the Martian equator - roughly the width of the continental United States. At its deepest it descends around seven kilometres below the surrounding plateau. At its widest it spans 600 kilometres from rim to rim. By comparison, the Grand Canyon is 450 kilometres long, 16 kilometres wide, and 1.8 kilometres deep.
The Valles Marineris was discovered in 1971 when the Mariner 9 spacecraft became the first probe to orbit Mars. It was named in the probe's honour.
How it formed
The formation of the Valles Marineris is not fully understood, but the dominant theory connects it to the Tharsis Bulge - a vast volcanic plateau on the opposite side of Mars. The weight and thermal effects of the Tharsis region are thought to have stretched and fractured the Martian crust, creating the initial rifts. These were then widened by a combination of erosion, slope collapse, and possibly the catastrophic release of subsurface water.
Candor Chasma - one of the widest sections of the system - shows layered sedimentary deposits recording millions of years of geological history. The HiRISE image of Candor Chasma reveals fine bedding planes and erosional patterns that would not look out of place in a geology textbook. They are on a planet 225 million kilometres away.
Why it looks the way it does
Unlike the Grand Canyon, which was carved primarily by a river, the Valles Marineris was not formed by surface water erosion. Mars has no flowing water today and has not had it for billions of years. The canyon's scale comes instead from tectonic forces operating over a planet with no plate tectonics to reset the process - once a feature forms on Mars, it tends to stay.
The result is a canyon so large that it creates its own weather. Temperature differences between the canyon floor and the rim drive daily wind cycles. Dust storms develop inside it and occasionally spread across the planet.
The Axisophy print
The Candor Chasma print from the Radiance collection shows a section of the Valles Marineris system at 25 centimetres per pixel - HiRISE resolution. Individual bedding planes in the canyon walls are visible. The image sits between documentary photography and abstract geology.
