Valles Marineris

Valles Marineris is a huge system of canyons on the planet Mars. It was named after the Mariner 9 spacecraft that first discovered it in 1971–72. This canyon is the largest in our whole Solar System. It stretches for more than 4,000 kilometers, which is about a quarter of Mars's circumference, and it can be up to 7 kilometers deep.

The canyon runs along the equator of Mars, just to the east of a big volcanic area called Tharsis. It starts in a place known as Noctis Labyrinthus and then continues with many sections such as Tithonium, Ius, Melas, Candor, Ophir, Coprates Chasma, Ganges, Capri, and Eos. Finally, it ends in a flat area called Chryse Planitia.

Scientists think Valles Marineris might have started as a big crack in Mars's surface caused by the planet's changing shape. Over time, wind, water, or even lava from nearby volcanoes may have made the canyon even wider and deeper. This amazing feature helps us learn more about the history and geology of Mars.

Formation

Most scientists think Valles Marineris was made by rift faults. Later, wind and water made it bigger. This is similar to how the East African Rift was made. The formation of Valles Marineris is linked to the Tharsis Bulge. The Tharsis Bulge formed from the Noachian to Late Hesperian period of Mars in three steps.

Landslides have left deposits on the floor of Valles Marineris and helped make it wider. Possible reasons for these landslides are quakes from tectonic activity or impacts. Mars has less tectonic activity than Earth, so big quakes are unlikely to have caused these landslides. However, some craters may have formed and caused some of the landslides.

Regions of Valles Marineris

Noctis Labyrinthus sits on the western edge of the Valles Marineris Rift System, north of the Syria Planum and east of Pavonis Mons. This area has a mixed terrain with huge, broken blocks. These blocks have canyons running in many directions and surround larger, older land pieces. The tops of these blocks are made of younger, broken rock from past volcanic activity. The sides of the blocks are made of solid rock. The spaces between the blocks have either rough or smooth ground. The rough ground is likely broken pieces from the walls, while the smooth ground might be from flowing water or lava.

Further east are Ius and Tithonium chasmata, running side by side with Ius to the south and Tithonium to the north. Ius is wider and leads to Melas Chasma, with a central ridge called Geryon Montes made of solid rock. The floor of Ius Chasma is mostly made of landslide material, and its walls have short valleys, much like features near the Grand Canyon. Tithonium Chasma looks similar to Ius but lacks these valley features on its south side and has a small area of smooth ground that seems to be eroded ash.

The next part of Valles Marineris includes three chasmata: Melas, Candor, and Ophir. Melas Chasma’s floor is mostly younger material, likely volcanic ash shaped by wind, mixed with rough material from eroded canyon walls. Between Candor and Melas chasmata, the floor has grooved material, possibly from ancient water or ice, along with layers of volcanic ash.

Coprates Chasma, further east, looks like Ius and Tithonium chasmata but has special layered deposits that might be from old lakes or repeated landslides. Near its deepest point, the canyon could have held a very deep lake before overflowing.

To the east lie Eos and Ganges chasmata. Eos Chasma’s western floor has etched material, possibly from volcanoes or wind, while its eastern end shows bars and lines from ancient flowing water. Ganges Chasma, a branch of Eos, has a floor made of alluvial deposits from its canyon walls.

Finally, Valles Marineris flows into the Chryse region, emptying into the northern plains of Mars. This area has chaotic terrain and outflow channels similar to flood-scarred lands on Earth, suggesting huge floods happened on Mars long ago.