A massive valley on Mars may hold some of the strongest evidence yet that enormous floods once rushed across the red planet billions of years ago.
New images from European Space Agency’s Mars Express spacecraft reveal stunning details of Shalbatana Vallis, a giant winding channel near the Martian equator that stretches for about 1,300 kilometers—roughly the length of Italy.
Scientists believe the valley formed around 3.5 billion years ago when huge amounts of underground water suddenly burst onto the surface.
These catastrophic floods carved deep channels into the rocky landscape as the water raced downhill across Mars.
The newly released images were captured by the spacecraft’s High Resolution Stereo Camera, which has been studying Mars since the mission launched in 2003.
The main valley shown in the images is enormous. It is about 10 kilometers wide and roughly 500 meters deep in some places. The channel snakes across the landscape in a gentle, winding pattern that strongly resembles river valleys on Earth.
Researchers think the valley was likely even deeper in the distant past but gradually filled with different materials over time. One dark patch inside the valley may contain volcanic ash that was later spread by Martian winds.
Shalbatana Vallis lies in an especially interesting part of Mars because it marks the boundary between two very different types of terrain. To one side are the heavily cratered southern highlands, which are among the oldest regions on the planet. To the other side are the smoother northern lowlands.
Nearby lies Chryse Planitia, one of the lowest regions on Mars. Many giant flood channels on the planet appear to end there, leading some scientists to suspect that a large ocean may once have existed in the northern lowlands when Mars was warmer and wetter.
The new images also reveal signs of chaotic terrain, one of the strangest landscapes on Mars. Chaotic terrain looks like a jumbled maze of broken blocks, collapsed ground, and rocky mounds.
Scientists believe this terrain may have formed when underground ice melted beneath the surface. As the hidden ice disappeared, the ground above collapsed and cracked apart, creating the chaotic landscape seen today.
The region also contains many impact craters formed by asteroid collisions over billions of years. Some craters remain clearly visible, while others have been partly buried or eroded away over time.
Scientists also spotted wrinkle ridges—raised, folded structures created when ancient lava flows cooled and contracted. This suggests volcanic activity once covered parts of the region with lava after the floods occurred.
Scattered flat-topped hills called mesas can also be seen rising above the landscape. These are thought to be remnants of an older surface that has slowly worn away through erosion.
For more than two decades, Mars Express has been helping scientists better understand the history of Mars by mapping the planet in color and in three dimensions. The mission has revealed evidence of ancient water, volcanoes, ice, and changing climates, transforming our understanding of what Mars may once have looked like long ago.
Source: European Space Agency.
