You Can See the Spot Where Lava Broke Through the Wall of a Martian Crater and Began Filling it Up

At a fundamental level, Mars is a volcanic planet. Its surface is home to the Solar System’s largest extinct volcano, Olympus Mons, and another trio of well-known volcanoes at Tharsis Montes. And those are just the highlights: there are many other volcanoes on the surface. Though that volcanic activity ceased long ago, the planet’s surface tells the tale of a world disrupted and shaped by powerful volcanic eruptions.

It’s difficult to imagine what Mars would’ve been like when Olympus Mons was active. The same goes for the Tharsis Montes trio. We may never know, but thanks to HiRISE, we can try to piece together some of the volcanic events that shaped Mars.

Olympus Mons and Tharsis Montes were the headliners in Mars’ ancient volcanic drama, and we learned of their existence first, thanks largely to NASA’s Mariner 9 spacecraft. In fact, they were spotted by ground observers long before that because they were visible when they protruded above global dust storms. But the surface of Mars is also dotted with other evidence of volcanism.

There are massive lava flows and extensive lava plains on the planet. In fact, about half of Mars’ surface is covered in volcanic material, though much of it has been further shaped by other processes over time. Most scientists think that the volcanic activity ended about 500 million years ago, while some think the planet may still be somewhat active.

Recently, the HiRISE (High-Resolution Imaging Science Experiment) team released images of a crater on Mars shaped by ancient lava flows. The crater has a clearly-visible channel through the rim where lava flowed. A short narrated video explains some of what happened and some of the questions scientists have around the feature.

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