A new study of planetary evidence on Mars suggests that the planet was once home to so-called supervolcanoes more than 30 miles wide. According to Joseph Michalski and Jacob Bleacher of National Geographic, volcanic pools once spread across the red planet "like fuming, open wounds."

Unlike the narrow-tipped volcanoes that the geological term normally brings to mind, these supervolcanoes were allegedly broad, plains of magma more than a mile deep. According to National Geographic, "The closest comparison on Earth might be the broad volcanic caldera beneath Yellowstone National Park, which has erupted three times over the last 2.1 million years."

Evidence suggests that the volcanoes existed at least 3 billion years ago, and the scientists' theory is bolstered by evidence similar to geological remains that calderas on earth leave, as well as regions of Mars covered in sulfur, a typical remnant of volcanic activity.

The scientists who published the report say that the potential discovery was actually incidental:

Michalski was actually studying Martian impact craters, not looking for volcanoes.

"We made the discovery by accident," he said. "As I went through [the images] of this one region, I found a number of them that were simply not impact craters," he said.

"One was clearly a volcano. ... It is quite possible there are many more of these," Michalski added.

While the full study is behind a paywall, Nature did produce a short segment on the calderas.

Back at the start of September, scientists discovered a volcano the size of New Mexico in the Pacific Ocean.