Here are two things you probably never suspected were ever on Mars: active volcanoes and massive glaciers.

In the Tharsis Montes region of Mars–the largest volcanic region on the planet–the slopes of the volcano Arsia Mons look a very specific way. The slopes have scars as if they had once been buried under glaciers that gurgled with lava. Lava and ice implies potential pockets of water, which means life might have been there too. New research confirms the former.

A new analysis published in the July 2014 edition of Icarus found that Arsia Mons’ slopes have all the markings of a meeting between fire and ice. Occurring roughly around 210 million years ago, some of the “englacial lakes” formed could have held volumes of meltwater close to one-third that of Lake Tahoe.

The ripples along the slopes of Arsia Mons show where glaciers likely sat.

To find evidence that the lava from Arsia Mons did in fact meet a glacier, study leader Kat Scanlon of Brown University used data collected from NASA’s Mars Reconnaissance Orbiter. What she found were the same kind of ridges and mounds that form here on Earth when lava flow is restricted by a glacier. She also found evidence of pillow lava, a formation that occurs when lava erupts on the seafloor and is quickly cooled by the surrounding water.

The topography of Arsia Mons. Arsia Mons is twice as tall as Mount Everest, but is only the third tallest on Mars. The tallest Martian volcano is Olympus Mons (cover photo) which reaches 21,229 meters.

By observing the sizes of two specific lava formations, the researchers calculated the potential size of their corresponding englacial lakes. The team estimated that both could have held as much as 40 cubic kilometers of water. Even in the freezing environment of Mars, that much water would have remained in a liquid state for hundreds of years, possibly even thousands of years. This may have been enough time for microbial life to colonize the lakes, providing there was microbial life hanging around Mars to begin with. As always, more research is needed.

HT: Icarus, Phys.org

IMAGES: Olympus mons by NASA, Arsia Mons THEMIS day IR 100m v11.05 0.5 by NASA/JPL-Caltech/Arizona State University, MOLA arsia mons by Power