National Geographic Society Newsroom

Whether in Iceland or on Mars, Follow the Water

Bethany Ehlmann is touring with students in Iceland to learn more about the dynamic geological processes that mold and carve our planet in order to gain insight on other planets, particularly Mars. The research that she and her students conduct can tell us more about how other planets work, how they might host life, and how we might one...

Lava beds in Berufjordur, sliced by glaciers to expose millions of years of history. The ocean water in the fjord was so calm we had the perfect reflection off the water. (Photo by Bethany Ehlmann)

Bethany Ehlmann is touring with students in Iceland to learn more about the dynamic geological processes that mold and carve our planet in order to gain insight on other planets, particularly Mars. The research that she and her students conduct can tell us more about how other planets work, how they might host life, and how we might one day colonize them.

We rounded the corner from the north and safely exited the paths of potential jokulhlaups from Bardarbunga, heading first east then south. The track of earthquakes continues to tack away from the volcanic center, moving up a fissure. You can follow the latest reports at the Icelandic Met Office (Update: just as I was sending in this post, Bardarbunga erupted. Not beneath the ice but a small lava burp on land!)

In the meantime: follow the water! It’s been a mantra driving Mars exploration, and it is also interwoven through our explorations. We finished our journey with unique Icelandic minerals and spectacular glacial ice.

First the eastern fjords, one of my personal favorites in Iceland. The car brakes burned—literally, and we had to give the vehicle a rest and walk the remaining kilometer to our accommodation as we navigated hairpin turns, stepping down from the highlands to the coast. Over 10-million years of history is exposed for view in the green cliffs, broken with the occasional waterfall as the landscapes plummet 1,000 meters to sea level. The beds of basaltic lavas tip inward to the center, an effect of the weight of Iceland’s ever-growing lava pile, fed by central fissures.

photo (2)
Zeolites! These aluminosilicate minerals have filled vesicles (cavities where there used to be air bubbles on lava). They indicate the basalt was “cooking” at temperatures between about 50 and 200 degrees Celsius as groundwaters flushed through. (Photo by Bethany Ehlmann)

The lavas here are much older than we’d previously explored with ages of about 9–12 million years. The center of volcanic activity has long since moved away from the relatively “quiet” east. Then, during the last ice age, glaciers carved out the fjords.

But, looking beyond the spectacular scenery with my Mars glasses on, what’s really interesting is what happens to the basalt with time as water and rock react. The landscape has waterfalls and rivers, but much of the action is underground. Waters from rain, snow and ice melt near the surface and penetrate the fractured rock. There’s a temperature gradient, and deeper is hotter as we move toward the Earth’s mantle. Minerals are the thermometer; particular types form at particular temperatures. If you find the mineral, you know what temperature the waters in the basalt were. East Iceland has a peculiar set of minerals—called zeolites—that form deep underground, filling the pores of volcanic rock (vesicles) where there was once nothing but air. The type of zeolite indicates temperature. Depending on what you’ve got, you can pin the temperature to between 50–200 degrees Celsius. And they’re beautiful to boot.

There’s a back story to the zeolites in Iceland for me personally. Back in 2008, we were getting some awesome infrared spectra from Mars that looked to all the world like zeolites. But it was a bit weird as most of the time zeolites are small, far less than the size of your hand, and we were looking at pixels a quarter of the size of a football field. Then I visited east Iceland, where the cliffs are filled with these minerals in the pores. At the scale of football fields. It became pretty clear we were viewing the evidence of heated groundwaters in some spots on Mars, and the zeolite-bearing cliffs of east Iceland were the key piece of the puzzle. It was great to be back.

photo (3)
Icebergs being released collect in the Jokulsarlon lagoon. Iceland’s vast Vatnajokull ice cap sheds into the north Atlantic. (Photo by Bethany Ehlmann)

For new explorations, far more dramatic for most of our crew was our climb up Svinafellsjokull glacier. And, as much as I love zeolites, even I’ll admit it: I’d never strapped on crampons and went up a glacier before. It took a little getting used to—walking sideways on a slope meant pointing one foot downhill. Necessary to get the best grip, it was a little like creating a limp in your walk. But it allowed us to trek about two kilometers into the lower face of the glacier, looking at the changes that took place in the orientation of crevasses and the nature of the ice.

Does Mars have glaciers? Well, it has ice caps. In the first photo images taken by orbiters, the ice wasn’t apparent. But around some of Mars’ ancient volcanic mountains, there were weird features in the first Viking images acquired in the 1970s. The term “lobate debris aprons” was coined to refer to the suggestive flow-like features in what looked like dirt, pasted on the mountain-sides.

Decades later, orbiters with radar around Mars revealed that beneath about a half meter of the debris was several hundred meters of water ice. It’s a relic of a past climate, but probably not that long ago. Just like Iceland’s glaciers formed during the last ice age, Mars too had a recent ice age. Mars tilts on its axis much more wildly than Earth, shifting 10–45 degrees in the space of a few hundreds of thousands of years. And so, like Earth, Mars experiences dramatic ice ages. On Mars and Earth, once the dirt on the glacier gets more than a few inches thick, it acts to insulate the ice, keeping it cold to prevent melting or sublimation. We see on Mars today relics of an icier climate not very much further in the past than Earth’s own ice ages.

And so our journey in Iceland concluded, threading the ridges and fissures of Svinafellsjokull glacier in a mist. Iceland’s a beautiful place, and I encourage anyone who can to enjoy the stark landscape of basalt, waterfalls, hydrothermal waters, and glaciers. When you explore, think about Mars and the geology that binds our two worlds.

Read More by Bethany Ehlmann

About National Geographic Society

The National Geographic Society is a global nonprofit organization that uses the power of science, exploration, education and storytelling to illuminate and protect the wonder of our world. Since 1888, National Geographic has pushed the boundaries of exploration, investing in bold people and transformative ideas, providing more than 14,000 grants for work across all seven continents, reaching 3 million students each year through education offerings, and engaging audiences around the globe through signature experiences, stories and content. To learn more, visit or follow us on Instagram, Twitter and Facebook.

Meet the Author

Bethany Ehlmann
National Geographic Emerging Explorer Bethany Ehlmann is a participating scientist on the NASA Mars Rover Curiosity mission, a research scientist at the Jet Propulsion Laboratory, and assistant professor of planetary science at Caltech. She explores our solar system, seeking to understand its history over billions of years of geologic time and searching for habitable environments for life.